On 11/19/22 21:38, gnandre wrote:
Thanks, Shawn. I am a bit wary of creating a total core just for this
health check purpose.
Isn't it a bit expensive to create a core, considering the caches and so
many things it registers? Or, is it fine in which case I might just proceed
with that solution.
I'm talking about a completely empty core that you never send queries
to. If it never gets queries, it should not need any significant memory
for caching.
This is the absolute minimum config and schema I was able to use to make
a new core like what you would need. There are no cache definitions, so
the Solr caches should not even be created. It would probably still
create some Lucene caches, but as those would be empty, they would be
very small. With this definition I don't think you CAN send it any queries:
solrconfig.xml:
---
<?xml version="1.0" encoding="UTF-8" ?>
<config>
<luceneMatchVersion>LATEST</luceneMatchVersion>
<requestHandler name="/your/handler/path" class="YOURCLASSNAME">
*** ANY CONFIG NEEDED FOR YOUR HANDLER ***
</requestHandler>
</config>
---
managed-schema.xml:
---
<?xml version="1.0" encoding="UTF-8"?>
<schema name="empty" version="1.6">
<fieldType name="string" class="solr.StrField" omitNorms="true"
sortMissingLast="true" docValues="true"/>
<fieldType name="long" class="solr.LongPointField"
positionIncrementGap="0" docValues="true"/>
<field name="id" type="string" indexed="true" required="true"
stored="true"/>
<field name="_version_" type="long" indexed="false" stored="false"/>
<uniqueKey>id</uniqueKey>
</schema>
---
This should result in the absolute minimum memory footprint for a core.
Probably only a few megabytes. And I think there is some work underway
to try and reduce the memory footprint for all cores in some future
version of Solr. That would in theory make the memory requirement for
this core even smaller.
In the future I hope that we can provide a way for users to register
global handlers and make this empty core nonsense unnecessary.
Thanks,
Shawn
