---
id: video/qABlX4AL3GM
type: video
title: "Business Central 29.0: Major Change to Table Extensions & SQL."
summary: "Business Central 29 (public preview) changes table extension storage: extension fields go into the same SQL table as the base table instead of companion tables. This enables indexes that mix base and extension fields and can speed up data loading. The speaker still recommends SetLoadFields (partial loading), advises against direct SQL in favor of AL, APIs and queries, and covers new compiler warnings for tables nearing the SQL column limit. His picture of the v29 SQL layout is his own assumption."
tier: community
language: en
tags:
  - table extensions
  - sql storage model
  - database performance
  - indexes
  - data modeling
  - al development
  - extension architecture
  - companion tables
  - partial loading
  - set load field
  - direct sql
  - apis
system: development
review:
  state: reviewed
  by: opus
  at: "2026-10-07T23:19:34.291Z"
  flags: []
generated:
  at: "2026-10-09T00:29:02.995Z"
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    summarize-video: 2
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evidence:
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s
    title: "Unified table storage for extensions: preview"
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 151
    quote: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s
    title: "Cross-field indexes spanning base and extension tables: preview"
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 151
    quote: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s
    title: "Compiler warnings for table column limit: preview"
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 151
    quote: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=103s
    title: "Business Central 29.0: Major Change to Table Extensions & SQL."
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 103
    quote: business 29 introduces a major change to the data model used for table extensions
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=114s
    title: "Business Central 29.0: Major Change to Table Extensions & SQL."
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 114
    quote: fields from table extensions are stored in the same database table as the base table instead of being stored
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s
    title: "Business Central 29.0: Major Change to Table Extensions & SQL."
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 151
    quote: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=568s
    title: "Business Central 29.0: Major Change to Table Extensions & SQL."
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 568
    quote: business center 29 onrem version is not available and on business center cloud I don't have access to the SQL server
  - kind: video
    url: https://www.youtube.com/watch?v=qABlX4AL3GM&t=603s
    title: "Business Central 29.0: Major Change to Table Extensions & SQL."
    date: "2026-09-07T06:00:31.000Z"
    commit: null
    t: 603
    quote: one business central table, AL table is equivalent to one SQL table. No companion table, no table per extension.
links:
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  objects:
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  features:
    - feature/573315
    - feature/573332
  topics: []
  localizations: []
  videos: []
  posts: []
  guidelines: []
video_id: qABlX4AL3GM
channel: yt-saurav
source_name: Saurav Dhyani
url: https://www.youtube.com/watch?v=qABlX4AL3GM
published_at: "2026-09-07T06:00:31.000Z"
duration_s: 2104
captions: derived
audience:
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  - functional consultant
  - administrator
chapters:
  - t: 0
    title: Introduction and overview of table extensions changes
  - t: 103
    title: Business Central 29 table extension data model changes
  - t: 163
    title: Historical evolution of table extension storage
  - t: 240
    title: "Stage one: separate SQL storage for extension data"
  - t: 377
    title: "Stage two: extension companion table model"
  - t: 556
    title: "Stage three: Business Central 29 unified table model"
  - t: 645
    title: Why Microsoft changed the data model
  - t: 751
    title: "Benefits: index capabilities and performance improvements"
  - t: 896
    title: Partial loading and set load field best practices
  - t: 1182
    title: SQL query examples with and without partial load
  - t: 1291
    title: Why to avoid direct SQL and use APIs instead
  - t: 1474
    title: Detecting table approaching SQL column limit warning
  - t: 1685
    title: Table extension changes in BC29 - FAQ and implications
  - t: 1880
    title: Summary - architectural lessons and closing
features:
  - name: Unified table storage for extensions
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    t: 103
    verified: true
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  - name: Cross-field indexes spanning base and extension tables
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  - name: Improved database operation performance for extensions
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  - name: Partial record loading with set load field
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    status_source: video
  - name: Compiler warnings for table column limit
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    status_source: video
objects_mentioned:
  - table item table
  - table item ledger entry
quotes:
  - t: 103
    text: business 29 introduces a major change to the data model used for table extensions
    check: exact
  - t: 114
    text: fields from table extensions are stored in the same database table as the base table instead of being stored
    check: fuzzy
  - t: 151
    text: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
    check: exact
  - t: 568
    text: business center 29 onrem version is not available and on business center cloud I don't have access to the SQL server
    check: exact
  - t: 603
    text: one business central table, AL table is equivalent to one SQL table. No companion table, no table per extension.
    check: exact
---

# Business Central 29.0: Major Change to Table Extensions & SQL.

> Business Central 29 (public preview) changes table extension storage: extension fields go into the same SQL table as the base table instead of companion tables. This enables indexes that mix base and extension fields and can speed up data loading. The speaker still recommends SetLoadFields (partial loading), advises against direct SQL in favor of AL, APIs and queries, and covers new compiler warnings for tables nearing the SQL column limit. His picture of the v29 SQL layout is his own assumption.

[Watch on YouTube](https://www.youtube.com/watch?v=qABlX4AL3GM) · Saurav Dhyani · 2026-09-07 · 35:04 · tier community · reviewed (checked by Opus)

## Overview

The video walks through how table extension data has been stored in SQL across three stages: separate SQL storage for extension data, extension companion tables, and the Business Central 29 model where one AL table maps to one SQL table. It explains why Microsoft made the change and what it means for developers.

The presenter covers the main effects: indexes can span base and extension fields, and gets and finds can load from one table instead of joining companion tables. He argues that partial loading with set load field is still needed, demonstrates SQL queries with and without partial load, and says direct SQL should be avoided in favor of AL, APIs or queries. The presenter notes that Business Central 29 is in public preview, that he had no access to the SQL server in the cloud, and that the exact threshold for the new column-limit compiler warning is not known to him.

## Key points

- In Business Central 29, fields from table extensions are stored in the same database table as the base table, replacing the extension companion table model.
- Storage has gone through three stages: a separate SQL table per extension, a shared $ext companion table, and now a single unified table.
- Keys/indexes can now combine fields from a base table and its table extensions, which the earlier two storage models did not allow.
- Finds and other reads can be faster because extension fields are in one table and no join to companion tables is needed.
- Keep using set load field (partial loading) in version 29 so only the needed fields are fetched and queries stay smaller.
- Do not read or write SQL directly; use AL, Business Central APIs or queries, and treat the physical SQL schema as an implementation detail that may change again.
- BC29 adds compiler warnings when tables or table extensions with many normal fields approach the SQL column limit; the speaker does not know the exact threshold or behavior and proposes testing it.

## Chapters

- [0:00](https://www.youtube.com/watch?v=qABlX4AL3GM&t=0s) Introduction and overview of table extensions changes
- [1:43](https://www.youtube.com/watch?v=qABlX4AL3GM&t=103s) Business Central 29 table extension data model changes
- [2:43](https://www.youtube.com/watch?v=qABlX4AL3GM&t=163s) Historical evolution of table extension storage
- [4:00](https://www.youtube.com/watch?v=qABlX4AL3GM&t=240s) Stage one: separate SQL storage for extension data
- [6:17](https://www.youtube.com/watch?v=qABlX4AL3GM&t=377s) Stage two: extension companion table model
- [9:16](https://www.youtube.com/watch?v=qABlX4AL3GM&t=556s) Stage three: Business Central 29 unified table model
- [10:45](https://www.youtube.com/watch?v=qABlX4AL3GM&t=645s) Why Microsoft changed the data model
- [12:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=751s) Benefits: index capabilities and performance improvements
- [14:56](https://www.youtube.com/watch?v=qABlX4AL3GM&t=896s) Partial loading and set load field best practices
- [19:42](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1182s) SQL query examples with and without partial load
- [21:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1291s) Why to avoid direct SQL and use APIs instead
- [24:34](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1474s) Detecting table approaching SQL column limit warning
- [28:05](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1685s) Table extension changes in BC29 - FAQ and implications
- [31:20](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1880s) Summary - architectural lessons and closing

## Features

| Feature | Status | At | Evidence |
|---|---|---|---|
| Unified table storage for extensions | generally available (roadmap [Faster data loading with improved data model for table extensions](../features/573332.md)) | [1:43](https://www.youtube.com/watch?v=qABlX4AL3GM&t=103s) | "business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability." ([2:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s)) |
| Cross-field indexes spanning base and extension tables | generally available (roadmap [Developers can define indexes that span fields from a base table and its table extensions](../features/573315.md)) | [12:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=751s) | "business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability." ([2:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s)) |
| Improved database operation performance for extensions | generally available (roadmap [Faster data loading with improved data model for table extensions](../features/573332.md)) | [12:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=751s) |  |
| Partial record loading with set load field | status not stated, demoed | [15:32](https://www.youtube.com/watch?v=qABlX4AL3GM&t=932s) |  |
| Compiler warnings for table column limit | preview | [24:34](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1474s) | "business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability." ([2:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s)) |

A status with a roadmap link comes from the Microsoft 365 roadmap feature this part of the video covers (matched by Haiku; links Opus dropped are not used); other statuses need a status word in the video itself.

## AL objects mentioned

As heard in the captions. A name that matches one object page by exact type and name links to it; the others stay as named.

- table "item table" at [4:25](https://www.youtube.com/watch?v=qABlX4AL3GM&t=265s)
- [table 32 "Item Ledger Entry"](../objects/table/32.md) at [16:59](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1019s)

Not found in BC28-30: table "item table".

## Quotes

- [1:43](https://www.youtube.com/watch?v=qABlX4AL3GM&t=103s) "business 29 introduces a major change to the data model used for table extensions"
- [1:54](https://www.youtube.com/watch?v=qABlX4AL3GM&t=114s) "fields from table extensions are stored in the same database table as the base table instead of being stored"
- [2:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s) "business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability."
- [9:28](https://www.youtube.com/watch?v=qABlX4AL3GM&t=568s) "business center 29 onrem version is not available and on business center cloud I don't have access to the SQL server"
- [10:03](https://www.youtube.com/watch?v=qABlX4AL3GM&t=603s) "one business central table, AL table is equivalent to one SQL table. No companion table, no table per extension."

## Disclaimers in the video

- [2:31](https://www.youtube.com/watch?v=qABlX4AL3GM&t=151s) preview: business 29 is currently in public preview. The platform behavior in Microsoft documentation may change before general availability.
- [9:28](https://www.youtube.com/watch?v=qABlX4AL3GM&t=568s) preview: Business center 29 onrem version is not available and on business center cloud I don't have access to the SQL server
- [25:40](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1540s) other: it'll be able to detect table approaching SQL column limit. Now this is very interesting. It is as new to ...
- [27:22](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1642s) other: I'm very sure that they would not have taken this decision in isolation of changing the underlying architecture. But I ...
- [28:05](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1685s) other: the Microsoft learn document or the release note very clearly says that it'll give you a compiler warning as it ...
- [28:24](https://www.youtube.com/watch?v=qABlX4AL3GM&t=1704s) other: I don't know what's the exact threshold what kind of compiler warning will be generated does a warning apply appears ...