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    Keyword searching on common words takes extremely long; multiple z97's

    • Article Type: General
    • Product: Aleph
    • Product Version: 18.01

    Description:
    Keyword searching on very common words, such as "to" and "a", has been getting progressively worse and now takes between 30 and 60 seconds. This is the case even when nothing else is happening on the server.

    Normally, there should be only one z97 record for a particular word. In this case, we have found that these common words have multiple z97 records (in some cases, thousands) for the same word.

    This can be seen by doing the SQL:

    SQL-xxx01> select z97_word from z97 group by z97_word having count (*) > 1;

    It seems that this is related to the problem described in Article 000045445 ("Keyword Index Not Working After Oracle/ALEPH Restart") where Oracle Statistics were sometimes interfering with keyword searching.

    Resolution:
    We have concluded that this can be solved by:

    1. eliminating the Oracle Statistics -- as described in Article 000046838 ("UTIL A / 8 (List Analyzed Tables/Indexes); 'Oracle Optimizer Changes for ALEPH'") -- (which has been done) in order to prevent the re-occurrence of the multiple z97's; and

    2. rebuilding the keyword indexes with p_manage_01 (in parallel mode) to eliminate the existing multiple z97's.