Further fixes for bogus list-slinging, scribbling on input, etc in type
coercion code. I'm beginning to wonder why we have separate candidate selection routines for functions, operators, and aggregates --- shouldn't this code all be unified? But meanwhile, SELECT 'a' LIKE 'a'; finally works; the code for dealing with unknown input types for operators was pretty busted.
This commit is contained in:
Tom Lane
parent
1d75298176
commit
c9f287e49b
@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.72 2000/02/20 23:04:06 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.73 2000/03/11 23:17:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -854,11 +854,6 @@ match_argtypes(int nargs,
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* for the function argtype array, attempt to resolve the conflict.
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* returns the selected argtype array if the conflict can be resolved,
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* otherwise returns NULL.
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*
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* If all input Oids are UNKNOWNOID, then try matching with TEXTOID.
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* Otherwise, could return first function arguments on list of candidates.
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* But for now, return NULL and make the user give a better hint.
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* - thomas 1998-03-17
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*/
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static Oid *
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func_select_candidate(int nargs,
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@ -869,12 +864,10 @@ func_select_candidate(int nargs,
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CandidateList last_candidate;
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Oid *current_typeids;
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int i;
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int ncandidates;
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int nbestMatch,
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nmatch,
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nident;
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ncompat;
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CATEGORY slot_category,
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current_category;
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Oid slot_type,
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@ -893,19 +886,29 @@ func_select_candidate(int nargs,
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{
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current_typeids = current_candidate->args;
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nmatch = 0;
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nident = 0;
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ncompat = 0;
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for (i = 0; i < nargs; i++)
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{
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if ((input_typeids[i] != UNKNOWNOID)
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&& (current_typeids[i] == input_typeids[i]))
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nmatch++;
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else if (IS_BINARY_COMPATIBLE(current_typeids[i], input_typeids[i]))
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nident++;
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if (input_typeids[i] != UNKNOWNOID)
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{
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if (current_typeids[i] == input_typeids[i])
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nmatch++;
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else if (IS_BINARY_COMPATIBLE(current_typeids[i],
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input_typeids[i]))
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ncompat++;
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}
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}
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if ((nmatch + nident) == nargs)
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/*
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* If we find an exact match at all arg positions, we're done;
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* there can be only one such candidate.
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*/
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if (nmatch == nargs)
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return current_candidate->args;
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/* Otherwise, use match+compat as the score. */
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nmatch += ncompat;
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/* take this one as the best choice so far? */
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if ((nmatch > nbestMatch) || (last_candidate == NULL))
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{
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@ -933,6 +936,16 @@ func_select_candidate(int nargs,
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/*
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* Still too many candidates?
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* Try assigning types for the unknown columns.
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*
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* We do this by examining each unknown argument position to see if all the
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* candidates agree on the type category of that slot. If so, and if some
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* candidates accept the preferred type in that category, eliminate the
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* candidates with other input types. If we are down to one candidate
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* at the end, we win.
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*
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* XXX It's kinda bogus to do this left-to-right, isn't it? If we eliminate
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* some candidates because they are non-preferred at the first slot, we won't
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* notice that they didn't have the same type category for a later slot.
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*/
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for (i = 0; i < nargs; i++)
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{
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@ -947,12 +960,12 @@ func_select_candidate(int nargs,
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{
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current_typeids = current_candidate->args;
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current_type = current_typeids[i];
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current_category = TypeCategory(current_typeids[i]);
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if (slot_category == InvalidOid)
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current_category = TypeCategory(current_type);
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if (slot_category == INVALID_TYPE)
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{
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slot_category = current_category;
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slot_type = current_type;
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last_candidate = current_candidate;
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}
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else if (current_category != slot_category)
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{
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.36 2000/02/27 02:48:15 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.37 2000/03/11 23:17:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -128,7 +128,7 @@ binary_oper_get_candidates(char *opname,
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*
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* This routine is new code, replacing binary_oper_select_candidate()
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* which dates from v4.2/v1.0.x days. It tries very hard to match up
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* operators with types, including allowing type coersions if necessary.
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* operators with types, including allowing type coercions if necessary.
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* The important thing is that the code do as much as possible,
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* while _never_ doing the wrong thing, where "the wrong thing" would
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* be returning an operator when other better choices are available,
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@ -185,7 +185,7 @@ oper_select_candidate(int nargs,
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/*
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* Run through all candidates and keep those with the most matches
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* on explicit types. Keep all candidates if none match.
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* on exact types. Keep all candidates if none match.
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*/
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ncandidates = 0;
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nbestMatch = 0;
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@ -236,7 +236,7 @@ oper_select_candidate(int nargs,
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/*
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* Still too many candidates?
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* Now look for candidates which allow coersion and are preferred types.
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* Now look for candidates which allow coercion and are preferred types.
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* Keep all candidates if none match.
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*/
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ncandidates = 0;
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@ -292,6 +292,13 @@ oper_select_candidate(int nargs,
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/*
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* Still too many candidates?
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* Try assigning types for the unknown columns.
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*
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* First try: if we have an unknown and a non-unknown input, see whether
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* there is a candidate all of whose input types are the same as the known
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* input type (there can be at most one such candidate). If so, use that
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* candidate. NOTE that this is cool only because operators can't
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* have more than 2 args, so taking the last non-unknown as current_type
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* can yield only one possibility if there is also an unknown.
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*/
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unknownOids = FALSE;
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current_type = UNKNOWNOID;
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@ -314,53 +321,82 @@ oper_select_candidate(int nargs,
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nmatch = 0;
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for (i = 0; i < nargs; i++)
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{
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if (current_type == current_typeids[i] ||
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IS_BINARY_COMPATIBLE(current_type, current_typeids[i]))
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if (current_type == current_typeids[i])
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nmatch++;
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}
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if (nmatch == nargs)
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return candidates->args;
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{
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/* coercion check here is probably redundant, but be safe */
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if (can_coerce_type(nargs, input_typeids, current_typeids))
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return current_typeids;
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}
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}
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}
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/*
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* Second try: examine each unknown argument position to see if all the
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* candidates agree on the type category of that slot. If so, and if some
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* candidates accept the preferred type in that category, eliminate the
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* candidates with other input types. If we are down to one candidate
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* at the end, we win.
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*
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* XXX It's kinda bogus to do this left-to-right, isn't it? If we eliminate
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* some candidates because they are non-preferred at the first slot, we won't
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* notice that they didn't have the same type category for a later slot.
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*/
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for (i = 0; i < nargs; i++)
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{
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if (input_typeids[i] == UNKNOWNOID)
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{
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slot_category = INVALID_TYPE;
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slot_type = InvalidOid;
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last_candidate = NULL;
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for (current_candidate = candidates;
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current_candidate != NULL;
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current_candidate = current_candidate->next)
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{
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current_typeids = current_candidate->args;
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current_type = current_typeids[i];
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current_category = TypeCategory(current_typeids[i]);
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if (slot_category == InvalidOid)
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current_category = TypeCategory(current_type);
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if (slot_category == INVALID_TYPE)
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{
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slot_category = current_category;
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slot_type = current_type;
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last_candidate = current_candidate;
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}
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else if (current_category != slot_category)
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{
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/* punt if more than one category for this slot */
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return NULL;
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}
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else if (current_type != slot_type)
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{
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if (IsPreferredType(slot_category, current_type))
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{
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slot_type = current_type;
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/* forget all previous candidates */
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candidates = current_candidate;
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last_candidate = current_candidate;
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}
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else if (IsPreferredType(slot_category, slot_type))
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{
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/* forget this candidate */
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if (last_candidate)
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last_candidate->next = current_candidate->next;
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else
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candidates = current_candidate->next;
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}
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else
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{
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}
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last_candidate = current_candidate;
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}
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else
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{
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/* keep this candidate */
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last_candidate = current_candidate;
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}
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}
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if (slot_type != InvalidOid)
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input_typeids[i] = slot_type;
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}
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else
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{
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if (last_candidate) /* terminate rebuilt list */
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last_candidate->next = NULL;
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}
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}
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