Function extension_rumgettuple_core

pg_documentdb/src/index_am/rum.c:1306–1365

bool
extension_rumgettuple_core(IndexScanDesc scan, ScanDirection direction,
						   IndexAmRoutine *coreRoutine)
{
	if (IsCompositeOpClass(scan->indexRelation))
	{
		DocumentDBRumIndexState *outerScanState =
			(DocumentDBRumIndexState *) scan->opaque;

		/* The caller will always pass ForwardScanDirection
		 * since PG always uses ForwardScanDirection in cases where we do
		 * amcanorderbyop. For the inner scan, we would need to pass the
		 * scanDirection as determined in amrescan from the index state.
		 */
		if (unlikely(direction != ForwardScanDirection))
		{
			ereport(ERROR, (errmsg("rumgettuple only supports forward scans")));
		}

		/* Push this to the inner scan */
		outerScanState->innerScan->kill_prior_tuple = scan->kill_prior_tuple;
		if (outerScanState->indexArrayState == NULL)
		{
			/* No arrays, or we don't support dedup - just return the basics */
			return GetOneTupleCore(outerScanState, scan, outerScanState->scanDirection,
								   coreRoutine);
		}
		else
		{
			bool result = GetOneTupleCore(outerScanState, scan,
										  outerScanState->scanDirection, coreRoutine);
			while (result)
			{
				/* if we could add it to the bitmap, return */
				if (IndexArrayStateFuncs->addItem(outerScanState->indexArrayState,
												  &scan->xs_heaptid))
				{
					return true;
				}
				else
				{
					outerScanState->numDuplicates++;
				}

				/* else, get the next tuple
				 * Ensure that we reset kill_prior_tuple since this is the duplicate path.
				 */
				outerScanState->innerScan->kill_prior_tuple = false;
				result = GetOneTupleCore(outerScanState, scan,
										 outerScanState->scanDirection, coreRoutine);
			}

			return result;
		}
	}
	else
	{
		return coreRoutine->amgettuple(scan, direction);