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GeezerVison is showing github.com — batchsql/multi_row.go at master · go-batchsql/batchsql

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multi_row.go

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// Copyright (c) 2016, M Bogus.
// This source file is part of the batchsql open source project
// Licensed under Apache License v2.0
// See LICENSE file for license information
package batchsql
import (
"database/sql"
"errors"
"fmt"
"regexp"
"strings"
)
const sqlComment = `(\/\*.*?\*\/)`
var (
reSQLValues = regexp.MustCompile(`.*VALUES(\n|\s)*?(?P<values>\(.+\)).*`)
reEmptyValues = regexp.MustCompile(`\(\s+\).*`)
reSQLInsertStmt = regexp.MustCompile(fmt.Sprintf(`(%s|\s)*INSERT(%s|\s)*INTO.+|\n*VALUES.*`, sqlComment, sqlComment))
reMySQLOnDuplicateKey = regexp.MustCompile("\\s*ON\\s+DUPLICATE\\s+KEY(?:[^\"'`]*[\"'`][^\"'`]*[\"'`])*[^\"'`]*$")
)
// MultiRow is a wrapper around sql.DB or sql.Tx supporting
// multi-row insert statements execution with arbitrary
// batch size
type MultiRow struct {
Conn Preparable
BatchSize int
}
// Preparable is an interface for any type able to prepare
// SQL statement
type Preparable interface {
Prepare(query string) (*sql.Stmt, error)
}
// CheckQuery is checking if query string is eligible for rewriting into a multi-row insert.
func CheckQuery(query string) error {
if reMySQLOnDuplicateKey.MatchString(query) {
query = reMySQLOnDuplicateKey.ReplaceAllString(query, "")
}
if !reSQLInsertStmt.MatchString(query) {
return errors.New("Invalid statement for multi-row INSERT: INSERT [ INTO ] <object> [ column_list ] VALUES sequence not recognized")
}
if !reSQLValues.MatchString(query) {
return errors.New("Invalid statement for multi-row INSERT: ... VALUES (? [, ...?]) ... sequence not recognized")
}
return nil
}
// MultiInsert is executing multi-row insert query iterating over the list of
// arguments in args. The query string is checked for eligibility for multi-row
// rewrite. INSERT statements are optimized by batching the data using common
// multi-row syntax and results are discarded
func (conn *MultiRow) MultiInsert(
query string,
args ...([]interface{})) error {
if len(args) == 0 {
return errors.New("Invalid multi-row INSERT call with no arguments")
}
if err := CheckQuery(query); err != nil {
return err
}
var err error
var size int
var stmt *sql.Stmt
values, err := extractValues(query)
if err != nil {
return err
}
for i := 0; i < len(args); i += conn.BatchSize {
j := min(i+conn.BatchSize, len(args))
batch := args[i:j]
if stmt == nil || len(batch) != size {
if stmt != nil {
stmt.Close()
}
size = len(batch)
multiQuery := rewriteInsertSQL(&query, &values, size)
stmt, err = conn.Conn.Prepare(multiQuery)
if err != nil {
return err
}
}
batchArgs := joinArgs(batch)
_, err := stmt.Exec(batchArgs...)
if err != nil {
stmt.Close()
return err
}
}
return stmt.Close()
}
func extractValues(query string) (string, error) {
if reMySQLOnDuplicateKey.MatchString(query) {
query = reMySQLOnDuplicateKey.ReplaceAllString(query, "")
}
names := reSQLValues.SubexpNames()
matches := reSQLValues.FindAllStringSubmatch(query, -1)
err := errors.New("Unable to parse VALUES (? [, ...?]) sequence")
if matches == nil || len(matches) == 0 {
return "", err
}
for i, name := range names {
if name == "values" {
if v := matches[0][i]; !reEmptyValues.Match([]byte(v)) {
return v, nil
}
break
}
}
return "", err
}
func min(a, b int) int {
if a <= b {
return a
}
return b
}
func rewriteInsertSQL(query *string, params *string, count int) string {
arr := make([]string, count, count)
for i := range arr {
arr[i] = *params
}
return strings.Replace(*query, *params, strings.Join(arr, ","), 1)
}
func joinArgs(args []([]interface{})) []interface{} {
var joined []interface{}
for _, p := range args {
joined = append(joined, p...)
}
return joined
}
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