Session level statistics for materialised subqueries

From: Dominic Brooks <dombrooks_at_hotmail.com>
Date: Tue, 11 Jan 2022 10:12:38 +0000
Message-ID: <AS8P193MB17502C81E5A82EBA7CBD3219A1519_at_AS8P193MB1750.EURP193.PROD.OUTLOOK.COM>

Has anyone had cause to look into the combination of 12c feature session-private statistics and materialised subqueries?

Just seen a second incident of “plan flips” where a key difference is the plan saying that session-private statistics were used but the only temp table involved seems to be a materialised subquery materialising to a SYS_TEMP_%%%%% temp table.

There seems no reason why the two features shouldn’t combine but I find it odd why unchanged application code would result in two different note sections on the execution plans.

Just thinking aloud.

Cheers,
Dominic

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Received on Tue Jan 11 2022 - 11:12:38 CET