Hi,

I just stumbled over a very hard to reproduce error. Running
a "VACUUM ANALYZE <table>" concurrently to a database heavy
under load caused a SELECT ... FOR UPDATE with full primary
key qualification to return multiple results from that table.
The table contains only a few rows which receive ton's of
updates.

System is 7.2B3 under Linux.

Will try to produce a test case, just to let ppl know early.


Jan

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  • Tom Lane at Nov 28, 2001 at 4:28 am

    Jan Wieck writes:
    I just stumbled over a very hard to reproduce error. Running
    a "VACUUM ANALYZE <table>" concurrently to a database heavy
    under load caused a SELECT ... FOR UPDATE with full primary
    key qualification to return multiple results from that table.
    Urgh. But I am not sure that you should be pointing the finger at
    VACUUM. It doesn't move any tuples around (at least not in ctid
    terms), so how could it possibly produce multiple tuple images in
    another scan? My early bet is that the problem is not directly
    related to VACUUM.

    Post as soon as you have any more info ... remember there are lots
    of eyeballs out here ...

    regards, tom lane
  • Mark L. Woodward at Nov 28, 2001 at 12:00 pm

    Jan Wieck wrote:

    Hi,

    I just stumbled over a very hard to reproduce error. Running
    a "VACUUM ANALYZE <table>" concurrently to a database heavy
    under load caused a SELECT ... FOR UPDATE with full primary
    key qualification to return multiple results from that table.
    The table contains only a few rows which receive ton's of
    updates.

    System is 7.2B3 under Linux.

    Will try to produce a test case, just to let ppl know early.
    Can you post an explain plan for the query along with a "\d" of the table?

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