# Schema Change > Use when changing the db-scheduler database schema (adding/removing/altering columns, indexes, or the scheduled_tasks table). Walks through the lock-step update across every supported DB dialect, the matching JdbcCustomization changes, and the documentation copies. Skip for code-only changes that don't touch table structure. - Skill: `tomevault-io/schema-change` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/schema-change` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/schema-change/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Docs & Writing - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/schema-change --- # Schema change checklist The library supports six DB dialects and ships DDL for each. A schema change that misses one dialect ships a broken release. Treat this as a single atomic change. ## 1. DDL files (test resources) Update **all six** in lock-step. Path: `db-scheduler/src/test/resources/` - `hsql_tables.sql` - `postgresql_tables.sql` - `mysql_tables.sql` - `mariadb_tables.sql` - `mssql_tables.sql` - `oracle_tables.sql` Read all six first; column ordering and types differ per dialect (e.g. `TIMESTAMP WITH TIME ZONE` vs `DATETIME2` vs `TIMESTAMP(6) WITH TIME ZONE`). Don't blindly copy from one dialect to another — preserve each dialect's existing type conventions. There's also `postgresql_custom_tablename.sql` under `src/test/resources/com/github/kagkarlsson/scheduler/` — check whether your change needs to be reflected there too (it tests configurable table name; usually yes if columns change). ## 2. JdbcCustomization classes Path: `db-scheduler/src/main/java/com/github/kagkarlsson/scheduler/jdbc/` If your change affects how rows are read/written (new column, type change, nullable→ not-null, etc.), update each relevant class: - `DefaultJdbcCustomization.java` — base behavior - `PostgreSqlJdbcCustomization.java` - `OracleJdbcCustomization.java` - `MssqlJdbcCustomization.java` - `MySQLJdbcCustomization.java` - `MySQL8JdbcCustomization.java` - `MariaDBJdbcCustomization.java` - `AutodetectJdbcCustomization.java` — only if dialect-detection logic changes - `JdbcCustomization.java` (interface) — if the contract itself changes Also check `JdbcTaskRepository.java` and `QueryBuilder.java` for SQL that references the changed columns. ## 3. Documentation DDL copies The README and/or `docs/` may carry copies of the DDL for users. Grep for a column name from the table to find them: ```bash grep -rn "scheduled_tasks" --include="*.md" . ``` Update any matching SQL blocks so users get the current schema. ## 4. Verify ```bash mvn -pl db-scheduler test # PostgreSQL tests ``` Dialects other than PostgreSQL currently need to be tested on CI (need to run on amd64 arch). ## 5. Migration note for users Schema changes are user-visible. Add a brief migration note to the changelog / release notes describing the required `ALTER TABLE` (per dialect if they differ). ## 6. Finalize Run `/finalize` before committing. --- > Source: [kagkarlsson/db-scheduler](https://github.com/kagkarlsson/db-scheduler) — distributed by [TomeVault](https://tomevault.io).