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Commit066926d

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Refactor some lsyscache routines to eliminate duplicate code and save
a couple of syscache lookups in make_pathkey_from_sortinfo().
1 parent98218e9 commit066926d

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3 files changed

+105
-104
lines changed

3 files changed

+105
-104
lines changed

‎src/backend/optimizer/path/pathkeys.c

Lines changed: 16 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
* Portions Copyright (c) 1994, Regents of the University of California
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.82 2007/01/20 20:45:39 tgl Exp $
14+
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.83 2007/01/21 00:57:15 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
@@ -240,13 +240,11 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
240240
boolnulls_first,
241241
boolcanonicalize)
242242
{
243+
Oidopfamily,
244+
opcintype;
245+
int16strategy;
243246
Oidequality_op;
244247
List*opfamilies;
245-
Oidopfamily,
246-
lefttype,
247-
righttype;
248-
intstrategy;
249-
ListCell*lc;
250248
EquivalenceClass*eclass;
251249

252250
/*
@@ -258,7 +256,17 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
258256
* easily be bigger. So, look up the equality operator that goes with
259257
* the ordering operator (this should be unique) and get its membership.
260258
*/
261-
equality_op=get_equality_op_for_ordering_op(ordering_op);
259+
260+
/* Find the operator in pg_amop --- failure shouldn't happen */
261+
if (!get_ordering_op_properties(ordering_op,
262+
&opfamily,&opcintype,&strategy))
263+
elog(ERROR,"operator %u is not a valid ordering operator",
264+
ordering_op);
265+
/* Get matching equality operator */
266+
equality_op=get_opfamily_member(opfamily,
267+
opcintype,
268+
opcintype,
269+
BTEqualStrategyNumber);
262270
if (!OidIsValid(equality_op))/* shouldn't happen */
263271
elog(ERROR,"could not find equality operator for ordering operator %u",
264272
ordering_op);
@@ -267,33 +275,8 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
267275
elog(ERROR,"could not find opfamilies for ordering operator %u",
268276
ordering_op);
269277

270-
/*
271-
* Next we have to determine the strategy number to put into the pathkey.
272-
* In the presence of reverse-sort opclasses there might be two answers.
273-
* We prefer the one associated with the first opfamilies member that
274-
* this ordering_op appears in (this will be consistently defined in
275-
* normal system operation; see comments for get_mergejoin_opfamilies()).
276-
*/
277-
opfamily=InvalidOid;
278-
strategy=0;
279-
foreach(lc,opfamilies)
280-
{
281-
opfamily=lfirst_oid(lc);
282-
strategy=get_op_opfamily_strategy(ordering_op,opfamily);
283-
if (strategy)
284-
break;
285-
}
286-
if (!(strategy==BTLessStrategyNumber||
287-
strategy==BTGreaterStrategyNumber))
288-
elog(ERROR,"ordering operator %u is has wrong strategy number %d",
289-
ordering_op,strategy);
290-
291-
/* Need the declared input type of the operator, too */
292-
op_input_types(ordering_op,&lefttype,&righttype);
293-
Assert(lefttype==righttype);
294-
295278
/* Now find or create a matching EquivalenceClass */
296-
eclass=get_eclass_for_sort_expr(root,expr,lefttype,opfamilies);
279+
eclass=get_eclass_for_sort_expr(root,expr,opcintype,opfamilies);
297280

298281
/* And finally we can find or create a PathKey node */
299282
if (canonicalize)

‎src/backend/utils/cache/lsyscache.c

Lines changed: 86 additions & 70 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.144 2007/01/20 20:45:40 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.145 2007/01/21 00:57:15 tgl Exp $
1111
*
1212
* NOTES
1313
* Eventually, the index information should go through here, too.
@@ -139,40 +139,41 @@ get_opfamily_member(Oid opfamily, Oid lefttype, Oid righttype,
139139
}
140140

141141
/*
142-
* get_compare_function_for_ordering_op
143-
*Get the OID of the datatype-specific btree comparison function
144-
*associated with an ordering operator (a "<" or ">" operator).
142+
* get_ordering_op_properties
143+
*Given the OID of an ordering operator (a btree "<" or ">" operator),
144+
*determine its opfamily, its declared input datatype, and its
145+
*strategy number (BTLessStrategyNumber or BTGreaterStrategyNumber).
145146
*
146-
* *cmpfunc receives the comparison function OID.
147-
* *reverse is set FALSE if the operator is "<", TRUE if it's ">"
148-
* (indicating the comparison result must be negated before use).
149-
*
150-
* Returns TRUE if successful, FALSE if no btree function can be found.
147+
* Returns TRUE if successful, FALSE if no matching pg_amop entry exists.
151148
* (This indicates that the operator is not a valid ordering operator.)
149+
*
150+
* Note: the operator could be registered in multiple families, for example
151+
* if someone were to build a "reverse sort" opfamily. This would result in
152+
* uncertainty as to whether "ORDER BY USING op" would default to NULLS FIRST
153+
* or NULLS LAST, as well as inefficient planning due to failure to match up
154+
* pathkeys that should be the same. So we want a determinate result here.
155+
* Because of the way the syscache search works, we'll use the interpretation
156+
* associated with the opfamily with smallest OID, which is probably
157+
* determinate enough. Since there is no longer any particularly good reason
158+
* to build reverse-sort opfamilies, it doesn't seem worth expending any
159+
* additional effort on ensuring consistency.
152160
*/
153161
bool
154-
get_compare_function_for_ordering_op(Oidopno,Oid*cmpfunc,bool*reverse)
162+
get_ordering_op_properties(Oidopno,
163+
Oid*opfamily,Oid*opcintype,int16*strategy)
155164
{
156165
boolresult= false;
157166
CatCList*catlist;
158167
inti;
159168

160-
/* ensure outputs are set on failure */
161-
*cmpfunc=InvalidOid;
162-
*reverse= false;
169+
/* ensure outputs are initialized on failure */
170+
*opfamily=InvalidOid;
171+
*opcintype=InvalidOid;
172+
*strategy=0;
163173

164174
/*
165175
* Search pg_amop to see if the target operator is registered as the "<"
166-
* or ">" operator of any btree opfamily. It's possible that it might be
167-
* registered both ways (if someone were to build a "reverse sort"
168-
* opfamily); assume we can use either interpretation. (Note: the
169-
* existence of a reverse-sort opfamily would result in uncertainty as
170-
* to whether "ORDER BY USING op" would default to NULLS FIRST or NULLS
171-
* LAST. Since there is no longer any particularly good reason to build
172-
* reverse-sort opfamilies, we don't bother expending any extra work to
173-
* make this more determinate. In practice, because of the way the
174-
* syscache search works, we'll use the interpretation associated with
175-
* the opfamily with smallest OID, which is probably determinate enough.)
176+
* or ">" operator of any btree opfamily.
176177
*/
177178
catlist=SearchSysCacheList(AMOPOPID,1,
178179
ObjectIdGetDatum(opno),
@@ -190,18 +191,16 @@ get_compare_function_for_ordering_op(Oid opno, Oid *cmpfunc, bool *reverse)
190191
if (aform->amopstrategy==BTLessStrategyNumber||
191192
aform->amopstrategy==BTGreaterStrategyNumber)
192193
{
193-
/* Found a suitable opfamily, get matching support function */
194-
*reverse= (aform->amopstrategy==BTGreaterStrategyNumber);
195-
*cmpfunc=get_opfamily_proc(aform->amopfamily,
196-
aform->amoplefttype,
197-
aform->amoprighttype,
198-
BTORDER_PROC);
199-
if (!OidIsValid(*cmpfunc))/* should not happen */
200-
elog(ERROR,"missing support function %d(%u,%u) in opfamily %u",
201-
BTORDER_PROC,aform->amoplefttype,aform->amoprighttype,
202-
aform->amopfamily);
203-
result= true;
204-
break;
194+
/* Found it ... should have consistent input types */
195+
if (aform->amoplefttype==aform->amoprighttype)
196+
{
197+
/* Found a suitable opfamily, return info */
198+
*opfamily=aform->amopfamily;
199+
*opcintype=aform->amoplefttype;
200+
*strategy=aform->amopstrategy;
201+
result= true;
202+
break;
203+
}
205204
}
206205
}
207206

@@ -210,6 +209,47 @@ get_compare_function_for_ordering_op(Oid opno, Oid *cmpfunc, bool *reverse)
210209
returnresult;
211210
}
212211

212+
/*
213+
* get_compare_function_for_ordering_op
214+
*Get the OID of the datatype-specific btree comparison function
215+
*associated with an ordering operator (a "<" or ">" operator).
216+
*
217+
* *cmpfunc receives the comparison function OID.
218+
* *reverse is set FALSE if the operator is "<", TRUE if it's ">"
219+
* (indicating the comparison result must be negated before use).
220+
*
221+
* Returns TRUE if successful, FALSE if no btree function can be found.
222+
* (This indicates that the operator is not a valid ordering operator.)
223+
*/
224+
bool
225+
get_compare_function_for_ordering_op(Oidopno,Oid*cmpfunc,bool*reverse)
226+
{
227+
Oidopfamily;
228+
Oidopcintype;
229+
int16strategy;
230+
231+
/* Find the operator in pg_amop */
232+
if (get_ordering_op_properties(opno,
233+
&opfamily,&opcintype,&strategy))
234+
{
235+
/* Found a suitable opfamily, get matching support function */
236+
*cmpfunc=get_opfamily_proc(opfamily,
237+
opcintype,
238+
opcintype,
239+
BTORDER_PROC);
240+
if (!OidIsValid(*cmpfunc))/* should not happen */
241+
elog(ERROR,"missing support function %d(%u,%u) in opfamily %u",
242+
BTORDER_PROC,opcintype,opcintype,opfamily);
243+
*reverse= (strategy==BTGreaterStrategyNumber);
244+
return true;
245+
}
246+
247+
/* ensure outputs are set on failure */
248+
*cmpfunc=InvalidOid;
249+
*reverse= false;
250+
return false;
251+
}
252+
213253
/*
214254
* get_equality_op_for_ordering_op
215255
*Get the OID of the datatype-specific btree equality operator
@@ -222,45 +262,21 @@ Oid
222262
get_equality_op_for_ordering_op(Oidopno)
223263
{
224264
Oidresult=InvalidOid;
225-
CatCList*catlist;
226-
inti;
265+
Oidopfamily;
266+
Oidopcintype;
267+
int16strategy;
227268

228-
/*
229-
* Search pg_amop to see if the target operator is registered as the "<"
230-
* or ">" operator of any btree opfamily. This is exactly like
231-
* get_compare_function_for_ordering_op except we don't care whether the
232-
* ordering op is "<" or ">" ... the equality operator will be the same
233-
* either way.
234-
*/
235-
catlist=SearchSysCacheList(AMOPOPID,1,
236-
ObjectIdGetDatum(opno),
237-
0,0,0);
238-
239-
for (i=0;i<catlist->n_members;i++)
269+
/* Find the operator in pg_amop */
270+
if (get_ordering_op_properties(opno,
271+
&opfamily,&opcintype,&strategy))
240272
{
241-
HeapTupletuple=&catlist->members[i]->tuple;
242-
Form_pg_amopaform= (Form_pg_amop)GETSTRUCT(tuple);
243-
244-
/* must be btree */
245-
if (aform->amopmethod!=BTREE_AM_OID)
246-
continue;
247-
248-
if (aform->amopstrategy==BTLessStrategyNumber||
249-
aform->amopstrategy==BTGreaterStrategyNumber)
250-
{
251-
/* Found a suitable opfamily, get matching equality operator */
252-
result=get_opfamily_member(aform->amopfamily,
253-
aform->amoplefttype,
254-
aform->amoprighttype,
255-
BTEqualStrategyNumber);
256-
if (OidIsValid(result))
257-
break;
258-
/* failure probably shouldn't happen, but keep looking if so */
259-
}
273+
/* Found a suitable opfamily, get matching equality operator */
274+
result=get_opfamily_member(opfamily,
275+
opcintype,
276+
opcintype,
277+
BTEqualStrategyNumber);
260278
}
261279

262-
ReleaseSysCacheList(catlist);
263-
264280
returnresult;
265281
}
266282

‎src/include/utils/lsyscache.h

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.113 2007/01/20 20:45:41 tgl Exp $
9+
* $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.114 2007/01/21 00:57:15 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -35,6 +35,8 @@ extern void get_op_opfamily_properties(Oid opno, Oid opfamily,
3535
bool*recheck);
3636
externOidget_opfamily_member(Oidopfamily,Oidlefttype,Oidrighttype,
3737
int16strategy);
38+
externboolget_ordering_op_properties(Oidopno,
39+
Oid*opfamily,Oid*opcintype,int16*strategy);
3840
externboolget_compare_function_for_ordering_op(Oidopno,
3941
Oid*cmpfunc,bool*reverse);
4042
externOidget_equality_op_for_ordering_op(Oidopno);

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