Method getIndexedRelationships

src/jrd/optimizer/InnerJoin.cpp:633–686

//

void InnerJoin::getIndexedRelationships(StreamInfo* testStream)
{
#ifdef OPT_DEBUG_RETRIEVAL
	const auto name = optimizer->getStreamName(testStream->number);
	optimizer->printf("Dependencies for stream %u (%s):\n",
					  testStream->number, name.c_str());
#endif

	const auto tail = &csb->csb_rpt[testStream->number];

	Retrieval retrieval(tdbb, optimizer, testStream->number, false, false, nullptr, true);
	const auto candidate = retrieval.getInversion();

	for (const auto baseStream : innerStreams)
	{
		if (baseStream->number != testStream->number &&
			candidate->dependentFromStreams.exist(baseStream->number))
		{
			// If the base stream already depends on the testing stream, don't store it again
			bool found = false;
			for (const auto& relationship : baseStream->indexedRelationships)
			{
				if (relationship.stream == testStream->number)
				{
					found = true;
					break;
				}
			}

			if (found)
				continue;

			if (candidate->dependentFromStreams.getCount() > IndexRelationship::MAX_DEP_STREAMS)
				continue;

			// If we could use more conjunctions on the testing stream
			// with the base stream active as without the base stream
			// then the test stream has a indexed relationship with the base stream.
			IndexRelationship indexRelationship;
			indexRelationship.stream = testStream->number;
			indexRelationship.unique = candidate->unique;
			indexRelationship.cost = candidate->cost;
			indexRelationship.cardinality = candidate->unique ?
				tail->csb_cardinality : tail->csb_cardinality * candidate->selectivity;

			for (const auto depStream : candidate->dependentFromStreams)
				indexRelationship.depStreams.add(depStream);

			// Relationships are kept sorted by cost and uniqueness in the array
			baseStream->indexedRelationships.add(indexRelationship);
			testStream->previousExpectedStreams++;
		}
	}
}


//