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From: Ron Johnson <[email protected]>
To: pgsql-general <[email protected]>
Subject: Re: Repeatable Read Isolation Level "transaction start time"
Date: Wed, 25 Sep 2024 17:16:19 -0400
Message-ID: <CANzqJaCn2ueCeoiH04ipGRKXQzfaaT+kE_GU7EoJ62bVEh8OsQ@mail.gmail.com> (raw)
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On Wed, Sep 25, 2024 at 4:50 PM Greg Sabino Mullane <[email protected]>
wrote:

> Since transactions should be "as short as possible, without being too
>>> short", how much time is there between when you run "BEGIN;" and the first
>>> "work statement"?
>>>
>>
> I don't know that it really matters. For something automated, it would be
> a few milliseconds.
>

That's what I'm thinking, too.  It might cause a problem if you're typing
transaction commands in between drinking coffee and poking around other
PgAdmin tabs, but that's *your* fault, not PG's fault.


> Either way, I'm sure most people/apps already think of the initial 'BEGIN
> ...' as the start of the transaction, and act accordingly.
>
> Maybe long-term something like
>
> BEGIN   ISOLATION MODE REPEATABLE READ   SNAPSHOT NOW;
>

Without the "NOW", that's essentially the command used by the legacy rdbms
which I used to work on.

I'm trying to remember, though, if "SET TRANSACTION READ WRITE RESERVING
foo FOR <isolation level>;" (it's syntax for beginning a transaction)
started the transaction, or waited until an "action" statement.  Been too
long.

-- 
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> crustacean!


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