Function FillSliceGangInfo

src/backend/executor/execUtils.c:1591–1653

static void
FillSliceGangInfo(ExecSlice *slice, PlanSlice *ps)
{
	int factor = ps->parallel_workers ? ps->parallel_workers : 1;
	int numsegments = ps->numsegments;

	DirectDispatchInfo *dd = &ps->directDispatch;

	slice->useMppParallelMode = (ps->parallel_workers != 0);
	slice->parallel_workers = factor;
	switch (slice->gangType)
	{
		case GANGTYPE_UNALLOCATED:
			/*
			 * It's either the root slice or an InitPlan slice that runs in
			 * the QD process, or really unused slice.
			 */
			/* CBDB_PARALLEL_FIXME: QD process should never be parallel, do we need to plus factor? */
			slice->planNumSegments = 1;
			break;
		case GANGTYPE_PRIMARY_WRITER:
		case GANGTYPE_PRIMARY_READER:
			slice->planNumSegments = numsegments * factor;
			if (dd->isDirectDispatch)
			{
				int i;
				ListCell *lc;

				foreach(lc, dd->contentIds)
				{
					int segment = lfirst_int(lc);
					for (i = 0; i < factor; i++)
						slice->segments = lappend_int(slice->segments, segment);
				}
			}
			else
			{
				int i, j;
				slice->segments = NIL;
				for (i = 0; i < numsegments; i++)
					for (j = 0; j < factor; j++)
						slice->segments = lappend_int(slice->segments, i % getgpsegmentCount());
			}
			break;
		case GANGTYPE_ENTRYDB_READER:
			/* CBDB_PARALLEL_FIXME: QD parallel is disabled */
			slice->planNumSegments = 1;
			slice->segments = list_make1_int(-1);
			break;
		case GANGTYPE_SINGLETON_READER:
			/*
			 * CBDB_PARALLEL_FIXME:
			 * Could be parallel, parallel scan on replica tables.
			 */
			slice->planNumSegments = 1 * factor;
			int i;
			for (i = 0; i < factor; i++)
				slice->segments = lappend_int(slice->segments, ps->segindex);