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copy_from.go
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copy_from.go
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package pgx
import (
"bytes"
"context"
"fmt"
"io"
"time"
"github.com/jackc/pgconn"
"github.com/jackc/pgio"
)
// CopyFromRows returns a CopyFromSource interface over the provided rows slice
// making it usable by *Conn.CopyFrom.
func CopyFromRows(rows [][]interface{}) CopyFromSource {
return ©FromRows{rows: rows, idx: -1}
}
type copyFromRows struct {
rows [][]interface{}
idx int
}
func (ctr *copyFromRows) Next() bool {
ctr.idx++
return ctr.idx < len(ctr.rows)
}
func (ctr *copyFromRows) Values() ([]interface{}, error) {
return ctr.rows[ctr.idx], nil
}
func (ctr *copyFromRows) Err() error {
return nil
}
// CopyFromSlice returns a CopyFromSource interface over a dynamic func
// making it usable by *Conn.CopyFrom.
func CopyFromSlice(length int, next func(int) ([]interface{}, error)) CopyFromSource {
return ©FromSlice{next: next, idx: -1, len: length}
}
type copyFromSlice struct {
next func(int) ([]interface{}, error)
idx int
len int
err error
}
func (cts *copyFromSlice) Next() bool {
cts.idx++
return cts.idx < cts.len
}
func (cts *copyFromSlice) Values() ([]interface{}, error) {
values, err := cts.next(cts.idx)
if err != nil {
cts.err = err
}
return values, err
}
func (cts *copyFromSlice) Err() error {
return cts.err
}
// CopyFromSource is the interface used by *Conn.CopyFrom as the source for copy data.
type CopyFromSource 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 CopyFromSource. If
// this is not nil *Conn.CopyFrom will abort the copy.
Err() error
}
type copyFrom struct {
conn *Conn
tableName Identifier
columnNames []string
rowSrc CopyFromSource
readerErrChan chan error
}
func (ct *copyFrom) run(ctx context.Context) (int64, error) {
quotedTableName := ct.tableName.Sanitize()
cbuf := &bytes.Buffer{}
for i, cn := range ct.columnNames {
if i != 0 {
cbuf.WriteString(", ")
}
cbuf.WriteString(quoteIdentifier(cn))
}
quotedColumnNames := cbuf.String()
sd, err := ct.conn.Prepare(ctx, "", fmt.Sprintf("select %s from %s", quotedColumnNames, quotedTableName))
if err != nil {
return 0, err
}
r, w := io.Pipe()
doneChan := make(chan struct{})
go func() {
defer close(doneChan)
// Purposely NOT using defer w.Close(). See https://github.com/golang/go/issues/24283.
buf := ct.conn.wbuf
buf = append(buf, "PGCOPY\n\377\r\n\000"...)
buf = pgio.AppendInt32(buf, 0)
buf = pgio.AppendInt32(buf, 0)
moreRows := true
for moreRows {
var err error
moreRows, buf, err = ct.buildCopyBuf(buf, sd)
if err != nil {
w.CloseWithError(err)
return
}
if ct.rowSrc.Err() != nil {
w.CloseWithError(ct.rowSrc.Err())
return
}
if len(buf) > 0 {
_, err = w.Write(buf)
if err != nil {
w.Close()
return
}
}
buf = buf[:0]
}
w.Close()
}()
startTime := time.Now()
commandTag, err := ct.conn.pgConn.CopyFrom(ctx, r, fmt.Sprintf("copy %s ( %s ) from stdin binary;", quotedTableName, quotedColumnNames))
r.Close()
<-doneChan
rowsAffected := commandTag.RowsAffected()
if err == nil {
if ct.conn.shouldLog(LogLevelInfo) {
endTime := time.Now()
ct.conn.log(ctx, LogLevelInfo, "CopyFrom", map[string]interface{}{"tableName": ct.tableName, "columnNames": ct.columnNames, "time": endTime.Sub(startTime), "rowCount": rowsAffected})
}
} else if ct.conn.shouldLog(LogLevelError) {
ct.conn.log(ctx, LogLevelError, "CopyFrom", map[string]interface{}{"err": err, "tableName": ct.tableName, "columnNames": ct.columnNames})
}
return rowsAffected, err
}
func (ct *copyFrom) buildCopyBuf(buf []byte, sd *pgconn.StatementDescription) (bool, []byte, error) {
for ct.rowSrc.Next() {
values, err := ct.rowSrc.Values()
if err != nil {
return false, nil, err
}
if len(values) != len(ct.columnNames) {
return false, nil, fmt.Errorf("expected %d values, got %d values", len(ct.columnNames), len(values))
}
buf = pgio.AppendInt16(buf, int16(len(ct.columnNames)))
for i, val := range values {
buf, err = encodePreparedStatementArgument(ct.conn.connInfo, buf, sd.Fields[i].DataTypeOID, val)
if err != nil {
return false, nil, err
}
}
if len(buf) > 65536 {
return true, buf, nil
}
}
return false, buf, nil
}
// CopyFrom uses the PostgreSQL copy protocol to perform bulk data insertion.
// It returns the number of rows copied and an error.
//
// CopyFrom 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) CopyFrom(ctx context.Context, tableName Identifier, columnNames []string, rowSrc CopyFromSource) (int64, error) {
ct := ©From{
conn: c,
tableName: tableName,
columnNames: columnNames,
rowSrc: rowSrc,
readerErrChan: make(chan error),
}
return ct.run(ctx)
}