示例#1
0
// prepQue ensures that the que table exists and que's prepared statements are
// run. It is meant to be used in a pgx.ConnPool's AfterConnect hook.
func prepQue(conn *pgx.Conn) error {
	_, err := conn.Exec(QueTableSQL)
	if err != nil {
		return err
	}

	return que.PrepareStatements(conn)
}
示例#2
0
func PrepareStatements(conn *pgx.Conn) error {
	for name, sql := range preparedStatements {
		if _, err := conn.Prepare(name, sql); err != nil {
			return err
		}
	}
	return nil
}
示例#3
0
// afterConnect creates the prepared statements that this application uses
func afterConnect(conn *pgx.Conn) (err error) {
	_, err = conn.Prepare("getUrl", `
    select url from shortened_urls where id=$1
  `)
	if err != nil {
		return
	}

	_, err = conn.Prepare("deleteUrl", `
    delete from shortened_urls where id=$1
  `)
	if err != nil {
		return
	}

	// There technically is a small race condition in doing an upsert with a CTE
	// where one of two simultaneous requests to the shortened URL would fail
	// with a unique index violation. As the point of this demo is pgx usage and
	// not how to perfectly upsert in PostgreSQL it is deemed acceptable.
	_, err = conn.Prepare("putUrl", `
    with upsert as (
      update shortened_urls
      set url=$2
      where id=$1
      returning *
    )
    insert into shortened_urls(id, url)
    select $1, $2 where not exists(select 1 from upsert)
  `)
	return
}