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    OPAC searches on common words excessively slow; relevancy ranking

    • Article Type: General
    • Product: Aleph
    • Product Version: 20

    Problem Symptoms:
    Poor performance of Word searching in OPAC:

    searches on common words (with many results) take much longer (20, 40, 60 seconds-up) than searches on uncommon words (with relatively few results).

    In performing a Word search in Aleph OPAC, a line such as the following is seen at the bottom of the screen while the search is in progress:
    "Waiting for ... func= ..."

    Initially, it shows "func=find-b",
    then "func=short rank".

    The func=find-b stage is very quick -- in every case, about 5 seconds.
    But *great* variation is seen in the second, "func=short rank" stage.
    For searches containing uncommon words it goes relatively quickly, but
    for searches containing common words (with many hits) the short-rank stage can take 20, 40, 60 seconds-up.

    "Sorted by: Relevance" is seen in the OPAC Results List.

    * The OPAC is set up to sort, initially, by default, by relevance.

    * It is taking a long time for the programs to determine the relevance of each entry in a large result set.

    * None yet for this sorting setup.This implementation of relevancy-ranking at this site is being studied to see if there's a configuration problem which is causing relevancy to take longer than it should.
    *Change your sorting default not to sort by relevancy ranking.

    Additional Information

    * It is *not* the normal case for the Aleph OPAC to take longer in displaying large result sets: the programs build the Result Set display only for the results on the first screen. In this implementation of relevancy sorting it's clear that each title in the result set is being evaluated and that there's a time associated with that.

    * In the www_server logs:
    > grep -c 'func=short-rank&action=RANK' www_server_4991.log

    while on servers without relevancy-ranking the above grep retrieves a value of "0".

    * The causes listed in System/search slowness **MASTER RECORD** were checked and did not apply.

    * Keyword searching on common words takes extremely long; multiple z97's describes an entirely different cause of slowness in searching on common words.

    Category: Web OPAC (500)

    • Article last edited: 10/8/2013