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copy_to.go
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copy_to.go
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package pgx
import (
"bytes"
"fmt"
)
// Deprecated. Use CopyFromRows instead. CopyToRows returns a CopyToSource
// interface over the provided rows slice making it usable by *Conn.CopyTo.
func CopyToRows(rows [][]interface{}) CopyToSource {
return ©ToRows{rows: rows, idx: -1}
}
type copyToRows struct {
rows [][]interface{}
idx int
}
func (ctr *copyToRows) Next() bool {
ctr.idx++
return ctr.idx < len(ctr.rows)
}
func (ctr *copyToRows) Values() ([]interface{}, error) {
return ctr.rows[ctr.idx], nil
}
func (ctr *copyToRows) Err() error {
return nil
}
// Deprecated. Use CopyFromSource instead. CopyToSource is the interface used by
// *Conn.CopyTo as the source for copy data.
type CopyToSource interface {
// Next returns true if there is another row and makes the next row data
// available to Values(). When there are no more rows available or an error
// has occurred it returns false.
Next() bool
// Values returns the values for the current row.
Values() ([]interface{}, error)
// Err returns any error that has been encountered by the CopyToSource. If
// this is not nil *Conn.CopyTo will abort the copy.
Err() error
}
type copyTo struct {
conn *Conn
tableName string
columnNames []string
rowSrc CopyToSource
readerErrChan chan error
}
func (ct *copyTo) readUntilReadyForQuery() {
for {
t, r, err := ct.conn.rxMsg()
if err != nil {
ct.readerErrChan <- err
close(ct.readerErrChan)
return
}
switch t {
case readyForQuery:
ct.conn.rxReadyForQuery(r)
close(ct.readerErrChan)
return
case commandComplete:
case errorResponse:
ct.readerErrChan <- ct.conn.rxErrorResponse(r)
default:
err = ct.conn.processContextFreeMsg(t, r)
if err != nil {
ct.readerErrChan <- ct.conn.processContextFreeMsg(t, r)
}
}
}
}
func (ct *copyTo) waitForReaderDone() error {
var err error
for err = range ct.readerErrChan {
}
return err
}
func (ct *copyTo) run() (int, error) {
quotedTableName := quoteIdentifier(ct.tableName)
buf := &bytes.Buffer{}
for i, cn := range ct.columnNames {
if i != 0 {
buf.WriteString(", ")
}
buf.WriteString(quoteIdentifier(cn))
}
quotedColumnNames := buf.String()
ps, err := ct.conn.Prepare("", fmt.Sprintf("select %s from %s", quotedColumnNames, quotedTableName))
if err != nil {
return 0, err
}
err = ct.conn.sendSimpleQuery(fmt.Sprintf("copy %s ( %s ) from stdin binary;", quotedTableName, quotedColumnNames))
if err != nil {
return 0, err
}
err = ct.conn.readUntilCopyInResponse()
if err != nil {
return 0, err
}
go ct.readUntilReadyForQuery()
defer ct.waitForReaderDone()
wbuf := newWriteBuf(ct.conn, copyData)
wbuf.WriteBytes([]byte("PGCOPY\n\377\r\n\000"))
wbuf.WriteInt32(0)
wbuf.WriteInt32(0)
var sentCount int
for ct.rowSrc.Next() {
select {
case err = <-ct.readerErrChan:
return 0, err
default:
}
if len(wbuf.buf) > 65536 {
wbuf.closeMsg()
_, err = ct.conn.conn.Write(wbuf.buf)
if err != nil {
ct.conn.die(err)
return 0, err
}
// Directly manipulate wbuf to reset to reuse the same buffer
wbuf.buf = wbuf.buf[0:5]
wbuf.buf[0] = copyData
wbuf.sizeIdx = 1
}
sentCount++
values, err := ct.rowSrc.Values()
if err != nil {
ct.cancelCopyIn()
return 0, err
}
if len(values) != len(ct.columnNames) {
ct.cancelCopyIn()
return 0, fmt.Errorf("expected %d values, got %d values", len(ct.columnNames), len(values))
}
wbuf.WriteInt16(int16(len(ct.columnNames)))
for i, val := range values {
err = Encode(wbuf, ps.FieldDescriptions[i].DataType, val)
if err != nil {
ct.cancelCopyIn()
return 0, err
}
}
}
if ct.rowSrc.Err() != nil {
ct.cancelCopyIn()
return 0, ct.rowSrc.Err()
}
wbuf.WriteInt16(-1) // terminate the copy stream
wbuf.startMsg(copyDone)
wbuf.closeMsg()
_, err = ct.conn.conn.Write(wbuf.buf)
if err != nil {
ct.conn.die(err)
return 0, err
}
err = ct.waitForReaderDone()
if err != nil {
return 0, err
}
return sentCount, nil
}
func (ct *copyTo) cancelCopyIn() error {
wbuf := newWriteBuf(ct.conn, copyFail)
wbuf.WriteCString("client error: abort")
wbuf.closeMsg()
_, err := ct.conn.conn.Write(wbuf.buf)
if err != nil {
ct.conn.die(err)
return err
}
return nil
}
// Deprecated. Use CopyFrom instead. CopyTo uses the PostgreSQL copy protocol to
// perform bulk data insertion. It returns the number of rows copied and an
// error.
//
// CopyTo requires all values use the binary format. Almost all types
// implemented by pgx use the binary format by default. Types implementing
// Encoder can only be used if they encode to the binary format.
func (c *Conn) CopyTo(tableName string, columnNames []string, rowSrc CopyToSource) (int, error) {
ct := ©To{
conn: c,
tableName: tableName,
columnNames: columnNames,
rowSrc: rowSrc,
readerErrChan: make(chan error),
}
return ct.run()
}