Summary

Adds a new Knative cloud function that transforms schema names in SQL using AST-based parsing with plpgsql-parser. The function accepts SQL and a schema mapping, then returns the transformed SQL with schema names replaced according to the mapping.

The transformation logic is adapted from @constructive-db/introspection's transform-schemas-ast.ts and handles:

• Schema-qualified identifiers in RangeVar nodes (schema.table in SELECT/FROM)
• Schema names in CreateSchemaStmt, DropStmt, GrantStmt nodes
• DDL statements with embedded relations: CreateStmt (CREATE TABLE), IndexStmt, AlterTableStmt, TruncateStmt, CreateTrigStmt, RuleStmt, CreatePolicyStmt
• Schema-qualified function names in FuncCall nodes
• Schema-qualified type names in TypeName nodes
• Schema names in VariableSetStmt (SET search_path)
• Schema names inside PL/pgSQL function bodies (hydrated AST)

API:

POST /
{
  "sql": "SELECT * FROM old_schema.users",
  "schema_mapping": { "old_schema": "new_schema" }
}
// Returns: { transformed_sql, schemas_found, schemas_transformed }

Updates since last revision

Fixed a bug where DDL statements like CREATE TABLE old_schema.users were not being transformed. The @pgsql/traverse walker looks for nodes by their key name (e.g., RangeVar), but DDL statements like CreateStmt store their relation directly without the RangeVar wrapper. Added explicit handlers for CreateStmt, IndexStmt, AlterTableStmt, TruncateStmt, CreateTrigStmt, RuleStmt, and CreatePolicyStmt.

Local testing confirmed the following transformations now work:

• CREATE SCHEMA old_schema → CREATE SCHEMA new_schema
• SET search_path TO old_schema → SET search_path TO new_schema
• CREATE TABLE old_schema.users → CREATE TABLE new_schema.users
• GRANT USAGE ON SCHEMA old_schema → GRANT USAGE ON SCHEMA new_schema
• SELECT * FROM old_schema.users → SELECT * FROM new_schema.users
• PL/pgSQL function bodies with schema-qualified calls

Review & Testing Checklist for Human

• Verify DDL coverage is complete - Other DDL statements may need similar handlers (e.g., ViewStmt, CreateSeqStmt, CommentStmt). Compare against the original transform-schemas-ast.ts in constructive-db
• Test edge cases - Quoted identifiers, nested schema references, %TYPE/%ROWTYPE suffixes
• Deploy and invoke - Verify the function can be deployed to Knative and invoked via HTTP

Recommended test plan:

1. Build and run locally: cd functions/sql-schema-transform && pnpm build && PORT=8080 node dist/index.js
2. Test with curl:

curl -X POST http://localhost:8080 \
  -H "Content-Type: application/json" \
  -d '{"sql": "CREATE SCHEMA old_schema; SET search_path TO old_schema; CREATE TABLE old_schema.users (id uuid, name text); GRANT USAGE ON SCHEMA old_schema TO authenticated; SELECT * FROM old_schema.users; CREATE FUNCTION old_schema.test() RETURNS void AS $$ BEGIN PERFORM old_schema.other_fn(); END; $$ LANGUAGE plpgsql;", "schema_mapping": {"old_schema": "new_schema"}}'

Notes

• No unit tests were added - consider adding tests before production use
• No README was added (unlike other functions in this directory)
• Uses any types for AST nodes which is consistent with the source code but reduces type safety
• Local testing was performed and a bug was found and fixed during development

Requested by: @pyramation
Link to Devin run: https://app.devin.ai/sessions/2eed6a2d4f0142349bb3bdd50334b23f