| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
| Cc: | Siraj G <tosiraj(dot)g(at)gmail(dot)com>, Scott Ribe <scott_ribe(at)elevated-dev(dot)com>, Pgsql-admin <pgsql-admin(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Does export operation cancel SQLs? |
| Date: | 2025-02-19 22:27:45 |
| Message-ID: | 2583155.1740004065@sss.pgh.pa.us |
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| Lists: | pgsql-admin |
"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> On Wed, Feb 19, 2025 at 1:57 PM Siraj G <tosiraj(dot)g(at)gmail(dot)com> wrote:
>> But I wonder if pg_dump does acquire locks?
> Everything acquires locks (basically). It is the specific nature of the
> locks held and requested that matter.
For more color on that see
https://www.postgresql.org/docs/current/explicit-locking.html#LOCKING-TABLES
particularly the table of lock mode conflicts. pg_dump generally
takes ACCESS SHARE locks on the tables it plans to dump, which is
the same lock level taken by a plain SELECT. That will only
block ACCESS EXCLUSIVE locks, which by and large are only taken
by major DDL operations.
regards, tom lane
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