SOLR-17669: Reduce Memory Consumption by 80-90% when using Dynamic fields (DocumentObjectBinder)

[ds-manzinger]

https://issues.apache.org/jira/browse/SOLR-17669

Description

Flame Graph in our Production System showed a siginificant high memory consumption of Pattern.matcher

Solution

Wildcard can only be at beginning or end of Field Name, we replaced Pattern Regex with startsWith and endsWith

Tests

No new tests needed, old tests are working fine with new code

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide

[psalagnac]

The doc mentions it is recommended to use simple mapping, not strictly required.

Is this functional change on purpose?

It is recommended that you include basic dynamic field mappings (like that shown above) in your schema. The mappings can be very useful.

[dsmiley]

@psalagnac , this isn't about the Solr schema, this is SolrJ, using a nifty feature to map Solr result documents from QueryResponse.getBeans to a user's domain object that has annotations.

+1 to the change

[ds-manzinger]

Yes, it is only in SolrJ. Our Company used that feature quite many years (I think since Solr 4).

If there is a case, where a * in the middle of the name is possible, we can add the Pattern.matcher as fallback.
What would you suggest?

[dsmiley]

Yes Pattern is fine (as it was).
I hope this is tested, but I suppose maybe it isn't if tests pass without the middle wildcard. Can you please add a test?

[ds-manzinger]

@dsmiley Now i added the Pattern as it was before and 2 additional Asserts with Wildcard in the middle and Wildcard at the beginning