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BC 2026 release wave 2unofficial launch event map, by waldo

Features › Developer tools

Keys spanning base and extension fields

GA · 7 min in 2 videos · dev relevance high · documented as Developers can define indexes that span fields from a base table and its table extensions high match

Keys spanning base and extension fields

Because table extensions are merged into the base table, a key or index can cover both base table and table extension fields. This was a long-requested item.

Area: Developer tools. Status: GA. Developer relevance: high. Airtime: 7 min across 2 videos.

Status evidence

  • Nothing said about status; launch event convention: generally available unless stated otherwise.

Where they talk about it

Quotes

  • 6:53 "we can now add an index that spans both the base table and your extension fields" - A long-requested capability that follows from the single-table model.
  • 7:04 "I think this actually completes our backlog for index management" - States that the index management work is considered finished.
  • 10:19 "they're actually merged into uh the the base uh table and that means that a key can now span uh both base and extension fields at the same time" - A design change in table extensions that enables keys across base and extension fields.
  • 11:34 "The public resources are actually consumable without a dependency." - Consumers of public resources do not need a dependency on the providing app.
  • 12:55 "if you try to get a private resource by and providing the app ID, you will get an error." - A limitation: only resources in public folders can be fetched with a provider app ID.
  • 13:07 "So be mindful about taking hard dependencies on specific apps on public resources because if they stop shipping it," - Warns that runtime errors occur if a provider app stops shipping a resource.
  • 13:40 "that sometimes the ledger entries or some of the other the sequence entries run out of numbers." - Gives the real-world reason for the integer to big integer change.
  • 13:53 "So we made it possible for you to switch to big integer by changing the type." - States the design decision to allow changing a field to big integer for large customers whose entries run out of numbers.

Prerequisites mentioned

  • Optimized table extension data model with extension fields on the base table

Documented features match

Docs checked on 2026-10-02: the match is against Microsoft's what's new pages for the wave as they were on that date. Microsoft keeps filling the documentation, so "no documented item" can go stale. The wider product documentation on learn.microsoft.com was searched for this feature on the same date; the feature's data lists an article when one was found.

Tags: al, keys, indexes, table-extensions, tables, extensibility, sql, performance, extensions, database

Generated by pipeline step 06. Source: YouTube auto-captions of the launch event videos, see the deep links. Not official.