Materialize JOIN Predicates for Updates to Temporary Tables
The passthru_upd_with_join hint materializes JOIN predicates for updates into temporary tables by default to compensate for correlated subquery support. This improves query performance.
Caution
Certain UPDATE statements in which the source and target tables are the same may fail if the passthru_upd_with_join parameter is enabled. In scenarios such as this, Datometry recommends that you disable passthru_upd_with_join.
The syntax for passthru_upd_with_join is:
passthru_upd_with_join=true | false
where:
Parameter | Description |
|---|---|
| Enables the hint. This is the default setting if not specified. |
| Disables the hint. |
Hint Scope
The passthru_upd_with_join hint can be specified at the request, session, and global level. To learn more about Hyper-Q SQL hints, and how to use them within a SQL query, see About Hyper-Q SQL Hints.
You can specify passthru_upd_with_join as a global setting in the Hyper-Q configuration file (dtm.ini). The default value is true.
"gateway".passthru_upd_with_join=true
To learn more about specifying a hint as a gateway option in the Hyper-Q configuration file, see Gateway Configuration Parameters.
You can specify passthru_upd_with_join as a query hint at either the request or session level. This example specifies that the hint be disabled (set to false) at the session level.
@--dtm_passthru_upd_with_join=false for session
To learn more about Hyper-Q SQL hints, and how to use them within a SQL query, see About Hyper-Q SQL Hints.