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planner: fix index heuristic rule will prune out hint preferred tiflash path (#46102) #46145

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merged 4 commits into from
Oct 16, 2023
Merged

planner: fix index heuristic rule will prune out hint preferred tiflash path (#46102) #46145

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01c74f7
fix heuristic rule will prune out hint preferred path
AilinKid Aug 15, 2023
3a0462b
remove useless code
AilinKid Aug 15, 2023
533c800
make fmt
AilinKid Aug 16, 2023
e52e85d
fix test
AilinKid Oct 16, 2023
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7 changes: 7 additions & 0 deletions planner/core/casetest/enforce_mpp_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@ func TestEnforceMPP(t *testing.T) {
tk.MustExec("drop table if exists t")
tk.MustExec("create table t(a int, b int)")
tk.MustExec("create index idx on t(a)")
tk.MustExec("CREATE TABLE `s` (\n `a` int(11) DEFAULT NULL,\n `b` int(11) DEFAULT NULL,\n `c` int(11) DEFAULT NULL,\n `d` int(11) DEFAULT NULL,\n UNIQUE KEY `a` (`a`),\n KEY `ii` (`a`,`b`)\n)")

// Default RPC encoding may cause statistics explain result differ and then the test unstable.
tk.MustExec("set @@tidb_enable_chunk_rpc = on")
Expand All @@ -55,6 +56,12 @@ func TestEnforceMPP(t *testing.T) {
Available: true,
}
}
if tblInfo.Name.L == "s" {
tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
Count: 1,
Available: true,
}
}
}

var input []string
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3 changes: 2 additions & 1 deletion planner/core/casetest/testdata/enforce_mpp_suite_in.json
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Expand Up @@ -21,7 +21,8 @@
"set @@tidb_enforce_mpp=1;",
"explain format='verbose' select count(*) from t where a=1",
"explain format='verbose' select /*+ read_from_storage(tikv[t]) */ count(*) from t where a=1",
"explain format='verbose' select /*+ read_from_storage(tiflash[t]) */ count(*) from t where a=1"
"explain format='verbose' select /*+ read_from_storage(tiflash[t]) */ count(*) from t where a=1",
"explain select /*+ READ_FROM_STORAGE(TIFLASH[s]) */ a from s where a = 10 and b is null; -- index path huristic rule will prune tiflash path"
]
},
{
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11 changes: 11 additions & 0 deletions planner/core/casetest/testdata/enforce_mpp_suite_out.json
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Expand Up @@ -173,6 +173,17 @@
" └─TableFullScan_25 10000.00 928000.00 batchCop[tiflash] table:t pushed down filter:empty, keep order:false, stats:pseudo"
],
"Warn": null
},
{
"SQL": "explain select /*+ READ_FROM_STORAGE(TIFLASH[s]) */ a from s where a = 10 and b is null; -- index path huristic rule will prune tiflash path",
"Plan": [
"TableReader_12 0.10 root MppVersion: 1, data:ExchangeSender_11",
"└─ExchangeSender_11 0.10 mpp[tiflash] ExchangeType: PassThrough",
" └─Projection_5 0.10 mpp[tiflash] test.s.a",
" └─Selection_10 0.10 mpp[tiflash] isnull(test.s.b)",
" └─TableFullScan_9 10.00 mpp[tiflash] table:s pushed down filter:eq(test.s.a, 10), keep order:false, stats:pseudo"
],
"Warn": null
}
]
},
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9 changes: 8 additions & 1 deletion planner/core/stats.go
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Expand Up @@ -24,6 +24,7 @@ import (
"github.com/pingcap/errors"
"github.com/pingcap/tidb/domain"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/parser/mysql"
"github.com/pingcap/tidb/planner/property"
Expand Down Expand Up @@ -415,8 +416,14 @@ func (ds *DataSource) derivePathStatsAndTryHeuristics() error {
selected = uniqueBest
}
}
// If some path matches a heuristic rule, just remove other possible paths
// heuristic rule pruning other path should consider hint prefer.
// If no hints and some path matches a heuristic rule, just remove other possible paths.
if selected != nil {
// if user wanna tiFlash read, while current heuristic choose a TiKV path. so we shouldn't prune other paths.
keep := ds.preferStoreType&preferTiFlash != 0 && selected.StoreType != kv.TiFlash
if keep {
return nil
}
ds.possibleAccessPaths[0] = selected
ds.possibleAccessPaths = ds.possibleAccessPaths[:1]
var tableName string
Expand Down