Challenge-1

[Ashraf8ila]

Improve PeerDB for Postgres-to-Postgres migrations — add schema, trigger, and index migration support (with tests)

[CLAassistant]

All committers have signed the CLA.

[Ashraf8ila]

1. Schema Migration (MigrateSchemaFromSource)
   Detects source table schemas (columns, data types, nullability, defaults)
   Creates tables if missing in target
   Alters existing tables to add missing columns
   Preserves primary keys and constraints
   Handles column data types, nullability, and default values

2. Trigger Migration (MigrateTriggersFromSource)
   Detects triggers using pg_get_triggerdef()
   Extracts timing (BEFORE/AFTER/INSTEAD OF) and events (INSERT/UPDATE/DELETE/TRUNCATE)
   Drops existing triggers on target before recreating
   Creates triggers with proper table name replacement
   Uses transactions for atomicity

3. Index Migration (MigrateIndexesFromSource)
   Migrates non-primary key indexes
   Preserves unique constraints
   Handles index methods (btree, hash, etc.)
   Skips primary key indexes (handled by schema migration)
   Drops existing indexes before recreating

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Testing
4 tests (all passing):
TestSchemaMigration — Verifies table creation, column migration, and primary key preservation
TestTriggerMigration — Verifies trigger migration with function dependencies
TestIndexMigration — Verifies index migration including unique indexes
TestFullMigration — Integration test combining all three migration types

[serprex]

can use type assertion like in flowable.go

[serprex]

not sure why this is method & other methods are free standing functions in migration.go