| From: | Kevin Grittner <kgrittn(at)gmail(dot)com> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Ants Aasma <ants(dot)aasma(at)eesti(dot)ee>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Kevin Grittner <kgrittn(at)postgresql(dot)org>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, "pgsql-committers(at)postgresql(dot)org" <pgsql-committers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Re: pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold < |
| Date: | 2016-06-15 19:00:30 |
| Message-ID: | CACjxUsM0csE2vUw6p2fsVVv9W+WN3z+RhGXcw+BG0_FfVo_cvA@mail.gmail.com |
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| Lists: | pgsql-committers pgsql-hackers |
On Wed, Jun 15, 2016 at 1:54 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Robert Haas wrote:
>> The expression index case is the one to worry about; if there is a
>> problem, that's where it is. What bothers me is that a function used
>> in an expression index could do anything at all - it can read any
>> table in the database.
>
> Hmm, but if it does that, then the code that actually implements that
> query would run the STO checks, right? The analyze code doesn't need
> to.
Right. In the described case, you would get a "snapshot too old"
error inside the expression which is trying to generate the index
value.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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