# Fabric Warehouse

> Use for T-SQL against Fabric Warehouse (NOT Fabric SQL Database — see fabric-database). Covers unsupported types (nvarchar/datetime/money/xml/tinyint/hierarchyid), unsupported features (FOR XML, recursive CTEs, triggers, CREATE USER, cursors), MERGE (GA Jan 2026), ALTER COLUMN (preview), schema evolution (ADD nullable / DROP COLUMN / sp_rename April 2025+, IDENTITY preview, transactional ALTER TA…

- **Type:** Skill
- **Install:** `agentstack add skill-wardawgmalvicious-claude-config-fabric-warehouse`
- **Verified:** Pending review
- **Seller:** [wardawgmalvicious](https://agentstack.voostack.com/s/wardawgmalvicious)
- **Installs:** 0
- **Category:** [Databases](https://agentstack.voostack.com/c/databases)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [wardawgmalvicious](https://github.com/wardawgmalvicious)
- **Source:** https://github.com/wardawgmalvicious/claude-config/tree/main/skills/fabric-warehouse

## Install

```sh
agentstack add skill-wardawgmalvicious-claude-config-fabric-warehouse
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Fabric Warehouse T-SQL surface area

**Note**: This skill applies to Fabric Warehouse only — the distributed Synapse-engine warehouse. Fabric SQL Database uses the full Azure SQL Database engine and does NOT have these restrictions. See the fabric-database skill.

## Unsupported Data Types — Use These Alternatives

| Unsupported Type | Use Instead | Notes |
|---|---|---|
| `nvarchar` / `nchar` | `varchar` / `char` | UTF-8 collation handles Unicode |
| `money` / `smallmoney` | `decimal(19,4)` | |
| `datetime` / `smalldatetime` | `datetime2(6)` | |
| `datetimeoffset` | `datetime2(6)` | Timezone offset is lost |
| `xml` | `varchar(max)` | XML functions lost |
| `ntext` / `text` | `varchar(max)` | |
| `image` | `varbinary(max)` | |
| `tinyint` | `smallint` | |
| `geometry` / `geography` | `varbinary` (WKB) or `varchar` (WKT) | Cast as needed |
| `sql_variant` | No equivalent | |
| `hierarchyid` | No equivalent | |

## Unsupported T-SQL Features

- `FOR XML` — use `FOR JSON` instead (and only as last operator, not in subqueries)
- Recursive CTEs
- `SET ROWCOUNT` / `SET TRANSACTION ISOLATION LEVEL`
- Materialized views
- Triggers
- **Cursors** — replace with `WHILE` + `ROW_NUMBER()`. Row-by-row is slow on a distributed engine; prefer set-based whenever possible.
- `CREATE USER` — users auto-created on GRANT/DENY
- Multi-column manual statistics
- `PREDICT`
- Schema/table names with `/` or `\`
- MARS (Multiple Active Result Sets) — remove from connection strings

## Supported Features

- Standard and nested CTEs
- Window functions (ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, aggregates OVER)
- CROSS APPLY / OUTER APPLY
- PIVOT / UNPIVOT
- FOR JSON (last operator only)
- COALESCE, NULLIF, IIF, CHOOSE
- Cross-database queries via 3-part naming (same workspace AND same region only)
- Session-scoped #temp tables (prefer distributed with `WITH (DISTRIBUTION = ROUND_ROBIN)`)

## Table Constraints and Limits

- **8,060-byte row limit** (error 511 / 611 on violation)
- **128-char limit** on table/column names
- **1,024-column max** per table
- No default value constraints; no computed columns (use views)
- **PK / UNIQUE / FK supported only as `NONCLUSTERED + NOT ENFORCED`** — metadata-only; the engine does not enforce them at DML time. They serve as optimizer hints, and Power BI uses FK relationships for automatic relationship detection.
- `DEFAULT` / `CHECK` not supported
- `NOT NULL` only via `CREATE TABLE` (cannot be added via `ALTER TABLE`)

## Schema Evolution

| Operation | Status | Syntax |
|---|---|---|
| Add nullable column | ✅ | `ALTER TABLE t ADD col type NULL` |
| Drop column | ✅ April 2025+ | `ALTER TABLE t DROP COLUMN col` (metadata-only) |
| Rename column | ✅ April 2025+ | `EXEC sp_rename 't.OldCol', 'NewCol', 'COLUMN'` |
| Rename table | ✅ | `EXEC sp_rename 'OldName', 'NewName'` |
| Add / drop `NONCLUSTERED NOT ENFORCED` PK / UNIQUE / FK | ✅ | `ALTER TABLE t ADD CONSTRAINT ... NONCLUSTERED NOT ENFORCED` / `DROP CONSTRAINT` |
| ALTER TABLE inside `BEGIN TRAN ... COMMIT` | ✅ April 2026+ GA | All supported ALTER TABLE variants run atomically; any failure rolls every schema change back |
| `ALTER COLUMN` — **widen** type (metadata-only) | 🔶 Preview | `ALTER TABLE t ALTER COLUMN col wider_type`. Metadata-only type-widening only (see subsection below). No narrowing, no `NULL`→`NOT NULL`. |
| `ALTER COLUMN` — narrow type / `NULL`→`NOT NULL` / retype IDENTITY / change collation | ❌ | Not supported even in preview. CTAS workaround: create new table with desired schema, `DROP TABLE`, `sp_rename`, re-add constraints/security |

CTAS workaround **destroys time-travel history and security (GRANT/DENY)** on the original table — re-apply security after the swap.

### `ALTER COLUMN` (Preview)

`ALTER TABLE ... ALTER COLUMN` is **in preview**. It supports **metadata-only schema evolution** — only changes that don't require validating or rewriting the underlying Parquet files (i.e. **type widening** compatible with existing stored data). Takes a **Sch-M lock** for the duration (blocks/blocked by concurrent workloads).

**Supported conversions (widening / interchange only):**

| Category | Source → Target |
|---|---|
| Integer widening | `smallint`→`int`/`bigint`; `int`→`bigint` |
| Floating-point widening | `real`→`float`; `smallint`/`int`→`float` |
| Decimal widening | `decimal(p,s)`→`decimal(p+k1, s+k2)` where k1 ≥ k2 ≥ 0; `smallint`/`int`→`decimal(10+k1, k2)` |
| Decimal / numeric interchange | `decimal(p,s)` ↔ `numeric(p,s)` |
| Float / real interchange | `float(n 0`), then branch into a notebook that runs `OPTIMIZE`. Note before `VACUUM`: removing old files permanently shortens the time-travel window.

## Source Control and CI/CD (Preview)

Source control for Fabric Warehouse is a **preview** feature — both Git integration and deployment pipelines.

- **Git integration** (workspace-level, Azure DevOps or GitHub): commit/sync warehouse objects, branch out to feature workspaces, revert, bi-directional sync; automatable via Fabric REST APIs. Warehouse appears as a supported item (preview) in the Source control panel.
- **Deployment pipelines**: promote across Dev → Test → Prod stages.
- **IDE / local**: VS Code with **DacFx** (SQL database projects) for schema management, **SSMS** for interactive dev; external CI/CD via **SQLPackage CLI**, DacFx tasks, and REST APIs.
- Use SQL database projects + Git for incremental object-level change and history; use deployment pipelines for environment promotion.
- **Collation-mismatch gotcha**: promoting/branching/merging when source and target warehouses were created with different collations is **not supported** — deployment may succeed but dataset collation isn't reconciled. Fix with the `dw-collation-error-update-tmsl` script in the Fabric toolbox.

## Default Collation

`Latin1_General_100_BIN2_UTF8` — case-sensitive, binary. Case-insensitive alternative: `Latin1_General_100_CI_AS_KS_WS_SC_UTF8`. Use explicit `COLLATE` in comparisons if case-insensitive is needed.

## Pipeline Integration

- **Use the Script activity** (with a Warehouse connection) to invoke Warehouse stored procedures from Fabric Data Pipelines.
- **The Stored Procedure activity does NOT support Fabric Warehouse** — it only supports Azure SQL / SQL MI. Common pitfall when wiring up DW from pipelines.

## Reference

- Microsoft Learn: [What is Fabric Data Warehouse?](https://learn.microsoft.com/fabric/data-warehouse/data-warehousing)
- Microsoft Learn: [Performance guidelines](https://learn.microsoft.com/fabric/data-warehouse/guidelines-warehouse-performance)
- Microsoft Learn: [Secure your Fabric Data Warehouse](https://learn.microsoft.com/fabric/data-warehouse/security)
- Comprehensive MS Learn link bundle (concept / connect / tables / ingestion / performance / monitoring / security / backup-restore / source control & CI/CD): [references/REFERENCE.md](references/REFERENCE.md)

## See also

- fabric-database skill — full Azure SQL engine inside Fabric, none of these restrictions apply
- fabric-monitoring skill — Query Insights, query labels, DMVs, KILL, Result Set Caching, statistics
- fabric-security skill — GRANT/DENY/RLS/CLS/DDM SQL syntax for Warehouse
- fabric-auth skill — TDS connection essentials (port 1433, Initial Catalog vs FQDN, Encrypt=Yes)
- fabric-gotchas skill — cross-cutting error index

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [wardawgmalvicious](https://github.com/wardawgmalvicious)
- **Source:** [wardawgmalvicious/claude-config](https://github.com/wardawgmalvicious/claude-config)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: flagged — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-wardawgmalvicious-claude-config-fabric-warehouse
- Seller: https://agentstack.voostack.com/s/wardawgmalvicious
- Browse the marketplace: https://agentstack.voostack.com/browse

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