D7 Backport: Drupal 8.x on Postgresql 12

Problem/Motivation

While testing the new 7.x-dev release I have run into an issue on one website running on PostgreSQL 12. The problem is with this patch: #2823488: Backport DatabaseSchema_pgsql::queryTableInformation() improvements (originally backported 6 years ago by @mradcliffe). After this patch there seems to be an error on PostgreSQL 12:

PDOException: SQLSTATE[42703]: Undefined column: 7 ERROR: column pg_attrdef.adsrc does not exist LINE 8: OR pg_attrdef.adsrc::text LIKE 'nextval%') ^: SELECT pg_attribute.attname AS column_name, format_type(pg_attribute.atttypid, pg_attribute.atttypmod) AS data_type, pg_get_expr(pg_attrdef.adbin, pg_attribute.attrelid) AS column_default FROM pg_attribute LEFT JOIN pg_attrdef ON pg_attrdef.adrelid = pg_attribute.attrelid AND pg_attrdef.adnum = pg_attribute.attnum WHERE pg_attribute.attnum > 0 AND NOT pg_attribute.attisdropped AND pg_attribute.attrelid = :key::regclass AND (format_type(pg_attribute.atttypid, pg_attribute.atttypmod) = 'bytea' OR pg_attrdef.adsrc LIKE 'nextval%'); Array ( [:key] => public.variable ) in variable_set()

The backport was correct but Drupal 8/9 had an additional patch following the original one, which fixed an issue with PostgreSQL 12 and newer.

The table column pg_attrdef.adsrc has been removed by PostgreSQL in version 12. See: https://www.postgresql.org/docs/current/catalog-pg-attrdef.html

Unfortunately this was not revealed with automated testing because PostgreSQL 12 is not set as the main version to test. The original D8 issue with the patch is here: #3058853: Drupal 8.x on Postgresql 12.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet