Re: Re: [COMMITTERS] pgsql: Adjust things so that the query_string of a cached plan and the

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: [COMMITTERS] pgsql: Adjust things so that the query_string of a cached plan and the
Date: 2009-01-07 23:46:58
Message-ID: 7615.1231372018@sss.pgh.pa.us
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Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Tom Lane wrote:
>> Well, hold on a minute. I said that was an alternative to look at,
>> not that it was necessarily better. Can you define in words of one
>> syllable which queries will be exposed this way? I don't believe
>> it's "all of them".

> Well, if you call a pl function, it is going to show you the current SPI
> function running rather than the user query. Because the comment next
> to the function says:

> * Expose the current query to the user (useful in stored procedures)

> I assume the portal string is better for stored procedures then
> debug_query_string for current_query().

Uh, no, not necessarily. As an example, if the thing were really
returning the most closely nested query (I'm not sure it is) then
a plpgsql function trying to inspect the value of current_query()
would always get back the result "SELECT current_query()". Not
too helpful, eh? So we actually do have to think a little bit
about exactly *which* query we want to return and whether the
ActivePortal can be counted on to be that one.

The good thing about using debug_query_string is that "the current
client query" is well-defined and easy to explain. I'm worried
whether using ActivePortal isn't likely to result in a rather
implementation-dependent behavior that changes from release to release.

Or maybe it really is the Right Thing ... but I'm not feeling
confident of that.

regards, tom lane

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