| From: | Noah Misch <noah(at)leadboat(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Erik Rijkers <er(at)xs4all(dot)nl>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Subject: | Re: HASH_BLOBS hazards (was Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions) |
| Date: | 2020-12-15 08:20:30 |
| Message-ID: | 20201215082030.GB2418109@rfd.leadboat.com |
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| Lists: | pgsql-hackers |
On Mon, Dec 14, 2020 at 01:59:03PM -0500, Tom Lane wrote:
> * Should we just have a blanket insistence that all callers supply
> HASH_ELEM? The default sizes that dynahash.c uses without that are
> undocumented and basically useless.
+1
> we should just rip out all those memsets as pointless, since there's
> basically no case where you'd use the memset to fill a field that
> you meant to pass as zero. The fact that hash_create() doesn't
> read fields it's not told to by a flag means we should not need
> the memsets to avoid uninitialized-memory reads.
On Mon, Dec 14, 2020 at 06:55:20PM -0500, Tom Lane wrote:
> Here's a rolled-up patch that does some further documentation work
> and gets rid of the unnecessary memset's as well.
+1 on removing the memset() calls. That said, it's not a big deal if more
creep in over time; it doesn't qualify as a project policy violation.
> @@ -329,6 +328,11 @@ InitShmemIndex(void)
> * whose maximum size is certain, this should be equal to max_size; that
> * ensures that no run-time out-of-shared-memory failures can occur.
> *
> + * *infoP and hash_flags should specify at least the entry sizes and key
s/should/must/
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