nbtutils.c

PostgreSQL7.4.6 for Linux

	{
		if (i < numberOfKeys)
		{
			/* See comments above: any NULL implies cannot match qual */
			if (cur->sk_flags & SK_ISNULL)
			{
				so->qual_ok = false;

				/*
				 * Quit processing so we don't try to invoke comparison
				 * routines on NULLs.
				 */
				return;
			}
		}

		/*
		 * If we are at the end of the keys for a particular attr, finish
		 * up processing and emit the cleaned-up keys.
		 */
		if (i == numberOfKeys || cur->sk_attno != attno)
		{
			bool		priorAllEqualSoFar = allEqualSoFar;

			/* check input keys are correctly ordered */
			if (i < numberOfKeys && cur->sk_attno != attno + 1)
				elog(ERROR, "key(s) for attribute %d missed", attno + 1);

			/*
			 * If = has been specified, no other key will be used. In case
			 * of key > 2 && key == 1 and so on we have to set qual_ok to
			 * false before discarding the other keys.
			 */
			if (init[BTEqualStrategyNumber - 1])
			{
				ScanKeyData *eq,
						   *chk;

				eq = &xform[BTEqualStrategyNumber - 1];
				for (j = BTMaxStrategyNumber; --j >= 0;)
				{
					if (!init[j] ||
						j == (BTEqualStrategyNumber - 1))
						continue;
					chk = &xform[j];
					test = OidFunctionCall2(chk->sk_procedure,
											eq->sk_argument,
											chk->sk_argument);
					if (!DatumGetBool(test))
						so->qual_ok = false;
				}
				init[BTLessStrategyNumber - 1] = false;
				init[BTLessEqualStrategyNumber - 1] = false;
				init[BTGreaterEqualStrategyNumber - 1] = false;
				init[BTGreaterStrategyNumber - 1] = false;
			}
			else
			{
				/*
				 * No "=" for this key, so we're done with required keys
				 */
				allEqualSoFar = false;
			}

			/* keep only one of <, <= */
			if (init[BTLessStrategyNumber - 1]
				&& init[BTLessEqualStrategyNumber - 1])
			{
				ScanKeyData *lt = &xform[BTLessStrategyNumber - 1];
				ScanKeyData *le = &xform[BTLessEqualStrategyNumber - 1];

				test = OidFunctionCall2(le->sk_procedure,
										lt->sk_argument,
										le->sk_argument);
				if (DatumGetBool(test))
					init[BTLessEqualStrategyNumber - 1] = false;
				else
					init[BTLessStrategyNumber - 1] = false;
			}

			/* keep only one of >, >= */
			if (init[BTGreaterStrategyNumber - 1]
				&& init[BTGreaterEqualStrategyNumber - 1])
			{
				ScanKeyData *gt = &xform[BTGreaterStrategyNumber - 1];
				ScanKeyData *ge = &xform[BTGreaterEqualStrategyNumber - 1];

				test = OidFunctionCall2(ge->sk_procedure,
										gt->sk_argument,
										ge->sk_argument);
				if (DatumGetBool(test))
					init[BTGreaterEqualStrategyNumber - 1] = false;
				else
					init[BTGreaterStrategyNumber - 1] = false;
			}

			/*
			 * Emit the cleaned-up keys back into the key[] array in the
			 * correct order.  Note we are overwriting our input here!
			 * It's OK because (a) xform[] is a physical copy of the keys
			 * we want, (b) we cannot emit more keys than we input, so we
			 * won't overwrite as-yet-unprocessed keys.
			 */
			for (j = BTMaxStrategyNumber; --j >= 0;)
			{
				if (init[j])
					memcpy(&key[new_numberOfKeys++], &xform[j],
						   sizeof(ScanKeyData));
			}

			/*
			 * If all attrs before this one had "=", include these keys
			 * into the required-keys count.
			 */
			if (priorAllEqualSoFar)
				so->numberOfRequiredKeys = new_numberOfKeys;

			/*
			 * Exit loop here if done.
			 */
			if (i == numberOfKeys)
				break;

			/* Re-initialize for new attno */
			attno = cur->sk_attno;
			map = IndexStrategyGetStrategyMap(RelationGetIndexStrategy(relation),
											  BTMaxStrategyNumber,
											  attno);
			MemSet(xform, 0, sizeof(xform));	/* not really necessary */
			MemSet(init, 0, sizeof(init));
		}

		/* figure out which strategy this key's operator corresponds to */
		j = _bt_getstrategynumber(cur->sk_procedure, map);

		/* have we seen one of these before? */
		if (init[j])
		{
			/* yup, keep the more restrictive value */
			test = FunctionCall2(&cur->sk_func,
								 cur->sk_argument,
								 xform[j].sk_argument);
			if (DatumGetBool(test))
				xform[j].sk_argument = cur->sk_argument;
			else if (j == (BTEqualStrategyNumber - 1))
				so->qual_ok = false;
			/* key == a && key == b, but a != b */
		}
		else
		{
			/* nope, so remember this scankey */
			memcpy(&xform[j], cur, sizeof(ScanKeyData));
			init[j] = true;
		}
	}

	so->numberOfKeys = new_numberOfKeys;

	/*
	 * If unique index and we have equality keys for all columns, set
	 * keys_are_unique flag for higher levels.
	 */
	if (allEqualSoFar && relation->rd_index->indisunique &&
		relation->rd_rel->relnatts == new_numberOfKeys)
		scan->keys_are_unique = true;
}

/*
 * Determine which btree strategy an operator procedure matches.
 *
 * Result is strategy number minus 1.
 */
static int
_bt_getstrategynumber(RegProcedure sk_procedure, StrategyMap map)
{
	int			j;

	for (j = BTMaxStrategyNumber; --j >= 0;)
	{
		if (sk_procedure == map->entry[j].sk_procedure)
			return j;
	}
	elog(ERROR, "could not identify operator %u", sk_procedure);
	return -1;					/* keep compiler quiet */
}

/*
 * Test whether an indextuple satisfies all the scankey conditions.
 *
 * If the tuple fails to pass the qual, we also determine whether there's
 * any need to continue the scan beyond this tuple, and set *continuescan
 * accordingly.  See comments for _bt_orderkeys(), above, about how this is
 * done.
 */
bool
_bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
			  ScanDirection dir, bool *continuescan)
{
	BTScanOpaque so = (BTScanOpaque) scan->opaque;
	int			keysz = so->numberOfKeys;
	int			keysok;
	TupleDesc	tupdesc;
	ScanKey		key;

	*continuescan = true;

	/* If no keys, always scan the whole index */
	if (keysz == 0)
		return true;

	tupdesc = RelationGetDescr(scan->indexRelation);
	key = so->keyData;
	keysok = 0;

	IncrIndexProcessed();

	while (keysz > 0)
	{
		Datum		datum;
		bool		isNull;
		Datum		test;

		datum = index_getattr(tuple,
							  key->sk_attno,
							  tupdesc,
							  &isNull);

		/* btree doesn't support 'A is null' clauses, yet */
		if (key->sk_flags & SK_ISNULL)
		{
			/* we shouldn't get here, really; see _bt_orderkeys() */
			*continuescan = false;
			return false;
		}

		if (isNull)
		{
			/*
			 * Since NULLs are sorted after non-NULLs, we know we have
			 * reached the upper limit of the range of values for this
			 * index attr.	On a forward scan, we can stop if this qual is
			 * one of the "must match" subset.	On a backward scan,
			 * however, we should keep going.
			 */
			if (keysok < so->numberOfRequiredKeys &&
				ScanDirectionIsForward(dir))
				*continuescan = false;

			/*
			 * In any case, this indextuple doesn't match the qual.
			 */
			return false;
		}

		if (key->sk_flags & SK_COMMUTE)
			test = FunctionCall2(&key->sk_func,
								 key->sk_argument, datum);
		else
			test = FunctionCall2(&key->sk_func,
								 datum, key->sk_argument);

		if (DatumGetBool(test) == !!(key->sk_flags & SK_NEGATE))
		{
			/*
			 * Tuple fails this qual.  If it's a required qual, then we
			 * can conclude no further tuples will pass, either.
			 */
			if (keysok < so->numberOfRequiredKeys)
				*continuescan = false;
			return false;
		}

		keysok++;
		key++;
		keysz--;
	}

	/* If we get here, the tuple passes all quals. */
	return true;
}