@@ -17,6 +17,8 @@ ENGINE_DEPENDENCIES=""
 
 if [ "$ENGINE" == "spark" ]; then
     ENGINE_DEPENDENCIES="default-jdk"
+elif [ "$ENGINE" == "db2" ]; then
+    ENGINE_DEPENDENCIES="libxml2-dev build-essential"
 elif [ "$ENGINE" == "fabric" ]; then
     echo "Installing Microsoft package repository"
 
 
@@ -90,6 +90,20 @@ risingwave_ready() {
     probe_port 4566
 }
 
+db2_ready() {
+    probe_port 50001
+
+    echo "Waiting for Db2 to finish initialising (this can take 2-4 minutes)..."
+    while true; do
+        if docker exec db2 su - db2inst1 -c "db2 connect to TESTDB" > /dev/null 2>&1; then
+            echo "Db2 is accepting connections"
+            break
+        fi
+        echo "Db2 not yet ready; sleeping 15s..."
+        sleep 15
+    done
+}
+
 echo "Waiting for $ENGINE to be ready..."
 
 READINESS_FUNC="${ENGINE}_ready"
 
@@ -0,0 +1,65 @@
+name: db2
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - 'sqlmesh/core/engine_adapter/db2.py'
+      - 'tests/core/engine_adapter/test_db2.py'
+      - 'tests/core/engine_adapter/integration/test_integration_db2.py'
+      - 'tests/core/engine_adapter/integration/docker/compose.db2.yaml'
+      - '.github/workflows/db2.yaml'
+      - 'pyproject.toml'
+  pull_request:
+    branches:
+      - main
+    paths:
+      - 'sqlmesh/core/engine_adapter/db2.py'
+      - 'tests/core/engine_adapter/test_db2.py'
+      - 'tests/core/engine_adapter/integration/test_integration_db2.py'
+      - 'tests/core/engine_adapter/integration/docker/compose.db2.yaml'
+      - '.github/workflows/db2.yaml'
+      - 'pyproject.toml'
+
+concurrency:
+  group: db2-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  db2-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 25
+    env:
+      PYTEST_XDIST_AUTO_NUM_WORKERS: 2
+      SQLMESH__DISABLE_ANONYMIZED_ANALYTICS: '1'
+      UV: '1'
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: '3.12'
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+      - name: Install SQLMesh dev dependencies
+        run: |
+          uv venv .venv
+          source .venv/bin/activate
+          make install-dev
+      - name: Install OS-level dependencies
+        run: ./.github/scripts/install-prerequisites.sh "db2"
+      - name: Run tests
+        run: |
+          source .venv/bin/activate
+          make db2-test
+      - name: Upload test results
+        uses: actions/upload-artifact@v7
+        if: ${{ !cancelled() }}
+        with:
+          name: test-results-docker-db2
+          path: test-results/
+          retention-days: 7
@@ -17,6 +17,7 @@ jobs:
       python: ${{ steps.filter.outputs.python }}
       client: ${{ steps.filter.outputs.client }}
       vscode: ${{ steps.filter.outputs.vscode }}
+      lsp: ${{ steps.filter.outputs.lsp }}
       ci: ${{ steps.filter.outputs.ci }}
     steps:
       - uses: actions/checkout@v7
@@ -37,6 +38,8 @@ jobs:
               - 'web/client/**'
             vscode:
               - 'vscode/**'
+            lsp:
+              - 'sqlmesh/lsp/**'
             ci:
               - '.github/**'
               - 'Makefile'
@@ -427,10 +430,12 @@ jobs:
       - name: Run CI
         run: pnpm run ci
   test-vscode-e2e:
-    runs-on:
-      labels: [ubuntu-2204-8]
-    # As at 2026-01-12 this job flakes 100% of the time. It needs investigation
-    if: false
+    needs: changes
+    if:
+      needs.changes.outputs.vscode == 'true' || needs.changes.outputs.lsp ==
+      'true' || needs.changes.outputs.ci == 'true' || github.ref ==
+      'refs/heads/main'
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v7
       - uses: actions/setup-node@v7
@@ -453,7 +458,9 @@ jobs:
           source .venv/bin/activate
           make install-dev
       - name: Install code-server
-        run: curl -fsSL https://code-server.dev/install.sh | sh
+        # Pinned so that a code-server release cannot change the editor UI the
+        # tests drive without the change showing up here first.
+        run: curl -fsSL https://code-server.dev/install.sh | sh -s -- --version 4.137.0
       - name: Install Playwright browsers
         working-directory: ./vscode/extension
         run: pnpm exec playwright install
@@ -558,7 +565,8 @@ jobs:
         run: |
           source ../../.venv/bin/activate
           sed -i 's/target: in_memory/target: postgres/g' profiles.yml
-          if [[ $(echo -e "${{ matrix.dbt-version }}\n1.5.0" | sort -V | head -n1) == "${{ matrix.dbt-version }}" ]] && [[ "${{ matrix.dbt-version }}" != "1.5.0" ]]; then
+          if [[ "${{ matrix.dbt-version }}" == "1.3" ]] || \
+             [[ "${{ matrix.dbt-version }}" == "1.4" ]]; then
             echo "DBT version is ${{ matrix.dbt-version }} (< 1.5.0), removing version parameters..."
             sed -i -e 's/, version=1) }}/) }}/g' -e 's/, v=1) }}/) }}/g' models/top_waiters.sql
           else
 
@@ -132,13 +132,13 @@ engine-up: engine-clickhouse-up engine-mssql-up engine-mysql-up engine-postgres-
 engine-down: engine-clickhouse-down engine-mssql-down engine-mysql-down engine-postgres-down engine-spark-down engine-trino-down
 
 fast-test:
-	pytest -n auto -m "fast and not cicdonly and not isolated" --junitxml=test-results/junit-fast-test.xml && pytest -m "isolated and not slow" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
+	pytest -n auto -m "fast and not cicdonly and not isolated" --junitxml=test-results/junit-fast-test.xml && pytest -m "isolated and not slow and not fork_isolated" && pytest tests/test_forking.py::test_parallel_load -m "isolated and fork_isolated and not slow" && pytest tests/test_forking.py::test_parallel_load_multi_repo -m "isolated and fork_isolated and not slow" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
 
 slow-test:
-	pytest -n auto -m "(fast or slow) and not cicdonly and not isolated" && pytest -m "isolated" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
+	pytest -n auto -m "(fast or slow) and not cicdonly and not isolated" && pytest -m "isolated and not fork_isolated" && pytest tests/test_forking.py::test_parallel_load -m "isolated and fork_isolated" && pytest tests/test_forking.py::test_parallel_load_multi_repo -m "isolated and fork_isolated" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
 
 cicd-test:
-	pytest -n auto -m "(fast or slow) and not pyspark and not isolated" --junitxml=test-results/junit-cicd.xml && pytest -m "pyspark" && pytest -m "isolated and not pyspark" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
+	pytest -n auto -m "(fast or slow) and not pyspark and not isolated" --junitxml=test-results/junit-cicd.xml && pytest -m "pyspark" && pytest -m "isolated and not pyspark and not fork_isolated" && pytest tests/test_forking.py::test_parallel_load -m "isolated and not pyspark and fork_isolated" && pytest tests/test_forking.py::test_parallel_load_multi_repo -m "isolated and not pyspark and fork_isolated" && pytest -m "registry_isolation" && pytest -m "dialect_isolated"
 
 core-fast-test:
 	pytest -n auto -m "fast and not web and not github and not dbt and not jupyter"
@@ -222,6 +222,9 @@ risingwave-test: engine-risingwave-up
 
 starrocks-test: engine-starrocks-up
 	pytest -n auto -m "starrocks" --reruns 3 --junitxml=test-results/junit-starrocks.xml
+	
+db2-test: engine-db2-up
+	pytest -n auto -m "db2" --reruns 3 --junitxml=test-results/junit-db2.xml
 
 #################
 # Cloud Engines #
@@ -235,7 +238,10 @@ bigquery-test: guard-BIGQUERY_KEYFILE engine-bigquery-install
 	pytest -n auto -m "bigquery" --reruns 3 --junitxml=test-results/junit-bigquery.xml
 
 databricks-test: guard-DATABRICKS_CATALOG guard-DATABRICKS_SERVER_HOSTNAME guard-DATABRICKS_HTTP_PATH guard-DATABRICKS_CONNECT_VERSION engine-databricks-install
-	$(PIP) install 'databricks-connect==${DATABRICKS_CONNECT_VERSION}'
+	# Connect 15.3.x requires numpy<2 and pyarrow>=4 (no upper bound). Cap PyArrow
+	# in the same resolve that downgrades NumPy, or PyArrow 25+ is left installed
+	# and cannot be imported.
+	$(PIP) install 'databricks-connect==${DATABRICKS_CONNECT_VERSION}' 'pyarrow<25'
 	pytest -n auto -m "databricks" --reruns 3 --junitxml=test-results/junit-databricks.xml
 
 redshift-test: guard-REDSHIFT_HOST guard-REDSHIFT_USER guard-REDSHIFT_PASSWORD guard-REDSHIFT_DATABASE engine-redshift-install
 
@@ -84,6 +84,7 @@ default_gateway: local_db
 * [BigQuery](../integrations/engines/bigquery.md)
 * [ClickHouse](../integrations/engines/clickhouse.md)
 * [Databricks](../integrations/engines/databricks.md)
+* [Db2](../integrations/engines/db2.md)
 * [DuckDB](../integrations/engines/duckdb.md)
 * [Fabric](../integrations/engines/fabric.md)
 * [MotherDuck](../integrations/engines/motherduck.md)
 
@@ -36,3 +36,26 @@ Migrations should ideally run when no one will be running plan/apply.
 Migrations should not be run in parallel. 
 Due to these constraints, it is better for a person responsible for managing SQLMesh to manually issue migrations. 
 Therefore, it is not recommended to issue migrations from CI/CD pipelines.
+
+## Rolling back a migration
+
+When `sqlmesh migrate` needs to change the project metadata, it first copies each state table to a backup table with a `_backup` suffix, unless `--skip-backup` is passed. The `sqlmesh rollback` command restores the metadata from those backups, returning it to the format used by the SQLMesh version that was installed before the migration. If a migration fails partway through, SQLMesh rolls it back automatically from the same backups.
+
+To undo a migration:
+
+1. Run `sqlmesh rollback` with the SQLMesh version that performed the migration still installed.
+2. Reinstall the SQLMesh version the project used before the upgrade, for example by reverting the version change in your requirements file.
+
+The second step is required. Rolling back does not change the installed version of SQLMesh, and the newer version will refuse to run against the restored metadata until it is migrated again:
+
+```bash
+> sqlmesh plan
+Error: SQLMesh (local) is using version '2' which is ahead of '1' (remote). Please run a migration ('sqlmesh migrate' command).
+```
+
+Keep the following in mind before rolling back:
+
+- Only the most recent migration can be rolled back. Restoring consumes the backup tables, so running `sqlmesh rollback` a second time fails with `There are no prior migrations to roll back to.`
+- The backups are taken at the moment of migration. Any changes made to the project metadata after the migration, such as plans applied with the newer version, are discarded.
+- Like `sqlmesh migrate`, rolling back affects all users of the project and should be issued manually by a single user.
+- Rollback is not possible if the migration was run with `--skip-backup`. It also does nothing useful after an upgrade that required no migration, such as a patch release, because no new backup was taken. In that case the backup tables, if present, come from an earlier migration.
@@ -49,7 +49,7 @@ In general, you must be connected to a ClickHouse server to execute commands. By
 
 To associate an object with a cluster, DDL commands that create or modify it must include the text `ON CLUSTER [your cluster name]`.
 
-If you provide a cluster name in your SQLMesh connection configuration, SQLMesh will automatically inject the `ON CLUSTER` statement into the DDL commands for all objects created while executing the project. We provide more information about clusters in SQLMesh [below](#cluster-specification).
+If you provide a cluster name in your SQLMesh connection configuration, SQLMesh automatically adds `ON CLUSTER` to object DDL, except for metadata DDL targeting `Replicated` databases, which replicate those changes themselves. We provide more information about clusters in SQLMesh [below](#cluster-specification).
 
 #### ClickHouse Cloud mode
 
@@ -96,7 +96,9 @@ For example, we could create a table `my_schema.my_table` on cluster `TheCluster
 
 To create SQLMesh objects on a cluster, provide the cluster name to the `cluster` key in the SQLMesh connection definition (see all connection parameters [below](#localbuilt-in-scheduler)).
 
-SQLMesh will automatically inject the `ON CLUSTER` clause and cluster name you provide into all project DDL statements.
+SQLMesh automatically adds the `ON CLUSTER` clause and cluster name you provide to object DDL, except for metadata DDL targeting `Replicated` databases. SQLMesh retains `ON CLUSTER` for database creation and removal and for partition operations.
+
+Partition overwrites in multi-shard `Replicated` databases remain unvalidated. ClickHouse can replicate an ALTER containing both `REPLACE PARTITION` and `DROP PARTITION`, which can conflict with `ON CLUSTER`. This behavior predates the metadata DDL policy described above and depends on the ClickHouse version.
 
 ## Model definition
 
 
@@ -0,0 +1,78 @@
+# Db2
+
+This page provides information about how to use SQLMesh with [IBM Db2](https://www.ibm.com/products/db2).
+
+!!! info
+    The Db2 engine adapter is a community contribution. Due to this, only limited community support is available.
+
+    This adapter depends on the external `db2-sqlglot-dialect` package, which pins its own SQLGlot version range. It isn't covered by SQLMesh's core CI and may temporarily break or fail to install after SQLMesh upgrades SQLGlot, until the plugin catches up.
+
+## Local/Built-in Scheduler
+
+**Engine Adapter Type**: `db2`
+
+### Installation
+
+```
+pip install "sqlmesh[db2]"
+```
+
+### Connection options
+
+| Option              | Description                                                                                    | Type   | Required |
+|---------------------|------------------------------------------------------------------------------------------------|:------:|:--------:|
+| `type`              | Engine type name - must be `db2`                                                               | string | Y        |
+| `host`              | The hostname of the Db2 server                                                                 | string | Y        |
+| `port`              | The port number of the Db2 server. Default: `50000`                                            | int    | N        |
+| `database`          | The name of the Db2 database to connect to                                                     | string | Y        |
+| `username`          | The username to use for authentication with the Db2 server                                     | string | Y        |
+| `password`          | The password to use for authentication with the Db2 server                                     | string | Y        |
+| `db2_schema`        | Sets `CURRENTSCHEMA` on the connection. Controls the default schema for unqualified references. Typically set to the same value as `username`. | string | Y        |
+| `ssl`               | Enable TLS/SSL encryption. Default: `false`                                                    | bool   | N        |
+| `connect_timeout`   | The number of seconds to wait for the connection to the server. Default: `30`                  | int    | N        |
+| `concurrent_tasks`  | Maximum number of tasks to run concurrently. Default: `4`                                      | int    | N        |
+
+## Important Notes
+
+**State connection:** Db2 is **not supported** as a SQLMesh `state_connection`. Use DuckDB (recommended) or another supported engine for SQLMesh state storage:
+
+```yaml linenums="1"
+gateways:
+  db2:
+    connection:
+      type: db2
+      host: localhost
+      port: 50000
+      database: TESTDB
+      username: db2inst1
+      password: your_password
+      db2_schema: db2inst1
+    state_connection:
+      type: duckdb
+      database: ./state/sqlmesh_state.db
+
+default_gateway: db2
+
+model_defaults:
+  dialect: db2
+```
+
+**Table naming:** Db2 rejects table names that start with an underscore (`_`). SQLMesh's default physical table naming convention can generate names beginning with `_`. To avoid this, set `physical_table_naming_convention` to `hash_md5` in your project config:
+
+```yaml
+physical_table_naming_convention: hash_md5
+```
+
+## Limitations
+
+- **SCD Type 2 unsupported**: SCD Type 2 models are currently not supported on Db2.
+- **Single catalog only**: Db2 operates in single-catalog mode; cross-catalog queries are not supported.
+- **No inline column comments**: Column-level comments cannot be set inline during table creation.
+- **No atomic table replacement**: Db2 does not support `CREATE OR REPLACE TABLE`, so full model refreshes are not atomic. There is a brief window during which the table may be empty or partially populated.
+- **Identifier length**: Maximum identifier length is 128 characters.
+- **No `SELECT ... FOR UPDATE`**: Db2 does not support `SELECT ... FOR UPDATE` in the same way as OLTP databases; SQLMesh removes this clause when executing queries.
+
+## Resources
+
+- [IBM Db2 Documentation](https://www.ibm.com/docs/en/db2)
+- [IBM Db2 SQL Reference](https://www.ibm.com/docs/en/db2/11.5?topic=db2-sql)
@@ -1,5 +1,8 @@
 # StarRocks
 
+!!! info
+    The StarRocks engine adapter is a community contribution. Due to this, only limited community support is available.
+
 ## Overview
 
 [StarRocks](https://www.starrocks.io/) is a next-generation sub-second MPP OLAP database designed for real-time analytics. It provides high concurrency, low latency, and supports both batch and stream processing.