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Re: [PATCH] Avoid open and lock the table Extendend Statistics (src/backend/commands/statscmds.c) - Mailing list pgsql-hackers

From Andres Freund
Subject Re: [PATCH] Avoid open and lock the table Extendend Statistics (src/backend/commands/statscmds.c)
Date
Msg-id 20220213214317.qhroocro46ligj6w@alap3.anarazel.de
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In response to [PATCH] Avoid open and lock the table Extendend Statistics (src/backend/commands/statscmds.c)  (Ranier Vilela <ranier.vf@gmail.com>)
Responses Re: [PATCH] Avoid open and lock the table Extendend Statistics (src/backend/commands/statscmds.c)  (Ranier Vilela <ranier.vf@gmail.com>)
Re: [PATCH] Avoid open and lock the table Extendend Statistics (src/backend/commands/statscmds.c)  (Tomas Vondra <tomas.vondra@enterprisedb.com>)
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Hi,

On 2022-02-13 18:21:38 -0300, Ranier Vilela wrote:
> Why open and lock the table Extended Statistics if it is not the owner.
> Check and return to avoid this.

I was about to say that this opens up time-to-check-time-to-use type
issues. But it's the wrong thing to lock to prevent those.

Having looked briefly at it, I don't understand what the locking scheme is?
Shouldn't there be at least some locking against concurrent ALTERs and between
ALTER and ANALYZE etc?

Greetings,

Andres Freund

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