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Regarding vacuum freeze locking mechanism
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* Regarding vacuum freeze locking mechanism
@ 2024-07-18 05:27  Durgamahesh Manne <[email protected]>
  0 siblings, 2 replies; 3+ messages in thread

From: Durgamahesh Manne @ 2024-07-18 05:27 UTC (permalink / raw)
  To: [email protected]; +Cc: [email protected]

Hi

Do new inserts block while performing vacuum freeze operations ?

when autovacuum runs , it will freeze the transaction ID (TXID) of the
table it's working on. This means that any transactions that started before
autovacuum began will be allowed to complete.but new transactions will be
blocked until the autovacuum finishes.

Could you please provide more clarity on this? Which lock triggers on the
tables are being used by freeze?

Your response is highly appreciated

Regards,
Durga Mahesh


^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Regarding vacuum freeze locking mechanism
@ 2024-07-18 05:28  Kashif Zeeshan <[email protected]>
  parent: Durgamahesh Manne <[email protected]>
  1 sibling, 0 replies; 3+ messages in thread

From: Kashif Zeeshan @ 2024-07-18 05:28 UTC (permalink / raw)
  To: Durgamahesh Manne <[email protected]>; +Cc: [email protected]; [email protected]

Hi

On Thu, Jul 18, 2024 at 10:26 AM Durgamahesh Manne <
[email protected]> wrote:

> Hi
>
> Do new inserts block while performing vacuum freeze operations ?
>
Generally, VACUUM FREEZE does not block inserts as PG uses Multi-Version
Concurrency Control (MVCC) which allows multiple transactions to operate on
the same table without interfering with each other.


>
> when autovacuum runs , it will freeze the transaction ID (TXID) of the
> table it's working on. This means that any transactions that started before
> autovacuum began will be allowed to complete.but new transactions will be
> blocked until the autovacuum finishes.
>
> Could you please provide more clarity on this? Which lock triggers on the
> tables are being used by freeze?
>
> Your response is highly appreciated
>
> Regards,
> Durga Mahesh
>
>
>


^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Regarding vacuum freeze locking mechanism
@ 2024-07-18 05:53  David G. Johnston <[email protected]>
  parent: Durgamahesh Manne <[email protected]>
  1 sibling, 0 replies; 3+ messages in thread

From: David G. Johnston @ 2024-07-18 05:53 UTC (permalink / raw)
  To: Durgamahesh Manne <[email protected]>; +Cc: [email protected] <[email protected]>; [email protected] <[email protected]>

On Wednesday, July 17, 2024, Durgamahesh Manne <[email protected]>
wrote:

> when autovacuum runs , it will freeze the transaction ID (TXID) of the
> table it's working on.
>

This statement is incorrect.  A table as a whole does not have a txid.
Freezing makes it so individual tuples get assigned an always-in-the-past
txid.  Then, the table can recompute how far away its furthest back txid is
from being considered in-the-future.  That gap should increase since the
furthest away txids were the ones being frozen.

Inserts might get delayed a brief moment if it just happens the page they
want to insert onto is presently being worked on.  But the odds there seem
low.

David J.


^ permalink  raw  reply  [nested|flat] 3+ messages in thread

end of thread, other threads:[~2024-07-18 05:53 UTC | newest]

Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
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2024-07-18 05:27 Regarding vacuum freeze locking mechanism Durgamahesh Manne <[email protected]>
2024-07-18 05:28 ` Kashif Zeeshan <[email protected]>
2024-07-18 05:53 ` David G. Johnston <[email protected]>

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