/*
* Mark a scankey with info from the index's indoption array.
*
* We copy the appropriate indoption value into the scankey sk_flags
* (shifting to avoid clobbering system-defined flag bits). Also, if
* the DESC option is set, commute (flip) the operator strategy number.
*
* This function is applied to the *input* scankey structure; therefore
* on a rescan we will be looking at already-processed scankeys. Hence
* we have to be careful not to re-commute the strategy if we already did it.
* It's a bit ugly to modify the caller's copy of the scankey but in practice
* there shouldn't be any problem, since the index's indoptions are certainly
* not going to change while the scankey survives.
*/
static void
_bt_mark_scankey_with_indoption(ScanKey skey, int16 *indoption)
{
int addflags;
addflags = indoption[skey->sk_attno - 1] << SK_BT_INDOPTION_SHIFT;
if ((addflags & SK_BT_DESC) && !(skey->sk_flags & SK_BT_DESC))
skey->sk_strategy = BTCommuteStrategyNumber(skey->sk_strategy);
skey->sk_flags |= addflags;
if (skey->sk_flags & SK_ROW_HEADER)
{
ScanKey subkey = (ScanKey) DatumGetPointer(skey->sk_argument);
for (;;)
{
Assert(subkey->sk_flags & SK_ROW_MEMBER);
addflags = indoption[subkey->sk_attno - 1] << SK_BT_INDOPTION_SHIFT;
if ((addflags & SK_BT_DESC) && !(subkey->sk_flags & SK_BT_DESC))
subkey->sk_strategy = BTCommuteStrategyNumber(subkey->sk_strategy);
subkey->sk_flags |= addflags;
if (subkey->sk_flags & SK_ROW_END)
break;
subkey++;
}
}
}
/*
* Adjust a scankey's strategy and flags setting as needed for indoptions.
*
* We copy the appropriate indoption value into the scankey sk_flags
* (shifting to avoid clobbering system-defined flag bits). Also, if
* the DESC option is set, commute (flip) the operator strategy number.
*
* A secondary purpose is to check for IS NULL/NOT NULL scankeys and set up
* the strategy field correctly for them.
*
* Lastly, for ordinary scankeys (not IS NULL/NOT NULL), we check for a
* NULL comparison value. Since all btree operators are assumed strict,
* a NULL means that the qual cannot be satisfied. We return TRUE if the
* comparison value isn't NULL, or FALSE if the scan should be abandoned.
*
* This function is applied to the *input* scankey structure; therefore
* on a rescan we will be looking at already-processed scankeys. Hence
* we have to be careful not to re-commute the strategy if we already did it.
* It's a bit ugly to modify the caller's copy of the scankey but in practice
* there shouldn't be any problem, since the index's indoptions are certainly
* not going to change while the scankey survives.
*/
static bool
_bt_fix_scankey_strategy(ScanKey skey, int16 *indoption)
{
int addflags;
addflags = indoption[skey->sk_attno - 1] << SK_BT_INDOPTION_SHIFT;
/*
* We treat all btree operators as strict (even if they're not so marked
* in pg_proc). This means that it is impossible for an operator condition
* with a NULL comparison constant to succeed, and we can reject it right
* away.
*
* However, we now also support "x IS NULL" clauses as search conditions,
* so in that case keep going. The planner has not filled in any
* particular strategy in this case, so set it to BTEqualStrategyNumber
* --- we can treat IS NULL as an equality operator for purposes of search
* strategy.
*
* Likewise, "x IS NOT NULL" is supported. We treat that as either "less
* than NULL" in a NULLS LAST index, or "greater than NULL" in a NULLS
* FIRST index.
*
* Note: someday we might have to fill in sk_collation from the index
* column's collation. At the moment this is a non-issue because we'll
* never actually call the comparison operator on a NULL.
*/
if (skey->sk_flags & SK_ISNULL)
{
/* SK_ISNULL shouldn't be set in a row header scankey */
Assert(!(skey->sk_flags & SK_ROW_HEADER));
/* Set indoption flags in scankey (might be done already) */
skey->sk_flags |= addflags;
/* Set correct strategy for IS NULL or NOT NULL search */
if (skey->sk_flags & SK_SEARCHNULL)
{
skey->sk_strategy = BTEqualStrategyNumber;
skey->sk_subtype = InvalidOid;
skey->sk_collation = InvalidOid;
}
else if (skey->sk_flags & SK_SEARCHNOTNULL)
{
if (skey->sk_flags & SK_BT_NULLS_FIRST)
skey->sk_strategy = BTGreaterStrategyNumber;
else
skey->sk_strategy = BTLessStrategyNumber;
skey->sk_subtype = InvalidOid;
skey->sk_collation = InvalidOid;
}
else
{
/* regular qual, so it cannot be satisfied */
return false;
}
/* Needn't do the rest */
return true;
}
/* Adjust strategy for DESC, if we didn't already */
if ((addflags & SK_BT_DESC) && !(skey->sk_flags & SK_BT_DESC))
skey->sk_strategy = BTCommuteStrategyNumber(skey->sk_strategy);
skey->sk_flags |= addflags;
/* If it's a row header, fix row member flags and strategies similarly */
if (skey->sk_flags & SK_ROW_HEADER)
{
ScanKey subkey = (ScanKey) DatumGetPointer(skey->sk_argument);
for (;;)
{
Assert(subkey->sk_flags & SK_ROW_MEMBER);
addflags = indoption[subkey->sk_attno - 1] << SK_BT_INDOPTION_SHIFT;
if ((addflags & SK_BT_DESC) && !(subkey->sk_flags & SK_BT_DESC))
subkey->sk_strategy = BTCommuteStrategyNumber(subkey->sk_strategy);
subkey->sk_flags |= addflags;
if (subkey->sk_flags & SK_ROW_END)
break;
subkey++;
}
}
return true;
}
/*
* Compare two scankey values using a specified operator. Both values
* must be already known non-NULL.
*
* The test we want to perform is logically "leftarg op rightarg", where
* leftarg and rightarg are the sk_argument values in those ScanKeys, and
* the comparison operator is the one in the op ScanKey. However, in
* cross-data-type situations we may need to look up the correct operator in
* the index's opfamily: it is the one having amopstrategy = op->sk_strategy
* and amoplefttype/amoprighttype equal to the two argument datatypes.
*
* If the opfamily doesn't supply a complete set of cross-type operators we
* may not be able to make the comparison. If we can make the comparison
* we store the operator result in *result and return TRUE. We return FALSE
* if the comparison could not be made.
*
* Note: op always points at the same ScanKey as either leftarg or rightarg.
* Since we don't scribble on the scankeys, this aliasing should cause no
* trouble.
*
* Note: this routine needs to be insensitive to any DESC option applied
* to the index column. For example, "x < 4" is a tighter constraint than
* "x < 5" regardless of which way the index is sorted. We don't worry about
* NULLS FIRST/LAST either, since the given values are never nulls.
*/
static bool
_bt_compare_scankey_args(IndexScanDesc scan, ScanKey op,
ScanKey leftarg, ScanKey rightarg,
bool *result)
{
Relation rel = scan->indexRelation;
Oid lefttype,
righttype,
optype,
opcintype,
cmp_op;
StrategyNumber strat;
/*
* The opfamily we need to worry about is identified by the index column.
*/
Assert(leftarg->sk_attno == rightarg->sk_attno);
opcintype = rel->rd_opcintype[leftarg->sk_attno - 1];
/*
* Determine the actual datatypes of the ScanKey arguments. We have to
* support the convention that sk_subtype == InvalidOid means the opclass
* input type; this is a hack to simplify life for ScanKeyInit().
*/
lefttype = leftarg->sk_subtype;
if (lefttype == InvalidOid)
lefttype = opcintype;
righttype = rightarg->sk_subtype;
if (righttype == InvalidOid)
righttype = opcintype;
optype = op->sk_subtype;
if (optype == InvalidOid)
optype = opcintype;
/*
* If leftarg and rightarg match the types expected for the "op" scankey,
* we can use its already-looked-up comparison function.
*/
if (lefttype == opcintype && righttype == optype)
{
*result = DatumGetBool(FunctionCall2(&op->sk_func,
leftarg->sk_argument,
rightarg->sk_argument));
return true;
}
/*
* Otherwise, we need to go to the syscache to find the appropriate
* operator. (This cannot result in infinite recursion, since no
* indexscan initiated by syscache lookup will use cross-data-type
* operators.)
*
* If the sk_strategy was flipped by _bt_mark_scankey_with_indoption, we
* have to un-flip it to get the correct opfamily member.
*/
strat = op->sk_strategy;
if (op->sk_flags & SK_BT_DESC)
strat = BTCommuteStrategyNumber(strat);
cmp_op = get_opfamily_member(rel->rd_opfamily[leftarg->sk_attno - 1],
lefttype,
righttype,
strat);
if (OidIsValid(cmp_op))
{
RegProcedure cmp_proc = get_opcode(cmp_op);
if (RegProcedureIsValid(cmp_proc))
{
*result = DatumGetBool(OidFunctionCall2(cmp_proc,
leftarg->sk_argument,
rightarg->sk_argument));
return true;
}
}
/* Can't make the comparison */
*result = false; /* suppress compiler warnings */
return false;
}
/*
* Compare two scankey values using a specified operator.
*
* The test we want to perform is logically "leftarg op rightarg", where
* leftarg and rightarg are the sk_argument values in those ScanKeys, and
* the comparison operator is the one in the op ScanKey. However, in
* cross-data-type situations we may need to look up the correct operator in
* the index's opfamily: it is the one having amopstrategy = op->sk_strategy
* and amoplefttype/amoprighttype equal to the two argument datatypes.
*
* If the opfamily doesn't supply a complete set of cross-type operators we
* may not be able to make the comparison. If we can make the comparison
* we store the operator result in *result and return TRUE. We return FALSE
* if the comparison could not be made.
*
* Note: op always points at the same ScanKey as either leftarg or rightarg.
* Since we don't scribble on the scankeys, this aliasing should cause no
* trouble.
*
* Note: this routine needs to be insensitive to any DESC option applied
* to the index column. For example, "x < 4" is a tighter constraint than
* "x < 5" regardless of which way the index is sorted.
*/
static bool
_bt_compare_scankey_args(IndexScanDesc scan, ScanKey op,
ScanKey leftarg, ScanKey rightarg,
bool *result)
{
Relation rel = scan->indexRelation;
Oid lefttype,
righttype,
optype,
opcintype,
cmp_op;
StrategyNumber strat;
/*
* First, deal with cases where one or both args are NULL. This should
* only happen when the scankeys represent IS NULL/NOT NULL conditions.
*/
if ((leftarg->sk_flags | rightarg->sk_flags) & SK_ISNULL)
{
bool leftnull,
rightnull;
if (leftarg->sk_flags & SK_ISNULL)
{
Assert(leftarg->sk_flags & (SK_SEARCHNULL | SK_SEARCHNOTNULL));
leftnull = true;
}
else
leftnull = false;
if (rightarg->sk_flags & SK_ISNULL)
{
Assert(rightarg->sk_flags & (SK_SEARCHNULL | SK_SEARCHNOTNULL));
rightnull = true;
}
else
rightnull = false;
/*
* We treat NULL as either greater than or less than all other values.
* Since true > false, the tests below work correctly for NULLS LAST
* logic. If the index is NULLS FIRST, we need to flip the strategy.
*/
strat = op->sk_strategy;
if (op->sk_flags & SK_BT_NULLS_FIRST)
strat = BTCommuteStrategyNumber(strat);
switch (strat)
{
case BTLessStrategyNumber:
*result = (leftnull < rightnull);
break;
case BTLessEqualStrategyNumber:
*result = (leftnull <= rightnull);
break;
case BTEqualStrategyNumber:
*result = (leftnull == rightnull);
break;
case BTGreaterEqualStrategyNumber:
*result = (leftnull >= rightnull);
break;
case BTGreaterStrategyNumber:
*result = (leftnull > rightnull);
break;
default:
elog(ERROR, "unrecognized StrategyNumber: %d", (int) strat);
*result = false; /* keep compiler quiet */
break;
}
return true;
}
/*
* The opfamily we need to worry about is identified by the index column.
*/
Assert(leftarg->sk_attno == rightarg->sk_attno);
opcintype = rel->rd_opcintype[leftarg->sk_attno - 1];
/*
* Determine the actual datatypes of the ScanKey arguments. We have to
* support the convention that sk_subtype == InvalidOid means the opclass
* input type; this is a hack to simplify life for ScanKeyInit().
*/
lefttype = leftarg->sk_subtype;
if (lefttype == InvalidOid)
lefttype = opcintype;
righttype = rightarg->sk_subtype;
if (righttype == InvalidOid)
righttype = opcintype;
optype = op->sk_subtype;
if (optype == InvalidOid)
optype = opcintype;
/*
* If leftarg and rightarg match the types expected for the "op" scankey,
* we can use its already-looked-up comparison function.
*/
if (lefttype == opcintype && righttype == optype)
{
*result = DatumGetBool(FunctionCall2Coll(&op->sk_func,
op->sk_collation,
leftarg->sk_argument,
rightarg->sk_argument));
return true;
}
/*
* Otherwise, we need to go to the syscache to find the appropriate
* operator. (This cannot result in infinite recursion, since no
* indexscan initiated by syscache lookup will use cross-data-type
* operators.)
*
* If the sk_strategy was flipped by _bt_fix_scankey_strategy, we have to
* un-flip it to get the correct opfamily member.
*/
strat = op->sk_strategy;
if (op->sk_flags & SK_BT_DESC)
strat = BTCommuteStrategyNumber(strat);
cmp_op = get_opfamily_member(rel->rd_opfamily[leftarg->sk_attno - 1],
lefttype,
righttype,
strat);
if (OidIsValid(cmp_op))
{
RegProcedure cmp_proc = get_opcode(cmp_op);
if (RegProcedureIsValid(cmp_proc))
{
*result = DatumGetBool(OidFunctionCall2Coll(cmp_proc,
op->sk_collation,
leftarg->sk_argument,
rightarg->sk_argument));
return true;
}
}
/* Can't make the comparison */
*result = false; /* suppress compiler warnings */
return false;
}
