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Re: [Fwd: C&SRF API patch (was Re: [HACKERS] revised sample

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Joe Conway <mail(at)joeconway(dot)com>
Cc: PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [Fwd: C&SRF API patch (was Re: [HACKERS] revised sample
Date: 2002-06-17 21:44:31
Message-ID: 200206172144.g5HLiVq15695@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-patches
Your patch has been added to the PostgreSQL unapplied patches list at:

	http://candle.pha.pa.us/cgi-bin/pgpatches

I will try to apply it within the next 48 hours.

---------------------------------------------------------------------------


Joe Conway wrote:
> Tom Lane wrote:
>  > Joe Conway <mail(at)joeconway(dot)com> writes:
>  >>Is the approach in my patch still too ugly to allow a builtin SRF (set
>  >>the function return type to 0 in pg_proc.h, create a view and fix the
>  >>pg_proc entry during initdb)?
>  >
>  > Too ugly for my taste anyway ...
> 
> OK.
> 
> Here is a patch for Composite and Set returning function support. I made
> two small changes to the API since last patch, which hopefully completes
> the decoupling of composite function support from SRF specific support.
> If there are no (further ;-)) objections, please apply. I'll send
> another post with a patch for contrib/showguc.
> 
> Thanks,
> 
> Joe
> 

> Index: src/backend/access/common/tupdesc.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql/src/backend/access/common/tupdesc.c,v
> retrieving revision 1.78
> diff -c -r1.78 tupdesc.c
> *** src/backend/access/common/tupdesc.c	29 Mar 2002 19:05:59 -0000	1.78
> --- src/backend/access/common/tupdesc.c	9 Jun 2002 21:00:31 -0000
> ***************
> *** 19,24 ****
> --- 19,27 ----
>   
>   #include "postgres.h"
>   
> + #include "funcapi.h"
> + #include "access/heapam.h"
> + #include "catalog/namespace.h"
>   #include "catalog/pg_type.h"
>   #include "nodes/parsenodes.h"
>   #include "parser/parse_type.h"
> ***************
> *** 548,551 ****
> --- 551,660 ----
>   		desc->constr = NULL;
>   	}
>   	return desc;
> + }
> + 
> + 
> + /*
> +  * RelationNameGetTupleDesc
> +  *
> +  * Given a (possibly qualified) relation name, build a TupleDesc.
> +  */
> + TupleDesc
> + RelationNameGetTupleDesc(char *relname)
> + {
> + 	RangeVar   *relvar;
> + 	Relation	rel;
> + 	TupleDesc	tupdesc;
> + 	List	   *relname_list;
> + 
> + 	/* Open relation and get the tuple description */
> + 	relname_list = stringToQualifiedNameList(relname, "RelationNameGetTupleDesc");
> + 	relvar = makeRangeVarFromNameList(relname_list);
> + 	rel = heap_openrv(relvar, AccessShareLock);
> + 	tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
> + 	relation_close(rel, AccessShareLock);
> + 
> + 	return tupdesc;
> + }
> + 
> + /*
> +  * TypeGetTupleDesc
> +  *
> +  * Given a type Oid, build a TupleDesc.
> +  *
> +  * If the type is composite, *and* a colaliases List is provided, *and*
> +  * the List is of natts length, use the aliases instead of the relation
> +  * attnames.
> +  *
> +  * If the type is a base type, a single item alias List is required.
> +  */
> + TupleDesc
> + TypeGetTupleDesc(Oid typeoid, List *colaliases)
> + {
> + 	Oid			relid = typeidTypeRelid(typeoid);
> + 	TupleDesc	tupdesc;
> + 
> + 	/*
> + 	 * Build a suitable tupledesc representing the output rows
> + 	 */
> + 	if (OidIsValid(relid))
> + 	{
> + 		/* Composite data type, i.e. a table's row type */
> + 		Relation	rel;
> + 		int			natts;
> + 
> + 		rel = relation_open(relid, AccessShareLock);
> + 		tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
> + 		natts = tupdesc->natts;
> + 		relation_close(rel, AccessShareLock);
> + 
> + 		/* check to see if we've given column aliases */
> + 		if(colaliases != NIL)
> + 		{
> + 			char	   *label;
> + 			int			varattno;
> + 
> + 			/* does the List length match the number of attributes */
> + 			if (length(colaliases) != natts)
> + 				elog(ERROR, "TypeGetTupleDesc: number of aliases does not match number of attributes");
> + 
> + 			/* OK, use the aliases instead */
> + 			for (varattno = 0; varattno < natts; varattno++)
> + 			{
> + 				label = strVal(nth(varattno, colaliases));
> + 
> + 				if (label != NULL)
> + 					namestrcpy(&(tupdesc->attrs[varattno]->attname), label);
> + 				else
> + 					MemSet(NameStr(tupdesc->attrs[varattno]->attname), 0, NAMEDATALEN);
> + 			}
> + 		}
> + 	}
> + 	else
> + 	{
> + 		/* Must be a base data type, i.e. scalar */
> + 		char	   *attname;
> + 
> + 		/* the alias List is required for base types */
> + 		if (colaliases == NIL)
> + 			elog(ERROR, "TypeGetTupleDesc: no column alias was provided");
> + 
> + 		/* the alias List length must be 1 */
> + 		if (length(colaliases) != 1)
> + 			elog(ERROR, "TypeGetTupleDesc: number of aliases does not match number of attributes");
> + 
> + 		/* OK, get the column alias */
> + 		attname = strVal(lfirst(colaliases));
> + 
> + 		tupdesc = CreateTemplateTupleDesc(1);
> + 		TupleDescInitEntry(tupdesc,
> + 						   (AttrNumber) 1,
> + 						   attname,
> + 						   typeoid,
> + 						   -1,
> + 						   0,
> + 						   false);
> + 	}
> + 
> + 	return tupdesc;
>   }
> Index: src/backend/executor/execTuples.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql/src/backend/executor/execTuples.c,v
> retrieving revision 1.51
> diff -c -r1.51 execTuples.c
> *** src/backend/executor/execTuples.c	21 Mar 2002 06:21:04 -0000	1.51
> --- src/backend/executor/execTuples.c	9 Jun 2002 21:00:31 -0000
> ***************
> *** 107,117 ****
>    */
>   #include "postgres.h"
>   
>   #include "access/heapam.h"
>   #include "catalog/pg_type.h"
>   #include "executor/executor.h"
>   
> - 
>   /* ----------------------------------------------------------------
>    *				  tuple table create/delete functions
>    * ----------------------------------------------------------------
> --- 107,117 ----
>    */
>   #include "postgres.h"
>   
> + #include "funcapi.h"
>   #include "access/heapam.h"
>   #include "catalog/pg_type.h"
>   #include "executor/executor.h"
>   
>   /* ----------------------------------------------------------------
>    *				  tuple table create/delete functions
>    * ----------------------------------------------------------------
> ***************
> *** 673,675 ****
> --- 673,795 ----
>   
>   	return typeInfo;
>   }
> + 
> + /*
> +  * TupleDescGetSlot - Initialize a slot based on the supplied
> +  * tupledesc
> +  */
> + TupleTableSlot *
> + TupleDescGetSlot(TupleDesc tupdesc)
> + {
> + 	TupleTableSlot	   *slot;
> + 
> + 	/* Make a standalone slot */
> + 	slot = MakeTupleTableSlot();
> + 
> + 	/* Bind the tuple description to the slot */
> + 	ExecSetSlotDescriptor(slot, tupdesc, true);
> + 
> + 	/* Return the slot */
> + 	return slot;
> + }
> + 
> + /*
> +  * TupleDescGetAttInMetadata - Get a pointer to AttInMetadata based on the
> +  * supplied TupleDesc. AttInMetadata can be used in conjunction with C strings
> +  * to produce a properly formed tuple.
> +  */
> + AttInMetadata *
> + TupleDescGetAttInMetadata(TupleDesc tupdesc)
> + {
> + 	int				natts;
> + 	int				i;
> + 	Oid				atttypeid;
> + 	Oid				attinfuncid;
> + 	Oid				attelem;
> + 	FmgrInfo	   *attinfuncinfo;
> + 	Oid			   *attelems;
> + 	int4		   *atttypmods;
> + 	AttInMetadata  *attinmeta;
> + 
> + 	attinmeta = (AttInMetadata *) palloc(sizeof(AttInMetadata));
> + 	natts = tupdesc->natts;
> + 
> + 	/*
> + 	 * Gather info needed later to call the "in" function for each attribute
> + 	 */
> + 	attinfuncinfo = (FmgrInfo *) palloc(natts * sizeof(FmgrInfo));
> + 	attelems = (Oid *) palloc(natts * sizeof(Oid));
> + 	atttypmods = (int4 *) palloc(natts * sizeof(int4));
> + 
> + 	for (i = 0; i < natts; i++)
> + 	{
> + 		atttypeid = tupdesc->attrs[i]->atttypid;
> + 		get_type_metadata(atttypeid, &attinfuncid, &attelem);
> + 
> + 		fmgr_info(attinfuncid, &attinfuncinfo[i]);
> + 		attelems[i] = attelem;
> + 		atttypmods[i] = tupdesc->attrs[i]->atttypmod;
> + 	}
> + 	attinmeta->tupdesc = tupdesc;
> + 	attinmeta->attinfuncs = attinfuncinfo;
> + 	attinmeta->attelems = attelems;
> + 	attinmeta->atttypmods = atttypmods;
> + 
> + 	return attinmeta;
> + }
> + 
> + /*
> +  * BuildTupleFromCStrings - 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.
> +  */
> + HeapTuple
> + BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values)
> + {
> + 	TupleDesc			tupdesc;
> + 	int					natts;
> + 	HeapTuple			tuple;
> + 	char			   *nulls;
> + 	int					i;
> + 	Datum			   *dvalues;
> + 	FmgrInfo			attinfuncinfo;
> + 	Oid					attelem;
> + 	int4				atttypmod;
> + 
> + 	tupdesc = attinmeta->tupdesc;
> + 	natts = tupdesc->natts;
> + 
> + 	dvalues = (Datum *) palloc(natts * sizeof(Datum));
> + 
> + 	/* Call the "in" function for each attribute */
> + 	for (i = 0; i < natts; i++)
> + 	{
> + 		if (values[i] != NULL)
> + 		{
> + 			attinfuncinfo = attinmeta->attinfuncs[i];
> + 			attelem = attinmeta->attelems[i];
> + 			atttypmod = attinmeta->atttypmods[i];
> + 
> + 			dvalues[i] = FunctionCall3(&attinfuncinfo, CStringGetDatum(values[i]),
> + 										ObjectIdGetDatum(attelem),
> + 										Int32GetDatum(atttypmod));
> + 		}
> + 		else
> + 			dvalues[i] = PointerGetDatum(NULL);
> + 	}
> + 
> + 	/*
> + 	 * Form a tuple
> + 	 */
> + 	nulls = (char *) palloc(natts * sizeof(char));
> + 	for (i = 0; i < natts; i++)
> + 	{
> + 		if (DatumGetPointer(dvalues[i]) != NULL)
> + 			nulls[i] = ' ';
> + 		else
> + 			nulls[i] = 'n';
> + 	}
> + 	tuple = heap_formtuple(tupdesc, dvalues, nulls);
> + 
> + 	return tuple;
> + }
> + 
> Index: src/backend/utils/adt/regproc.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql/src/backend/utils/adt/regproc.c,v
> retrieving revision 1.68
> diff -c -r1.68 regproc.c
> *** src/backend/utils/adt/regproc.c	11 May 2002 00:24:16 -0000	1.68
> --- src/backend/utils/adt/regproc.c	9 Jun 2002 21:00:31 -0000
> ***************
> *** 37,44 ****
>   #include "utils/lsyscache.h"
>   #include "utils/syscache.h"
>   
> - 
> - static List *stringToQualifiedNameList(const char *string, const char *caller);
>   static void parseNameAndArgTypes(const char *string, const char *caller,
>   								 const char *type0_spelling,
>   								 List **names, int *nargs, Oid *argtypes);
> --- 37,42 ----
> ***************
> *** 960,973 ****
>   }
>   
>   
> - /*****************************************************************************
> -  *	 SUPPORT ROUTINES														 *
> -  *****************************************************************************/
> - 
>   /*
>    * Given a C string, parse it into a qualified-name list.
>    */
> ! static List *
>   stringToQualifiedNameList(const char *string, const char *caller)
>   {
>   	char	   *rawname;
> --- 958,967 ----
>   }
>   
>   
>   /*
>    * Given a C string, parse it into a qualified-name list.
>    */
> ! List *
>   stringToQualifiedNameList(const char *string, const char *caller)
>   {
>   	char	   *rawname;
> ***************
> *** 996,1001 ****
> --- 990,999 ----
>   
>   	return result;
>   }
> + 
> + /*****************************************************************************
> +  *	 SUPPORT ROUTINES														 *
> +  *****************************************************************************/
>   
>   /*
>    * Given a C string, parse it into a qualified function or operator name
> Index: src/backend/utils/fmgr/Makefile
> ===================================================================
> RCS file: /opt/src/cvs/pgsql/src/backend/utils/fmgr/Makefile,v
> retrieving revision 1.12
> diff -c -r1.12 Makefile
> *** src/backend/utils/fmgr/Makefile	16 Sep 2001 16:11:11 -0000	1.12
> --- src/backend/utils/fmgr/Makefile	9 Jun 2002 21:00:31 -0000
> ***************
> *** 12,18 ****
>   top_builddir = ../../../..
>   include $(top_builddir)/src/Makefile.global
>   
> ! OBJS = dfmgr.o fmgr.o
>   
>   override CPPFLAGS += -DPKGLIBDIR=\"$(pkglibdir)\" -DDLSUFFIX=\"$(DLSUFFIX)\"
>   
> --- 12,18 ----
>   top_builddir = ../../../..
>   include $(top_builddir)/src/Makefile.global
>   
> ! OBJS = dfmgr.o fmgr.o funcapi.o
>   
>   override CPPFLAGS += -DPKGLIBDIR=\"$(pkglibdir)\" -DDLSUFFIX=\"$(DLSUFFIX)\"
>   
> Index: src/backend/utils/fmgr/funcapi.c
> ===================================================================
> RCS file: src/backend/utils/fmgr/funcapi.c
> diff -N src/backend/utils/fmgr/funcapi.c
> *** /dev/null	1 Jan 1970 00:00:00 -0000
> --- src/backend/utils/fmgr/funcapi.c	9 Jun 2002 22:55:47 -0000
> ***************
> *** 0 ****
> --- 1,122 ----
> + /*-------------------------------------------------------------------------
> +  *
> +  * funcapi.c
> +  *	  Utility and convenience functions for fmgr functions that return
> +  *	  sets and/or composite types.
> +  *
> +  * Copyright (c) 2002, PostgreSQL Global Development Group
> +  *
> +  *-------------------------------------------------------------------------
> +  */
> + 
> + #include "funcapi.h"
> + #include "catalog/pg_type.h"
> + #include "utils/syscache.h"
> + 
> + /*
> +  * init_MultiFuncCall
> +  * Create an empty FuncCallContext data structure
> +  * and do some other basic Multi-function call setup
> +  * and error checking
> +  */
> + FuncCallContext *
> + init_MultiFuncCall(PG_FUNCTION_ARGS)
> + {
> + 	FuncCallContext *retval;
> + 
> + 	/*
> + 	 * Bail if we're called in the wrong context
> + 	 */
> + 	if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
> + 		elog(ERROR, "function called in context that does not accept a set result");
> + 
> + 	if (fcinfo->flinfo->fn_extra == NULL)
> + 	{
> + 		/*
> + 		 * First call
> + 		 */
> + 		MemoryContext oldcontext;
> + 
> + 		/* switch to the appropriate memory context */
> + 		oldcontext = MemoryContextSwitchTo(fcinfo->flinfo->fn_mcxt);
> + 
> + 		/*
> + 		 * allocate space and zero it
> + 		 */
> + 		retval = (FuncCallContext *) palloc(sizeof(FuncCallContext));
> + 		MemSet(retval, 0, sizeof(FuncCallContext));
> + 
> + 		/*
> + 		 * initialize the elements
> + 		 */
> + 		retval->call_cntr = 0;
> + 		retval->max_calls = 0;
> + 		retval->slot = NULL;
> + 		retval->fctx = NULL;
> + 		retval->attinmeta = NULL;
> + 		retval->fmctx = fcinfo->flinfo->fn_mcxt;
> + 
> + 		/*
> + 		 * save the pointer for cross-call use
> + 		 */
> + 		fcinfo->flinfo->fn_extra = retval;
> + 
> + 		/* back to the original memory context */
> + 		MemoryContextSwitchTo(oldcontext);
> + 	}
> + 	else	/* second and subsequent calls */
> + 	{
> + 		elog(ERROR, "init_MultiFuncCall may not be called more than once");
> + 
> + 		/* never reached, but keep compiler happy */
> + 		retval = NULL;
> + 	}
> + 
> + 	return retval;
> + }
> + 
> + /*
> +  * end_MultiFuncCall
> +  * Clean up after init_MultiFuncCall
> +  */
> + void
> + end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx)
> + {
> + 	MemoryContext oldcontext;
> + 
> + 	/* unbind from fcinfo */
> + 	fcinfo->flinfo->fn_extra = NULL;
> + 
> + 	/*
> + 	 * Caller is responsible to free up memory for individual
> + 	 * struct elements other than att_in_funcinfo and elements.
> + 	 */
> + 	oldcontext = MemoryContextSwitchTo(funcctx->fmctx);
> + 
> + 	if (funcctx->attinmeta != NULL)
> + 		pfree(funcctx->attinmeta);
> + 
> + 	pfree(funcctx);
> + 
> + 	MemoryContextSwitchTo(oldcontext);
> + }
> + 
> + void
> + get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem)
> + {
> + 	HeapTuple		typeTuple;
> + 	Form_pg_type	typtup;
> + 
> + 	typeTuple = SearchSysCache(TYPEOID,
> + 							   ObjectIdGetDatum(typeid),
> + 							   0, 0, 0);
> + 	if (!HeapTupleIsValid(typeTuple))
> + 		elog(ERROR, "get_type_metadata: Cache lookup of type %u failed", typeid);
> + 
> + 	typtup = (Form_pg_type) GETSTRUCT(typeTuple);
> + 
> + 	*attinfuncid = typtup->typinput;
> + 	*attelem = typtup->typelem;
> + 
> + 	ReleaseSysCache(typeTuple);
> + }
> Index: src/include/funcapi.h
> ===================================================================
> RCS file: src/include/funcapi.h
> diff -N src/include/funcapi.h
> *** /dev/null	1 Jan 1970 00:00:00 -0000
> --- src/include/funcapi.h	10 Jun 2002 00:22:42 -0000
> ***************
> *** 0 ****
> --- 1,197 ----
> + /*-------------------------------------------------------------------------
> +  *
> +  * funcapi.h
> +  *	  Definitions for functions which return composite type and/or sets
> +  *
> +  * This file must be included by all Postgres modules that either define
> +  * or call FUNCAPI-callable functions or macros.
> +  *
> +  *
> +  * Copyright (c) 2002, PostgreSQL Global Development Group
> +  *
> +  *
> +  *-------------------------------------------------------------------------
> +  */
> + #ifndef FUNCAPI_H
> + #define FUNCAPI_H
> + 
> + #include "postgres.h"
> + 
> + #include "fmgr.h"
> + #include "access/htup.h"
> + #include "access/tupdesc.h"
> + #include "executor/executor.h"
> + #include "executor/tuptable.h"
> + 
> + /*
> +  * All functions that can be called directly by fmgr must have this signature.
> +  * (Other functions can be called by using a handler that does have this
> +  * signature.)
> +  */
> + 
> + 
> + /*-------------------------------------------------------------------------
> +  *	Support to ease writing Functions returning composite types
> +  *-------------------------------------------------------------------------
> +  *
> +  * This struct holds arrays of individual attribute information
> +  * needed to create a tuple from raw C strings. It also requires
> +  * a copy of the TupleDesc. The information carried here
> +  * is derived from the TupleDesc, but it is stored here to
> +  * avoid redundant cpu cycles on each call to an SRF.
> +  */
> + typedef struct
> + {
> + 	/* full TupleDesc */
> + 	TupleDesc	   tupdesc;
> + 
> + 	/* pointer to array of attribute "type"in finfo */
> + 	FmgrInfo	   *attinfuncs;
> + 
> + 	/* pointer to array of attribute type typelem */
> + 	Oid			   *attelems;
> + 
> + 	/* pointer to array of attribute type typtypmod */
> + 	int4		   *atttypmods;
> + 
> + }	AttInMetadata;
> + 
> + /*-------------------------------------------------------------------------
> +  *		Support struct to ease writing Set Returning Functions (SRFs)
> +  *-------------------------------------------------------------------------
> +  * 
> +  * This struct holds function context for Set Returning Functions.
> +  * Use fn_extra to hold a pointer to it across calls
> +  */
> + typedef struct
> + {
> + 	/* Number of times we've been called before */
> + 	uint			call_cntr;
> + 
> + 	/* Maximum number of calls */
> + 	uint			max_calls;
> + 
> + 	/* pointer to result slot */
> + 	TupleTableSlot *slot;
> + 
> + 	/* pointer to misc context info */
> + 	void		   *fctx;
> + 
> + 	/* pointer to struct containing arrays of attribute type input metainfo */
> + 	AttInMetadata	   *attinmeta;
> + 
> + 	/* memory context used to initialize structure */
> + 	MemoryContext	fmctx;
> + 
> + }	FuncCallContext;
> + 
> + /*-------------------------------------------------------------------------
> +  *	Support to ease writing Functions returning composite types
> +  *
> +  * External declarations:
> +  * TupleDesc RelationNameGetTupleDesc(char *relname) - Use to get a TupleDesc
> +  *		based on the function's return type relation.
> +  * TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases) - Use to get a
> +  *		TupleDesc based on the function's type oid. This can be used to get
> +  *		a TupleDesc for a base (scalar), or composite (relation) type.
> +  * TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc) - Initialize a slot
> +  *		given a TupleDesc.
> +  * AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc) - Get a pointer
> +  *		to AttInMetadata based on the function's TupleDesc. AttInMetadata can
> +  *		be used in conjunction with C strings to produce a properly formed
> +  *		tuple. Store the metadata here for use across calls to avoid redundant
> +  *		work.
> +  * 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.
> +  *
> +  * Macro declarations:
> +  * TupleGetDatum(TupleTableSlot *slot, HeapTuple tuple) - get a Datum
> +  *		given a tuple and a slot.
> +  */
> + 
> + /* from tupdesc.c */
> + extern TupleDesc RelationNameGetTupleDesc(char *relname);
> + extern TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases);
> + 
> + /* from execTuples.c */
> + extern TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc);
> + extern AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc);
> + extern HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values);
> + 
> + /* from funcapi.c */
> + extern void get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem);
> + 
> + #define TupleGetDatum(_slot, _tuple) \
> + 	PointerGetDatum(ExecStoreTuple(_tuple, _slot, InvalidBuffer, true))
> + 
> + /*-------------------------------------------------------------------------
> +  *		Support for Set Returning Functions (SRFs)
> +  *
> +  * The basic API for SRFs looks something like:
> +  *
> +  * Datum
> +  * my_Set_Returning_Function(PG_FUNCTION_ARGS)
> +  * {
> +  * 	FuncCallContext	   *funcctx;
> +  * 	Datum				result;
> +  * 	<user defined declarations>
> +  * 
> +  * 	if(SRF_IS_FIRSTPASS())
> +  * 	{
> +  * 		<user defined code>
> +  * 		funcctx = SRF_FIRSTCALL_INIT();
> +  * 		<if returning composite>
> +  * 			<obtain slot>
> +  * 			funcctx->slot = slot;
> +  * 		<endif returning composite>
> +  * 		<user defined code>
> +  *  }
> +  * 	<user defined code>
> +  * 	funcctx = SRF_PERCALL_SETUP(funcctx);
> +  * 	<user defined code>
> +  * 
> +  * 	if (funcctx->call_cntr < funcctx->max_calls)
> +  * 	{
> +  * 		<user defined code>
> +  * 		<obtain result Datum>
> +  * 		SRF_RETURN_NEXT(funcctx, result);
> +  * 	}
> +  * 	else
> +  * 	{
> +  * 		SRF_RETURN_DONE(funcctx);
> +  * 	}
> +  * }
> +  *
> +  */
> + 
> + /* from funcapi.c */
> + extern FuncCallContext *init_MultiFuncCall(PG_FUNCTION_ARGS);
> + extern void end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx);
> + 
> + #define SRF_IS_FIRSTPASS() (fcinfo->flinfo->fn_extra == NULL)
> + #define SRF_FIRSTCALL_INIT() init_MultiFuncCall(fcinfo)
> + #define SRF_PERCALL_SETUP(_funcctx) \
> + 	fcinfo->flinfo->fn_extra; \
> + 	if(_funcctx->slot != NULL) \
> + 		ExecClearTuple(_funcctx->slot)
> + #define SRF_RETURN_NEXT(_funcctx, _result) \
> + 	do { \
> + 		ReturnSetInfo	   *rsi; \
> + 		_funcctx->call_cntr++; \
> + 		rsi = (ReturnSetInfo *) fcinfo->resultinfo; \
> + 		rsi->isDone = ExprMultipleResult; \
> + 		PG_RETURN_DATUM(_result); \
> + 	} while (0)
> + 
> + #define  SRF_RETURN_DONE(_funcctx) \
> + 	do { \
> + 		ReturnSetInfo	   *rsi; \
> + 		end_MultiFuncCall(fcinfo, _funcctx); \
> + 		rsi = (ReturnSetInfo *) fcinfo->resultinfo; \
> + 		rsi->isDone = ExprEndResult; \
> + 		_funcctx->slot = NULL; \
> + 		PG_RETURN_NULL(); \
> + 	} while (0)
> + 
> + #endif   /* FUNCAPI_H */
> Index: src/include/utils/builtins.h
> ===================================================================
> RCS file: /opt/src/cvs/pgsql/src/include/utils/builtins.h,v
> retrieving revision 1.182
> diff -c -r1.182 builtins.h
> *** src/include/utils/builtins.h	18 May 2002 21:38:41 -0000	1.182
> --- src/include/utils/builtins.h	9 Jun 2002 21:00:31 -0000
> ***************
> *** 341,346 ****
> --- 341,347 ----
>   extern Datum regclassout(PG_FUNCTION_ARGS);
>   extern Datum regtypein(PG_FUNCTION_ARGS);
>   extern Datum regtypeout(PG_FUNCTION_ARGS);
> + extern List *stringToQualifiedNameList(const char *string, const char *caller);
>   
>   /* ruleutils.c */
>   extern Datum pg_get_ruledef(PG_FUNCTION_ARGS);
> 

> 
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> 

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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