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455 lines
12 KiB
Go
455 lines
12 KiB
Go
// Package postgres implements the sq driver for postgres.
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package postgres
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import (
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"context"
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"database/sql"
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"fmt"
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"strconv"
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"strings"
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// Import jackc/pgx, which is our postgres driver.
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_ "github.com/jackc/pgx/v4/stdlib"
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"github.com/neilotoole/lg"
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"github.com/neilotoole/sq/libsq/ast/sqlbuilder"
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"github.com/neilotoole/sq/libsq/core/errz"
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"github.com/neilotoole/sq/libsq/core/kind"
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"github.com/neilotoole/sq/libsq/core/sqlz"
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"github.com/neilotoole/sq/libsq/core/stringz"
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"github.com/neilotoole/sq/libsq/driver"
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"github.com/neilotoole/sq/libsq/source"
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"github.com/neilotoole/sq/libsq/sqlmodel"
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)
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const (
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// Type is the postgres source driver type.
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Type = source.Type("postgres")
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// dbDrvr is the backing postgres SQL driver impl name.
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dbDrvr = "pgx"
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)
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// Provider is the postgres implementation of driver.Provider.
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type Provider struct {
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Log lg.Log
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}
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// DriverFor implements driver.Provider.
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func (p *Provider) DriverFor(typ source.Type) (driver.Driver, error) {
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if typ != Type {
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return nil, errz.Errorf("unsupported driver type %q", typ)
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}
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return &driveri{log: p.Log}, nil
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}
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// driveri is the postgres implementation of driver.Driver.
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type driveri struct {
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log lg.Log
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}
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// DriverMetadata implements driver.Driver.
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func (d *driveri) DriverMetadata() driver.Metadata {
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return driver.Metadata{
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Type: Type,
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Description: "PostgreSQL",
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Doc: "https://github.com/jackc/pgx",
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IsSQL: true,
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}
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}
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// Dialect implements driver.SQLDriver.
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func (d *driveri) Dialect() driver.Dialect {
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return driver.Dialect{
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Type: Type,
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Placeholders: placeholders,
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Quote: '"',
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MaxBatchValues: 1000,
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}
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}
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func placeholders(numCols, numRows int) string {
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rows := make([]string, numRows)
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n := 1
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var sb strings.Builder
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for i := 0; i < numRows; i++ {
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sb.Reset()
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sb.WriteRune('(')
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for j := 1; j <= numCols; j++ {
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sb.WriteRune('$')
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sb.WriteString(strconv.Itoa(n))
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n++
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if j < numCols {
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sb.WriteString(driver.Comma)
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}
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}
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sb.WriteRune(')')
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rows[i] = sb.String()
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}
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return strings.Join(rows, driver.Comma)
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}
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// SQLBuilder implements driver.SQLDriver.
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func (d *driveri) SQLBuilder() (sqlbuilder.FragmentBuilder, sqlbuilder.QueryBuilder) {
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return newFragmentBuilder(d.log), &sqlbuilder.BaseQueryBuilder{}
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}
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// Open implements driver.Driver.
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func (d *driveri) Open(ctx context.Context, src *source.Source) (driver.Database, error) {
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db, err := sql.Open(dbDrvr, src.Location)
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if err != nil {
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return nil, errz.Err(err)
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}
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return &database{log: d.log, db: db, src: src, drvr: d}, nil
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}
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// ValidateSource implements driver.Driver.
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func (d *driveri) ValidateSource(src *source.Source) (*source.Source, error) {
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if src.Type != Type {
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return nil, errz.Errorf("expected source type %q but got %q", Type, src.Type)
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}
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return src, nil
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}
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// Ping implements driver.Driver.
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func (d *driveri) Ping(ctx context.Context, src *source.Source) error {
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dbase, err := d.Open(context.TODO(), src)
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if err != nil {
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return err
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}
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defer d.log.WarnIfCloseError(dbase.DB())
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return dbase.DB().Ping()
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}
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// Truncate implements driver.Driver.
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func (d *driveri) Truncate(ctx context.Context, src *source.Source, tbl string, reset bool) (affected int64, err error) {
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// https://www.postgresql.org/docs/9.1/sql-truncate.html
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// RESTART IDENTITY and CASCADE/RESTRICT are from pg 8.2 onwards
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// TODO: should first check the pg version for < pg8.2 support
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db, err := sql.Open(dbDrvr, src.Location)
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if err != nil {
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return affected, errz.Err(err)
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}
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query := fmt.Sprintf("TRUNCATE TABLE %q", tbl)
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if reset {
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// if reset & src.DBVersion >= 8.2
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query += " RESTART IDENTITY" // default is CONTINUE IDENTITY
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}
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// We could add RESTRICT here; alternative is CASCADE
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affected, err = sqlz.ExecResult(ctx, db, query)
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return affected, err
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}
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// CreateTable implements driver.SQLDriver.
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func (d *driveri) CreateTable(ctx context.Context, db sqlz.DB, tblDef *sqlmodel.TableDef) error {
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stmt := buildCreateTableStmt(tblDef)
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_, err := db.ExecContext(ctx, stmt)
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return errz.Err(err)
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}
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// AlterTableAddColumn implements driver.SQLDriver.
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func (d *driveri) AlterTableAddColumn(ctx context.Context, db *sql.DB, tbl string, col string, kind kind.Kind) error {
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q := fmt.Sprintf("ALTER TABLE %q ADD COLUMN %q ", tbl, col) + dbTypeNameFromKind(kind)
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_, err := db.ExecContext(ctx, q)
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if err != nil {
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return errz.Wrapf(err, "alter table: failed to add column %q to table %q", col, tbl)
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}
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return nil
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}
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// PrepareInsertStmt implements driver.SQLDriver.
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func (d *driveri) PrepareInsertStmt(ctx context.Context, db sqlz.DB, destTbl string, destColNames []string, numRows int) (*driver.StmtExecer, error) {
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// Note that the pgx driver doesn't support res.LastInsertId.
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// https://github.com/jackc/pgx/issues/411
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destColsMeta, err := d.getTableRecordMeta(ctx, db, destTbl, destColNames)
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if err != nil {
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return nil, err
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}
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stmt, err := driver.PrepareInsertStmt(ctx, d, db, destTbl, destColsMeta.Names(), numRows)
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if err != nil {
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return nil, err
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}
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execer := driver.NewStmtExecer(stmt, driver.DefaultInsertMungeFunc(destTbl, destColsMeta), newStmtExecFunc(stmt), destColsMeta)
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return execer, nil
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}
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// PrepareUpdateStmt implements driver.SQLDriver.
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func (d *driveri) PrepareUpdateStmt(ctx context.Context, db sqlz.DB, destTbl string, destColNames []string, where string) (*driver.StmtExecer, error) {
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destColsMeta, err := d.getTableRecordMeta(ctx, db, destTbl, destColNames)
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if err != nil {
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return nil, err
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}
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query, err := buildUpdateStmt(destTbl, destColNames, where)
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if err != nil {
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return nil, err
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}
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stmt, err := db.PrepareContext(ctx, query)
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if err != nil {
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return nil, err
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}
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execer := driver.NewStmtExecer(stmt, driver.DefaultInsertMungeFunc(destTbl, destColsMeta), newStmtExecFunc(stmt), destColsMeta)
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return execer, nil
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}
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func newStmtExecFunc(stmt *sql.Stmt) driver.StmtExecFunc {
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return func(ctx context.Context, args ...interface{}) (int64, error) {
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res, err := stmt.ExecContext(ctx, args...)
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if err != nil {
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return 0, errz.Err(err)
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}
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affected, err := res.RowsAffected()
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return affected, errz.Err(err)
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}
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}
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// CopyTable implements driver.SQLDriver.
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func (d *driveri) CopyTable(ctx context.Context, db sqlz.DB, fromTable, toTable string, copyData bool) (int64, error) {
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stmt := fmt.Sprintf("CREATE TABLE %q AS TABLE %q", toTable, fromTable)
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if !copyData {
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stmt += " WITH NO DATA"
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}
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affected, err := sqlz.ExecResult(ctx, db, stmt)
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if err != nil {
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return 0, errz.Err(err)
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}
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return affected, nil
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}
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// DropTable implements driver.SQLDriver.
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func (d *driveri) DropTable(ctx context.Context, db sqlz.DB, tbl string, ifExists bool) error {
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var stmt string
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if ifExists {
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stmt = fmt.Sprintf("DROP TABLE IF EXISTS %q RESTRICT", tbl)
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} else {
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stmt = fmt.Sprintf("DROP TABLE %q RESTRICT", tbl)
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}
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_, err := db.ExecContext(ctx, stmt)
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return errz.Err(err)
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}
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// TableColumnTypes implements driver.SQLDriver.
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func (d *driveri) TableColumnTypes(ctx context.Context, db sqlz.DB, tblName string, colNames []string) ([]*sql.ColumnType, error) {
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// We have to do some funky stuff to get the column types
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// from when the table has no rows.
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// https://stackoverflow.com/questions/8098795/return-a-value-if-no-record-is-found
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// If tblName is "person" and we want cols "username"
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// and "email", the query will look like:
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//
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// SELECT
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// (SELECT username FROM person LIMIT 1) AS username,
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// (SELECT email FROM person LIMIT 1) AS email
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// LIMIT 1;
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quote := string(d.Dialect().Quote)
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tblNameQuoted := stringz.Surround(tblName, quote)
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var query string
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if len(colNames) == 0 {
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// When the table is empty, and colNames are not provided,
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// then we need to fetch the table col names independently.
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var err error
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colNames, err = getTableColumnNames(ctx, d.log, db, tblName)
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if err != nil {
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return nil, err
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}
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}
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var sb strings.Builder
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sb.WriteString("SELECT\n")
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for i, colName := range colNames {
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colNameQuoted := stringz.Surround(colName, quote)
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sb.WriteString(fmt.Sprintf(" (SELECT %s FROM %s LIMIT 1) AS %s", colNameQuoted, tblNameQuoted, colNameQuoted))
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if i < len(colNames)-1 {
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sb.WriteRune(',')
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}
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sb.WriteString("\n")
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}
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sb.WriteString("LIMIT 1")
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query = sb.String()
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rows, err := db.QueryContext(ctx, query)
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if err != nil {
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return nil, errz.Err(err)
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}
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colTypes, err := rows.ColumnTypes()
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if err != nil {
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d.log.WarnIfFuncError(rows.Close)
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return nil, errz.Err(err)
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}
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err = rows.Err()
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if err != nil {
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d.log.WarnIfFuncError(rows.Close)
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return nil, errz.Err(err)
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}
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err = rows.Close()
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if err != nil {
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return nil, errz.Err(err)
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}
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return colTypes, nil
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}
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func (d *driveri) getTableRecordMeta(ctx context.Context, db sqlz.DB, tblName string, colNames []string) (sqlz.RecordMeta, error) {
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colTypes, err := d.TableColumnTypes(ctx, db, tblName, colNames)
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if err != nil {
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return nil, err
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}
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destCols, _, err := d.RecordMeta(colTypes)
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if err != nil {
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return nil, err
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}
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return destCols, nil
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}
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// getTableColumnNames consults postgres's information_schema.columns table,
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// returning the names of the table's columns in oridinal order.
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func getTableColumnNames(ctx context.Context, log lg.Log, db sqlz.DB, tblName string) ([]string, error) {
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const query = `SELECT column_name FROM information_schema.columns
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WHERE table_schema = current_schema()
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AND table_name = $1
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ORDER BY ordinal_position`
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rows, err := db.QueryContext(ctx, query, tblName)
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if err != nil {
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return nil, errz.Err(err)
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}
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var colNames []string
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var colName string
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for rows.Next() {
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err = rows.Scan(&colName)
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if err != nil {
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log.WarnIfCloseError(rows)
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return nil, errz.Err(err)
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}
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colNames = append(colNames, colName)
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}
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if rows.Err() != nil {
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log.WarnIfCloseError(rows)
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return nil, errz.Err(err)
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}
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err = rows.Close()
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if err != nil {
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return nil, errz.Err(err)
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}
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return colNames, nil
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}
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// RecordMeta implements driver.SQLDriver.
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func (d *driveri) RecordMeta(colTypes []*sql.ColumnType) (sqlz.RecordMeta, driver.NewRecordFunc, error) {
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// The jackc/pgx driver doesn't report nullability (sql.ColumnType)
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// Apparently this is due to what postgres sends over the wire.
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// See https://github.com/jackc/pgx/issues/276#issuecomment-526831493
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// So, we'll set the scan type for each column to the nullable
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// version below.
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recMeta := make(sqlz.RecordMeta, len(colTypes))
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for i, colType := range colTypes {
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kind := kindFromDBTypeName(d.log, colType.Name(), colType.DatabaseTypeName())
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colTypeData := sqlz.NewColumnTypeData(colType, kind)
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setScanType(d.log, colTypeData, kind)
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recMeta[i] = sqlz.NewFieldMeta(colTypeData)
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}
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mungeFn := func(vals []interface{}) (sqlz.Record, error) {
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// postgres doesn't need to do any special munging, so we
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// just use the default munging.
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rec, skipped := driver.NewRecordFromScanRow(recMeta, vals, nil)
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if len(skipped) > 0 {
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var skippedDetails []string
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for _, skip := range skipped {
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meta := recMeta[skip]
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skippedDetails = append(skippedDetails,
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fmt.Sprintf("[%d] %s: db(%s) --> kind(%s) --> scan(%s)",
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skip, meta.Name(), meta.DatabaseTypeName(), meta.Kind(), meta.ScanType()))
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}
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return nil, errz.Errorf("expected zero skipped cols but have %d:\n %s",
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skipped, strings.Join(skippedDetails, "\n "))
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}
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return rec, nil
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}
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return recMeta, mungeFn, nil
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}
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// database is the postgres implementation of driver.Database.
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type database struct {
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log lg.Log
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drvr *driveri
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db *sql.DB
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src *source.Source
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}
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// DB implements driver.Database.
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func (d *database) DB() *sql.DB {
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return d.db
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}
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// SQLDriver implements driver.Database.
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func (d *database) SQLDriver() driver.SQLDriver {
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return d.drvr
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}
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// Source implements driver.Database.
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func (d *database) Source() *source.Source {
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return d.src
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}
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// TableMetadata implements driver.Database.
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func (d *database) TableMetadata(ctx context.Context, tblName string) (*source.TableMetadata, error) {
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return getTableMetadata(ctx, d.log, d.DB(), tblName)
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}
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// SourceMetadata implements driver.Database.
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func (d *database) SourceMetadata(ctx context.Context) (*source.Metadata, error) {
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return getSourceMetadata(ctx, d.log, d.src, d.DB())
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}
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// Close implements driver.Database.
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func (d *database) Close() error {
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d.log.Debugf("Close database: %s", d.src)
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err := d.db.Close()
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if err != nil {
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return errz.Err(err)
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}
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return nil
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}
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