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From: Tom Lane <[email protected]>
To: zhangjinyu <[email protected]>
Cc: [email protected]
Cc: [email protected]
Subject: Re: [BUGS] Re: BUG #13541: There is a visibility issue when run some DDL and Query. The time window is very shot
Date: Fri, 14 Aug 2015 10:23:10 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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zhangjinyu <[email protected]> writes:
> The DDL query(alter ...set data type ) rewrites all tuples with new
> transaction xid,  so if the transaction isolation level is repeatable read,
> that will cause wrong result.

Yes.  This is unlikely to change, but we ought to document it.

I see that we have documentation warning about this sort of effect in the
TRUNCATE reference page, but not in ALTER TABLE's.  Rather than
copy-and-paste that, ISTM it'd be better to move the warning to somewhere
in mvcc.sgml.

			regards, tom lane


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