[jira] [Created] (CONNECTORS-618) MySQL orders null values to the front of the index, which breaks the stuffing query

["Karl Wright (JIRA)" <ji...@apache.org>]

Karl Wright created CONNECTORS-618:
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             Summary: MySQL orders null values to the front of the index, which breaks the stuffing query
                 Key: CONNECTORS-618
                 URL: https://issues.apache.org/jira/browse/CONNECTORS-618
             Project: ManifoldCF
          Issue Type: Bug
          Components: Framework core
    Affects Versions: ManifoldCF 1.0.1, ManifoldCF 1.1
            Reporter: Karl Wright
            Assignee: Karl Wright


MySQL attempts to read all null values from the docpriority index before it encounters anything useful.  If there are a lot of records from other stopped jobs around, this makes ManifoldCF stuffing very slow.

There is no way to cause MySQL to order null values in indexes differently, unfortunately.  So the only options are:

(1) Use a special value instead of NULL, which is problematic because this column contains a float, and therefore has rounding errors;
(2) Use null, but order the index backwards in the case of MySQL.  This implies that we need to actually change what we put in as a data value based on database type - doable but also definitely scary.


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