Re: array support patch phase 1 patch - Mailing list pgsql-patches

Tom Lane wrote:
> That is surely not what you intended.  The test must be whether arg1 and
> arg2 are (separately) coercible to the operator's two input types.
> Moreover, the test must not be symmetric, any more than
> IsBinaryCoercible is.  You can coerce int[] to ANYARRAY but not vice
> versa.
>
> A bigger problem is that I doubt this will actually work.  Most of the
> places that call compatible_oper will then proceed to call the function
> from specialized code that does not bother with consing up an expression
> tree --- so a polymorphic function is going to fail anyway...
>

How's this attempt?

Couple of issues it raised:

1.) In conjunction with the phase2 patch, which changes array_eq to do
an element-by-element equality comparison, I discovered that type
"aclitem" has no equality operator, and apparently nothing
binary-coercible either. Should I invent "=" for aclitem, or have
array_eq fall back to its original byte-by-byte comparison if it doesn't
find an equality operator?

2.) I noticed that if I start the postmaster without redirecting to a
logfile, I see double error messages in psql. Is this intended? Maybe
due to some conf setting?

[postgres@dev postgres]$ pg_ctl start
LOG:  database system was shut down at 2003-06-01 08:58:18 PDT
IN:  StartupXLOG (xlog.c:2510)
LOG:  checkpoint record is at 0/5BCDA4
IN:  StartupXLOG (xlog.c:2538)
LOG:  redo record is at 0/5BCDA4; undo record is at 0/0; shutdown TRUE
IN:  StartupXLOG (xlog.c:2558)
LOG:  next transaction id: 475; next oid: 17079
IN:  StartupXLOG (xlog.c:2562)
postmaster successfully started
[postgres@dev postgres]$ LOG:  database system is ready
IN:  StartupXLOG (xlog.c:2819)

[postgres@dev postgres]$ psql template1
Welcome to psql 7.4devel, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
        \h for help with SQL commands
        \? for help on internal slash commands
        \g or terminate with semicolon to execute query
        \q to quit

template1=# select distinct array(select f1 from tse);
ERROR:  Unable to identify an ordering operator for type integer[]
         Use an explicit ordering operator or modify the query
IN:  ordering_oper (parse_oper.c:202)
ERROR:  Unable to identify an ordering operator for type integer[]
         Use an explicit ordering operator or modify the query


Joe
Index: src/backend/parser/parse_coerce.c
===================================================================
RCS file: /opt/src/cvs/pgsql-server/src/backend/parser/parse_coerce.c,v
retrieving revision 2.97
diff -c -r2.97 parse_coerce.c
*** src/backend/parser/parse_coerce.c    26 May 2003 00:11:27 -0000    2.97
--- src/backend/parser/parse_coerce.c    1 Jun 2003 15:50:25 -0000
***************
*** 1187,1192 ****
--- 1195,1222 ----
      return result;
  }

+ /* IsPolymorphicCoercible()
+  *        Check if srctype and targettype are a polymorphic compatible pair.
+  *
+  * We consider two types polymorphic-coercible if:
+  * 1) both are the same
+  * 2) target is ANYARRAY and source is an array type
+  */
+ bool
+ IsPolymorphicCoercible(Oid srctype, Oid targettype)
+ {
+     /* Case 1: fast path if same type */
+     if (srctype == targettype)
+         return true;
+
+     /* Case 2: check for matching arrays */
+     if (targettype == ANYARRAYOID)
+         if (get_element_type(srctype) != InvalidOid)
+             return true;
+
+     /* if all else fails... */
+     return false;
+ }

  /*
   * find_coercion_pathway
Index: src/backend/parser/parse_oper.c
===================================================================
RCS file: /opt/src/cvs/pgsql-server/src/backend/parser/parse_oper.c,v
retrieving revision 1.64
diff -c -r1.64 parse_oper.c
*** src/backend/parser/parse_oper.c    26 May 2003 00:11:27 -0000    1.64
--- src/backend/parser/parse_oper.c    1 Jun 2003 15:54:41 -0000
***************
*** 412,417 ****
--- 412,422 ----
          IsBinaryCoercible(arg2, opform->oprright))
          return optup;

+     /* last check -- polymorphic types? */
+     if (IsPolymorphicCoercible(arg1 , opform->oprleft) &&
+         IsPolymorphicCoercible(arg2, opform->oprright))
+         return optup;
+
      /* nope... */
      ReleaseSysCache(optup);

Index: src/include/parser/parse_coerce.h
===================================================================
RCS file: /opt/src/cvs/pgsql-server/src/include/parser/parse_coerce.h,v
retrieving revision 1.51
diff -c -r1.51 parse_coerce.h
*** src/include/parser/parse_coerce.h    29 Apr 2003 22:13:11 -0000    1.51
--- src/include/parser/parse_coerce.h    1 Jun 2003 15:41:23 -0000
***************
*** 36,41 ****
--- 36,42 ----


  extern bool IsBinaryCoercible(Oid srctype, Oid targettype);
+ extern bool IsPolymorphicCoercible(Oid srctype, Oid targettype);
  extern bool IsPreferredType(CATEGORY category, Oid type);
  extern CATEGORY TypeCategory(Oid type);