Purpose
Determines whether the Teradata Database query Optimizer uses newer or older join planning techniques.
Field Group
Performance
Valid Settings
| Setting | Description |
|---|---|
| TRUE | Causes the Teradata Database query Optimizer to use older join planning logic, and limits the maximum number of tables that can be used for join planning to 64. To restrict all users to no more than 64 tables joined per query block, set RevertJoinPlanning in DBS Control to TRUE. |
| FALSE | Causes the Teradata Database query Optimizer to use new join planning logic, unless the RevertJoinPlanning option for the cost profile is set to TRUE, in which case the cost profile option takes precedence. In that case, the Teradata Database query Optimizer uses the older join planning logic and table limit. The normal case is RevertJoinPlanning equal FALSE in both the DBS Control record and in the cost profile. |
To restrict only certain users to no more than 64 tables joined per query block, leave RevertJoinPlanning in DBS Control set to FALSE, and assign the restricted users to a special cost profile that has RevertJoinPlanning set in the profile to TRUE.
Default
FALSE
Changes Take Effect
After the DBS Control record has been written.
Related Topics
| For more information on… | See… |
|---|---|
| the maximum number of tables that can be joined | MaxJoinTables |
| join planning, optimization, and cost profiles | SQL Request and Transaction Processing |