RE: what could cause a high elap value for the exec system call (for a select statement)?
From: Allen, Brandon <Brandon.Allen_at_OneNeck.com>
Date: Tue, 3 Nov 2009 09:49:41 -0700
Message-ID: <64BAF54438380142A0BF94A23224A31E112E6AF589_at_ONEWS06.oneneck.corp>
When bind variable peeking occurs, the optimization (CBO activity) actually occurs in the EXECUTE phase instead of the PARSE phase - see the note at the bottom of Metalink 199273.1 for more detail. To help confirm if this is what you're seeing, you could try testing with _optimizer_max_permutations=10 (or some other low number) and see if that cuts down on the time in the EXEC phase, but beware it might give you a poor execution plan. Some things I've seen cause long parse/optimization times in the past are using the old FIRST_ROWS hint (instead of the newer FIRST_ROWS(n)), and using ANSI outer join syntax instead of Oracle's old (+) syntax.
Date: Tue, 3 Nov 2009 09:49:41 -0700
Message-ID: <64BAF54438380142A0BF94A23224A31E112E6AF589_at_ONEWS06.oneneck.corp>
When bind variable peeking occurs, the optimization (CBO activity) actually occurs in the EXECUTE phase instead of the PARSE phase - see the note at the bottom of Metalink 199273.1 for more detail. To help confirm if this is what you're seeing, you could try testing with _optimizer_max_permutations=10 (or some other low number) and see if that cuts down on the time in the EXEC phase, but beware it might give you a poor execution plan. Some things I've seen cause long parse/optimization times in the past are using the old FIRST_ROWS hint (instead of the newer FIRST_ROWS(n)), and using ANSI outer join syntax instead of Oracle's old (+) syntax.
Regards,
Brandon
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