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https://issues.apache.org/jira/browse/SOLR-9941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15813309#comment-15813309
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Ishan Chattopadhyaya edited comment on SOLR-9941 at 1/10/17 12:14 AM:
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{quote}
Seems to me that updates arriving during the log replay (in TestRecovery) are
being silently dropped.
{quote}
One possible explanation came to mind: During log replay, the state of the core
is REPLAYING. Hence, perhaps, incoming updates are not applied (and dropped)
until the recovery has finished and state is back to ACTIVE?
was (Author: ichattopadhyaya):
{quote}
Seems to me that updates arriving during the log replay (in TestRecovery) are
being silently dropped.
{quote}
One possible explanation came to mind: During log replay, the state of the core
is REPLAYING. Hence, perhaps, incoming updates are not applied until the
recovery has finished and state is back to ACTIVE?
> 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
> Attachments: SOLR-9941.hoss-test-experiment.patch, SOLR-9941.patch,
> SOLR-9941.patch, SOLR-9941.patch
>
>
> 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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