Movatterモバイル変換

Recall fromChapter 19 that thePostgreSQL server provides a large number of run-time configuration variables. You can set database-specific default values for many of these settings.

For example, if for some reason you want to disable theGEQO optimizer for a given database, you'd ordinarily have to either disable it for all databases or make sure that every connecting client is careful to issueSET geqo TO off. To make this setting the default within a particular database, you can execute the command:

ALTER DATABASE mydb SET geqo TO off;

This will save the setting (but not set it immediately). In subsequent connections to this database it will appear as thoughSET geqo TO off; had been executed just before the session started. Note that users can still alter this setting during their sessions; it will only be the default. To undo any such setting, useALTER DATABASEdbname RESETvarname.