LOCK (original) (raw)

LOCK statement obtains a table-level lock, waiting if necessary for any conflicting locks to be released.
More about LOCK statement can be found:
PostgreSQL - https://www.postgresql.org/docs/11/sql-lock.html
MySQL - https://dev.mysql.com/doc/refman/8.0/en/lock-tables.html
MariaDB - https://mariadb.com/kb/en/library/lock-tables/

Following clauses are supported:

• IN(mode) - mode specifies which locks this lock conflicts with.
  • For PostgreSQL mode can be:
    * LOCK_ACCESS_SHARE
    * LOCK_ROW_SHARE
    * LOCK_ROW_EXCLUSIVE
    * LOCK_SHARE_UPDATE_EXCLUSIVE
    * LOCK_SHARE
    * LOCK_SHARE_ROW_EXCLUSIVE
    * LOCK_EXCLUSIVE
    * LOCK_ACCESS_EXCLUSIVE
  • For MySQL and MariaDB mode can be:
    * READ
    * WRITE
• NOWAIT() - locked table should not wait for any conflicting locks to be released. If the specified lock(s) cannot be acquired immediately without waiting, the transaction is aborted.

Example

lockStmt := Address. LOCK(). IN(LOCK_ACCESS_SHARE). NOWAIT()

Debug SQL of above statement:

LOCK TABLE dvds.address IN ACCESS SHARE MODE NOWAIT;

Execute statement

To execute update statement and get sql.Result:

res, err := lockStmt.Exec(db)

Use ExecContext to provide context object to execution.