[jira] [Created] (SOLR-9941) log replay redundently (pre-)applies DBQs as if they were out of order

["Hoss Man (JIRA)" <ji...@apache.org>]

Hoss Man created SOLR-9941:
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             Summary: log replay redundently (pre-)applies DBQs as if they were out of order
                 Key: SOLR-9941
                 URL: https://issues.apache.org/jira/browse/SOLR-9941
             Project: Solr
          Issue Type: Improvement
      Security Level: Public (Default Security Level. Issues are Public)
            Reporter: Hoss Man



There's kind of an odd situation that arises when a Solr node starts up (after a crash) and tries to recover from it's tlog that causes deletes to be redundantly & excessively applied -- at a minimum it causes confusing really log messages....

* {{UpdateLog.init(...)}} creates {{TransactionLog}} instances for the most recent log files found (based on numRecordsToKeep) and then builds a {{RecentUpdates}} instance from them
* Delete entries from the {{RecentUpdates}} are used to populate 2 lists:
** {{deleteByQueries}}
** {{oldDeletes}} (for deleteById).
* Then when {{UpdateLog.recoverFromLog}} is called a {{LogReplayer}} is used to replay any (uncommited) {{TransactionLog}} enteries
** during replay {{UpdateLog}} delegates to the UpdateRequestProcessorChain to for the various adds/deletes, etc...
** when an add makes it to {{RunUpdateProcessor}} it delegates to {{DirectUpdateHandler2}}, which (independent of the fact that we're in log replay) calls {{UpdateLog.getDBQNewer}} for every add, looking for any "Reordered" deletes that have a version greater then the add
*** if it finds _any_ DBQs "newer" then the document being added, it does a low level {{IndexWriter.updateDocument}} and then immediately executes _all_ the newer DBQs ... _once per add_
** these deletes are *also* still executed as part of the normal tlog replay, because they are in the tlog.

Which means if you are recovering from a tlog with 90 addDocs, followed by 5 DBQs, then *each* of those 5 DBQs will each be executed 91 times -- and for 90 of those executions, a DUH2 INFO log messages will say {{"Reordered DBQs detected. ..."}} even tough the only reason they are out of order is because Solr is deliberately applying them out of order.

* At a minimum we should improve the log messages
* Ideally we should stop (pre-emptively) applying these deletes during tlog replay.




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