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From: George Dunlap <George.Dunlap@citrix.com>
To: Ian Jackson <Ian.Jackson@citrix.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [OSSTEST PATCH 05/14] sg-report-flight: Use WITH to use best index use for $flightsq
Date: Wed, 22 Jul 2020 12:47:47 +0000
Message-ID: <12D6C675-582D-467A-A882-B779652AF635@citrix.com> (raw)
In-Reply-To: <20200721184205.15232-6-ian.jackson@eu.citrix.com>



> On Jul 21, 2020, at 7:41 PM, Ian Jackson <ian.jackson@eu.citrix.com> wrote:
> 
> While we're here, convert this EXISTS subquery to a JOIN.
> 
> Perf: runtime of my test case now ~200-300s.
> 
> Example query before (from the Perl DBI trace):
> 
>      SELECT * FROM (
>        SELECT DISTINCT flight, blessing
>             FROM flights
>             JOIN runvars r1 USING (flight)
> 
>            WHERE (branch='xen-unstable')
>              AND ( (TRUE AND flight <= 151903) AND (blessing='real') )
>                  AND EXISTS (SELECT 1
>                            FROM jobs
>                           WHERE jobs.flight = flights.flight
>                             AND jobs.job = ?)
> 
>              AND r1.name LIKE 'built_revision_%'
>              AND r1.name = ?
>              AND r1.val= ?
> 
>            ORDER BY flight DESC
>            LIMIT 1000
>      ) AS sub
>      ORDER BY blessing ASC, flight DESC
> 
> With bind variables:
> 
>     "test-armhf-armhf-libvirt"
>     'built_revision_xen'
>     '165f3afbfc3db70fcfdccad07085cde0a03c858b'
> 
> After:
> 
>      WITH sub AS (
>        SELECT DISTINCT flight, blessing
>             FROM flights
>             JOIN runvars r1 USING (flight)
> 
>            WHERE (branch='xen-unstable')
>              AND ( (TRUE AND flight <= 151903) AND (blessing='real') )
>              AND r1.name LIKE 'built_revision_%'
>              AND r1.name = ?
>              AND r1.val= ?
> 
>            ORDER BY flight DESC
>            LIMIT 1000
>      )
>      SELECT *
>        FROM sub
>        JOIN jobs USING (flight)
> 
>       WHERE (1=1)
>                  AND jobs.job = ?
> 
>      ORDER BY blessing ASC, flight DESC

I was wondering if it would be useful converting this to a join would be useful. :-)

Again, not sure what the “(1=1) AND” bit is for; something to poke the query planner somehow?

The main thing I see here is that there’s nothing *in the query* that guarantees you won’t get multiple flights if there are multiple jobs for that flight whose ‘job’ value; but given the naming scheme so far, I’m guessing job is unique…?  As long as there’s something else preventing duplication I think it’s fine.

 -George


  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-21 18:41 [OSSTEST PATCH 00/14] Flight report performance improvements Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 01/14] sg-report-flight: Add a comment re same-flight search narrowing Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 02/14] sg-report-flight: Sort failures by job name as last resort Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 03/14] schema: Provide indices for sg-report-flight Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 04/14] sg-report-flight: Ask the db for flights of interest Ian Jackson
2020-07-22 12:10   ` George Dunlap
2020-07-22 14:03     ` Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 05/14] sg-report-flight: Use WITH to use best index use for $flightsq Ian Jackson
2020-07-22 12:47   ` George Dunlap [this message]
2020-07-22 14:06     ` Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 06/14] sg-report-flight: Use WITH clause to use index for $anypassq Ian Jackson
2020-07-27 16:15   ` George Dunlap
2020-07-31 10:41     ` Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 07/14] sg-report-flight: Use the job row from the intitial query Ian Jackson
2020-07-21 18:41 ` [OSSTEST PATCH 08/14] Executive: Use index for report__find_test Ian Jackson
2020-07-22 11:33   ` George Dunlap
2020-07-22 13:49     ` Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 09/14] duration_estimator: Ignore truncated jobs unless we know the step Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 10/14] duration_estimator: Introduce some _qtxt variables Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 11/14] duration_estimator: Explicitly provide null in general host q Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 12/14] duration_estimator: Return job column in first query Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 13/14] duration_estimator: Move $uptincl_testid to separate @x_params Ian Jackson
2020-07-21 18:42 ` [OSSTEST PATCH 14/14] duration_estimator: Move duration query loop into database Ian Jackson
2020-07-27 17:43   ` George Dunlap
2020-07-31 10:39     ` Ian Jackson
2020-07-31 10:45       ` George Dunlap

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