Function ExplainPrintSliceTable

src/backend/commands/explain.c:1058–1117

* ExplainPrintSliceTable - * convert the MPP slice table text and append it to es->str */

 *	  convert the MPP slice table text and append it to es->str
 */
void
ExplainPrintSliceTable(ExplainState *es, QueryDesc *queryDesc)
{
	SliceTable *sliceTable = queryDesc->estate->es_sliceTable;
	int			numSlices = (sliceTable ? sliceTable->numSlices : 0);

	ExplainOpenGroup("Slice Table", "Slice Table", false, es);

	for (int i = 0; i < numSlices; i++)
	{
		ExecSlice *slice = &sliceTable->slices[i];
		const char *gangType = "???";

		switch (slice->gangType)
		{
			case GANGTYPE_UNALLOCATED:
				gangType = "Dispatcher";
				break;
			case GANGTYPE_ENTRYDB_READER:
				gangType = "Entry DB Reader";
				break;
			case GANGTYPE_SINGLETON_READER:
				gangType = "Singleton Reader";
				break;
			case GANGTYPE_PRIMARY_READER:
				gangType = "Reader";
				break;
			case GANGTYPE_PRIMARY_WRITER:
				gangType = "Primary Writer";
				break;
		}

		if (es->format == EXPLAIN_FORMAT_TEXT)
		{
			appendStringInfo(es->str, "Slice %d: %s; root %d; parent %d; gang size %d",
							 i,
							 gangType,
							 slice->rootIndex,
							 slice->parentIndex,
							 list_length(slice->segments));
			if (slice->gangType == GANGTYPE_SINGLETON_READER)
				appendStringInfo(es->str, "; segment %d", linitial_int(slice->segments));
			appendStringInfoString(es->str, "\n");
		}
		else
		{
			ExplainOpenGroup("Slice", NULL, true, es);
			ExplainPropertyInteger("Slice ID", NULL, i, es);
			ExplainPropertyText("Gang Type", gangType, es);
			ExplainPropertyInteger("Root", NULL, slice->rootIndex, es);
			ExplainPropertyInteger("Parent", NULL, slice->parentIndex, es);
			ExplainPropertyInteger("Gang Size", NULL, list_length(slice->segments), es);
			if (slice->gangType == GANGTYPE_SINGLETON_READER)
				ExplainPropertyInteger("Segment", NULL, linitial_int(slice->segments), es);
			ExplainCloseGroup("Slice", NULL, true, es);
		}
	}