FAQ
It's been a few days since I've run through my usual builds and
tests, and I just discovered that part of my routine was broken by
this commit:

http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=846af54dd5a77dc02feeb5e34283608012cfb217

The isolation tests are broken when run against a database with
default_transaction_isolation = 'repeatable read' or 'serializable'.
(Which is ironic, really.)

Adding the attached files to src/test/isolation/expected/ causes
those stricter isolation levels to work in my tests so far, but I
get random failures in 'read committed' due to apparent randomness
in which process is chosen as the deadlock victim. I seem to
remember Noah mentioning this and a suggested fix, but the problem
in manifest in a current checkout of head.

Of course, another approach to this would be to set transaction
isolation level in the new tests. If we do that, we might want to
create tests at all three levels, for completeness.

-Kevin

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  • Alvaro Herrera at Jul 15, 2011 at 11:11 pm

    Excerpts from Kevin Grittner's message of vie jul 15 18:23:10 -0400 2011:
    It's been a few days since I've run through my usual builds and
    tests, and I just discovered that part of my routine was broken by
    this commit:

    http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=846af54dd5a77dc02feeb5e34283608012cfb217
    Sorry 'bout that.
    The isolation tests are broken when run against a database with
    default_transaction_isolation = 'repeatable read' or 'serializable'.
    (Which is ironic, really.)

    Adding the attached files to src/test/isolation/expected/ causes
    those stricter isolation levels to work in my tests so far, but I
    get random failures in 'read committed' due to apparent randomness
    in which process is chosen as the deadlock victim. I seem to
    remember Noah mentioning this and a suggested fix, but the problem
    in manifest in a current checkout of head.
    Yeah, the patch I committed from Noah should fix the issues in read
    committed. It hadn't crossed my mind that I need to manually set the
    level to serializable in order for the tests to be meaningful :-(
    Shouldn't we be running the tests three times with the different useful
    isolation levels?
    Of course, another approach to this would be to set transaction
    isolation level in the new tests. If we do that, we might want to
    create tests at all three levels, for completeness.
    I think your approach of adding alternative expected outputs makes more
    sense.

    --
    Álvaro Herrera <alvherre@commandprompt.com>
    The PostgreSQL Company - Command Prompt, Inc.
    PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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postedJul 15, '11 at 10:23p
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