I'd probably start by reading the developer FAQ: https://wiki.postgresql.org/wiki/Developer_FAQ#How_do_I_get_involved_in_PostgreSQL_development.3F and subscribing to the pgsql-novice@lists.postgresql.org mailing list. To get a copy of the source on your machine, the docs: https://www.postgresql.org/docs/current/git.html and https://wiki.postgresql.org/wiki/Working_with_Git may also be helpful.
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Соглашаюсь с условиями обработки персональных данных