feat: selectable database driver (psycopg or asyncpg) - #62
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Replace synchronous psycopg3 with asyncpg for the database introspection path (src/pgmig/_build/*). build_db_info keeps its sync signature via asyncio.run, so api.py, the CLI, and tests are untouched. The 10 loaders and _run_query become async; connect uses server_settings for the read-only transaction. Bad-DSN/connection failures are surfaced as PgmigError (catching OSError, PostgresError, InterfaceError). asyncpg uses the binary protocol, which decodes the pg internal "char" type as bytes. A non-identity attidentity is byte \x00, which pydantic coerced to the non-empty string '\x00' and broke the identity check. Casting the four returned "char" columns (attidentity, contype, prokind, relkind) to ::text restores the old text-protocol values. Test fixtures stay on psycopg (DDL setup, orthogonal to the read path). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Resolve conflicts from the _build->_introspect rename (#112) and the async-psycopg introspection refactor (#124): - Drop the obsolete _build/* edits; re-apply the asyncpg driver swap onto the current _introspect read path (_core, _engine, _context). - _connect: asyncpg.connect with session read-only + REPEATABLE READ, and a json/jsonb text codec so nested jsonb parses into models. - run_introspection_query: fetch via asyncpg and build models from records. - Cast attidentity::text to match the other char columns. - Regenerate uv.lock for asyncpg.
# Conflicts: # src/pgmig/_introspect/_context.py # src/pgmig/_introspect/_core.py # src/pgmig/_introspect/_engine.py
match driver in _db.py, thread driver arg through api/cli/engine, --driver pytest flag, both drivers in dev deps, cast char catalog cols to text. Both driver suites pass (316 each). Lint/type-check + packaging default TBD.
Add a driver argument to generate/agenerate (and --driver / PGMIG_DRIVER on the CLI) selecting psycopg (default) or asyncpg behind the _db abstraction. Package psycopg as the base dependency with binary/c/asyncpg install extras. Cast char catalog columns to text so both drivers agree. Run one asyncpg cell (py3.14/pg18) in CI. Document the driver/build tradeoffs in the README FAQ.
Apakottur
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Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_014h6yDcdivduaRr31BviN1C
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What
Make the database driver selectable rather than hard-swapping psycopg for asyncpg. Both drivers sit behind the
_dbabstraction; adriverargument picks one.drivertogenerate/agenerate("psycopg"default, or"asyncpg"), and--driver/PGMIG_DRIVERon the CLI. Threaded down tointrospect_dband the connection._db.pygrows an asyncpg implementation alongside psycopg, chosen withmatch driver:inconnect/execute/introspect.pgmig[binary](psycopg prebuilt wheel),pgmig[c](psycopg compiled against system libpq),pgmig[asyncpg]."char"catalog columns (attgenerated, matviewrelkind) totextso asyncpg and psycopg return identical values.--driverpytest flag; CI runs one asyncpg cell (py3.14 / pg18).Behavior
No change to emitted SQL. Both drivers produce identical migrations — the full suite (316 tests) passes under each. Default is
driver="psycopg", so existing users are unaffected; asyncpg is opt-in via the extra plus the argument.Notes
Benchmarked psycopg vs asyncpg on introspection: psycopg is ~1.2–1.3x faster (introspection is a handful of one-shot catalog queries, where asyncpg's per-statement prepare cost outweighs its throughput edge; psycopg's
binary/cbuilds widen the gap). Hence psycopg is the default.pgmig[binary]is offered but not the default — its bundled libpq/OpenSSL only update with the wheel, which psycopg discourages for production;pgmig[c]is the production-fast option.