Hello,
Postgres can produce a plan with a nested loop node having rows estimate
much more than the product of underlying nodes' estimates, relying only
on outer relation size:
alexey=# explain
SELECT oid, relname
FROM (
SELECT m.oid, m.relname
FROM pg_class m
UNION ALL
attached for a performance test: create
3000 tables with 10 columns and a PK each and select * from the view.
The last statement works for 22 seconds on master branch, 34
milliseconds optimized on my laptop.
Best Regards,
Alexey Bashtanov
many-constraints.sql
Description: application/sql
diff
ExplainPropertyText/ExplainPropertyList?
Otherwise are you pretty sure ExplainPropertyText and
ExplainPropertyList are not going perform any pallocs without immediate
pfrees in current memory context even in future?
Regards,
Alexey Bashtanov
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it after a plan node is generated.
Any reasons to treat this idea as bad?
BTW in this case explain execution is also quite long (I got tens of
seconds). But I have no immediate ideas how to improve it.
Regards,
Alexey Bashtanov
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, disabled by default)?
Best regards,
Alexey Bashtanov
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