Troubleshooting PostgreSQL and SQLAlchemy problems in the Definable backend
Database connection failures
Could not connect to server: Connection refused
OperationalError: (psycopg2.OperationalError) connection to server at "localhost" (::1), port 5432 failed
psql -U postgres -c "SELECT datname FROM pg_database;"
asyncpg connection issues
asyncpg.exceptions.PostgresConnectionError: connection to server was closed
asyncpg.exceptions.InvalidAuthorizationSpecificationError: password authentication failed
SSL connection issues
ssl_error_want_read
or ssl_error_want_write
SSL SYSCALL error: EOF detected
Alembic migration failures
FAILED: Multiple head revisions are present
Can't locate revision identified by '...'
alembic.ini
has correct database URLenv.py
imports your SQLAlchemy models correctlyMigration conflicts
Error: Target database is not up to date.
Can't locate revision identified by '...'
down_revision
in migration files to fix the chainalembic history
to understand the current chainAutogenerate issues
alembic revision --autogenerate
doesnβt detect model changesMigration execution errors
ProgrammingError: column X does not exist
SQLAlchemy engine connection issues
TimeoutError: Connection attempt timed out
max_connections
in postgresql.conf)SELECT count(*) FROM pg_stat_activity;
SQLAlchemy async session issues
AssertionError: A sync operation occurred within an async transaction.
InterfaceError: connection is closed
.all()
with await session.execute(query).all()
.first()
with await session.execute(query).first()
await session.commit()
instead of session.commit()
SQLAlchemy query problems
AttributeError: 'Query' object has no attribute 'xxx'
.scalars()
to get model instances.mappings()
to get dictionariespgvector-related errors
Schema permission errors
permission denied for schema public
permission denied for relation your_table
Full-text search issues
Slow queries
LIMIT
to restrict result sizeConnection pooling issues
FATAL: too many connections
Large result sets
UUID generation problems
invalid input syntax for type uuid
Foreign key constraint violations
violates foreign key constraint
insert or update on table violates foreign key constraint
Unique constraint violations
duplicate key value violates unique constraint
JSON/JSONB field issues
Unexpected JSON type
Transaction management issues
current transaction is aborted, commands ignored until end of transaction block
pgvector performance issues
IPv4 vs IPv6 connection problems
could not connect to server: Connection timed out (0x0000274C/10060) Is the server running on host "db.abcdefghijkl.supabase.co" and accepting TCP/IP connections on port 5432?
Network and firewall issues with Supabase
OperationalError: could not connect to server: Connection refused
ssl_error_syscall
with Supabase connectionSupabase connection pool exhaustion
remaining connection slots are reserved for non-replication superuser connections
sorry, too many clients already
when multiple services connectRegion and latency issues with Supabase
SSL and TLS issues with Supabase
SSL SYSCALL error: EOF detected
ssl_error_want_read
or ssl_error_want_write
SSL error: certificate verify failed
Supabase pricing tier limitations
sorry, too many clients already
despite proper connection pooling