Thread

[PATCH] psql: Allow connection string parameters as positional arguments

Daymel Bonne Solís <daymelbonne@gmail.com> — 2025-12-18T20:23:46Z

Hi hackers,

I'd like to propose a small enhancement to psql that improves usability
when working with connection services and other libpq connection parameters.

Problem

Currently, when users try to use connection string parameters like
service=myservice as positional arguments to psql, the behavior is
confusing. For example:

psql service=production dbname=postgres -c "SELECT current_database()"

This fails with:
Password for user dbname=postgres:
psql: error: password authentication failed for user "dbname=postgres"

The issue is that psql interprets service=centraldb as the database name
(first positional arg) and dbname=postgres as the username (second
positional arg), treating them as literal strings rather than connection
parameters.

Use Case

This is particularly inconvenient when working with pg_service.conf, where
users define connection profiles but occasionally need to override specific
parameters. Currently, the workaround requires quoting the entire
connection string:

# Current workaround (verbose)
psql -d "service=centraldb dbname=postgres" -c "SELECT current_database()"

# Desired syntax (intuitive)
psql service=centraldb -d postgres -c "SELECT current_database()"

The proposed syntax is more intuitive and aligns with how other tools
handle similar parameter overrides.

Solution

This patch modifies psql to recognize positional arguments containing = as
connection string parameters. These are collected into a connection string
that serves as the base for the connection. Explicit options (-d, -h, -p,
-U) override corresponding values.

The implementation:
- Adds a connstring field to struct adhoc_opts
- Modifies parse_psql_options() to detect and collect key=value arguments
- Updates the connection logic to merge connstring with explicit options

Backward Compatibility

This change is fully backward compatible:
- Regular positional arguments (without =) continue to work as database
name and username
- Database names containing = are rare and can still be specified via -d
"db=name"
- All existing command-line patterns remain functional

Examples

# Use service with database override
psql service=production -d postgres

# Multiple connection parameters
psql host=localhost port=5433 sslmode=require -d mydb

# Mix key=value with regular positional arg
psql host=localhost port=5433 mydb

Testing

The patch includes a new TAP test file (t/002_connstring.pl) with 17 test
cases covering:
- Basic key=value positional arguments
- Override behavior with -d flag
- Multiple key=value parameters
- Mixed key=value and regular positional arguments
- Parameter ordering variations

All existing psql tests continue to pass.

Patch attached.

Feedback welcome!

---
Best regards, Daymel Bonne