Re: Fix overflow of nbatch
От | Melanie Plageman |
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Тема | Re: Fix overflow of nbatch |
Дата | |
Msg-id | CAAKRu_YF4P62gNezZyekhmNuV3k+Gy4Z7hWDJ2wYCYoCHNF-wg@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Fix overflow of nbatch (Melanie Plageman <melanieplageman@gmail.com>) |
Ответы |
Re: Fix overflow of nbatch
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Список | pgsql-hackers |
On Wed, Oct 8, 2025 at 1:37 PM Melanie Plageman <melanieplageman@gmail.com> wrote: > > I have updated my patch to fix the mistakes above. I also noticed then > that I wasn't doubling space_allowed in the loop but instead setting > it to hash_table_bytes at the end. This doesn't produce a power of 2 > because we subtract skew_mcvs from the hash_table_bytes. So, we have > to keep using space_allowed if we want a power of 2 in the end. > > I've changed my patch to do this, but this made me wonder if we want > to be doing this or instead take hash_table_bytes at the end and round > it up to a power of 2 and set space_allowed to that. If the skew > hashtable is large, we may be allocating way more space_allowed than > we need for new hash_table_bytes + skew hashtable buckets. Oh wait, that doesn't make sense because each batch could have a skew hashtable. - Melanie
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