Description
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
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.
But as discussed on SOLR-12635 , Joel provided an example
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.
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>
Attachments
Attachments
Issue Links
- relates to
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SOLR-12683 HashQuery should validate if more than 4 partitionKeys are provided
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- Closed
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SOLR-12635 HashQParserPlugin should be run as a post filter cost is not explicitly defined
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- Resolved
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