guc GetConfigOptionByNum and tablefunc API - minor changes - Mailing list pgsql-patches

Tom Lane wrote:
> One thing that possibly needs discussion is the handling of
> GUC_NO_SHOW_ALL.  I moved that test into the SHOW ALL code because
> the intended behavior is for the marked variable to not be in the
> SHOW ALL output at all, rather than be there with a null value as
> your patch originally behaved.  Now that was fine for SHOW ALL because
> it can examine the config record directly anyway, but what of external
> callers of GetConfigOptionByNum?  There aren't any right now so I'm
> kind of speculating in a vacuum about what they'll want.  But it seems
> possible that they will want to be able to discover whether the var is
> marked NO_SHOW_ALL or not.  Maybe that should be an additional return
> variable from GetConfigOptionByNum, along the lines of
>
>     GetConfigOptionByNum(..., bool *noshow)
>     {
>         if (noshow)
>         *noshow = (conf->flags & GUC_NO_SHOW_ALL) ? true : false;
>     }
>
> Any thoughts?
>
> Oh btw: an Assert() verifying that the arg of GetConfigOptionByNum is
> in range wouldn't be out of place, I think.

Here are two patches. The guc_and_tablefunc patch addresses the two
changes mentioned above, and also adds a new function to the tablefunc
API. The tablefunc API change adds the following function:

* Oid foidGetTypeId(Oid foid) - Get a function's typeid given the
* function Oid. Use this together with TypeGetTupleDesc() to get a
* TupleDesc which is derived from the function's declared return type.

In the next post I'll send the contrib/tablefunc patch, which
illustrates the usage of this new function. Also attached is a doc patch
for this change. The doc patch also adds a function that I failed to
document previously.

If there are no objections, please apply.

Thanks,

Joe

Index: doc/src/sgml/xfunc.sgml
===================================================================
RCS file: /opt/src/cvs/pgsql/doc/src/sgml/xfunc.sgml,v
retrieving revision 1.53
diff -c -r1.53 xfunc.sgml
*** doc/src/sgml/xfunc.sgml    18 Jul 2002 04:47:17 -0000    1.53
--- doc/src/sgml/xfunc.sgml    21 Jul 2002 01:51:10 -0000
***************
*** 1557,1562 ****
--- 1557,1580 ----
      </para>

      <para>
+      In order to get an attribute "in" function and typelem value given the
+      typeid, use
+ <programlisting>
+ void get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem)
+ </programlisting>
+     </para>
+
+     <para>
+      You can use this next function together with TypeGetTupleDesc(), to get
+      a TupleDesc which is derived from the function's declared return type.
+ <programlisting>
+ Oid foidGetTypeId(Oid foid)
+ </programlisting>
+      This allows you to avoid hard-coding the return data type name into your
+      function.
+     </para>
+
+     <para>
       Finally, in order to return a tuple using the SRF portion of the API
       (described below), the tuple must be converted into a Datum. Use
  <programlisting>
Index: src/backend/utils/fmgr/funcapi.c
===================================================================
RCS file: /opt/src/cvs/pgsql/src/backend/utils/fmgr/funcapi.c,v
retrieving revision 1.2
diff -c -r1.2 funcapi.c
*** src/backend/utils/fmgr/funcapi.c    18 Jul 2002 04:40:30 -0000    1.2
--- src/backend/utils/fmgr/funcapi.c    21 Jul 2002 01:04:51 -0000
***************
*** 10,15 ****
--- 10,16 ----
   */

  #include "funcapi.h"
+ #include "catalog/pg_proc.h"
  #include "catalog/pg_type.h"
  #include "utils/syscache.h"

***************
*** 136,139 ****
--- 137,168 ----
      *attelem = typtup->typelem;

      ReleaseSysCache(typeTuple);
+ }
+
+ /*
+  * get the typeid for a function given the function Oid
+  */
+ Oid
+ foidGetTypeId(Oid foid)
+ {
+     HeapTuple    procedureTuple;
+     Form_pg_proc procedureStruct;
+     Oid            functypeid;
+
+     /* get the procedure tuple corresponding to the given function Oid */
+     procedureTuple = SearchSysCache(PROCOID,
+                                     ObjectIdGetDatum(foid),
+                                     0, 0, 0);
+     if (!HeapTupleIsValid(procedureTuple))
+         elog(ERROR, "foidGetTypeId: Cache lookup failed for procedure %u",
+              foid);
+
+     procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
+
+     functypeid = procedureStruct->prorettype;
+
+     /* clean up */
+     ReleaseSysCache(procedureTuple);
+
+     return functypeid;
  }
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /opt/src/cvs/pgsql/src/backend/utils/misc/guc.c,v
retrieving revision 1.75
diff -c -r1.75 guc.c
*** src/backend/utils/misc/guc.c    20 Jul 2002 15:12:55 -0000    1.75
--- src/backend/utils/misc/guc.c    21 Jul 2002 01:36:12 -0000
***************
*** 2347,2358 ****
   * form of name.  Return value is palloc'd.
   */
  char *
! GetConfigOptionByNum(int varnum, const char **varname)
  {
!     struct config_generic *conf = guc_variables[varnum];

      if (varname)
          *varname = conf->name;

      return _ShowOption(conf);
  }
--- 2347,2366 ----
   * form of name.  Return value is palloc'd.
   */
  char *
! GetConfigOptionByNum(int varnum, const char **varname, bool *noshow)
  {
!     struct config_generic *conf;
!
!     /* check requested variable number valid */
!     Assert((varnum >= 0) && (varnum < num_guc_variables));
!
!     conf = guc_variables[varnum];

      if (varname)
          *varname = conf->name;
+
+     if (noshow)
+         *noshow = (conf->flags & GUC_NO_SHOW_ALL) ? true : false;

      return _ShowOption(conf);
  }
Index: src/include/funcapi.h
===================================================================
RCS file: /opt/src/cvs/pgsql/src/include/funcapi.h,v
retrieving revision 1.3
diff -c -r1.3 funcapi.h
*** src/include/funcapi.h    18 Jul 2002 04:40:30 -0000    1.3
--- src/include/funcapi.h    21 Jul 2002 01:02:26 -0000
***************
*** 139,144 ****
--- 139,149 ----
   * HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values) -
   *        build a HeapTuple given user data in C string form. values is an array
   *        of C strings, one for each attribute of the return tuple.
+  * void get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem) - Get
+  *      an attribute "in" function and typelem value given the typeid.
+  * Oid foidGetTypeId(Oid foid) - Get a function's typeid given the function
+  *     Oid. Use this together with TypeGetTupleDesc() to get a TupleDesc
+  *     which is derived from the function's declared return type.
   *
   * Macro declarations:
   * TupleGetDatum(TupleTableSlot *slot, HeapTuple tuple) - get a Datum
***************
*** 156,161 ****
--- 161,167 ----

  /* from funcapi.c */
  extern void get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem);
+ extern Oid foidGetTypeId(Oid foid);

  #define TupleGetDatum(_slot, _tuple) \
      PointerGetDatum(ExecStoreTuple(_tuple, _slot, InvalidBuffer, true))
Index: src/include/utils/guc.h
===================================================================
RCS file: /opt/src/cvs/pgsql/src/include/utils/guc.h,v
retrieving revision 1.19
diff -c -r1.19 guc.h
*** src/include/utils/guc.h    20 Jul 2002 15:12:56 -0000    1.19
--- src/include/utils/guc.h    20 Jul 2002 23:44:52 -0000
***************
*** 87,93 ****
  extern void ShowGUCConfigOption(const char *name);
  extern void ShowAllGUCConfig(void);
  extern char *GetConfigOptionByName(const char *name, const char **varname);
! extern char *GetConfigOptionByNum(int varnum, const char **varname);
  extern int GetNumConfigOptions(void);

  extern void SetPGVariable(const char *name, List *args, bool is_local);
--- 87,93 ----
  extern void ShowGUCConfigOption(const char *name);
  extern void ShowAllGUCConfig(void);
  extern char *GetConfigOptionByName(const char *name, const char **varname);
! extern char *GetConfigOptionByNum(int varnum, const char **varname, bool *noshow);
  extern int GetNumConfigOptions(void);

  extern void SetPGVariable(const char *name, List *args, bool is_local);