HHi Jonathan,
thanks. It seems I need a similar statement that does parse without
error. I need to do furter tests, e.g. how big the influence of the
case statement is.
Current testing is tricky, since the result "it failed quicker" than
without the hint is not a base I want to work with.
Would you know by hard if opt_param works with "_no_or_expansion"?
I used "_fix_control"='16923858 without getting an TIMER entries in the
optimizer trace. Do you know a possible reason?
BTW:
Thanks
Lothar
Am 17.01.2022 um 15:06 schrieb Jonathan Lewis:
If this is a common problem, and not susceptible to SQL Patch treatment, or the addition of /*+ no_or_expand */ hints at the start of the query pattern, then you could brute force it by setting "_no_or_expansion" to true if you can identify the sessions that need it, or just set it system-wide. You should get much faster optimization times - though the 55 way union all would have to be optimized in 55 parts.
Regards
Jonathan Lewis
On Mon, 17 Jan 2022 at 12:59, Lothar Flatz <l.flatz@xxxxxxxxxx> wrote:
Hi,
At one customer site we see generated statements, actually
reports. The
parsetime for such a statement is over an hour, if it finishes at all.
It is possible we see "ORA-04031:" when we run out of memory in the
shared pool.
How big these statements are is hard to tell, since it depends on
formatting. With sql developer formatting i get in one typical
example >
130000 lines.
The statements are constructed relatively simple.
It seems to be a kind of change report where columns from different
tables are retrieved.
At the beginning is a big case statement where a meaningful name is
generated for a value followed by this values. I counted 7400 case
entries as per statement in one case.
I addition we have a number of big inlists.
All this is running against a union view of 55 Tables.
In other words: If i want to stress the parser I would construct a
statement exactly like this.
However, one hour seems to be a unrealistically long parse time.
Even though that statement needs to be rewritten, but this will
take time.
I want to know if there is any quick fix like increasing the
shared pool
a lot. (Which I can't test unfortunately any time soon due lack of
memory).
Any ideas how to speed up the parse time?
Database version is 19.7. Shared Pool size is 20GB
Thanks
Lothar
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