Method checkIndexCondition

src/jrd/optimizer/Retrieval.cpp:725–800

}

bool Retrieval::checkIndexCondition(index_desc& idx, MatchedBooleanList& matches) const
{
	fb_assert(idx.idx_condition);

	if (!idx.idx_condition->containsStream(0, true))
		return false;

	fb_assert(matches.isEmpty());

	auto iter = optimizer->getConjuncts(outerFlag, innerFlag);

	BoolExprNodeStack idxConjuncts;
	const auto conjunctCount = optimizer->decomposeBoolean(idx.idx_condition, idxConjuncts);
	fb_assert(conjunctCount);

	idx.idx_fraction = MAXIMUM_SELECTIVITY;

	for (BoolExprNodeStack::const_iterator idxIter(idxConjuncts);
		idxIter.hasData(); ++idxIter)
	{
		const auto boolean = idxIter.object();

		// If the index condition is (A OR B) and any of the {A, B} is present
		// among the available booleans, then the index is possibly usable.
		// Note: this check also includes the exact match.

		for (iter.rewind(); iter.hasData(); ++iter)
		{
			if (!iter->containsStream(stream))
				continue;

			if (matchSubset(boolean, *iter))
			{
				matches.add(*iter);
				break;
			}
		}

		// If the index condition is (A IS NOT NULL) and the available booleans
		// includes any comparative predicate that explicitly mentions A,
		// then the index is possibly usable

		const auto notNode = nodeAs<NotBoolNode>(boolean);
		const auto missingNode = notNode ? nodeAs<MissingBoolNode>(notNode->arg) : nullptr;
		if (missingNode)
		{
			for (iter.rewind(); iter.hasData(); ++iter)
			{
				if (!iter->containsStream(stream))
					continue;

				const auto cmpNode = nodeAs<ComparativeBoolNode>(*iter);
				if (cmpNode && cmpNode->blrOp != blr_equiv)
				{
					if (cmpNode->arg1->sameAs(missingNode->arg, true) ||
						cmpNode->arg2->sameAs(missingNode->arg, true))
					{
						matches.add(*iter);