Function LogSortKeysCore

pg_documentdb/src/explain/documentdb_explain.c:1083–1125

static void
LogSortKeysCore(pgbson_writer *sortKeyWriter, Sort *plan, PlanState *leftTree,
				int startIndex, int numCols)
{
	for (int i = startIndex; i < startIndex + numCols; i++)
	{
		TargetEntry *entry = list_nth(plan->plan.targetlist, plan->sortColIdx[i] - 1);

		Expr *entryExpr = entry->expr;
		if (IsA(entry->expr, Var) && leftTree != NULL)
		{
			Var *var = (Var *) entry->expr;
			if (list_length(leftTree->plan->targetlist) >= var->varattno)
			{
				TargetEntry *subTargetEntry = list_nth(leftTree->plan->targetlist,
													   var->varattno - 1);
				entryExpr = subTargetEntry->expr;
			}
		}

		if (IsA(entryExpr, FuncExpr))
		{
			FuncExpr *funcExpr = (FuncExpr *) entryExpr;
			if (funcExpr->funcid == BsonOrderByFunctionOid())
			{
				Expr *secondExpr = lsecond(funcExpr->args);
				if (IsA(secondExpr, Const))
				{
					Const *secondConst = (Const *) secondExpr;
					pgbson *orderBson = DatumGetPgBson(secondConst->constvalue);
					pgbsonelement sortElement;
					PgbsonToSinglePgbsonElementWithCollation(orderBson, &sortElement);
					PgbsonWriterAppendValue(sortKeyWriter, sortElement.path,
											sortElement.pathLength,
											&sortElement.bsonValue);
					continue;
				}
			}
		}

		PgbsonWriterAppendInt32(sortKeyWriter, "unknown-sort-operator", -1, 0);
	}
}


static void