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Commitc9f287e

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Further fixes for bogus list-slinging, scribbling on input, etc in type
coercion code. I'm beginning to wonder why we have separate candidateselection routines for functions, operators, and aggregates --- shouldn'tthis code all be unified? But meanwhile,SELECT 'a' LIKE 'a';finally works; the code for dealing with unknown input types for operatorswas pretty busted.
1 parent1d75298 commitc9f287e

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2 files changed

+84
-35
lines changed

2 files changed

+84
-35
lines changed

‎src/backend/parser/parse_func.c

Lines changed: 32 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.72 2000/02/20 23:04:06 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.73 2000/03/11 23:17:47 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -854,11 +854,6 @@ match_argtypes(int nargs,
854854
* for the function argtype array, attempt to resolve the conflict.
855855
* returns the selected argtype array if the conflict can be resolved,
856856
* otherwise returns NULL.
857-
*
858-
* If all input Oids are UNKNOWNOID, then try matching with TEXTOID.
859-
* Otherwise, could return first function arguments on list of candidates.
860-
* But for now, return NULL and make the user give a better hint.
861-
* - thomas 1998-03-17
862857
*/
863858
staticOid*
864859
func_select_candidate(intnargs,
@@ -869,12 +864,10 @@ func_select_candidate(int nargs,
869864
CandidateListlast_candidate;
870865
Oid*current_typeids;
871866
inti;
872-
873867
intncandidates;
874868
intnbestMatch,
875869
nmatch,
876-
nident;
877-
870+
ncompat;
878871
CATEGORYslot_category,
879872
current_category;
880873
Oidslot_type,
@@ -893,19 +886,29 @@ func_select_candidate(int nargs,
893886
{
894887
current_typeids=current_candidate->args;
895888
nmatch=0;
896-
nident=0;
889+
ncompat=0;
897890
for (i=0;i<nargs;i++)
898891
{
899-
if ((input_typeids[i]!=UNKNOWNOID)
900-
&& (current_typeids[i]==input_typeids[i]))
901-
nmatch++;
902-
elseif (IS_BINARY_COMPATIBLE(current_typeids[i],input_typeids[i]))
903-
nident++;
892+
if (input_typeids[i]!=UNKNOWNOID)
893+
{
894+
if (current_typeids[i]==input_typeids[i])
895+
nmatch++;
896+
elseif (IS_BINARY_COMPATIBLE(current_typeids[i],
897+
input_typeids[i]))
898+
ncompat++;
899+
}
904900
}
905901

906-
if ((nmatch+nident)==nargs)
902+
/*
903+
* If we find an exact match at all arg positions, we're done;
904+
* there can be only one such candidate.
905+
*/
906+
if (nmatch==nargs)
907907
returncurrent_candidate->args;
908908

909+
/* Otherwise, use match+compat as the score. */
910+
nmatch+=ncompat;
911+
909912
/* take this one as the best choice so far? */
910913
if ((nmatch>nbestMatch)|| (last_candidate==NULL))
911914
{
@@ -933,6 +936,16 @@ func_select_candidate(int nargs,
933936
/*
934937
* Still too many candidates?
935938
* Try assigning types for the unknown columns.
939+
*
940+
* We do this by examining each unknown argument position to see if all the
941+
* candidates agree on the type category of that slot. If so, and if some
942+
* candidates accept the preferred type in that category, eliminate the
943+
* candidates with other input types. If we are down to one candidate
944+
* at the end, we win.
945+
*
946+
* XXX It's kinda bogus to do this left-to-right, isn't it? If we eliminate
947+
* some candidates because they are non-preferred at the first slot, we won't
948+
* notice that they didn't have the same type category for a later slot.
936949
*/
937950
for (i=0;i<nargs;i++)
938951
{
@@ -947,12 +960,12 @@ func_select_candidate(int nargs,
947960
{
948961
current_typeids=current_candidate->args;
949962
current_type=current_typeids[i];
950-
current_category=TypeCategory(current_typeids[i]);
951-
952-
if (slot_category==InvalidOid)
963+
current_category=TypeCategory(current_type);
964+
if (slot_category==INVALID_TYPE)
953965
{
954966
slot_category=current_category;
955967
slot_type=current_type;
968+
last_candidate=current_candidate;
956969
}
957970
elseif (current_category!=slot_category)
958971
{

‎src/backend/parser/parse_oper.c

Lines changed: 52 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.36 2000/02/27 02:48:15 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.37 2000/03/11 23:17:47 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -128,7 +128,7 @@ binary_oper_get_candidates(char *opname,
128128
*
129129
* This routine is new code, replacing binary_oper_select_candidate()
130130
* which dates from v4.2/v1.0.x days. It tries very hard to match up
131-
* operators with types, including allowing typecoersions if necessary.
131+
* operators with types, including allowing typecoercions if necessary.
132132
* The important thing is that the code do as much as possible,
133133
* while _never_ doing the wrong thing, where "the wrong thing" would
134134
* be returning an operator when other better choices are available,
@@ -185,7 +185,7 @@ oper_select_candidate(int nargs,
185185

186186
/*
187187
* Run through all candidates and keep those with the most matches
188-
*onexplicit types. Keep all candidates if none match.
188+
*onexact types. Keep all candidates if none match.
189189
*/
190190
ncandidates=0;
191191
nbestMatch=0;
@@ -236,7 +236,7 @@ oper_select_candidate(int nargs,
236236

237237
/*
238238
* Still too many candidates?
239-
* Now look for candidates which allowcoersion and are preferred types.
239+
* Now look for candidates which allowcoercion and are preferred types.
240240
* Keep all candidates if none match.
241241
*/
242242
ncandidates=0;
@@ -292,6 +292,13 @@ oper_select_candidate(int nargs,
292292
/*
293293
* Still too many candidates?
294294
* Try assigning types for the unknown columns.
295+
*
296+
* First try: if we have an unknown and a non-unknown input, see whether
297+
* there is a candidate all of whose input types are the same as the known
298+
* input type (there can be at most one such candidate). If so, use that
299+
* candidate. NOTE that this is cool only because operators can't
300+
* have more than 2 args, so taking the last non-unknown as current_type
301+
* can yield only one possibility if there is also an unknown.
295302
*/
296303
unknownOids= FALSE;
297304
current_type=UNKNOWNOID;
@@ -314,53 +321,82 @@ oper_select_candidate(int nargs,
314321
nmatch=0;
315322
for (i=0;i<nargs;i++)
316323
{
317-
if (current_type==current_typeids[i]||
318-
IS_BINARY_COMPATIBLE(current_type,current_typeids[i]))
324+
if (current_type==current_typeids[i])
319325
nmatch++;
320326
}
321327
if (nmatch==nargs)
322-
returncandidates->args;
328+
{
329+
/* coercion check here is probably redundant, but be safe */
330+
if (can_coerce_type(nargs,input_typeids,current_typeids))
331+
returncurrent_typeids;
332+
}
323333
}
324334
}
325335

336+
/*
337+
* Second try: examine each unknown argument position to see if all the
338+
* candidates agree on the type category of that slot. If so, and if some
339+
* candidates accept the preferred type in that category, eliminate the
340+
* candidates with other input types. If we are down to one candidate
341+
* at the end, we win.
342+
*
343+
* XXX It's kinda bogus to do this left-to-right, isn't it? If we eliminate
344+
* some candidates because they are non-preferred at the first slot, we won't
345+
* notice that they didn't have the same type category for a later slot.
346+
*/
326347
for (i=0;i<nargs;i++)
327348
{
328349
if (input_typeids[i]==UNKNOWNOID)
329350
{
330351
slot_category=INVALID_TYPE;
331352
slot_type=InvalidOid;
353+
last_candidate=NULL;
332354
for (current_candidate=candidates;
333355
current_candidate!=NULL;
334356
current_candidate=current_candidate->next)
335357
{
336358
current_typeids=current_candidate->args;
337359
current_type=current_typeids[i];
338-
current_category=TypeCategory(current_typeids[i]);
339-
if (slot_category==InvalidOid)
360+
current_category=TypeCategory(current_type);
361+
if (slot_category==INVALID_TYPE)
340362
{
341363
slot_category=current_category;
342364
slot_type=current_type;
365+
last_candidate=current_candidate;
343366
}
344367
elseif (current_category!=slot_category)
368+
{
369+
/* punt if more than one category for this slot */
345370
returnNULL;
371+
}
346372
elseif (current_type!=slot_type)
347373
{
348374
if (IsPreferredType(slot_category,current_type))
349375
{
350376
slot_type=current_type;
377+
/* forget all previous candidates */
351378
candidates=current_candidate;
379+
last_candidate=current_candidate;
352380
}
353-
else
381+
elseif (IsPreferredType(slot_category,slot_type))
354382
{
383+
/* forget this candidate */
384+
if (last_candidate)
385+
last_candidate->next=current_candidate->next;
386+
else
387+
candidates=current_candidate->next;
355388
}
389+
else
390+
last_candidate=current_candidate;
391+
}
392+
else
393+
{
394+
/* keep this candidate */
395+
last_candidate=current_candidate;
356396
}
357397
}
358-
359-
if (slot_type!=InvalidOid)
360-
input_typeids[i]=slot_type;
361-
}
362-
else
363-
{
398+
if (last_candidate)/* terminate rebuilt list */
399+
last_candidate->next=NULL;
364400
}
365401
}
366402

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