SET PREDICATE_PUSH_DOWN#
Controls whether Querona pushes filter predicates down into the queries it sends to each source.
When ON (the default), a WHERE predicate is copied into the per-source subqueries so each
source filters its own rows before the data is combined. When OFF, predicate push-down is disabled
and filtering happens after the data is retrieved.
Tip
This is an advanced query-planning option, on by default. It affects only how a query is planned and executed, not its results — change it for diagnostics or to work around a specific issue.
Syntax#
SET PREDICATE_PUSH_DOWN { ON | OFF } [;]
Remarks#
Pushing a predicate down lets each source return fewer rows, which usually reduces the data
transferred and the work done by a federator. For a query that joins a table on one source with a
table on another, the same WHERE condition is applied inside each source’s subquery. The default
is ON.
Permissions#
Requires membership in the public role.
Examples#
SET PREDICATE_PUSH_DOWN OFF;