postgresql cli - list databases errors because of missing pg_encoding_to_char udf

[ybrs]

Postgresql cli sends this query for \l (list databases)

query: "select d.datname as \"name\", pg_get_userbyid(d.datdba) as \"owner\", pg_encoding_to_char(d.encoding) as \"encoding\", case d.datlocprovider when 'c' then 'libc' when 'i' then 'icu' end as \"locale provider\", d.datcollate as \"collate\", d.datctype as \"ctype\", d.daticulocale as \"icu locale\", d.daticurules as \"icu rules\", array_to_string(d.datacl, e'\\n') as \"access privileges\" from pg_catalog.pg_database as d order by 1"

Which results in

[2025-09-20T21:14:05Z INFO  datafusion_postgres::handlers] Sending error: Error during planning: Invalid function 'pg_encoding_to_char'.
    Did you mean 'string_to_array'?

To reproduce

Testing with latest master with

cargo run -- --csv data:delhiclimate.csv

and connect with psql 16 client.

psql -h localhost  -U postgres
psql (16.10 (Ubuntu 16.10-0ubuntu0.24.04.1), server 16.6-pgwire-0.32.1)
Type "help" for help.

postgres=> \l
ERROR:  Error during planning: Invalid function 'pg_encoding_to_char'.
Did you mean 'pg_get_expr'?

[sunng87]

We will need to add udf pg_encoding_to_char: https://pgpedia.info/p/pg_encoding_to_char.html

At least we can define a function that returns fixed result.

[sunng87]

I'm working on it.