| From: | Tender Wang <tndrwang(at)gmail(dot)com> |
|---|---|
| To: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MergeJoin beats HashJoin in the case of multiple hash clauses |
| Date: | 2025-04-14 06:17:17 |
| Message-ID: | CAHewXNnA+5sjiZTF+4nEDNM1F-+2yP+1cpqZXwUkm6uwmPUW0w@mail.gmail.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
While I debug hashjoin codes, in estimate_multivariate_bucketsize(), I
find that
the list_copy(hashclauses) below is unnecessary if we have a single join
clause.
List *clauses = list_copy(hashclauses);
...
I adjust the place of list_copy() call as the attached patch.
This can save some overhead of function calls and memory copies.
Any thoughts?
--
Thanks, Tender Wang
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-Adjust-the-place-of-list_copy-in-estimate_multivaria.patch | text/plain | 1.3 KB |
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