Function assign_client_encoding

src/backend/commands/variable.c:734–766

}

void
assign_client_encoding(const char *newval, void *extra)
{
	int			encoding = *((int *) extra);

	/*
	 * Parallel workers send data to the leader, not the client.  They always
	 * send data using the database encoding.
	 */
	if (IsParallelWorker())
	{
		/*
		 * During parallel worker startup, we want to accept the leader's
		 * client_encoding setting so that anyone who looks at the value in
		 * the worker sees the same value that they would see in the leader.
		 */
		if (InitializingParallelWorker)
			return;

		/*
		 * A change other than during startup, for example due to a SET clause
		 * attached to a function definition, should be rejected, as there is
		 * nothing we can do inside the worker to make it take effect.
		 */
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
				 errmsg("cannot change client_encoding during a parallel operation")));
	}

	/* We do not expect an error if PrepareClientEncoding succeeded */
	if (SetClientEncoding(encoding) < 0)
		elog(LOG, "SetClientEncoding(%d) failed", encoding);
}


/*