From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Antonin Houska <ah@cybertec.at>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Incorrect visibility test function assigned to snapshot
Date: Wed, 30 May 2018 09:28:54 -0400
Message-ID: <20180530132854.tkv37qiamepu3slh@alvherre.pgsql> (raw)
In-Reply-To: <23215.1527665193@localhost>
On 2018-May-30, Antonin Houska wrote:
> In the header comment, SnapBuildInitialSnapshot() claims to set
> snapshot->satisfies to the HeapTupleSatisfiesMVCC test function, and indeed it
> converts the "xid" array to match its semantics (i.e. the xid items eventually
> represent running transactions as opposed to the committed ones). However the
> test function remains HeapTupleSatisfiesHistoricMVCC as set by
> SnapBuildBuildSnapshot().
Interesting. While this sounds like an oversight that should have
horrible consequences, it's seems not to because the current callers
don't seem to care about the ->satisfies function. Are you able to come
up with some scenario in which it causes an actual problem?
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, ah@cybertec.at
Subject: Re: Incorrect visibility test function assigned to snapshot
In-Reply-To: <20180530132854.tkv37qiamepu3slh@alvherre.pgsql>
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