// note this function is only used for benchmarks -- it doesn't escape tableName
// or columnNames
func multiInsert(conn *pgx.Conn, tableName string, columnNames []string, rowSrc pgx.CopyToSource) (int, error) {
maxRowsPerInsert := 65535 / len(columnNames)
rowsThisInsert := 0
rowCount := 0
sqlBuf := &bytes.Buffer{}
args := make(pgx.QueryArgs, 0)
resetQuery := func() {
sqlBuf.Reset()
fmt.Fprintf(sqlBuf, "insert into %s(%s) values", tableName, strings.Join(columnNames, ", "))
args = args[0:0]
rowsThisInsert = 0
}
resetQuery()
tx, err := conn.Begin()
if err != nil {
return 0, err
}
defer tx.Rollback()
for rowSrc.Next() {
if rowsThisInsert > 0 {
sqlBuf.WriteByte(',')
}
sqlBuf.WriteByte('(')
values, err := rowSrc.Values()
if err != nil {
return 0, err
}
for i, val := range values {
if i > 0 {
sqlBuf.WriteByte(',')
}
sqlBuf.WriteString(args.Append(val))
}
sqlBuf.WriteByte(')')
rowsThisInsert++
if rowsThisInsert == maxRowsPerInsert {
_, err := tx.Exec(sqlBuf.String(), args...)
if err != nil {
return 0, err
}
rowCount += rowsThisInsert
resetQuery()
}
}
if rowsThisInsert > 0 {
_, err := tx.Exec(sqlBuf.String(), args...)
if err != nil {
return 0, err
}
rowCount += rowsThisInsert
}
if err := tx.Commit(); err != nil {
return 0, nil
}
return rowCount, nil
}