Implementation for match_only_text field

[rishabhmaurya]

Description

• Implementation of match_only_text field with index_options fixed to docs, norms disabled to optimize on storage.
• Supports query types with added latency - Phrase, Prefix, MultiPhrase & MultiPhrasePrefix.
• It supports all features same as text field type except following -

Features not supported -

• Interval Queries
• Span queries
• Queries on index time phrase and index prefix fields.
• Aggregation queries - just like text field isn't meant for aggregation queries.
• Disabling _sourcefield will disable any positional query support (Note: instead of not allowing disabling _source field, I have decided to throw exceptions when positional queries would be executed for users who don't have use case of positional queries and want to save on space).
• update to index_options to any value other than docs isn't allowed.
• Scoring, boost may not work as expected, so this field type isn't meant to be used for relevancy purposes.

Best used for -

• In log analytics, where the goal is to search for log entries based on specific keywords or error codes or exception type in error message, the focus may be on retrieving relevant logs rather than analyzing the frequency or position of terms within each log entry.
• In a job portal, users often search for jobs based on job titles, skills, or locations. The frequency and position of terms within job descriptions may be less significant for these searches.
• In a news application, users might search for articles based on keywords in headlines or summaries. The focus is on finding relevant news articles rather than analyzing the frequency or position of terms within each article.

Migration from text field

reindex api can be used to migrate the index from text to match_only_text field and viceversa.

Implementation breakdown -

1. New MatchOnlyTextFieldMapper which extends TextFieldMapper with few constraints and different defaults
2. New FieldType for MatchOnlyTextFieldMapper which adds constraints specific to match_only_text field and supports positional queries by reading value of the match_only_text field from the _source field.
3. SourceFieldMatchQuery - query which accepts a delegate query, to apply various filters to prune the resultset, and a source filter query. It loads the _source for each hit from result of delegate query, creates a single doc Lucene MemoryIndex for each hit and runs source filter query against it. It uses ConstantScoreWeight to disable scoring.

Testing done

1. Unit tests for Mapper - asserting the OpenSearch DSL query to the SourceFieldMatchQuery created by the MatchOnlyTextFieldMapper. It also validates various unsupported cases.
2. Unit tests for SourceFieldMatchQuery - it create a Lucene index and tries to check possible scenarios for SourceFieldMatchQuery like -
   1. docs matching both delegate and filter query
   2. docs matching only delegate query
   3. docs matching only filter query
   4. docs matching neither delegate nor filter query
   5. Expected behavior when source field is disabled
   6. Expected behavior when there is a missing field.
3. Created clone of various integration tests where text field was getting used by replacing text with match_only_text field. Overridden the expected behavior wherever necessary.

TODOs

1. Support for interval queries?
2. Add support for match_only_field type on dashboard
3. Public documentation - [DOC] match_only_text handler  documentation-website#5427
4. Performance testing -
5. Cache logic validation

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

#6836
opensearch-project/documentation-website#5427

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/29409/
• CommitID: e437959
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
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[github-actions]

Compatibility status:

Checks if related components are compatible with change f1fb443

Incompatible components

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/performance-analyzer.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/29410/
• CommitID: 0f5485c
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

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Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/29418/
• CommitID: a1c2fab
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❌ Gradle check result for ccab297: FAILURE

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✅ Gradle check result for e879baf: SUCCESS

[codecov]

Codecov Report

Attention: 25 lines in your changes are missing coverage. Please review.

Comparison is base (63f4f13) 71.47% compared to head (f1fb443) 71.40%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
.../opensearch/index/query/SourceFieldMatchQuery.java	67.34%	8 Missing and 8 partials ⚠️
...nsearch/index/mapper/MatchOnlyTextFieldMapper.java	93.54%	4 Missing and 4 partials ⚠️
...a/org/opensearch/index/search/MultiMatchQuery.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #11039      +/-   ##
============================================
- Coverage     71.47%   71.40%   -0.07%     
+ Complexity    59253    59240      -13     
============================================
  Files          4907     4909       +2     
  Lines        278248   278426     +178     
  Branches      40428    40460      +32     
============================================
- Hits         198871   198817      -54     
- Misses        62850    63093     +243     
+ Partials      16527    16516      -11     

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[andrross]

Looks good, just one changelog entry nitpick

[github-actions]

❕ Gradle check result for f1fb443: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.search.SearchWeightedRoutingIT.testMultiGetWithNetworkDisruption_FailOpenEnabled

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.