Merge lp://staging/~gmb/launchpad/bugjob-indices-bug-539382 into lp://staging/launchpad/db-devel

I can't recall why I let this table get created without indexes. Possibly because I didn't think it should get as big as it has (2.5 million jobs, with nearly 1 million of them completed over a month ago that nobody has bothered to garbage collect).

Should BugJob.job be UNIQUE?

Should BugJob.bug be UNIQUE?

Should (BugJob.bug, BugJob.job) be UNIQUE?

To know if the indexes are going to be used, I'll need some more information about the queries being made. In particular, if we search for 'jobs for bug NNN with type ZZZ' we should create an index on (bug, job_type) rather than separate indexes on bug and job_type. If we are querying for 'All bug jobs of type ZZZ' then we should separate the indexes.

Allocated patch number is patch-2207-53-0.sql

Indexes should be named with a __idx suffix, as per the following. If we are creating UNIQUE constraints instead, we will create them with a __key suffix.

SET client_min_messages=ERROR;

-- Indices for BugJob
CREATE INDEX bugjob__job__idx ON BugJob(job);
CREATE INDEX bugjob__bug__idx ON BugJob(bug);
CREATE INDEX bugjob__job_type__idx ON BugJob(job_type);

-- Indices for Job
CREATE INDEX job__scheduled_start__idx ON Job(scheduled_start);
CREATE INDEX job__lease_expires__idx ON Job(lease_expires);

INSERT INTO LaunchpadDatabaseRevision VALUES (2207, 53, 0);

On 28 April 2010 05:51, Stuart Bishop <email address hidden>
wrote:
> Review: Needs Information I can't recall why I let this table get
> created without indexes. Possibly because I didn't think it should get
> as big as it has (2.5 million jobs, with nearly 1 million of them
> completed over a month ago that nobody has bothered to garbage
> collect).

There are 2 million rows in BugJob? That's suboptimal; I'll file a bug
to add a task to garbo-daily to expunge old jobs (we don't need them
once they've run, so we can probably remove all but the last 24 hours'
worth (if we even need those)).

> Should BugJob.job be UNIQUE?

Yes.

> Should BugJob.bug be UNIQUE?

No.

> Should (BugJob.bug, BugJob.job) be UNIQUE?

Yes.

> To know if the indexes are going to be used, I'll need some more
> information about the queries being made. In particular, if we search
> for 'jobs for bug NNN with type ZZZ' we should create an index on
> (bug, job_type) rather than separate indexes on bug and job_type. If
> we are querying for 'All bug jobs of type ZZZ' then we should separate
> the indexes.

I think (bug, job_type) is probably a better index to have. The query
that's been causing us some problems is this one:

    SELECT BugJob.*
      FROM BugJob, Job
     WHERE BugJob.bug = 1
       AND BugJob.job_type = 1
       AND BugJob.job = Job.id
       AND Job.id IN (
           SELECT Job.id
             FROM Job WHERE Job.status = 1
              AND (
                  Job.lease_expires IS NULL
                  OR Job.lease_expires < (CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))
              AND (
                  Job.scheduled_start IS NULL
                  OR Job.scheduled_start <= (
                      CURRENT_TIMESTAMP AT TIME ZONE 'UTC')))
     LIMIT 1

Which gets run when a new CalculateBugHeatJob gets created because we
only allow one ready CalculateBugHeatJob to exist per bug at once (I'd
love to be able to make (BugJob.job, BugJob.job_type) UNIQUE, but we
can't since there may be several jobs of a given type generated for a
Bug before they get gc'd).

> Allocated patch number is patch-2207-53-0.sql
>
> Indexes should be named with a __idx suffix, as per the following. If
> we are creating UNIQUE constraints instead, we will create them with a
> __key suffix.
>
> SET client_min_messages=ERROR;
>
> -- Indices for BugJob
> CREATE INDEX bugjob__job__idx ON BugJob(job);
> CREATE INDEX bugjob__bug__idx ON BugJob(bug); CREATE INDEX
> bugjob__job_type__idx ON BugJob(job_type);
>
> -- Indices for Job
> CREATE INDEX job__scheduled_start__idx ON
> Job(scheduled_start); CREATE INDEX job__lease_expires__idx ON
> Job(lease_expires);
>
> INSERT INTO LaunchpadDatabaseRevision VALUES (2207, 53, 0);
>

Okay, thanks. I'll update the patch appropriately.

The following version is approved. Although there is no real functional difference, a little more metadata ends up stored in the database using the ALTER TABLE syntax for defining uniqueness.

SET client_min_messages=ERROR;

-- Indices for BugJob
ALTER TABLE BugJob ADD CONSTRAINT bugjob__job__key UNIQUE (job);
CREATE INDEX bugjob__bug__job_type__idx ON BugJob(bug, job_type);

-- Indices for Job
CREATE INDEX job__scheduled_start__idx ON Job(scheduled_start);
CREATE INDEX job__lease_expires__idx ON Job(lease_expires);

INSERT INTO LaunchpadDatabaseRevision VALUES (2207, 53, 0);

Your example query is better written as following BTW:

SELECT BugJob.*
FROM BugJob, Job
WHERE
    BugJob.bug = 1
    AND BugJob.job_type = 1
    AND BugJob.job = Job.id
    AND Job.status = 1
    AND (
        Job.lease_expires IS NULL
        OR Job.lease_expires < (CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))
    AND (
        Job.scheduled_start IS NULL
        OR Job.scheduled_start <= (CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))
LIMIT 1;

On 28 April 2010 10:53, Stuart Bishop <email address hidden> wrote:
> Review: Approve db
> The following version is approved. Although there is no real functional difference, a little more metadata ends up stored in the database using the ALTER TABLE syntax for defining uniqueness.
>
> SET client_min_messages=ERROR;
>
> -- Indices for BugJob
> ALTER TABLE BugJob ADD CONSTRAINT bugjob__job__key UNIQUE (job);
> CREATE INDEX bugjob__bug__job_type__idx ON BugJob(bug, job_type);
>
> -- Indices for Job
> CREATE INDEX job__scheduled_start__idx ON Job(scheduled_start);
> CREATE INDEX job__lease_expires__idx ON Job(lease_expires);
>
> INSERT INTO LaunchpadDatabaseRevision VALUES (2207, 53, 0);

Thanks. I'll update the patch accordingly.

>
> Your example query is better written as following BTW:
>
> SELECT BugJob.*
> FROM BugJob, Job
> WHERE
>    BugJob.bug = 1
>    AND BugJob.job_type = 1
>    AND BugJob.job = Job.id
>    AND Job.status = 1
>    AND (
>        Job.lease_expires IS NULL
>        OR Job.lease_expires < (CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))
>    AND (
>        Job.scheduled_start IS NULL
>        OR Job.scheduled_start <= (CURRENT_TIMESTAMP AT TIME ZONE 'UTC'))
> LIMIT 1;
>

Noted. Although what I pasted was the Storm-generated query that came
from an OOPS report.