DOC-12294: GSI Vector Index

[simon-dew]

Jira issue: DOC-12294

Adds all the documentation for Hyperscale Vector Indexes and Composite Vector Indexes.
This includes the following pull requests — follow the links for previous reviews and discussion:

• DOC-12565 vector search concepts #325
• DOC-12434: DDL for GSI Indexes with a Vector field #275
• DOC-12437: Similarity functions #407

Docs preview:

• Use Vector Indexes for AI Applications
  • Choose the Right Vector Index
  • Vector Search Using Hyperscale Vector Indexes
    • Use Scalar Columns to Filter Hyperscale Vector Index Scans
    • Hyperscale Vector Index Reranking and Full Vector Persistence
  • Filtered Search Using Composite Vector Indexes
  • Hyperscale and Composite Vector Index Best Practices
  • Vector Search Using Search Vector Indexes
• SQL++ for Query Reference
  • CREATE VECTOR INDEX
  • CREATE INDEX — updated to cover Composite Vector Indexes
  • ALTER VECTOR INDEX
  • DROP VECTOR INDEX
  • Vector Functions

Credentials: Preview docs for internal review

Important

• Avoid merging small edits directly into this PR. Where possible, try to use separate PRs to merge any further changes into the DOC-12294-GSI-vector-index branch.
• Rebase and merge this PR! Do not squash and merge!

Merge at the same time as the following PR:

• DOC-12565 vector search concepts couchbase/docs-server#3879

[ksaikrishnateja]

Is it possible to have dedicated page for Composite Vector index under Create Index Tab like that of Array Index and Partitioned Index

[kaminijagtiani]

@simon-dew
We would need to update the section on optimizer as well and add some context around how the appropriate index would be selected.

[ksaikrishnateja]

persist_full_vector needs to be defined in the with nodes clause for Create Vector Index its only in the example. We will also need information on how to enable reranking at scan time.

[simon-dew]

persist_full_vector needs to be defined in the with nodes clause for Create Vector Index its only in the example. We will also need information on how to enable reranking at scan time.

Fixed

[simon-dew]

We would need to update the section on optimizer as well and add some context around how the appropriate index would be selected.

This is now mentioned on both the Hyperscale Vector Indexes page and the Composite Vector Indexes page, and covered in detail in the documentation on the APPROX_VECTOR_DISTANCE() function.

[simon-dew]

Is it possible to have dedicated page for Composite Vector index under Create Index Tab like that of Array Index and Partitioned Index

I did consider this, but creating a Composite Vector index is so similar to creating a secondary index that I decided to document them together in the CREATE INDEX page.

[simon-dew]

All comments addressed. I'm now merging this into the release/8.0 branch. Any further issues can be addressed there before GA.