Home
SQL programmingYou can use the HCL OneDB™ implementation of the SQL language to develop applications for HCL OneDB™ database servers.
Guide to SQL: SyntaxThe HCL OneDB™ Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the HCL OneDB™ dialect of the SQL language.
SQL statementsThis chapter describes the syntax and semantics of SQL statements that are recognized by HCL OneDB™.
SET LOCK MODE statementUse the SET LOCK MODE statement to define how the database server handles a process that tries to access a locked row or table.
WAIT Clause

WAIT Clause

The WAIT clause causes the database server to suspend the process until the lock is released or until a specified number of seconds have passed without the lock being released.

The database server protects against the possibility of a deadlock when you request the WAIT option. Before the database server suspends a process, it checks whether suspending the process could create a deadlock. If the database server discovers that a deadlock could occur, it ends the operation (overruling your instruction to wait) and returns an error code. In the case of either a suspected or actual deadlock, the database server returns an error.

Cautiously use the unlimited waiting period that was created when you specify the WAIT option without seconds. If you do not specify an upper limit, and the process that placed the lock somehow fails to release it, suspended processes could wait indefinitely. Because a true deadlock situation does not exist, the database server does not take corrective action.

In a network environment, the DBA uses the ONCONFIG parameter DEADLOCK_TIMEOUT to establish a default value for seconds. If you use a SET LOCK MODE statement to set an upper limit, your value applies only when your waiting period is shorter than the system default.