Re: A performance issue with Memoize - Mailing list pgsql-hackers

From Arne Roland
Subject Re: A performance issue with Memoize
Date
Msg-id 542c1950-2bea-4fc2-911c-b18c0ec5d62b@malkut.net
Whole thread Raw
In response to Re: A performance issue with Memoize  (Richard Guo <guofenglinux@gmail.com>)
List pgsql-hackers
Hi Richard,

I can tell this a real world problem. I have seen this multiple times in 
production.

The fix seems surprisingly simple.

I hope my questions here aren't completely off. I still struggle to 
think about the implications.

I wonder, if there is any stuff we are breaking by bluntly forgetting 
about the subplan params. Maybe some table valued function scan within a 
subquery scan? Or something about casts on a join condition, that could 
be performed differently?

I wasn't able to construct a problem case. I might be just missing 
context here. But I am not yet fully convinced whether this is safe to 
do in all cases.

Regards
Arne





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