| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Antonin Houska <ah(at)cybertec(dot)at> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Incorrect visibility test function assigned to snapshot |
| Date: | 2018-05-30 13:28:54 |
| Message-ID: | 20180530132854.tkv37qiamepu3slh@alvherre.pgsql |
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| Thread: | |
| Lists: | pgsql-hackers |
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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