15.6Optimizer Configuration

15.6.1SET OPTIMIZE

Configures whether the optimizer should optimize for fetching first or all rows.

Syntax

  |SET OPTIMIZE <optimize-mode>
  | 
  |<optimize-mode> ::=
  |    FOR {FIRST | ALL} ROWS
  |  | TO DEFAULT

This feature allows the optimizer to consider another (hopefully better) plan if only a subset or rows is fetched initially by the user application (with the remaining rows being fetched on demand), thus improving the response time.

It can also be specified at the statement level using the OPTIMIZE FOR clause.

The default behaviour can be specified globally using the OptimizeForFirstRows setting in firebird.conf or databases.conf.