Function ExecShutdownHash

src/backend/executor/nodeHash.c:3357–3367

* Collect EXPLAIN stats if needed, saving them into DSM memory if * ExecHashInitializeWorker was called, or local storage if not. In the * parallel case, this must be done in ExecShutdownHash() rather than * ExecEndHash() because the latter runs after we've detached from the DSM * segment. */

 * segment.
 */
void
ExecShutdownHash(HashState *node)
{
	/* Allocate save space if EXPLAIN'ing and we didn't do so already */
	if (node->ps.instrument && !node->hinstrument)
		node->hinstrument = (HashInstrumentation *)
			palloc0(sizeof(HashInstrumentation));
	/* Now accumulate data for the current (final) hash table */
	if (node->hinstrument && node->hashtable)
		ExecHashAccumInstrumentation(node->hinstrument, node->hashtable);
}

/*
 * Retrieve instrumentation data from workers before the DSM segment is