fragment_internal_test.go

// Copyright 2017 Pilosa Corp.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pilosa

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"math"
	"math/rand"
	"os"
	"reflect"
	"sort"
	"sync/atomic"
	"testing"
	"testing/quick"

	"golang.org/x/sync/errgroup"

	"github.com/davecgh/go-spew/spew"
	"github.com/pilosa/pilosa/v2/pql"
	"github.com/pilosa/pilosa/v2/roaring"
	"github.com/pkg/errors"
)

// Test flags
var (
	// In order to generate the sample fragment file,
	// run an import and copy PILOSA_DATA_DIR/INDEX_NAME/FRAME_NAME/0 to testdata/sample_view
	FragmentPath = flag.String("fragment", "testdata/sample_view/0", "fragment path")

	TempDir = flag.String("temp-dir", "", "Directory in which to place temporary data (e.g. for benchmarking). Useful if you are trying to benchmark different storage configurations.")
)

// Ensure a fragment can set a bit and retrieve it.
func TestFragment_SetBit(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set bits on the fragment.
	if _, err := f.setBit(120, 1); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(120, 6); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(121, 0); err != nil {
		t.Fatal(err)
	}

	// Verify counts on rows.
	if n := f.row(120).Count(); n != 2 {
		t.Fatalf("unexpected count: %d", n)
	} else if n := f.row(121).Count(); n != 1 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(120).Count(); n != 2 {
		t.Fatalf("unexpected count (reopen): %d", n)
	} else if n := f.row(121).Count(); n != 1 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// Ensure a fragment can clear a set bit.
func TestFragment_ClearBit(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set and then clear bits on the fragment.
	if _, err := f.setBit(1000, 1); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(1000, 2); err != nil {
		t.Fatal(err)
	} else if _, err := f.clearBit(1000, 1); err != nil {
		t.Fatal(err)
	}

	// Verify count on row.
	if n := f.row(1000).Count(); n != 1 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 1 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// What about rowcache timing.
func TestFragment_RowcacheMap(t *testing.T) {
	var done int64
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	ch := make(chan struct{})

	for i := 0; i < f.MaxOpN; i++ {
		_, _ = f.setBit(0, uint64(i*32))
	}
	// force snapshot so we get a mmapped row...
	_ = f.Snapshot()
	row := f.row(0)
	segment := row.Segments()[0]
	bitmap := segment.data

	// request information from the frozen bitmap we got back
	go func() {
		for atomic.LoadInt64(&done) == 0 {
			for i := 0; i < f.MaxOpN; i++ {
				_ = bitmap.Contains(uint64(i * 32))
			}
		}
		close(ch)
	}()

	// modify the original bitmap, until it causes a snapshot, which
	// then invalidates the other map...
	for j := 0; j < 5; j++ {
		for i := 0; i < f.MaxOpN; i++ {
			_, _ = f.setBit(0, uint64(i*32+j+1))
		}
	}
	atomic.StoreInt64(&done, 1)
	<-ch
}

// Ensure a fragment can clear a row.
func TestFragment_ClearRow(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set and then clear bits on the fragment.
	if _, err := f.setBit(1000, 1); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(1000, 65536); err != nil {
		t.Fatal(err)
	} else if _, err := f.unprotectedClearRow(1000); err != nil {
		t.Fatal(err)
	}

	// Verify count on row.
	if n := f.row(1000).Count(); n != 0 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 0 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// Ensure a fragment can set a row.
func TestFragment_SetRow(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 7, "")
	defer f.Clean(t)

	rowID := uint64(1000)

	// Set bits on the fragment.
	if _, err := f.setBit(rowID, 7*ShardWidth+1); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(rowID, 7*ShardWidth+65536); err != nil {
		t.Fatal(err)
	}

	// Verify data on row.
	if cols := f.row(rowID).Columns(); !reflect.DeepEqual(cols, []uint64{7*ShardWidth + 1, 7*ShardWidth + 65536}) {
		t.Fatalf("unexpected columns: %+v", cols)
	}
	// Verify count on row.
	if n := f.row(rowID).Count(); n != 2 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Set row (overwrite existing data).
	row := NewRow(7*ShardWidth+1, 7*ShardWidth+65537, 7*ShardWidth+140000)
	if changed, err := f.unprotectedSetRow(row, rowID); err != nil {
		t.Fatal(err)
	} else if !changed {
		t.Fatalf("expected changed value: %v", changed)
	}

	// Verify data on row.
	if cols := f.row(rowID).Columns(); !reflect.DeepEqual(cols, []uint64{7*ShardWidth + 1, 7*ShardWidth + 65537, 7*ShardWidth + 140000}) {
		t.Fatalf("unexpected columns after set row: %+v", cols)
	}
	// Verify count on row.
	if n := f.row(rowID).Count(); n != 3 {
		t.Fatalf("unexpected count after set row: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(rowID).Count(); n != 3 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// Ensure a fragment can set & read a value.
func TestFragment_SetValue(t *testing.T) {
	t.Run("OK", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set value.
		if changed, err := f.setValue(100, 16, 3829); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Read value.
		if value, exists, err := f.value(100, 16); err != nil {
			t.Fatal(err)
		} else if value != 3829 {
			t.Fatalf("unexpected value: %d", value)
		} else if !exists {
			t.Fatal("expected to exist")
		}

		// Setting value should return no change.
		if changed, err := f.setValue(100, 16, 3829); err != nil {
			t.Fatal(err)
		} else if changed {
			t.Fatal("expected no change")
		}
	})

	t.Run("Overwrite", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set value.
		if changed, err := f.setValue(100, 16, 3829); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Overwriting value should overwrite all bits.
		if changed, err := f.setValue(100, 16, 2028); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Read value.
		if value, exists, err := f.value(100, 16); err != nil {
			t.Fatal(err)
		} else if value != 2028 {
			t.Fatalf("unexpected value: %d", value)
		} else if !exists {
			t.Fatal("expected to exist")
		}
	})

	t.Run("Clear", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set value.
		if changed, err := f.setValue(100, 16, 3829); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Clear value should overwrite all bits, and set not-null to 0.
		if changed, err := f.clearValue(100, 16, 2028); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Read value.
		if value, exists, err := f.value(100, 16); err != nil {
			t.Fatal(err)
		} else if value != 0 {
			t.Fatalf("unexpected value: %d", value)
		} else if exists {
			t.Fatal("expected to not exist")
		}
	})

	t.Run("NotExists", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set value.
		if changed, err := f.setValue(100, 10, 20); err != nil {
			t.Fatal(err)
		} else if !changed {
			t.Fatal("expected change")
		}

		// Non-existent value.
		if value, exists, err := f.value(101, 11); err != nil {
			t.Fatal(err)
		} else if value != 0 {
			t.Fatalf("unexpected value: %d", value)
		} else if exists {
			t.Fatal("expected to not exist")
		}
	})

	t.Run("QuickCheck", func(t *testing.T) {
		if err := quick.Check(func(bitDepth uint, bitN uint64, values []uint64) bool {
			// Limit bit depth & maximum values.
			bitDepth = (bitDepth % 62) + 1
			bitN = (bitN % 99) + 1

			for i := range values {
				values[i] = values[i] % (1 << bitDepth)
			}

			f := mustOpenFragment("i", "f", viewStandard, 0, "")
			defer f.Clean(t)

			// Set values.
			m := make(map[uint64]int64)
			for _, value := range values {
				columnID := value % bitN

				m[columnID] = int64(value)

				if _, err := f.setValue(columnID, bitDepth, int64(value)); err != nil {
					t.Fatal(err)
				}
			}

			// Ensure values are set.
			for columnID, value := range m {
				v, exists, err := f.value(columnID, bitDepth)
				if err != nil {
					t.Fatal(err)
				} else if value != int64(v) {
					t.Fatalf("value mismatch: columnID=%d, bitdepth=%d, value: %d != %d", columnID, bitDepth, value, v)
				} else if !exists {
					t.Fatalf("value should exist: columnID=%d", columnID)
				}
			}

			return true
		}, nil); err != nil {
			t.Fatal(err)
		}
	})
}

// Ensure a fragment can sum values.
func TestFragment_Sum(t *testing.T) {
	const bitDepth = 16

	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set values.
	if _, err := f.setValue(1000, bitDepth, 382); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(3000, bitDepth, 2818); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(4000, bitDepth, 300); err != nil {
		t.Fatal(err)
	}

	t.Run("NoFilter", func(t *testing.T) {
		if sum, n, err := f.sum(nil, bitDepth); err != nil {
			t.Fatal(err)
		} else if n != 4 {
			t.Fatalf("unexpected count: %d", n)
		} else if sum != 3800 {
			t.Fatalf("unexpected sum: %d", sum)
		}
	})

	t.Run("WithFilter", func(t *testing.T) {
		if sum, n, err := f.sum(NewRow(2000, 4000, 5000), bitDepth); err != nil {
			t.Fatal(err)
		} else if n != 2 {
			t.Fatalf("unexpected count: %d", n)
		} else if sum != 600 {
			t.Fatalf("unexpected sum: %d", sum)
		}
	})

	// verify that clearValue clears values
	if _, err := f.clearValue(1000, bitDepth, 23); err != nil {
		t.Fatal(err)
	}
	t.Run("ClearValue", func(t *testing.T) {
		if sum, n, err := f.sum(nil, bitDepth); err != nil {
			t.Fatal(err)
		} else if n != 3 {
			t.Fatalf("unexpected count: %d", n)
		} else if sum != (3800 - 382) {
			t.Fatalf("unexpected sum: got %d, expecting %d", sum, 3800-382)
		}
	})
}

// Ensure a fragment can find the min and max of values.
func TestFragment_MinMax(t *testing.T) {
	const bitDepth = 16

	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set values.
	if _, err := f.setValue(1000, bitDepth, 382); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(3000, bitDepth, 2818); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(4000, bitDepth, 300); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(5000, bitDepth, 2818); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(6000, bitDepth, 2817); err != nil {
		t.Fatal(err)
	} else if _, err := f.setValue(7000, bitDepth, 0); err != nil {
		t.Fatal(err)
	}

	t.Run("Min", func(t *testing.T) {
		tests := []struct {
			filter *Row
			exp    int64
			cnt    uint64
		}{
			{filter: nil, exp: 0, cnt: 1},
			{filter: NewRow(2000, 4000, 5000), exp: 300, cnt: 2},
			{filter: NewRow(2000, 4000), exp: 300, cnt: 2},
			{filter: NewRow(1), exp: 0, cnt: 0},
			{filter: NewRow(1000), exp: 382, cnt: 1},
			{filter: NewRow(7000), exp: 0, cnt: 1},
		}
		for i, test := range tests {
			if min, cnt, err := f.min(test.filter, bitDepth); err != nil {
				t.Fatal(err)
			} else if min != test.exp {
				t.Errorf("test %d expected min: %v, but got: %v", i, test.exp, min)
			} else if cnt != test.cnt {
				t.Errorf("test %d expected cnt: %v, but got: %v", i, test.cnt, cnt)
			}
		}
	})

	t.Run("Max", func(t *testing.T) {
		tests := []struct {
			filter *Row
			exp    int64
			cnt    uint64
		}{
			{filter: nil, exp: 2818, cnt: 2},
			{filter: NewRow(2000, 4000, 5000), exp: 2818, cnt: 1},
			{filter: NewRow(2000, 4000), exp: 300, cnt: 2},
			{filter: NewRow(1), exp: 0, cnt: 0},
			{filter: NewRow(1000), exp: 382, cnt: 1},
			{filter: NewRow(7000), exp: 0, cnt: 1},
		}
		for i, test := range tests {
			var columns []uint64
			if test.filter != nil {
				columns = test.filter.Columns()
			}

			if max, cnt, err := f.max(test.filter, bitDepth); err != nil {
				t.Fatal(err)
			} else if max != test.exp || cnt != test.cnt {
				t.Errorf("%d. max(%v, %v)=(%v, %v), expected (%v, %v)", i, columns, bitDepth, max, cnt, test.exp, test.cnt)
			}
		}
	})
}

// Ensure a fragment query for matching values.
func TestFragment_Range(t *testing.T) {
	const bitDepth = 16

	t.Run("EQ", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set values.
		if _, err := f.setValue(1000, bitDepth, 382); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(3000, bitDepth, 2818); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(4000, bitDepth, 300); err != nil {
			t.Fatal(err)
		}

		// Query for equality.
		if b, err := f.rangeOp(pql.EQ, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{2000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}
	})

	t.Run("NEQ", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set values.
		if _, err := f.setValue(1000, bitDepth, 382); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(3000, bitDepth, 2818); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(4000, bitDepth, 300); err != nil {
			t.Fatal(err)
		}

		// Query for inequality.
		if b, err := f.rangeOp(pql.NEQ, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 3000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}
	})

	t.Run("LT", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set values.
		if _, err := f.setValue(1000, bitDepth, 382); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(3000, bitDepth, 2817); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(4000, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(5000, bitDepth, 1); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(6000, bitDepth, 0); err != nil {
			t.Fatal(err)
		}

		// Query for values less than (ending with set column).
		if b, err := f.rangeOp(pql.LT, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{2000, 5000, 6000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values less than (ending with unset column).
		if b, err := f.rangeOp(pql.LT, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{5000, 6000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values less than or equal to (ending with set column).
		if b, err := f.rangeOp(pql.LTE, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{2000, 4000, 5000, 6000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values less than or equal to (ending with unset column).
		if b, err := f.rangeOp(pql.LTE, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{2000, 5000, 6000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}
	})

	t.Run("GT", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set values.
		if _, err := f.setValue(1000, bitDepth, 382); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(3000, bitDepth, 2817); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(4000, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(5000, bitDepth, 1); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(6000, bitDepth, 0); err != nil {
			t.Fatal(err)
		}

		// Query for values greater than (ending with unset bit).
		if b, err := f.rangeOp(pql.GT, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 3000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than (ending with set bit).
		if b, err := f.rangeOp(pql.GT, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 3000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than or equal to (ending with unset bit).
		if b, err := f.rangeOp(pql.GTE, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 2000, 3000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than or equal to (ending with set bit).
		if b, err := f.rangeOp(pql.GTE, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 3000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}
	})

	t.Run("BETWEEN", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		// Set values.
		if _, err := f.setValue(1000, bitDepth, 382); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(2000, bitDepth, 300); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(3000, bitDepth, 2817); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(4000, bitDepth, 301); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(5000, bitDepth, 1); err != nil {
			t.Fatal(err)
		} else if _, err := f.setValue(6000, bitDepth, 0); err != nil {
			t.Fatal(err)
		}

		// Query for values greater than (ending with unset column).
		if b, err := f.rangeBetween(bitDepth, 300, 2817); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 2000, 3000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than (ending with set column).
		if b, err := f.rangeBetween(bitDepth, 301, 2817); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 3000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than or equal to (ending with unset column).
		if b, err := f.rangeBetween(bitDepth, 301, 2816); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}

		// Query for values greater than or equal to (ending with set column).
		if b, err := f.rangeBetween(bitDepth, 300, 2816); err != nil {
			t.Fatal(err)
		} else if !reflect.DeepEqual(b.Columns(), []uint64{1000, 2000, 4000}) {
			t.Fatalf("unexpected columns: %+v", b.Columns())
		}
	})
}

// benchmarkSetValues is a helper function to explore, very roughly, the cost
// of setting values.
func benchmarkSetValues(b *testing.B, bitDepth uint, f *fragment, cfunc func(uint64) uint64) {
	column := uint64(0)
	for i := 0; i < b.N; i++ {
		// We're not checking the error because this is a benchmark.
		// That does mean the result could be completely wrong...
		_, _ = f.setValue(column, bitDepth, int64(i))
		column = cfunc(column)
	}
}

// Benchmark performance of setValue for BSI ranges.
func BenchmarkFragment_SetValue(b *testing.B) {
	depths := []uint{4, 8, 16}
	for _, bitDepth := range depths {
		name := fmt.Sprintf("Depth%d", bitDepth)
		f := mustOpenFragment("i", "f", viewBSIGroupPrefix+"foo", 0, "none")
		b.Run(name+"_Sparse", func(b *testing.B) {
			benchmarkSetValues(b, bitDepth, f, func(u uint64) uint64 { return (u + 70000) & (ShardWidth - 1) })
		})
		f.Clean(b)
		f = mustOpenFragment("i", "f", viewBSIGroupPrefix+"foo", 0, "none")
		b.Run(name+"_Dense", func(b *testing.B) {
			benchmarkSetValues(b, bitDepth, f, func(u uint64) uint64 { return (u + 1) & (ShardWidth - 1) })
		})
		f.Clean(b)
	}
}

// benchmarkImportValues is a helper function to explore, very roughly, the cost
// of setting values using the special setter used for imports.
func benchmarkImportValues(b *testing.B, bitDepth uint, f *fragment, cfunc func(uint64) uint64) {
	column := uint64(0)
	b.StopTimer()
	columns := make([]uint64, b.N)
	values := make([]int64, b.N)
	for i := 0; i < b.N; i++ {
		values[i] = int64(i)
		columns[i] = column
		column = cfunc(column)
	}
	b.StartTimer()
	err := f.importValue(columns, values, bitDepth, false)
	if err != nil {
		b.Fatalf("error importing values: %s", err)
	}
}

// Benchmark performance of setValue for BSI ranges.
func BenchmarkFragment_ImportValue(b *testing.B) {
	depths := []uint{4, 8, 16}
	for _, bitDepth := range depths {
		name := fmt.Sprintf("Depth%d", bitDepth)
		f := mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
		b.Run(name+"_Sparse", func(b *testing.B) {
			benchmarkImportValues(b, bitDepth, f, func(u uint64) uint64 { return (u + 70000) & (ShardWidth - 1) })
		})
		f.Clean(b)
		f = mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
		b.Run(name+"_Dense", func(b *testing.B) {
			benchmarkImportValues(b, bitDepth, f, func(u uint64) uint64 { return (u + 1) & (ShardWidth - 1) })
		})
		f.Clean(b)
	}
}

// BenchmarkFragment_RepeatedSmallImports tests the situation where updates are
// constantly coming in across a large column space so that each fragment gets
// only a few updates during each import.
//
// We test a variety of combinations of the number of separate updates(imports),
// the number of bits in the import, the number of rows in the fragment (which
// is a pretty good proxy for fragment size on disk), and the MaxOpN on the
// fragment which controls how many set bits occur before a snapshot is done. If
// the number of bits in a given import is greater than MaxOpN, bulkImport will
// always go through the standard snapshotting import path.
func BenchmarkFragment_RepeatedSmallImports(b *testing.B) {
	for _, numUpdates := range []int{100} {
		for _, bitsPerUpdate := range []int{100, 1000} {
			for _, numRows := range []int{1000, 100000, 1000000} {
				for _, opN := range []int{1, 5000, 50000} {
					b.Run(fmt.Sprintf("Rows%dUpdates%dBits%dOpN%d", numRows, numUpdates, bitsPerUpdate, opN), func(b *testing.B) {
						for a := 0; a < b.N; a++ {
							b.StopTimer()
							// build the update data set all at once - this will get applied
							// to a fragment in numUpdates batches
							updateRows := make([]uint64, numUpdates*bitsPerUpdate)
							updateCols := make([]uint64, numUpdates*bitsPerUpdate)
							for i := 0; i < numUpdates*bitsPerUpdate; i++ {
								updateRows[i] = uint64(rand.Int63n(int64(numRows))) // row id
								updateCols[i] = uint64(rand.Int63n(ShardWidth))     // column id
							}
							f := mustOpenFragment("i", "f", viewStandard, 0, "")
							f.MaxOpN = opN
							defer f.Clean(b)
							err := f.importRoaringT(getZipfRowsSliceRoaring(uint64(numRows), 1, 0, ShardWidth), false)
							if err != nil {
								b.Fatalf("importing base data for benchmark: %v", err)
							}
							b.StartTimer()
							for i := 0; i < numUpdates; i++ {
								err := f.bulkImportStandard(
									updateRows[bitsPerUpdate*i:bitsPerUpdate*(i+1)],
									updateRows[bitsPerUpdate*i:bitsPerUpdate*(i+1)],
									&ImportOptions{},
								)
								if err != nil {
									b.Fatalf("doing small bulk import: %v", err)
								}
							}
						}
					})
				}
			}
		}
	}
}

func BenchmarkFragment_RepeatedSmallImportsRoaring(b *testing.B) {
	for _, numUpdates := range []int{100} {
		for _, bitsPerUpdate := range []uint64{100, 1000} {
			for _, numRows := range []uint64{1000, 100000, 1000000} {
				for _, opN := range []int{1, 5000, 50000} {
					b.Run(fmt.Sprintf("Rows%dUpdates%dBits%dOpN%d", numRows, numUpdates, bitsPerUpdate, opN), func(b *testing.B) {
						for a := 0; a < b.N; a++ {
							b.StopTimer()
							// build the update data set all at once - this will get applied
							// to a fragment in numUpdates batches
							f := mustOpenFragment("i", "f", viewStandard, 0, "")
							f.MaxOpN = opN
							defer f.Clean(b)
							err := f.importRoaringT(getZipfRowsSliceRoaring(numRows, 1, 0, ShardWidth), false)
							if err != nil {
								b.Fatalf("importing base data for benchmark: %v", err)
							}
							for i := 0; i < numUpdates; i++ {
								data := getUpdataRoaring(numRows, bitsPerUpdate, int64(i))
								b.StartTimer()
								err := f.importRoaringT(data, false)
								b.StopTimer()
								if err != nil {
									b.Fatalf("doing small roaring import: %v", err)
								}
							}
						}
					})
				}
			}
		}
	}
}

func BenchmarkFragment_RepeatedSmallValueImports(b *testing.B) {
	initialCols := make([]uint64, 0, ShardWidth)
	initialVals := make([]int64, 0, ShardWidth)
	for i := uint64(0); i < ShardWidth; i++ {
		// every 29 columns, skip between 0 and 12 columns
		if i%29 == 0 {
			i += i % 13
		}
		initialCols = append(initialCols, i)
		initialVals = append(initialVals, int64(rand.Int63n(1<<21)))
	}

	for _, numUpdates := range []int{100} {
		for _, valsPerUpdate := range []int{10, 100} {
			updateCols := make([]uint64, numUpdates*valsPerUpdate)
			updateVals := make([]int64, numUpdates*valsPerUpdate)
			for i := 0; i < numUpdates*valsPerUpdate; i++ {
				updateCols[i] = uint64(rand.Int63n(ShardWidth))
				updateVals[i] = int64(rand.Int63n(1 << 21))
			}

			for _, opN := range []int{1, 5000, 50000} {
				b.Run(fmt.Sprintf("Updates%dVals%dOpN%d", numUpdates, valsPerUpdate, opN), func(b *testing.B) {
					for i := 0; i < b.N; i++ {
						b.StopTimer()
						f := mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
						f.MaxOpN = opN
						err := f.importValue(initialCols, initialVals, 21, false)
						if err != nil {
							b.Fatalf("initial value import: %v", err)
						}
						b.StartTimer()
						for j := 0; j < numUpdates; j++ {
							err := f.importValue(
								updateCols[valsPerUpdate*j:valsPerUpdate*(j+1)],
								updateVals[valsPerUpdate*j:valsPerUpdate*(j+1)],
								21,
								false,
							)
							if err != nil {
								b.Fatalf("importing values: %v", err)
							}
						}
					}
				})
			}

		}
	}
}

// Ensure a fragment can snapshot correctly.
func TestFragment_Snapshot(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set and then clear bits on the fragment.
	if _, err := f.setBit(1000, 1); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(1000, 2); err != nil {
		t.Fatal(err)
	} else if _, err := f.clearBit(1000, 1); err != nil {
		t.Fatal(err)
	}

	// Snapshot bitmap and verify data.
	if err := f.Snapshot(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 1 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 1 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// Ensure a fragment can iterate over all bits in order.
func TestFragment_ForEachBit(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set bits on the fragment.
	if _, err := f.setBit(100, 20); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(2, 38); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(2, 37); err != nil {
		t.Fatal(err)
	}

	// Iterate over bits.
	var result [][2]uint64
	if err := f.forEachBit(func(rowID, columnID uint64) error {
		result = append(result, [2]uint64{rowID, columnID})
		return nil
	}); err != nil {
		t.Fatal(err)
	}

	// Verify bits are correct.
	if !reflect.DeepEqual(result, [][2]uint64{{2, 37}, {2, 38}, {100, 20}}) {
		t.Fatalf("unexpected result: %#v", result)
	}
}

// Ensure a fragment can return the top n results.
func TestFragment_Top(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)
	// Set bits on the rows 100, 101, & 102.
	f.mustSetBits(100, 1, 3, 200)
	f.mustSetBits(101, 1)
	f.mustSetBits(102, 1, 2)
	f.RecalculateCache()

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{N: 2}); err != nil {
		t.Fatal(err)
	} else if len(pairs) != 2 {
		t.Fatalf("unexpected count: %d", len(pairs))
	} else if pairs[0] != (Pair{ID: 100, Count: 3}) {
		t.Fatalf("unexpected pair(0): %v", pairs[0])
	} else if pairs[1] != (Pair{ID: 102, Count: 2}) {
		t.Fatalf("unexpected pair(1): %v", pairs[1])
	}
}

// Ensure a fragment can filter rows when retrieving the top n rows.
func TestFragment_Top_Filter(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	// Set bits on the rows 100, 101, & 102.
	f.mustSetBits(100, 1, 3, 200)
	f.mustSetBits(101, 1)
	f.mustSetBits(102, 1, 2)
	f.RecalculateCache()
	// Assign attributes.
	err := f.RowAttrStore.SetAttrs(101, map[string]interface{}{"x": int64(10)})
	if err != nil {
		t.Fatalf("setAttrs: %v", err)
	}
	err = f.RowAttrStore.SetAttrs(102, map[string]interface{}{"x": int64(20)})
	if err != nil {
		t.Fatalf("setAttrs: %v", err)
	}

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{
		N:            2,
		FilterName:   "x",
		FilterValues: []interface{}{int64(10), int64(15), int64(20)},
	}); err != nil {
		t.Fatal(err)
	} else if len(pairs) != 2 {
		t.Fatalf("unexpected count: %d", len(pairs))
	} else if pairs[0] != (Pair{ID: 102, Count: 2}) {
		t.Fatalf("unexpected pair(0): %v", pairs[0])
	} else if pairs[1] != (Pair{ID: 101, Count: 1}) {
		t.Fatalf("unexpected pair(1): %v", pairs[1])
	}
}

// Ensure a fragment can return top rows that intersect with an input row.
func TestFragment_TopN_Intersect(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	// Create an intersecting input row.
	src := NewRow(1, 2, 3)

	// Set bits on various rows.
	f.mustSetBits(100, 1, 10, 11, 12)    // one intersection
	f.mustSetBits(101, 1, 2, 3, 4)       // three intersections
	f.mustSetBits(102, 1, 2, 4, 5, 6)    // two intersections
	f.mustSetBits(103, 1000, 1001, 1002) // no intersection
	f.RecalculateCache()

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{N: 3, Src: src}); err != nil {
		t.Fatal(err)
	} else if !reflect.DeepEqual(pairs, []Pair{
		{ID: 101, Count: 3},
		{ID: 102, Count: 2},
		{ID: 100, Count: 1},
	}) {
		t.Fatalf("unexpected pairs: %s", spew.Sdump(pairs))
	}
}

// Ensure a fragment can return top rows that have many columns set.
func TestFragment_TopN_Intersect_Large(t *testing.T) {
	if testing.Short() {
		t.Skip("short mode")
	}

	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	// Create an intersecting input row.
	src := NewRow(
		980, 981, 982, 983, 984, 985, 986, 987, 988, 989,
		990, 991, 992, 993, 994, 995, 996, 997, 998, 999,
	)

	bm := roaring.NewBTreeBitmap()
	// Set bits on rows 0 - 999. Higher rows have higher bit counts.
	for i := uint64(0); i < 1000; i++ {
		for j := uint64(0); j < i; j++ {
			addToBitmap(bm, i, j)
		}
	}
	b := &bytes.Buffer{}
	_, err := bm.WriteTo(b)
	if err != nil {
		t.Fatalf("writing to bytes: %v", err)
	}
	err = f.importRoaringT(b.Bytes(), false)
	if err != nil {
		t.Fatalf("importing data: %v", err)
	}
	f.RecalculateCache()

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{N: 10, Src: src}); err != nil {
		t.Fatal(err)
	} else if !reflect.DeepEqual(pairs, []Pair{
		{ID: 999, Count: 19},
		{ID: 998, Count: 18},
		{ID: 997, Count: 17},
		{ID: 996, Count: 16},
		{ID: 995, Count: 15},
		{ID: 994, Count: 14},
		{ID: 993, Count: 13},
		{ID: 992, Count: 12},
		{ID: 991, Count: 11},
		{ID: 990, Count: 10},
	}) {
		t.Fatalf("unexpected pairs: %s", spew.Sdump(pairs))
	}
}

// Ensure a fragment can return top rows when specified by ID.
func TestFragment_TopN_IDs(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	// Set bits on various rows.
	f.mustSetBits(100, 1, 2, 3)
	f.mustSetBits(101, 4, 5, 6, 7)
	f.mustSetBits(102, 8, 9, 10, 11, 12)

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{RowIDs: []uint64{100, 101, 200}}); err != nil {
		t.Fatal(err)
	} else if !reflect.DeepEqual(pairs, []Pair{
		{ID: 101, Count: 4},
		{ID: 100, Count: 3},
	}) {
		t.Fatalf("unexpected pairs: %s", spew.Sdump(pairs))
	}
}

// Ensure a fragment return none if CacheTypeNone is set
func TestFragment_TopN_NopCache(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeNone)
	defer f.Clean(t)

	// Set bits on various rows.
	f.mustSetBits(100, 1, 2, 3)
	f.mustSetBits(101, 4, 5, 6, 7)
	f.mustSetBits(102, 8, 9, 10, 11, 12)

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{RowIDs: []uint64{100, 101, 200}}); err != nil {
		t.Fatal(err)
	} else if !reflect.DeepEqual(pairs, []Pair{}) {
		t.Fatalf("unexpected pairs: %s", spew.Sdump(pairs))
	}
}

// Ensure the fragment cache limit works
func TestFragment_TopN_CacheSize(t *testing.T) {
	shard := uint64(0)
	cacheSize := uint32(3)

	// Create Index.
	index := mustOpenIndex(IndexOptions{})
	defer index.Close()

	// Create field.
	field, err := index.CreateFieldIfNotExists("f", OptFieldTypeSet(CacheTypeRanked, cacheSize))
	if err != nil {
		t.Fatal(err)
	}

	// Create view.
	view, err := field.createViewIfNotExists(viewStandard)
	if err != nil {
		t.Fatal(err)
	}

	// Create fragment.
	frag, err := view.CreateFragmentIfNotExists(shard)
	if err != nil {
		t.Fatal(err)
	}
	// Close the storage so we can re-open it without encountering a flock.
	frag.Close()

	f := frag
	if err := f.Open(); err != nil {
		panic(err)
	}
	defer f.Clean(t)

	// Set bits on various rows.
	f.mustSetBits(100, 1, 2, 3)
	f.mustSetBits(101, 4, 5, 6, 7)
	f.mustSetBits(102, 8, 9, 10, 11, 12)
	f.mustSetBits(103, 8, 9, 10, 11, 12, 13)
	f.mustSetBits(104, 8, 9, 10, 11, 12, 13, 14)
	f.mustSetBits(105, 10, 11)

	f.RecalculateCache()

	p := []Pair{
		{ID: 104, Count: 7},
		{ID: 103, Count: 6},
		{ID: 102, Count: 5},
	}

	// Retrieve top rows.
	if pairs, err := f.top(topOptions{N: 5}); err != nil {
		t.Fatal(err)
	} else if len(pairs) > int(cacheSize) {
		t.Fatalf("TopN count cannot exceed cache size: %d", cacheSize)
	} else if pairs[0] != (Pair{ID: 104, Count: 7}) {
		t.Fatalf("unexpected pair(0): %v", pairs)
	} else if !reflect.DeepEqual(pairs, p) {
		t.Fatalf("Invalid TopN result set: %s", spew.Sdump(pairs))
	}
}

// Ensure fragment can return a checksum for its blocks.
func TestFragment_Checksum(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Retrieve checksum and set bits.
	orig := f.Checksum()
	if _, err := f.setBit(1, 200); err != nil {
		t.Fatal(err)
	} else if _, err := f.setBit(HashBlockSize*2, 200); err != nil {
		t.Fatal(err)
	}

	// Ensure new checksum is different.
	if chksum := f.Checksum(); bytes.Equal(chksum, orig) {
		t.Fatalf("expected checksum to change: %x - %x", chksum, orig)
	}
}

// Ensure fragment can return a checksum for a given block.
func TestFragment_Blocks(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Retrieve initial checksum.
	var prev []FragmentBlock

	// Set first bit.
	if _, err := f.setBit(0, 0); err != nil {
		t.Fatal(err)
	}
	blocks := f.Blocks()
	if blocks[0].Checksum == nil {
		t.Fatalf("expected checksum: %x", blocks[0].Checksum)
	}
	prev = blocks

	// Set bit on different row.
	if _, err := f.setBit(20, 0); err != nil {
		t.Fatal(err)
	}
	blocks = f.Blocks()
	if bytes.Equal(blocks[0].Checksum, prev[0].Checksum) {
		t.Fatalf("expected checksum to change: %x", blocks[0].Checksum)
	}
	prev = blocks

	// Set bit on different column.
	if _, err := f.setBit(20, 100); err != nil {
		t.Fatal(err)
	}
	blocks = f.Blocks()
	if bytes.Equal(blocks[0].Checksum, prev[0].Checksum) {
		t.Fatalf("expected checksum to change: %x", blocks[0].Checksum)
	}
}

// Ensure fragment returns an empty checksum if no data exists for a block.
func TestFragment_Blocks_Empty(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set bits on a different block.
	if _, err := f.setBit(100, 1); err != nil {
		t.Fatal(err)
	}

	// Ensure checksum for block 1 is blank.
	if blocks := f.Blocks(); len(blocks) != 1 {
		t.Fatalf("unexpected block count: %d", len(blocks))
	} else if blocks[0].ID != 1 {
		t.Fatalf("unexpected block id: %d", blocks[0].ID)
	}
}

// Ensure a fragment's cache can be persisted between restarts.
func TestFragment_LRUCache_Persistence(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeLRU)
	defer f.Clean(t)

	// Set bits on the fragment.
	for i := uint64(0); i < 1000; i++ {
		if _, err := f.setBit(i, 0); err != nil {
			t.Fatal(err)
		}
	}

	// Verify correct cache type and size.
	if cache, ok := f.cache.(*lruCache); !ok {
		t.Fatalf("unexpected cache: %T", f.cache)
	} else if cache.Len() != 1000 {
		t.Fatalf("unexpected cache len: %d", cache.Len())
	}

	// Reopen the fragment.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	}

	// Re-verify correct cache type and size.
	if cache, ok := f.cache.(*lruCache); !ok {
		t.Fatalf("unexpected cache: %T", f.cache)
	} else if cache.Len() != 1000 {
		t.Fatalf("unexpected cache len: %d", cache.Len())
	}
}

// Ensure a fragment's cache can be persisted between restarts.
func TestFragment_RankCache_Persistence(t *testing.T) {
	index := mustOpenIndex(IndexOptions{})
	defer index.Close()

	// Create field.
	field, err := index.CreateFieldIfNotExists("f", OptFieldTypeSet(CacheTypeRanked, DefaultCacheSize))
	if err != nil {
		t.Fatal(err)
	}

	// Create view.
	view, err := field.createViewIfNotExists(viewStandard)
	if err != nil {
		t.Fatal(err)
	}

	// Create fragment.
	f, err := view.CreateFragmentIfNotExists(0)
	if err != nil {
		t.Fatal(err)
	}

	// Set bits on the fragment.
	for i := uint64(0); i < 1000; i++ {
		if _, err := f.setBit(i, 0); err != nil {
			t.Fatal(err)
		}
	}

	// Verify correct cache type and size.
	if cache, ok := f.cache.(*rankCache); !ok {
		t.Fatalf("unexpected cache: %T", f.cache)
	} else if cache.Len() != 1000 {
		t.Fatalf("unexpected cache len: %d", cache.Len())
	}

	// Reopen the index.
	if err := index.reopen(); err != nil {
		t.Fatal(err)
	}

	// Re-fetch fragment.
	f = index.Field("f").view(viewStandard).Fragment(0)

	// Re-verify correct cache type and size.
	if cache, ok := f.cache.(*rankCache); !ok {
		t.Fatalf("unexpected cache: %T", f.cache)
	} else if cache.Len() != 1000 {
		t.Fatalf("unexpected cache len: %d", cache.Len())
	}
}

// Ensure a fragment can be copied to another fragment.
func TestFragment_WriteTo_ReadFrom(t *testing.T) {
	f0 := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f0.Clean(t)

	// Set and then clear bits on the fragment.
	if _, err := f0.setBit(1000, 1); err != nil {
		t.Fatal(err)
	} else if _, err := f0.setBit(1000, 2); err != nil {
		t.Fatal(err)
	} else if _, err := f0.clearBit(1000, 1); err != nil {
		t.Fatal(err)
	}

	// Verify cache is populated.
	if n := f0.cache.Len(); n != 1 {
		t.Fatalf("unexpected cache size: %d", n)
	}

	// Write fragment to a buffer.
	var buf bytes.Buffer
	wn, err := f0.WriteTo(&buf)
	if err != nil {
		t.Fatal(err)
	}

	// Read into another fragment.
	f1 := mustOpenFragment("i", "f", viewStandard, 0, "")
	if rn, err := f1.ReadFrom(&buf); err != nil {
		t.Fatal(err)
	} else if wn != rn {
		t.Fatalf("read/write byte count mismatch: wn=%d, rn=%d", wn, rn)
	}

	// Verify cache is in other fragment.
	if n := f1.cache.Len(); n != 1 {
		t.Fatalf("unexpected cache size: %d", n)
	}

	// Verify data in other fragment.
	if a := f1.row(1000).Columns(); !reflect.DeepEqual(a, []uint64{2}) {
		t.Fatalf("unexpected columns: %+v", a)
	}

	// Close and reopen the fragment & verify the data.
	if err := f1.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f1.cache.Len(); n != 1 {
		t.Fatalf("unexpected cache size (reopen): %d", n)
	} else if a := f1.row(1000).Columns(); !reflect.DeepEqual(a, []uint64{2}) {
		t.Fatalf("unexpected columns (reopen): %+v", a)
	}
}

func BenchmarkFragment_Blocks(b *testing.B) {
	if *FragmentPath == "" {
		b.Skip("no fragment specified")
	}

	// Open the fragment specified by the path.
	f := newFragment(*FragmentPath, "i", "f", viewStandard, 0, 0)
	if err := f.Open(); err != nil {
		b.Fatal(err)
	}
	defer f.CleanKeep(b)

	// Reset timer and execute benchmark.
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if a := f.Blocks(); len(a) == 0 {
			b.Fatal("no blocks in fragment")
		}
	}
}

func BenchmarkFragment_IntersectionCount(b *testing.B) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(b)
	f.MaxOpN = math.MaxInt32

	// Generate some intersecting data.
	for i := 0; i < 10000; i += 2 {
		if _, err := f.setBit(1, uint64(i)); err != nil {
			b.Fatal(err)
		}
	}
	for i := 0; i < 10000; i += 3 {
		if _, err := f.setBit(2, uint64(i)); err != nil {
			b.Fatal(err)
		}
	}

	// Snapshot to disk before benchmarking.
	if err := f.Snapshot(); err != nil {
		b.Fatal(err)
	}

	// Start benchmark
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if n := f.row(1).intersectionCount(f.row(2)); n == 0 {
			b.Fatalf("unexpected count: %d", n)
		}
	}
}

func TestFragment_Tanimoto(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	src := NewRow(1, 2, 3)

	// Set bits on the rows 100, 101, & 102.
	f.mustSetBits(100, 1, 3, 2, 200)
	f.mustSetBits(101, 1, 3)
	f.mustSetBits(102, 1, 2, 10, 12)
	f.RecalculateCache()

	if pairs, err := f.top(topOptions{TanimotoThreshold: 50, Src: src}); err != nil {
		t.Fatal(err)
	} else if len(pairs) != 2 {
		t.Fatalf("unexpected count: %d", len(pairs))
	} else if pairs[0] != (Pair{ID: 100, Count: 3}) {
		t.Fatalf("unexpected pair(0): %v", pairs[0])
	} else if pairs[1] != (Pair{ID: 101, Count: 2}) {
		t.Fatalf("unexpected pair(1): %v", pairs[1])
	}
}

func TestFragment_Zero_Tanimoto(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	src := NewRow(1, 2, 3)

	// Set bits on the rows 100, 101, & 102.
	f.mustSetBits(100, 1, 3, 2, 200)
	f.mustSetBits(101, 1, 3)
	f.mustSetBits(102, 1, 2, 10, 12)
	f.RecalculateCache()

	if pairs, err := f.top(topOptions{TanimotoThreshold: 0, Src: src}); err != nil {
		t.Fatal(err)
	} else if len(pairs) != 3 {
		t.Fatalf("unexpected count: %d", len(pairs))
	} else if pairs[0] != (Pair{ID: 100, Count: 3}) {
		t.Fatalf("unexpected pair(0): %v", pairs[0])
	} else if pairs[1] != (Pair{ID: 101, Count: 2}) {
		t.Fatalf("unexpected pair(1): %v", pairs[1])
	} else if pairs[2] != (Pair{ID: 102, Count: 2}) {
		t.Fatalf("unexpected pair(1): %v", pairs[2])
	}
}

func TestFragment_Snapshot_Run(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	// Set bits on the fragment.
	for i := uint64(1); i < 3; i++ {
		if _, err := f.setBit(1000, i); err != nil {
			t.Fatal(err)
		}
	}

	// Snapshot bitmap and verify data.
	if err := f.Snapshot(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 2 {
		t.Fatalf("unexpected count: %d", n)
	}

	// Close and reopen the fragment & verify the data.
	if err := f.Reopen(); err != nil {
		t.Fatal(err)
	} else if n := f.row(1000).Count(); n != 2 {
		t.Fatalf("unexpected count (reopen): %d", n)
	}
}

// Ensure a fragment can set mutually exclusive values.
func TestFragment_SetMutex(t *testing.T) {
	f := mustOpenMutexFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(t)

	var cols []uint64

	// Set a value on column 100.
	if _, err := f.setBit(1, 100); err != nil {
		t.Fatal(err)
	}
	// Verify the value was set.
	cols = f.row(1).Columns()
	if !reflect.DeepEqual(cols, []uint64{100}) {
		t.Fatalf("mutex unexpected columns: %v", cols)
	}

	// Set a different value on column 100.
	if _, err := f.setBit(2, 100); err != nil {
		t.Fatal(err)
	}
	// Verify that value (row 1) was replaced (by row 2).
	cols = f.row(1).Columns()
	if !reflect.DeepEqual(cols, []uint64{}) {
		t.Fatalf("mutex unexpected columns: %v", cols)
	}
	cols = f.row(2).Columns()
	if !reflect.DeepEqual(cols, []uint64{100}) {
		t.Fatalf("mutex unexpected columns: %v", cols)
	}
}

// Ensure a fragment can import into set fields.
func TestFragment_ImportSet(t *testing.T) {
	tests := []struct {
		setRowIDs   []uint64
		setColIDs   []uint64
		setExp      map[uint64][]uint64
		clearRowIDs []uint64
		clearColIDs []uint64
		clearExp    map[uint64][]uint64
	}{
		{
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
			[]uint64{},
			[]uint64{},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2, 2, 2, 2},
			[]uint64{0, 1, 2, 3, 0, 1, 2, 3},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
				2: {0, 1, 2, 3},
			},
			[]uint64{1, 1, 2},
			[]uint64{1, 2, 3},
			map[uint64][]uint64{
				1: {0, 3},
				2: {0, 1, 2},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2},
			[]uint64{0, 1, 2, 3, 1},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
				2: {1},
			},
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				1: {},
				2: {1},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2, 2, 1},
			[]uint64{0, 1, 2, 3, 1, 8, 1},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
				2: {1, 8},
			},
			[]uint64{1, 1},
			[]uint64{0, 0},
			map[uint64][]uint64{
				1: {1, 2, 3},
				2: {1, 8},
			},
		},
		{
			[]uint64{1, 2, 3},
			[]uint64{8, 8, 8},
			map[uint64][]uint64{
				1: {8},
				2: {8},
				3: {8},
			},
			[]uint64{1, 2, 3},
			[]uint64{9, 9, 9},
			map[uint64][]uint64{
				1: {8},
				2: {8},
				3: {8},
			},
		},
	}

	for i, test := range tests {
		t.Run(fmt.Sprintf("importset%d", i), func(t *testing.T) {
			f := mustOpenFragment("i", "f", viewStandard, 0, "")
			defer f.Clean(t)

			// Set import.
			err := f.bulkImport(test.setRowIDs, test.setColIDs, &ImportOptions{})
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.setExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("expected: %v, but got: %v", v, cols)
				}
			}

			// Clear import.
			err = f.bulkImport(test.clearRowIDs, test.clearColIDs, &ImportOptions{Clear: true})
			if err != nil {
				t.Fatalf("bulk clearing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.clearExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("expected: %v, but got: %v", v, cols)
				}
			}
		})
	}
}

func TestFragment_ConcurrentImport(t *testing.T) {
	t.Run("bulkImportStandard", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		eg := errgroup.Group{}
		eg.Go(func() error { return f.bulkImportStandard([]uint64{1, 2}, []uint64{1, 2}, &ImportOptions{}) })
		eg.Go(func() error { return f.bulkImportStandard([]uint64{3, 4}, []uint64{3, 4}, &ImportOptions{}) })
		err := eg.Wait()
		if err != nil {
			t.Fatalf("importing data to fragment: %v", err)
		}
	})
}

// Ensure a fragment can import mutually exclusive values.
func TestFragment_ImportMutex(t *testing.T) {
	tests := []struct {
		setRowIDs   []uint64
		setColIDs   []uint64
		setExp      map[uint64][]uint64
		clearRowIDs []uint64
		clearColIDs []uint64
		clearExp    map[uint64][]uint64
	}{
		{
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
			[]uint64{},
			[]uint64{},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2, 2, 2, 2},
			[]uint64{0, 1, 2, 3, 0, 1, 2, 3},
			map[uint64][]uint64{
				1: {},
				2: {0, 1, 2, 3},
			},
			[]uint64{1, 1, 2},
			[]uint64{1, 2, 3},
			map[uint64][]uint64{
				1: {},
				2: {0, 1, 2},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2},
			[]uint64{0, 1, 2, 3, 1},
			map[uint64][]uint64{
				1: {0, 2, 3},
				2: {1},
			},
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				1: {},
				2: {1},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 2, 2, 1},
			[]uint64{0, 1, 2, 3, 1, 8, 1},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
				2: {8},
			},
			[]uint64{1, 1},
			[]uint64{0, 0},
			map[uint64][]uint64{
				1: {1, 2, 3},
				2: {8},
			},
		},
		{
			[]uint64{1, 2, 3},
			[]uint64{8, 8, 8},
			map[uint64][]uint64{
				1: {},
				2: {},
				3: {8},
			},
			[]uint64{1, 2, 3},
			[]uint64{9, 9, 9},
			map[uint64][]uint64{
				1: {},
				2: {},
				3: {8},
			},
		},
	}

	for i, test := range tests {
		t.Run(fmt.Sprintf("importmutex%d", i), func(t *testing.T) {
			f := mustOpenMutexFragment("i", "f", viewStandard, 0, "")
			defer f.Clean(t)

			// Set import.
			err := f.bulkImport(test.setRowIDs, test.setColIDs, &ImportOptions{})
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.setExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("row: %d, expected: %v, but got: %v", k, v, cols)
				}
			}

			// Clear import.
			err = f.bulkImport(test.clearRowIDs, test.clearColIDs, &ImportOptions{Clear: true})
			if err != nil {
				t.Fatalf("bulk clearing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.clearExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("row: %d expected: %v, but got: %v", k, v, cols)
				}
			}
		})
	}
}

// Ensure a fragment can import bool values.
func TestFragment_ImportBool(t *testing.T) {
	tests := []struct {
		setRowIDs   []uint64
		setColIDs   []uint64
		setExp      map[uint64][]uint64
		clearRowIDs []uint64
		clearColIDs []uint64
		clearExp    map[uint64][]uint64
	}{
		{
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
			[]uint64{},
			[]uint64{},
			map[uint64][]uint64{
				1: {0, 1, 2, 3},
			},
		},
		{
			[]uint64{0, 0, 0, 0, 1, 1, 1, 1},
			[]uint64{0, 1, 2, 3, 0, 1, 2, 3},
			map[uint64][]uint64{
				0: {},
				1: {0, 1, 2, 3},
			},
			[]uint64{1, 1, 2},
			[]uint64{1, 2, 3},
			map[uint64][]uint64{
				0: {},
				1: {0, 3},
				2: {},
			},
		},
		{
			[]uint64{0, 0, 0, 0, 1},
			[]uint64{0, 1, 2, 3, 1},
			map[uint64][]uint64{
				0: {0, 2, 3},
				1: {1},
			},
			[]uint64{1, 1, 1, 1},
			[]uint64{0, 1, 2, 3},
			map[uint64][]uint64{
				0: {0, 2, 3},
				1: {},
			},
		},
		{
			[]uint64{1, 1, 1, 1, 0, 0, 1},
			[]uint64{0, 1, 2, 3, 1, 8, 1},
			map[uint64][]uint64{
				0: {8},
				1: {0, 1, 2, 3},
			},
			[]uint64{1, 1},
			[]uint64{0, 0},
			map[uint64][]uint64{
				0: {8},
				1: {1, 2, 3},
			},
		},
		{
			[]uint64{0, 1, 2},
			[]uint64{8, 8, 8},
			map[uint64][]uint64{
				0: {},
				1: {}, // This isn't {8} because fragment doesn't validate bool values.
				2: {8},
			},
			[]uint64{1, 2, 3},
			[]uint64{9, 9, 9},
			map[uint64][]uint64{
				0: {},
				1: {},
				2: {8},
			},
		},
	}

	for i, test := range tests {
		t.Run(fmt.Sprintf("importmutex%d", i), func(t *testing.T) {
			f := mustOpenBoolFragment("i", "f", viewStandard, 0, "")
			defer f.Clean(t)

			// Set import.
			err := f.bulkImport(test.setRowIDs, test.setColIDs, &ImportOptions{})
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.setExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("expected: %v, but got: %v", v, cols)
				}
			}

			// Clear import.
			err = f.bulkImport(test.clearRowIDs, test.clearColIDs, &ImportOptions{Clear: true})
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}

			// Check for expected results.
			for k, v := range test.clearExp {
				cols := f.row(k).Columns()
				if !reflect.DeepEqual(cols, v) {
					t.Fatalf("expected: %v, but got: %v", v, cols)
				}
			}
		})
	}
}

func BenchmarkFragment_Snapshot(b *testing.B) {
	if *FragmentPath == "" {
		b.Skip("no fragment specified")
	}

	b.ReportAllocs()
	// Open the fragment specified by the path.
	f := newFragment(*FragmentPath, "i", "f", viewStandard, 0, 0)
	if err := f.Open(); err != nil {
		b.Fatal(err)
	}
	defer f.CleanKeep(b)
	b.ResetTimer()

	// Reset timer and execute benchmark.
	b.ResetTimer()
	b.ReportAllocs()
	for i := 0; i < b.N; i++ {
		err := f.Snapshot()
		if err != nil {
			b.Fatalf("unexpected count (reopen): %s", err)
		}
	}
}

func BenchmarkFragment_FullSnapshot(b *testing.B) {
	f := mustOpenFragment("i", "f", viewStandard, 0, "")
	defer f.Clean(b)
	// Generate some intersecting data.
	maxX := ShardWidth / 2
	sz := maxX
	rows := make([]uint64, sz)
	cols := make([]uint64, sz)

	options := &ImportOptions{}
	max := 0
	for row := 0; row < 100; row++ {
		val := 1
		i := 0
		for col := 0; col < ShardWidth/2; col++ {
			rows[i] = uint64(row)
			cols[i] = uint64(val)
			val += 2
			i++
		}
		if err := f.bulkImport(rows, cols, options); err != nil {
			b.Fatalf("Error Building Sample: %s", err)
		}
		if row > max {
			max = row
		}
	}

	b.ResetTimer()
	b.ReportAllocs()

	for i := 0; i < b.N; i++ {
		if err := f.Snapshot(); err != nil {
			b.Fatal(err)
		}
	}
}

func BenchmarkFragment_Import(b *testing.B) {
	b.StopTimer()
	maxX := ShardWidth * 5 * 2
	sz := maxX
	rows := make([]uint64, sz)
	cols := make([]uint64, sz)
	i := 0
	for row := 0; row < 100; row++ {
		val := 1
		for col := 0; col < ShardWidth/2; col++ {
			rows[i] = uint64(row)
			cols[i] = uint64(val)
			val += 2
			i++
		}
		if i == maxX {
			break
		}
	}
	rowsUse, colsUse := make([]uint64, len(rows)), make([]uint64, len(cols))
	b.ReportAllocs()
	options := &ImportOptions{}
	for i := 0; i < b.N; i++ {
		// since bulkImport modifies the input slices, we make new copies for each round
		copy(rowsUse, rows)
		copy(colsUse, cols)
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		b.StartTimer()
		if err := f.bulkImport(rowsUse, colsUse, options); err != nil {
			b.Errorf("Error Building Sample: %s", err)
		}
		b.StopTimer()
		f.Clean(b)
	}
}

var (
	rowCases         = []uint64{2, 50, 1000, 10000, 100000}
	colCases         = []uint64{20, 1000, 5000, 50000, 500000}
	concurrencyCases = []int{2, 4, 16}
	cacheCases       = []string{CacheTypeNone, CacheTypeRanked}
)

func BenchmarkImportRoaring(b *testing.B) {
	for _, numRows := range rowCases {
		data := getZipfRowsSliceRoaring(numRows, 1, 0, ShardWidth)
		b.Logf("%dRows: %.2fMB\n", numRows, float64(len(data))/1024/1024)
		for _, cacheType := range cacheCases {
			b.Run(fmt.Sprintf("Rows%dCache_%s", numRows, cacheType), func(b *testing.B) {
				b.StopTimer()
				for i := 0; i < b.N; i++ {
					f := mustOpenFragment("i", fmt.Sprintf("r%dc%s", numRows, cacheType), viewStandard, 0, cacheType)
					b.StartTimer()
					err := f.importRoaringT(data, false)
					if err != nil {
						f.awaitSnapshot()
						f.Clean(b)
						b.Fatalf("import error: %v", err)
					}
					b.StopTimer()
					f.Clean(b)
				}
			})
		}
	}
}

func BenchmarkImportRoaringConcurrent(b *testing.B) {
	if testing.Short() {
		b.SkipNow()
	}
	for _, numRows := range rowCases {
		data := make([][]byte, 0, len(concurrencyCases))
		data = append(data, getZipfRowsSliceRoaring(numRows, 0, 0, ShardWidth))
		b.Logf("%dRows: %.2fMB\n", numRows, float64(len(data[0]))/1024/1024)
		for _, concurrency := range concurrencyCases {
			// add more data sets
			for j := len(data); j < concurrency; j++ {
				data = append(data, getZipfRowsSliceRoaring(numRows, int64(j), 0, ShardWidth))
			}
			for _, cacheType := range cacheCases {
				b.Run(fmt.Sprintf("Rows%dConcurrency%dCache_%s", numRows, concurrency, cacheType), func(b *testing.B) {
					b.StopTimer()
					frags := make([]*fragment, concurrency)
					for i := 0; i < b.N; i++ {
						for j := 0; j < concurrency; j++ {
							frags[j] = mustOpenFragment("i", "f", viewStandard, uint64(j), cacheType)
						}
						eg := errgroup.Group{}
						b.StartTimer()
						for j := 0; j < concurrency; j++ {
							j := j
							eg.Go(func() error {
								err := frags[j].importRoaringT(data[j], false)
								frags[j].awaitSnapshot()
								return err
							})
						}
						err := eg.Wait()
						if err != nil {
							b.Errorf("importing fragment: %v", err)
						}
						b.StopTimer()
						for j := 0; j < concurrency; j++ {
							frags[j].Clean(b)
						}
					}
				})
			}
		}
	}
}
func BenchmarkImportRoaringUpdateConcurrent(b *testing.B) {
	if testing.Short() {
		b.SkipNow()
	}
	for _, numRows := range rowCases {
		for _, numCols := range colCases {
			data := getZipfRowsSliceRoaring(numRows, 1, 0, ShardWidth)
			updata := getUpdataRoaring(numRows, numCols, 1)
			for _, concurrency := range concurrencyCases {
				for _, cacheType := range cacheCases {
					b.Run(fmt.Sprintf("Rows%dCols%dConcurrency%dCache_%s", numRows, numCols, concurrency, cacheType), func(b *testing.B) {
						b.StopTimer()
						frags := make([]*fragment, concurrency)
						for i := 0; i < b.N; i++ {
							for j := 0; j < concurrency; j++ {
								frags[j] = mustOpenFragment("i", "f", viewStandard, uint64(j), cacheType)
								// the cost of actually doing the op log for the large initial data set
								// is excessive. force storage into snapshotted state, then use import
								// to generate an op log and/or snapshot.
								_, _, err := frags[j].storage.ImportRoaringBits(data, false, false, 0)
								frags[j].enqueueSnapshot()
								frags[j].awaitSnapshot()
								if err != nil {
									b.Fatalf("importing roaring: %v", err)
								}
							}
							eg := errgroup.Group{}
							b.StartTimer()
							for j := 0; j < concurrency; j++ {
								j := j
								eg.Go(func() error {
									err := frags[j].importRoaringT(updata, false)
									frags[j].awaitSnapshot()
									return err
								})
							}
							err := eg.Wait()
							if err != nil {
								b.Errorf("importing fragment: %v", err)
							}
							b.StopTimer()
							for j := 0; j < concurrency; j++ {
								frags[j].Clean(b)
							}
						}
					})
				}
			}
		}
	}
}

func BenchmarkImportStandard(b *testing.B) {
	for _, cacheType := range cacheCases {
		for _, numRows := range rowCases {
			rowIDsOrig, columnIDsOrig := getZipfRowsSliceStandard(numRows, 1, 0, ShardWidth)
			rowIDs, columnIDs := make([]uint64, len(rowIDsOrig)), make([]uint64, len(columnIDsOrig))
			b.Run(fmt.Sprintf("Rows%dCache_%s", numRows, cacheType), func(b *testing.B) {
				b.StopTimer()
				for i := 0; i < b.N; i++ {
					copy(rowIDs, rowIDsOrig)
					copy(columnIDs, columnIDsOrig)
					f := mustOpenFragment("i", fmt.Sprintf("r%dc%s", numRows, cacheType), viewStandard, 0, cacheType)
					b.StartTimer()
					err := f.bulkImport(rowIDs, columnIDs, &ImportOptions{})
					if err != nil {
						b.Errorf("import error: %v", err)
					}
					b.StopTimer()
					f.Clean(b)
				}
			})
		}
	}
}

func BenchmarkImportRoaringUpdate(b *testing.B) {
	fileSize := make(map[string]int64)
	names := []string{}
	for _, numRows := range rowCases {
		data := getZipfRowsSliceRoaring(numRows, 1, 0, ShardWidth)
		for _, numCols := range colCases {
			updata := getUpdataRoaring(numRows, numCols, 1)
			for _, cacheType := range cacheCases {
				name := fmt.Sprintf("Rows%dCols%dCache_%s", numRows, numCols, cacheType)
				names = append(names, name)
				b.Run(name, func(b *testing.B) {
					b.StopTimer()
					for i := 0; i < b.N; i++ {
						f := mustOpenFragment("i", fmt.Sprintf("r%dc%dcache_%s", numRows, numCols, cacheType), viewStandard, 0, cacheType)
						// the cost of actually doing the op log for the large initial data set
						// is excessive. force storage into snapshotted state, then use import
						// to generate an op log and/or snapshot.
						_, _, err := f.storage.ImportRoaringBits(data, false, false, 0)
						f.enqueueSnapshot()
						f.awaitSnapshot()
						if err != nil {
							b.Errorf("import error: %v", err)
						}
						b.StartTimer()
						err = f.importRoaringT(updata, false)
						f.awaitSnapshot()
						if err != nil {
							f.Clean(b)
							b.Errorf("import error: %v", err)
						}
						b.StopTimer()
						stat, _ := f.file.Stat()
						fileSize[name] = stat.Size()
						f.Clean(b)
					}
				})

			}
		}
	}
	for _, name := range names {
		b.Logf("%s: %.2fMB\n", name, float64(fileSize[name])/1024/1024)
	}
}

// BenchmarkUpdatePathological imports more data into an existing fragment than
// already exists, but the larger data comes after the smaller data. If
// SliceContainers are in use, this can cause horrible performance.
func BenchmarkUpdatePathological(b *testing.B) {
	exists := getZipfRowsSliceRoaring(100000, 1, 0, 400000)
	inc := getZipfRowsSliceRoaring(100000, 2, 400000, ShardWidth)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		b.StopTimer()
		f := mustOpenFragment("i", "f", viewStandard, 0, DefaultCacheType)
		err := f.importRoaringT(exists, false)
		if err != nil {
			b.Fatalf("importing roaring: %v", err)
		}
		b.StartTimer()
		err = f.importRoaringT(inc, false)
		if err != nil {
			b.Fatalf("importing second: %v", err)
		}

	}

}

var bigFrag string

func initBigFrag() {
	if bigFrag == "" {
		f := mustOpenFragment("i", "f", viewStandard, 0, DefaultCacheType)
		for i := int64(0); i < 10; i++ {
			// 10 million rows, 1 bit per column, random seeded by i
			data := getZipfRowsSliceRoaring(10000000, i, 0, ShardWidth)
			err := f.importRoaringT(data, false)
			if err != nil {
				panic(fmt.Sprintf("setting up fragment data: %v", err))
			}
		}
		err := f.Close()
		if err != nil {
			panic(fmt.Sprintf("closing fragment: %v", err))
		}
		bigFrag = f.path
	}
}

func BenchmarkImportIntoLargeFragment(b *testing.B) {
	b.StopTimer()
	initBigFrag()
	rowsOrig, colsOrig := getUpdataSlices(10000000, 11000, 0)
	rows, cols := make([]uint64, len(rowsOrig)), make([]uint64, len(colsOrig))
	opts := &ImportOptions{}
	for i := 0; i < b.N; i++ {
		origF, err := os.Open(bigFrag)
		if err != nil {
			b.Fatalf("opening frag file: %v", err)
		}
		fi, err := ioutil.TempFile(*TempDir, "")
		if err != nil {
			b.Fatalf("getting temp file: %v", err)
		}
		_, err = io.Copy(fi, origF)
		if err != nil {
			b.Fatalf("copying fragment file: %v", err)
		}
		origF.Close()
		fi.Close()
		nf := newFragment(fi.Name(), "i", "f", viewStandard, 0, 0)
		err = nf.Open()
		if err != nil {
			b.Fatalf("opening fragment: %v", err)
		}
		copy(rows, rowsOrig)
		copy(cols, colsOrig)
		b.StartTimer()
		err = nf.bulkImport(rows, cols, opts)
		b.StopTimer()
		if err != nil {
			b.Fatalf("bulkImport: %v", err)
		}

		nf.Clean(b)
	}
}

func BenchmarkImportRoaringIntoLargeFragment(b *testing.B) {
	b.StopTimer()
	initBigFrag()
	updata := getUpdataRoaring(10000000, 11000, 0)
	for i := 0; i < b.N; i++ {
		origF, err := os.Open(bigFrag)
		if err != nil {
			b.Fatalf("opening frag file: %v", err)
		}
		fi, err := ioutil.TempFile(*TempDir, "")
		if err != nil {
			b.Fatalf("getting temp file: %v", err)
		}
		_, err = io.Copy(fi, origF)
		if err != nil {
			b.Fatalf("copying fragment file: %v", err)
		}
		origF.Close()
		fi.Close()
		nf := newFragment(fi.Name(), "i", "f", viewStandard, 0, 0)
		err = nf.Open()
		if err != nil {
			b.Fatalf("opening fragment: %v", err)
		}
		b.StartTimer()
		err = nf.importRoaringT(updata, false)
		b.StopTimer()
		if err != nil {
			b.Fatalf("bulkImport: %v", err)
		}

		nf.Clean(b)
	}
}

func TestGetZipfRowsSliceRoaring(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, DefaultCacheType)
	data := getZipfRowsSliceRoaring(10, 1, 0, ShardWidth)
	err := f.importRoaringT(data, false)
	if err != nil {
		t.Fatalf("importing roaring: %v", err)
	}
	if !reflect.DeepEqual(f.rows(0), []uint64{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}) {
		t.Fatalf("unexpected rows: %v", f.rows(0))
	}
	for i := uint64(1); i < 10; i++ {
		if f.row(i).Count() >= f.row(i-1).Count() {
			t.Fatalf("suspect distribution from getZipfRowsSliceRoaring")
		}
	}
}

// getZipfRowsSliceRoaring generates a random fragment with the given number of
// rows, and 1 bit set in each column. The row each bit is set in is chosen via
// the Zipf generator, and so will be skewed toward lower row numbers. If this
// is edited to change the data distribution, getZipfRowsSliceStandard should be
// edited as well. TODO switch to generating row-major for perf boost
func getZipfRowsSliceRoaring(numRows uint64, seed int64, startCol, endCol uint64) []byte {
	b := roaring.NewBTreeBitmap()
	s := rand.NewSource(seed)
	r := rand.New(s)
	z := rand.NewZipf(r, 1.6, 50, numRows-1)
	bufSize := 1 << 14
	posBuf := make([]uint64, 0, bufSize)
	for i := uint64(startCol); i < endCol; i++ {
		row := z.Uint64()
		posBuf = append(posBuf, row*ShardWidth+i)
		if len(posBuf) == bufSize {
			sort.Slice(posBuf, func(i int, j int) bool { return posBuf[i] < posBuf[j] })
			b.DirectAddN(posBuf...)
		}
	}
	b.DirectAddN(posBuf...)
	buf := bytes.NewBuffer(make([]byte, 0, 100000))
	_, err := b.WriteTo(buf)
	if err != nil {
		panic(err)
	}
	return buf.Bytes()
}

func getUpdataSlices(numRows, numCols uint64, seed int64) (rows, cols []uint64) {
	getUpdataInto(func(row, col uint64) bool {
		rows = append(rows, row)
		cols = append(cols, col)
		return true
	}, numRows, numCols, seed)
	return rows, cols
}

// getUpdataRoaring gets a byte slice containing a roaring bitmap which
// represents numCols set bits distributed randomly throughout a shard's column
// space and zipfianly throughout numRows rows.
func getUpdataRoaring(numRows, numCols uint64, seed int64) []byte {
	b := roaring.NewBitmap()

	getUpdataInto(func(row, col uint64) bool {
		return b.DirectAdd(row*ShardWidth + col)
	}, numRows, numCols, seed)

	buf := bytes.NewBuffer(make([]byte, 0, 100000))
	_, err := b.WriteTo(buf)
	if err != nil {
		panic(err)
	}
	return buf.Bytes()
}

func getUpdataInto(f func(row, col uint64) bool, numRows, numCols uint64, seed int64) int {
	s := rand.NewSource(seed)
	r := rand.New(s)
	z := rand.NewZipf(r, 1.6, 50, numRows-1)

	i := uint64(0)
	// ensure we get exactly the number we asked for. it turns out we had
	// a horrible pathological edge case for exactly 10,000 entries in an
	// imported bitmap, and hit it only occasionally...
	for i < numCols {
		col := uint64(r.Int63n(ShardWidth))
		row := z.Uint64()
		if f(row, col) {
			i++
		}
	}
	return int(i)
}

// getZipfRowsSliceStandard is the same as getZipfRowsSliceRoaring, but returns
// row and column ids instead of a byte slice containing roaring bitmap data.
func getZipfRowsSliceStandard(numRows uint64, seed int64, startCol, endCol uint64) (rowIDs, columnIDs []uint64) {
	s := rand.NewSource(seed)
	r := rand.New(s)
	z := rand.NewZipf(r, 1.6, 50, numRows-1)
	rowIDs, columnIDs = make([]uint64, ShardWidth), make([]uint64, ShardWidth)
	for i := uint64(startCol); i < endCol; i++ {
		rowIDs[i] = z.Uint64()
		columnIDs[i] = i
	}
	return rowIDs, columnIDs
}

func BenchmarkFileWrite(b *testing.B) {
	for _, numRows := range rowCases {
		data := getZipfRowsSliceRoaring(numRows, 1, 0, ShardWidth)
		b.Run(fmt.Sprintf("Rows%d", numRows), func(b *testing.B) {
			b.StopTimer()
			for i := 0; i < b.N; i++ {
				f, err := ioutil.TempFile(*TempDir, "")
				if err != nil {
					b.Fatalf("getting temp file: %v", err)
				}
				b.StartTimer()
				_, err = f.Write(data)
				if err != nil {
					b.Fatal(err)
				}
				err = f.Sync()
				if err != nil {
					b.Fatal(err)
				}
				err = f.Close()
				if err != nil {
					b.Fatal(err)
				}
				b.StopTimer()
				os.Remove(f.Name())
			}
		})
	}

}

/////////////////////////////////////////////////////////////////////

func (f *fragment) sanityCheck(t testing.TB) {
	newBM := roaring.NewFileBitmap()
	file, err := os.Open(f.path)
	if err != nil {
		t.Fatalf("sanityCheck couldn't open file %s: %v", f.path, err)
	}
	defer file.Close()
	data, err := ioutil.ReadAll(file)
	if err != nil {
		t.Fatalf("sanityCheck couldn't read fragment %s: %v", f.path, err)
	}
	err = newBM.UnmarshalBinary(data)
	if err != nil {
		t.Fatalf("sanityCheck couldn't unmarshal fragment %s: %v", f.path, err)
	}
	if equal, reason := newBM.BitwiseEqual(f.storage); !equal {
		t.Fatalf("fragment %s: unmarshalled bitmap different: %v", f.path, reason)
	}
}

func (f *fragment) Clean(t testing.TB) {
	f.awaitSnapshot()
	f.sanityCheck(t)
	errc := f.Close()
	errf := os.Remove(f.path)
	errp := os.Remove(f.cachePath())
	if errc != nil || errf != nil {
		t.Fatal("cleaning up fragment: ", errc, errf, errp)
	}
	if f.snapshotQueue != nil {
		close(f.snapshotQueue)
		f.snapshotQueue = nil
	}
	// not all fragments have cache files
	if errp != nil && !os.IsNotExist(errp) {
		t.Fatalf("cleaning up fragment cache: %v", errp)
	}
}

// importRoaringT calls importRoaring with context.Background() for convenience
func (f *fragment) importRoaringT(data []byte, clear bool) error {
	return f.importRoaring(context.Background(), data, clear)
}

// CleanKeep is just like Clean(), but it doesn't remove the
// fragment file (note that it DOES remove the cache file).
func (f *fragment) CleanKeep(t testing.TB) {
	errc := f.Close()
	errp := os.Remove(f.cachePath())
	if errc != nil {
		t.Fatal("closing fragment: ", errc, errp)
	}
	if f.snapshotQueue != nil {
		close(f.snapshotQueue)
		f.snapshotQueue = nil
	}
	// not all fragments have cache files
	if errp != nil && !os.IsNotExist(errp) {
		t.Fatalf("cleaning up fragment cache: %v", errp)
	}
}

// mustOpenFragment returns a new instance of Fragment with a temporary path.
func mustOpenFragment(index, field, view string, shard uint64, cacheType string) *fragment {
	return mustOpenFragmentFlags(index, field, view, shard, cacheType, 0)
}

func mustOpenBSIFragment(index, field, view string, shard uint64) *fragment {
	return mustOpenFragmentFlags(index, field, view, shard, "", 1)
}

// mustOpenFragment returns a new instance of Fragment with a temporary path.
func mustOpenFragmentFlags(index, field, view string, shard uint64, cacheType string, flags byte) *fragment {
	file, err := ioutil.TempFile(*TempDir, "pilosa-fragment-")
	if err != nil {
		panic(err)
	}
	file.Close()

	if cacheType == "" {
		cacheType = DefaultCacheType
	}

	f := newFragment(file.Name(), index, field, view, shard, flags)
	f.CacheType = cacheType
	f.RowAttrStore = &memAttrStore{
		store: make(map[uint64]map[string]interface{}),
	}
	f.snapshotQueue = newSnapshotQueue(1, 1, nil)

	if err := f.Open(); err != nil {
		panic(err)
	}
	return f
}

// mustOpenMutexFragment returns a new instance of Fragment for a mutex field.
func mustOpenMutexFragment(index, field, view string, shard uint64, cacheType string) *fragment {
	frag := mustOpenFragment(index, field, view, shard, cacheType)
	frag.mutexVector = newRowsVector(frag)
	return frag
}

// mustOpenBoolFragment returns a new instance of Fragment for a bool field.
func mustOpenBoolFragment(index, field, view string, shard uint64, cacheType string) *fragment {
	frag := mustOpenFragment(index, field, view, shard, cacheType)
	frag.mutexVector = newBoolVector(frag)
	return frag
}

// Reopen closes the fragment and reopens it as a new instance.
func (f *fragment) Reopen() error {
	if err := f.Close(); err != nil {
		return err
	}
	if err := f.Open(); err != nil {
		return err
	}
	return nil
}

// mustSetBits sets columns on a row. Panic on error.
// This function does not accept a timestamp or quantum.
func (f *fragment) mustSetBits(rowID uint64, columnIDs ...uint64) {
	for _, columnID := range columnIDs {
		if _, err := f.setBit(rowID, columnID); err != nil {
			panic(err)
		}
	}
}

func addToBitmap(bm *roaring.Bitmap, rowID uint64, columnIDs ...uint64) {
	// we'll reuse the columnIDs slice and fill it with positions for DirectAddN
	for i, c := range columnIDs {
		columnIDs[i] = rowID*ShardWidth + c%ShardWidth
	}
	bm.DirectAddN(columnIDs...)
}

// Test Various methods of retrieving RowIDs
func TestFragment_RowsIteration(t *testing.T) {
	t.Run("firstContainer", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		expectedAll := make([]uint64, 0)
		expectedOdd := make([]uint64, 0)
		for i := uint64(100); i < uint64(200); i++ {
			if _, err := f.setBit(i, i%2); err != nil {
				t.Fatal(err)
			}
			expectedAll = append(expectedAll, i)
			if i%2 == 1 {
				expectedOdd = append(expectedOdd, i)
			}
		}

		ids := f.rows(0)
		if !reflect.DeepEqual(expectedAll, ids) {
			t.Fatalf("Do not match %v %v", expectedAll, ids)
		}

		ids = f.rows(0, filterColumn(1))
		if !reflect.DeepEqual(expectedOdd, ids) {
			t.Fatalf("Do not match %v %v", expectedOdd, ids)
		}
	})

	t.Run("secondRow", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		expected := []uint64{1, 2}
		if _, err := f.setBit(1, 66000); err != nil {
			t.Fatal(err)
		} else if _, err := f.setBit(2, 66000); err != nil {
			t.Fatal(err)
		} else if _, err := f.setBit(2, 166000); err != nil {
			t.Fatal(err)
		}

		ids := f.rows(0)
		if !reflect.DeepEqual(expected, ids) {
			t.Fatalf("Do not match %v %v", expected, ids)
		}

		ids = f.rows(0, filterColumn(66000))
		if !reflect.DeepEqual(expected, ids) {
			t.Fatalf("Do not match %v %v", expected, ids)
		}
	})

	t.Run("combinations", func(t *testing.T) {
		f := mustOpenFragment("i", "f", viewStandard, 0, "")
		defer f.Clean(t)

		expectedRows := make([]uint64, 0)
		for r := uint64(1); r < uint64(10000); r += 100 {
			expectedRows = append(expectedRows, r)
			for c := uint64(1); c < uint64(ShardWidth-1); c += 10000 {
				if _, err := f.setBit(r, c); err != nil {
					t.Fatal(err)
				}

				ids := f.rows(0)
				if !reflect.DeepEqual(expectedRows, ids) {
					t.Fatalf("Do not match %v %v", expectedRows, ids)
				}
				ids = f.rows(0, filterColumn(c))
				if !reflect.DeepEqual(expectedRows, ids) {
					t.Fatalf("Do not match %v %v", expectedRows, ids)
				}
			}
		}
	})
}

// Test Importing roaring data.
func TestFragment_RoaringImport(t *testing.T) {
	tests := [][][]uint64{
		{
			[]uint64{0},
			[]uint64{1},
		},
		{
			[]uint64{0, 65535, 65536, 65537, 65538, 65539, 130000},
			[]uint64{1000, 67000, 130000},
		},
		{
			[]uint64{0, 65535, 65536, 65537, 65538, 65539, 130000},
			[]uint64{0, 65535, 65536, 65537, 65538, 65539, 130000},
		},
		{
			[]uint64{0, 65535, 65536, 1<<20 + 1, 1<<20*2 + 1},
			[]uint64{1, 1<<20 + 2, 1<<20*2 + 2},
		},
	}

	for i, test := range tests {
		t.Run(fmt.Sprintf("importroaring%d", i), func(t *testing.T) {
			f := mustOpenFragment("i", "f", viewStandard, 0, "")
			defer f.Clean(t)
			for num, input := range test {
				buf := &bytes.Buffer{}
				bm := roaring.NewBitmap(input...)
				_, err := bm.WriteTo(buf)
				if err != nil {
					t.Fatalf("writing to buffer: %v", err)
				}
				err = f.importRoaringT(buf.Bytes(), false)
				if err != nil {
					t.Fatalf("importing roaring: %v", err)
				}
				exp := calcExpected(test[:num+1]...)
				for row, expCols := range exp {
					cols := f.row(uint64(row)).Columns()
					t.Logf("\nrow: %d\n  exp:%v\n  got:%v", row, expCols, cols)
					if !reflect.DeepEqual(cols, expCols) {
						t.Fatalf("input%d, row %d\n  exp:%v\n  got:%v", num, row, expCols, cols)
					}
				}
			}
		})
	}
}

// Test Importing roaring data.
func TestFragment_RoaringImportTopN(t *testing.T) {
	tests := []struct {
		rowIDs  []uint64
		colIDs  []uint64
		rowIDs2 []uint64
		colIDs2 []uint64
		roaring []uint64
	}{
		{
			rowIDs:  []uint64{4, 4, 4, 4},
			colIDs:  []uint64{0, 1, 2, 3},
			rowIDs2: []uint64{5, 5, 5, 5, 5},
			colIDs2: []uint64{0, 1, 2, 3, 4},
			roaring: []uint64{0, 65535, 65536, 1<<20 + 1, 1<<20 + 2, 1<<20*2 + 1},
		},
	}

	for i, test := range tests {
		t.Run(fmt.Sprintf("importroaring%d", i), func(t *testing.T) {
			f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
			defer f.Clean(t)

			options := &ImportOptions{}
			err := f.bulkImport(test.rowIDs, test.colIDs, options)
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}
			expPairs := calcTop(test.rowIDs, test.colIDs)
			pairs, err := f.top(topOptions{})
			if err != nil {
				t.Fatalf("executing top after bulk import: %v", err)
			}
			if !reflect.DeepEqual(expPairs, pairs) {
				t.Fatalf("post bulk import:\n  exp: %v\n  got: %v\n", expPairs, pairs)
			}

			err = f.bulkImport(test.rowIDs2, test.colIDs2, options)
			if err != nil {
				t.Fatalf("bulk importing ids: %v", err)
			}
			test.rowIDs = append(test.rowIDs, test.rowIDs2...)
			test.colIDs = append(test.colIDs, test.colIDs2...)
			expPairs = calcTop(test.rowIDs, test.colIDs)
			pairs, err = f.top(topOptions{})
			if err != nil {
				t.Fatalf("executing top after bulk import: %v", err)
			}
			if !reflect.DeepEqual(expPairs, pairs) {
				t.Fatalf("post bulk import2:\n  exp: %v\n  got: %v\n", expPairs, pairs)
			}

			buf := &bytes.Buffer{}
			bm := roaring.NewBitmap(test.roaring...)
			_, err = bm.WriteTo(buf)
			if err != nil {
				t.Fatalf("writing to buffer: %v", err)
			}
			err = f.importRoaringT(buf.Bytes(), false)
			if err != nil {
				t.Fatalf("importing roaring: %v", err)
			}
			rows, cols := toRowsCols(test.roaring)
			expPairs = calcTop(append(test.rowIDs, rows...), append(test.colIDs, cols...))
			pairs, err = f.top(topOptions{})
			if err != nil {
				t.Fatalf("executing top after roaring import: %v", err)
			}
			if !reflect.DeepEqual(expPairs, pairs) {
				t.Fatalf("post Roaring:\n  exp: %v\n  got: %v\n", expPairs, pairs)
			}
		})
	}
}

func toRowsCols(roaring []uint64) (rowIDs, colIDs []uint64) {
	rowIDs, colIDs = make([]uint64, len(roaring)), make([]uint64, len(roaring))
	for i, bit := range roaring {
		rowIDs[i] = bit / ShardWidth
		colIDs[i] = bit % ShardWidth
	}
	return rowIDs, colIDs
}

func calcTop(rowIDs, colIDs []uint64) []Pair {
	if len(rowIDs) != len(colIDs) {
		panic("row and col ids must be of equal len")
	}
	// make map of rowID to colID set in order to dedup
	counts := make(map[uint64]map[uint64]struct{})
	for i := 0; i < len(rowIDs); i++ {
		row, col := rowIDs[i], colIDs[i]
		m, ok := counts[row]
		if !ok {
			m = make(map[uint64]struct{})
			counts[row] = m
		}
		m[col] = struct{}{}
	}

	// build slice of pairs from map
	ret := make([]Pair, 0)
	for row, cols := range counts {
		ret = append(ret, Pair{ID: row, Count: uint64(len(cols))})
	}

	// reverse sort by count
	sort.Slice(ret, func(i, j int) bool { return ret[i].Count > ret[j].Count })
	return ret
}

// calcExpected takes a number of slices of uint64 represented data to be added
// to a fragment. It calculates which rows and bits set in each row would be
// expected after importing that data, and returns a [][]uint64 where the index
// into the first slice is row id.
func calcExpected(inputs ...[]uint64) [][]uint64 {
	// create map of row id to set of column values in that row.
	rows := make(map[uint64]map[uint64]struct{})
	var maxrow uint64
	for _, input := range inputs {
		for _, val := range input {
			row := val / ShardWidth
			if row > maxrow {
				maxrow = row
			}
			m, ok := rows[row]
			if !ok {
				m = make(map[uint64]struct{})
				rows[row] = m
			}
			m[val%ShardWidth] = struct{}{}
		}
	}

	// initialize ret slice
	ret := make([][]uint64, maxrow+1)
	for i := range ret {
		ret[i] = make([]uint64, 0)
	}

	// populate ret slices from rows map
	for row, vals := range rows {
		for val := range vals {
			ret[row] = append(ret[row], val)
		}
	}

	// sort ret slices
	for _, slice := range ret {
		sort.Slice(slice, func(i int, j int) bool { return slice[i] < slice[j] })
	}

	return ret
}

func TestFragmentRowIterator(t *testing.T) {
	t.Run("basic", func(t *testing.T) {
		f := mustOpenFragment("i", "f", "v", 0, CacheTypeRanked)
		defer f.Clean(t)
		f.mustSetBits(0, 0)
		f.mustSetBits(1, 0)
		f.mustSetBits(2, 0)
		f.mustSetBits(3, 0)

		iter := f.rowIterator(false)
		for i := uint64(0); i < 4; i++ {
			row, id, wrapped := iter.Next()
			if id != i {
				t.Fatalf("expected row %d but got %d", i, id)
			}
			if wrapped {
				t.Fatalf("shouldn't have wrapped")
			}
			if !reflect.DeepEqual(row.Columns(), []uint64{0}) {
				t.Fatalf("got wrong columns back on iteration %d - should just be 0 but %v", i, row.Columns())
			}
		}
		row, id, wrapped := iter.Next()
		if row != nil {
			t.Fatalf("row should be nil after iterator is exhausted, got %v", row.Columns())
		}
		if id != 0 {
			t.Fatalf("id should be 0 after iterator is exhausted, got %d", id)
		}
		if !wrapped {
			t.Fatalf("wrapped should be true after iterator is exhausted")
		}
	})

	t.Run("skipped rows", func(t *testing.T) {
		f := mustOpenFragment("i", "f", "v", 0, CacheTypeRanked)
		defer f.Clean(t)
		f.mustSetBits(1, 0)
		f.mustSetBits(3, 0)
		f.mustSetBits(5, 0)
		f.mustSetBits(7, 0)

		iter := f.rowIterator(false)
		for i := uint64(1); i < 8; i += 2 {
			row, id, wrapped := iter.Next()
			if id != i {
				t.Fatalf("expected row %d but got %d", i, id)
			}
			if wrapped {
				t.Fatalf("shouldn't have wrapped")
			}
			if !reflect.DeepEqual(row.Columns(), []uint64{0}) {
				t.Fatalf("got wrong columns back on iteration %d - should just be 0 but %v", i, row.Columns())
			}
		}
		row, id, wrapped := iter.Next()
		if row != nil {
			t.Fatalf("row should be nil after iterator is exhausted, got %v", row.Columns())
		}
		if id != 0 {
			t.Fatalf("id should be 0 after iterator is exhausted, got %d", id)
		}
		if !wrapped {
			t.Fatalf("wrapped should be true after iterator is exhausted")
		}
	})

	t.Run("basic wrapped", func(t *testing.T) {
		f := mustOpenFragment("i", "f", "v", 0, CacheTypeRanked)
		defer f.Clean(t)
		f.mustSetBits(0, 0)
		f.mustSetBits(1, 0)
		f.mustSetBits(2, 0)
		f.mustSetBits(3, 0)

		iter := f.rowIterator(true)
		for i := uint64(0); i < 5; i++ {
			row, id, wrapped := iter.Next()
			if id != i%4 {
				t.Fatalf("expected row %d but got %d", i%4, id)
			}
			if wrapped && i < 4 {
				t.Fatalf("shouldn't have wrapped")
			} else if !wrapped && i >= 4 {
				t.Fatalf("should have wrapped")
			}
			if !reflect.DeepEqual(row.Columns(), []uint64{0}) {
				t.Fatalf("got wrong columns back on iteration %d - should just be 0 but %v", i, row.Columns())
			}
		}
	})

	t.Run("skipped rows wrapped", func(t *testing.T) {
		f := mustOpenFragment("i", "f", "v", 0, CacheTypeRanked)
		defer f.Clean(t)
		f.mustSetBits(1, 0)
		f.mustSetBits(3, 0)
		f.mustSetBits(5, 0)
		f.mustSetBits(7, 0)

		iter := f.rowIterator(true)
		for i := uint64(1); i < 10; i += 2 {
			row, id, wrapped := iter.Next()
			if id != i%8 {
				t.Errorf("expected row %d but got %d", i%8, id)
			}
			if wrapped && i < 8 {
				t.Errorf("shouldn't have wrapped")
			} else if !wrapped && i >= 8 {
				t.Errorf("should have wrapped")
			}
			if !reflect.DeepEqual(row.Columns(), []uint64{0}) {
				t.Fatalf("got wrong columns back on iteration %d - should just be 0 but %v", i, row.Columns())
			}
		}
	})
}

func TestUnionInPlaceMapped(t *testing.T) {
	f := mustOpenFragment("i", "f", "v", 0, CacheTypeNone)
	defer f.Clean(t)
	// I know this doesn't actually matter in our current context, but
	// strictly speaking, we do say you have to hold the lock while calling
	// unprotectedWriteToFragment...
	f.mu.Lock()
	defer f.mu.Unlock()
	r0 := rand.New(rand.NewSource(2))
	r1 := rand.New(rand.NewSource(1))
	data0 := randPositions(1000000, r0)
	setBM0 := roaring.NewBitmap()
	setBM0.OpWriter = nil
	_, err := setBM0.Add(data0...)
	if err != nil {
		t.Fatalf("adding bits: %v", err)
	}
	count0 := setBM0.Count()

	data1 := randPositions(1000000, r1)
	setBM1 := roaring.NewBitmap()
	setBM1.OpWriter = nil
	_, err = setBM1.Add(data1...)
	if err != nil {
		t.Fatalf("adding bits: %v", err)
	}
	count1 := setBM1.Count()

	// now we write setBM0 into f.storage.
	_, err = unprotectedWriteToFragment(f, setBM0)
	if err != nil {
		t.Fatalf("trying to flush fragment to disk: %v", err)
	}
	countF := f.storage.Count()

	f.storage.UnionInPlace(setBM1)
	countUnion := f.storage.Count()
	// UnionInPlace produces no ops log, we have to make it snapshot, to
	// ensure that the on-disk representation is correct.
	f.enqueueSnapshot()

	if count0 != countF {
		t.Fatalf("writing bitmap to storage changed count: %d => %d", count0, countF)
	}
	min := count0
	if count1 > min {
		min = count1
	}
	max := count0 + count1
	// We don't know how many bits we should have, because of overlap,
	// but it should be between the size of the largest bitmap and the
	// sum of the bitmaps.
	if countUnion < min || countUnion > max {
		t.Fatalf("union of sets with cardinality %d and %d should be between %d and %d, got %d",
			count0, count1, min, max, countUnion)
	}
}

func randPositions(n int, r *rand.Rand) []uint64 {
	ret := make([]uint64, n)
	for i := 0; i < n; i++ {
		ret[i] = uint64(r.Int63n(ShardWidth))
	}
	return ret
}

func TestFragmentPositionsForValue(t *testing.T) {
	f := mustOpenFragment("i", "f", "v", 0, CacheTypeNone)
	defer f.Clean(t)

	tests := []struct {
		columnID uint64
		bitDepth uint
		value    int64
		clear    bool
		toSet    []uint64
		toClear  []uint64
	}{
		{
			columnID: 0,
			bitDepth: 1,
			value:    0,
			toSet:    []uint64{0},                          // exists bit only
			toClear:  []uint64{ShardWidth, ShardWidth * 2}, // sign bit & 1-position
		},
		{
			columnID: 0,
			bitDepth: 3,
			value:    0,
			toSet:    []uint64{0},                                                              // exists bit only
			toClear:  []uint64{ShardWidth * 1, ShardWidth * 2, ShardWidth * 3, ShardWidth * 4}, // sign bit, 1, 2, 4
		},
		{
			columnID: 1,
			bitDepth: 3,
			value:    0,
			toSet:    []uint64{1},                                                                    // exists bit only
			toClear:  []uint64{ShardWidth + 1, ShardWidth*2 + 1, ShardWidth*3 + 1, ShardWidth*4 + 1}, // sign bit, 1, 2, 4
		},
		{
			columnID: 0,
			bitDepth: 1,
			value:    1,
			toSet:    []uint64{0, ShardWidth * 2}, // exists bit, 1
			toClear:  []uint64{ShardWidth},        // sign bit only
		},
		{
			columnID: 0,
			bitDepth: 4,
			value:    10,
			toSet:    []uint64{0, ShardWidth * 3, ShardWidth * 5},              // exists bit, 2, 8
			toClear:  []uint64{ShardWidth * 1, ShardWidth * 2, ShardWidth * 4}, // sign bit, 1, 4
		},
		{
			columnID: 0,
			bitDepth: 5,
			value:    10,
			toSet:    []uint64{0, ShardWidth * 3, ShardWidth * 5},                              // exists bit, 2, 8
			toClear:  []uint64{ShardWidth * 1, ShardWidth * 2, ShardWidth * 4, ShardWidth * 6}, // sign bit, 1, 4, 16
		},
	}

	for i, test := range tests {
		toSet, toClear := make([]uint64, 0), make([]uint64, 0)
		var err error
		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
			toSet, toClear, err = f.positionsForValue(test.columnID, test.bitDepth, test.value, test.clear, toSet, toClear)
			if err != nil {
				t.Fatalf("getting positions: %v", err)
			}

			if len(toSet) != len(test.toSet) || len(toClear) != len(test.toClear) {
				t.Fatalf("differing lengths (exp/got): set\n%v\n%v\nclear\n%v\n%v\n", test.toSet, toSet, test.toClear, toClear)
			}
			for i := 0; i < len(toSet); i++ {
				if toSet[i] != test.toSet[i] {
					t.Errorf("toSet don't match at %d - exp:%d and got:%d", i, test.toSet[i], toSet[i])
				}
			}
			for i := 0; i < len(toClear); i++ {
				if toClear[i] != test.toClear[i] {
					t.Errorf("toClear don't match at %d - exp:%d and got:%d", i, test.toClear[i], toClear[i])
				}
			}
		})
	}
}

func TestImportClearRestart(t *testing.T) {
	tests := []struct {
		rows []uint64
		cols []uint64
	}{
		{
			rows: []uint64{1},
			cols: []uint64{1},
		},
		{
			rows: []uint64{1, 2, 3, 4, 5, 6, 7, 8, 9, 1},
			cols: []uint64{1, 2, 3, 4, 5, 6, 7, 8, 9, 500000},
		},
		{
			rows: []uint64{0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
			cols: []uint64{0, 65535, 65536, 131071, 131072, 196607, 196608, 262143, 262144, 1000000},
		},
		{
			rows: []uint64{1, 2, 20, 200, 2000, 200000},
			cols: []uint64{1, 1, 1, 1, 1, 1},
		},
	}

	for i, test := range tests {
		for _, maxOpN := range []int{0, 10000} {
			t.Run(fmt.Sprintf("%dMaxOpN%d", i, maxOpN), func(t *testing.T) {
				testrows, testcols := make([]uint64, len(test.rows)), make([]uint64, len(test.rows))
				copy(testrows, test.rows)
				copy(testcols, test.cols)
				exp := make(map[uint64]map[uint64]struct{}) // row num to cols
				if len(testrows) != len(testcols) {
					t.Fatalf("bad test spec-need same number of rows/cols, %d/%d", len(testrows), len(testcols))
				}
				// set up expected data
				expOpN := 0
				for i := range testrows {
					row, col := testrows[i], testcols[i]
					cols, ok := exp[row]
					if !ok {
						exp[row] = make(map[uint64]struct{})
						cols = exp[row]
					}
					if _, ok = cols[col]; !ok {
						expOpN++
						cols[col] = struct{}{}
					}
				}

				f := mustOpenFragment("i", "f", viewStandard, 0, "")
				f.MaxOpN = maxOpN
				err := f.bulkImport(testrows, testcols, &ImportOptions{})
				if err != nil {
					t.Fatalf("initial small import: %v", err)
				}
				if expOpN <= maxOpN && f.opN != expOpN {
					t.Errorf("unexpected opN - %d is not %d", f.opN, expOpN)
				}
				check(t, f, exp)

				err = f.Close()
				if err != nil {
					t.Fatalf("closing fragment: %v", err)
				}

				err = f.Open()
				if err != nil {
					t.Fatalf("reopening fragment: %v", err)
				}

				if expOpN <= maxOpN && f.opN != expOpN {
					t.Errorf("unexpected opN after close/open %d is not %d", f.opN, expOpN)
				}

				check(t, f, exp)

				f2 := newFragment(f.path, "i", "f", viewStandard, 0, 0)
				f2.MaxOpN = maxOpN
				f2.CacheType = f.CacheType

				err = f.closeStorage(true)
				if err != nil {
					t.Fatalf("closing storage: %v", err)
				}

				err = f2.Open()
				if err != nil {
					t.Fatalf("opening new fragment: %v", err)
				}

				if expOpN <= maxOpN && f2.opN != expOpN {
					t.Errorf("unexpected opN after close/open %d is not %d", f2.opN, expOpN)
				}

				check(t, f2, exp)

				copy(testrows, test.rows)
				copy(testcols, test.cols)
				err = f2.bulkImport(testrows, testcols, &ImportOptions{Clear: true})
				if err != nil {
					t.Fatalf("clearing imported data: %v", err)
				}

				// clear exp, but leave rows in so we re-query them in `check`
				for row := range exp {
					exp[row] = nil
				}

				check(t, f2, exp)

				f3 := newFragment(f2.path, "i", "f", viewStandard, 0, 0)
				f3.MaxOpN = maxOpN
				f3.CacheType = f.CacheType

				err = f2.closeStorage(true)
				if err != nil {
					t.Fatalf("f2 closing storage: %v", err)
				}

				err = f3.Open()
				if err != nil {
					t.Fatalf("opening f3: %v", err)
				}
				defer f3.Clean(t)

				check(t, f3, exp)

			})

		}
	}
}

func check(t *testing.T, f *fragment, exp map[uint64]map[uint64]struct{}) {
	for rowID, colsExp := range exp {
		colsAct := f.row(rowID).Columns()
		if len(colsAct) != len(colsExp) {
			t.Errorf("row %d len mismatch got: %d exp:%d", rowID, len(colsAct), len(colsExp))
		}
		for _, colAct := range colsAct {
			if _, ok := colsExp[colAct]; !ok {
				t.Errorf("extra column: %d", colAct)
			}
		}
		for colExp := range colsExp {
			found := false
			for _, colAct := range colsAct {
				if colExp == colAct {
					found = true
					break
				}
			}
			if !found {
				t.Errorf("expected %d, but not found", colExp)
			}
		}
	}

}

func TestImportValueConcurrent(t *testing.T) {
	f := mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
	eg := &errgroup.Group{}
	for i := 0; i < 4; i++ {
		i := i
		eg.Go(func() error {
			for j := uint64(0); j < 10; j++ {
				err := f.importValue([]uint64{j}, []int64{int64(rand.Int63n(1000))}, 10, i%2 == 0)
				if err != nil {
					return err
				}
			}
			return nil
		})
	}
	err := eg.Wait()
	if err != nil {
		t.Fatalf("concurrently importing values: %v", err)
	}
}

func TestImportMultipleValues(t *testing.T) {
	tests := []struct {
		cols      []uint64
		vals      []int64
		checkCols []uint64
		checkVals []int64
		depth     uint
	}{
		{
			cols:      []uint64{0, 0},
			vals:      []int64{97, 100},
			depth:     7,
			checkCols: []uint64{0},
			checkVals: []int64{100},
		},
	}

	for i, test := range tests {
		for _, maxOpN := range []int{0, 10000} { // test small/large write
			t.Run(fmt.Sprintf("%dLowOpN", i), func(t *testing.T) {
				f := mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
				f.MaxOpN = maxOpN
				defer f.Clean(t)
				err := f.importValue(test.cols, test.vals, test.depth, false)
				if err != nil {
					t.Fatalf("importing values: %v", err)
				}

				for i := range test.checkCols {
					cc, cv := test.checkCols[i], test.checkVals[i]
					n, exists, err := f.value(cc, test.depth)
					if err != nil {
						t.Fatalf("getting value: %v", err)
					}
					if !exists {
						t.Errorf("column %d should exist", cc)
					}
					if n != cv {
						t.Errorf("wrong value: %d is not %d", n, cv)
					}
				}
			})

		}
	}
}

func TestImportValueRowCache(t *testing.T) {
	type testCase struct {
		cols      []uint64
		vals      []int64
		checkCols []uint64
		depth     uint
	}
	tests := []struct {
		tc1 testCase
		tc2 testCase
	}{
		{
			tc1: testCase{
				cols:      []uint64{2},
				vals:      []int64{1},
				depth:     1,
				checkCols: []uint64{2},
			},
			tc2: testCase{
				cols:      []uint64{1000},
				vals:      []int64{1},
				depth:     1,
				checkCols: []uint64{2, 1000},
			},
		},
	}

	for i, test := range tests {
		for _, maxOpN := range []int{1, 10000} {
			t.Run(fmt.Sprintf("%dMaxOpN%d", i, maxOpN), func(t *testing.T) {
				f := mustOpenBSIFragment("i", "f", viewBSIGroupPrefix+"foo", 0)
				f.MaxOpN = maxOpN
				defer f.Clean(t)

				// First import (tc1)
				if err := f.importValue(test.tc1.cols, test.tc1.vals, test.tc1.depth, false); err != nil {
					t.Fatalf("importing values: %v", err)
				}

				if r, err := f.rangeOp(pql.GT, test.tc1.depth, 0); err != nil {
					t.Error("getting range of values")
				} else if !reflect.DeepEqual(r.Columns(), test.tc1.checkCols) {
					t.Errorf("wrong column values. expected: %v, but got: %v", test.tc1.checkCols, r.Columns())
				}

				// Second import (tc2)
				if err := f.importValue(test.tc2.cols, test.tc2.vals, test.tc2.depth, false); err != nil {
					t.Fatalf("importing values: %v", err)
				}

				if r, err := f.rangeOp(pql.GT, test.tc2.depth, 0); err != nil {
					t.Error("getting range of values")
				} else if !reflect.DeepEqual(r.Columns(), test.tc2.checkCols) {
					t.Errorf("wrong column values. expected: %v, but got: %v", test.tc2.checkCols, r.Columns())
				}
			})
		}
	}
}

func TestFragmentConcurrentReadWrite(t *testing.T) {
	f := mustOpenFragment("i", "f", viewStandard, 0, CacheTypeRanked)
	defer f.Clean(t)

	eg := &errgroup.Group{}
	eg.Go(func() error {
		for i := uint64(0); i < 1000; i++ {
			_, err := f.setBit(i%4, i)
			if err != nil {
				return errors.Wrap(err, "setting bit")
			}
		}
		return nil
	})

	acc := uint64(0)
	for i := uint64(0); i < 100; i++ {
		r := f.row(i % 4)
		acc += r.Count()
	}
	if err := eg.Wait(); err != nil {
		t.Errorf("error from setting a bit: %v", err)
	}

	t.Logf("%d", acc)
}