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db-migration-scripts

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Writing database migration SQL scripts. Use when creating or modifying migration files under db/migration/ directories, adding tables, indexes, or columns.

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Database Migration Scripts

Dual-Database Support

Every migration must be written for both PostgreSQL and SQLite. Migration files live in parallel directories:

  • db/migration/postgres/NNN_description.sql
  • db/migration/sqlite/NNN_description.sql

Both files must have the same numbered prefix and name. Use the appropriate SQL dialect for each (e.g., BIGSERIAL vs INTEGER PRIMARY KEY AUTOINCREMENT, UUID vs TEXT, TIMESTAMPTZ vs TEXT).

File Naming

Migration files are numbered sequentially with zero-padded three-digit prefixes:

001_init.sql
002_code_first_routes.sql
003_wasi_config.sql

Check existing files to determine the next number.

Index Naming Convention

Index names follow the format: <table>_<column(s)>_<idx|uk>

  • _idx for regular indexes
  • _uk for unique indexes

Examples:

CREATE INDEX accounts_deleted_at_idx ON accounts (deleted_at);
CREATE UNIQUE INDEX accounts_email_uk ON accounts (email) WHERE deleted_at IS NULL;
CREATE UNIQUE INDEX plugins_name_version_uk ON plugins (account_id, name, version);

Primary Keys

  • Do not create indexes on primary key columns. Both PostgreSQL and SQLite automatically create an index for primary key columns.
  • Name primary key constraints as <table>_pk: 
    CONSTRAINT accounts_pk PRIMARY KEY (account_id)

Column Types

Use the same column types in PostgreSQL and SQLite whenever possible, to make it easier to write queries that work on both databases. Only use database-specific types (e.g., BIGSERIAL vs INTEGER PRIMARY KEY AUTOINCREMENT, UUID vs TEXT, TIMESTAMPTZ vs TEXT, TEXT[] vs TEXT) when there is no common alternative.

Table Style

  • Use uppercase SQL keywords (CREATE TABLE, NOT NULL, PRIMARY KEY)
  • Column definitions are indented and aligned
  • Primary key constraints are defined inline or as named table constraints