Function ExecHashTableExplainEnd

src/backend/executor/nodeHash.c:2578–2679

* ExecHashTableExplainEnd * Called before ExecutorEnd to finish EXPLAIN ANALYZE reporting. */

 *      Called before ExecutorEnd to finish EXPLAIN ANALYZE reporting.
 */
static void
ExecHashTableExplainEnd(PlanState *planstate, struct StringInfoData *buf)
{
    HashJoinState      *hjstate = (HashJoinState *)planstate;
    HashJoinTable       hashtable = hjstate->hj_HashTable;
    HashJoinTableStats *stats;
    Instrumentation    *jinstrument = hjstate->js.ps.instrument;
    int                 total_buckets;
    int                 i;

    if (!hashtable ||
        !hashtable->stats ||
        hashtable->nbatch < 1 ||
        !jinstrument ||
        !jinstrument->need_cdb)
        return;

    stats = hashtable->stats;

	Assert(stats->batchstats);

	if (!hashtable->eagerlyReleased)
	{		
		HashState *hashState = (HashState *) innerPlanState(hjstate);

		/* Report on batch in progress, in case the join is being ended early. */
		ExecHashTableExplainBatchEnd(hashState, hashtable);
	}
	
    /* Report actual work_mem high water mark. */
    jinstrument->workmemused = Max(jinstrument->workmemused, stats->workmem_max);

    /* How much work_mem would suffice to hold all inner tuples in memory? */
    if (hashtable->nbatch > 1)
    {
        uint64  workmemwanted = 0;

        /* Space actually taken by hash rows in completed batches... */
        for (i = 0; i <= stats->endedbatch; i++)
            workmemwanted += stats->batchstats[i].hashspace_final;

        /* ... plus workfile size for original batches not reached, plus... */
        for (; i < hashtable->nbatch_original; i++)
            workmemwanted += stats->batchstats[i].innerfilesize;

        /* ... rows spilled to unreached oflo batches, in case quitting early */
        for (; i < stats->nbatchstats; i++)
            workmemwanted += stats->batchstats[i].spillspace_in;

        /*
         * Sometimes workfiles are used even though all the data would fit
         * in work_mem.  For example, if the planner overestimated the inner
         * rel size, it might have instructed us to use more initial batches
         * than were actually needed, causing unnecessary workfile I/O.  To
         * avoid this I/O, the user would have to increase work_mem based on
         * the planner's estimate rather than our runtime observations.  For
         * now, we don't try to second-guess the planner; just keep quiet.
         */