The previous coding here threw an error from assign_client_encoding if it was invoked in a parallel worker. That's a very fundamental violation of the GUC hook API: assign hooks must not throw errors. The place to complain is in the check hook, so move the test to there, and use the regular check-hook API (ie return false) to report it. The reason this coding is a problem is that it breaks GUC rollback, which may occur after we leave InitializingParallelWorker state. That case seems not actually reachable before now, but commit f5f30c22e made it reachable, so we need to fix this before that can be un-reverted. In passing, improve the commentary in ParallelWorkerMain, and add a check for failure of SetClientEncoding. That's another case that can't happen now but might become possible after foreseeable code rearrangements (notably, if the shortcut of skipping PrepareClientEncoding stops being OK). Discussion: https://postgr.es/m/18545-feba138862f19aaa@postgresql.org
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
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