Re: "type with xxxx does not exist" when doing ExecMemoize()

Andrei Lepikhov <a.lepikhov@postgrespro.ru>

From: Andrei Lepikhov <a.lepikhov@postgrespro.ru>
To: Tender Wang <tndrwang@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-02-26T05:38:09Z
Lists: pgsql-bugs, pgsql-hackers

Attachments

On 26/2/2024 09:52, Andrei Lepikhov wrote:
> On 25/2/2024 20:32, Tender Wang wrote:
>> I think in prepare_probe_slot(), should called datumCopy as the 
>> attached patch does.
>>
>> Any thoughts? Thanks.
> Thanks for the report.
> I think it is better to invent a Runtime Memory Context; likewise, it is 
> already designed in IndexScan and derivatives. Here, you just allocate 
> the value in some upper memory context.
> Also, I'm curious why such a trivial error hasn't been found for a long 
> time
Hmmm. I see the problem (test.sql in attachment for reproduction and 
results). We only detect it by the number of Hits:
   Cache Key: t1.x, (t1.t)::numeric
   Cache Mode: logical
   Hits: 0  Misses: 30  Evictions: 0  Overflows: 0  Memory Usage: 8kB

We see no hits in logical mode and 100 hits in binary mode. We see 15 
hits for both logical and binary mode if parameters are integer numbers 
- no problems with resetting expression context.

Your patch resolves the issue for logical mode - I see 15 hits for 
integer and complex keys. But I still see 100 hits in binary mode. Maybe 
we still have a problem?

What's more, why the Memoize node doesn't see the problem at all?

-- 
regards,
Andrei Lepikhov
Postgres Professional

Commits

  1. Fix incorrect accessing of pfree'd memory in Memoize

  2. Fix memory leak in Memoize code