Varun Thacker created SOLR-12684:
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Summary: Document speed gotchas and partitionKeys usage for
ParallelStream
Key: SOLR-12684
URL: https://issues.apache.org/jira/browse/SOLR-12684
Project: Solr
Issue Type: Bug
Security Level: Public (Default Security Level. Issues are Public)
Reporter: Varun Thacker
Assignee: Varun Thacker
The aim of this Jira is to beef up the ref guide around parallel stream
There are two things I want to address:
Firstly usage of partitionKeys :
This line in the ref guide indicates that parallel stream keys should always be
the same as the underlying sort criteria
{code:java}
The parallel function maintains the sort order of the tuples returned by the
worker nodes, so the sort criteria of the parallel function must match up with
the sort order of the tuples returned by the workers.
{code}
But as discussed on SOLR-12635 , Joel provided an example
{code:java}
The hash partitioner just needs to send documents to the same worker node. You
could do that with just one partitioning key
For example if you sort on year, month and day. You could partition on year
only and still be fine as long as there was enough different years to spread
the records around the worker nodes.{code}
So we should make this more clear in the ref guide.
Let's also document that specifying more than 4 partitionKeys will throw an
error after SOLR-12683
At this point the user will understand how to use partitonKeys . It's related
to the sort criteria but should not have all the sort fields
We should now mention a trick where the user could warn up the hash queries as
they are always run on the whole document set ( irrespective of the filter
criterias )
also users should only use parallel when the docs matching post filter
criterias is very large .
<listener event="newSearcher" class="solr.QuerySenderListener">
<arr name="queries">
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=0}</str><str name="partitionKeys">myPartitionKey</str></lst>
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=1}</str><str name="partitionKeys">myPartitionKey</str></lst>
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=2}</str><str name="partitionKeys">myPartitionKey</str></lst>
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=3}</str><str name="partitionKeys">myPartitionKey</str></lst>
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=4}</str><str name="partitionKeys">myPartitionKey</str></lst>
<lst><str name="q">*:*</str><str name="fq">\{!hash workers=6
worker=5}</str><str name="partitionKeys">myPartitionKey</str></lst>
</arr>
</listener>
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