update pg_textsearch documentation

[erinmikailstaples]

Describe your changes

This pull request updates documentation to announce the general availability (GA) of the pg_textsearch extension (v1.0.0) and revises guidance to reflect its production-ready status. It introduces new features, updated usage examples, configuration options, and clarifies current limitations and best practices for both cloud and self-hosted environments.

Major documentation updates for GA release:

• GA Announcement and Feature Highlights:
  • Added a changelog entry and tags to announce pg_textsearch v1.0.0 as production ready, including new features such as the bm25_force_merge() function, implicit query syntax, new GUCs for tuning and debugging, and support for PostgreSQL 17 and 18. [1] [2] [3] [4] [5]

Updated usage and best practices:

• Query Syntax Improvements:

  • Updated examples and procedures to recommend the new implicit <@> query syntax and clarified when to use explicit index specification with to_bm25query(), especially in PL/pgSQL contexts. [1] [2] [3] [4]

• Filtering and Performance Guidance:

  • Added a new section on filtering strategies (pre-filtering vs. post-filtering) and their tradeoffs for BM25 index scans.

New and revised reference content:

• bm25query Data Type and Operators:

  • Documented the bm25query data type, constructor functions, cast syntax, and available operators for advanced query scenarios.

• Configuration and Maintenance:

  • Added documentation for new GUCs (segments_per_level, log_scores), force merge operation, and clarified index maintenance and diagnostic functions, including restrictions in production builds. [1] [2] [3]

Limitations and deployment:

• Current Limitations and Self-hosting:
  • Updated and expanded the limitations section, including phrase search, expression indexing, faceted search, write performance, and PL/pgSQL syntax restrictions. Added instructions for self-hosted installation and clarified crash recovery behavior.

These changes ensure the documentation accurately reflects the production readiness of pg_textsearch and provides clear, up-to-date guidance for users deploying and operating the extension.

Related Issues

N/A

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[github-actions]

Allow 10 minutes from last push for the staging site to build. If the link doesn't work, try using incognito mode instead. For internal reviewers, check web-documentation repo actions for staging build status. Link to build for this PR: http://docs-dev.timescale.com/docs-feat-add-pg-text-search

[tjgreen42]

The example involving counts is a little weird. We should just show a query with a WHERE clause that involves filtering based on other columns of the table (e.g., "price < X" or whatever). We should avoid showing WHERE clauses that filter on the numeric value produced by <@>, the robot loves these for some reason but they don't make much practical sense.