mirror of https://github.com/postgres/postgres
Add another missing SRF file.
This commit is contained in:
Bruce Momjian
parent
27bce57766
commit
7191652005
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@ -0,0 +1,197 @@
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/*-------------------------------------------------------------------------
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*
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* funcapi.h
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* Definitions for functions which return composite type and/or sets
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*
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* This file must be included by all Postgres modules that either define
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* or call FUNCAPI-callable functions or macros.
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*
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*
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* Copyright (c) 2002, PostgreSQL Global Development Group
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*
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FUNCAPI_H
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#define FUNCAPI_H
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#include "postgres.h"
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#include "fmgr.h"
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#include "access/htup.h"
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#include "access/tupdesc.h"
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#include "executor/executor.h"
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#include "executor/tuptable.h"
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/*
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* All functions that can be called directly by fmgr must have this signature.
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* (Other functions can be called by using a handler that does have this
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* signature.)
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*/
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/*-------------------------------------------------------------------------
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* Support to ease writing Functions returning composite types
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*-------------------------------------------------------------------------
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*
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* This struct holds arrays of individual attribute information
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* needed to create a tuple from raw C strings. It also requires
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* a copy of the TupleDesc. The information carried here
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* is derived from the TupleDesc, but it is stored here to
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* avoid redundant cpu cycles on each call to an SRF.
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*/
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typedef struct
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{
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/* full TupleDesc */
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TupleDesc tupdesc;
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/* pointer to array of attribute "type"in finfo */
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FmgrInfo *attinfuncs;
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/* pointer to array of attribute type typelem */
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Oid *attelems;
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/* pointer to array of attribute type typtypmod */
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int4 *atttypmods;
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} AttInMetadata;
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/*-------------------------------------------------------------------------
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* Support struct to ease writing Set Returning Functions (SRFs)
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*-------------------------------------------------------------------------
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*
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* This struct holds function context for Set Returning Functions.
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* Use fn_extra to hold a pointer to it across calls
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*/
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typedef struct
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{
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/* Number of times we've been called before */
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uint call_cntr;
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/* Maximum number of calls */
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uint max_calls;
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/* pointer to result slot */
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TupleTableSlot *slot;
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/* pointer to misc context info */
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void *fctx;
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/* pointer to struct containing arrays of attribute type input metainfo */
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AttInMetadata *attinmeta;
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/* memory context used to initialize structure */
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MemoryContext fmctx;
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} FuncCallContext;
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/*-------------------------------------------------------------------------
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* Support to ease writing Functions returning composite types
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*
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* External declarations:
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* TupleDesc RelationNameGetTupleDesc(char *relname) - Use to get a TupleDesc
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* based on the function's return type relation.
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* TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases) - Use to get a
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* TupleDesc based on the function's type oid. This can be used to get
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* a TupleDesc for a base (scalar), or composite (relation) type.
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* TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc) - Initialize a slot
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* given a TupleDesc.
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* AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc) - Get a pointer
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* to AttInMetadata based on the function's TupleDesc. AttInMetadata can
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* be used in conjunction with C strings to produce a properly formed
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* tuple. Store the metadata here for use across calls to avoid redundant
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* work.
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* HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values) -
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* build a HeapTuple given user data in C string form. values is an array
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* of C strings, one for each attribute of the return tuple.
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*
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* Macro declarations:
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* TupleGetDatum(TupleTableSlot *slot, HeapTuple tuple) - get a Datum
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* given a tuple and a slot.
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*/
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/* from tupdesc.c */
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extern TupleDesc RelationNameGetTupleDesc(char *relname);
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extern TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases);
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/* from execTuples.c */
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extern TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc);
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extern AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc);
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extern HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values);
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/* from funcapi.c */
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extern void get_type_metadata(Oid typeid, Oid *attinfuncid, Oid *attelem);
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#define TupleGetDatum(_slot, _tuple) \
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PointerGetDatum(ExecStoreTuple(_tuple, _slot, InvalidBuffer, true))
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/*-------------------------------------------------------------------------
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* Support for Set Returning Functions (SRFs)
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*
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* The basic API for SRFs looks something like:
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*
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* Datum
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* my_Set_Returning_Function(PG_FUNCTION_ARGS)
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* {
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* FuncCallContext *funcctx;
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* Datum result;
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* <user defined declarations>
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*
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* if(SRF_IS_FIRSTPASS())
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* {
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* <user defined code>
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* funcctx = SRF_FIRSTCALL_INIT();
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* <if returning composite>
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* <obtain slot>
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* funcctx->slot = slot;
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* <endif returning composite>
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* <user defined code>
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* }
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* <user defined code>
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* funcctx = SRF_PERCALL_SETUP(funcctx);
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* <user defined code>
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*
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* if (funcctx->call_cntr < funcctx->max_calls)
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* {
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* <user defined code>
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* <obtain result Datum>
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* SRF_RETURN_NEXT(funcctx, result);
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* }
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* else
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* {
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* SRF_RETURN_DONE(funcctx);
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* }
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* }
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*
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*/
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/* from funcapi.c */
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extern FuncCallContext *init_MultiFuncCall(PG_FUNCTION_ARGS);
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extern void end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx);
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#define SRF_IS_FIRSTPASS() (fcinfo->flinfo->fn_extra == NULL)
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#define SRF_FIRSTCALL_INIT() init_MultiFuncCall(fcinfo)
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#define SRF_PERCALL_SETUP(_funcctx) \
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fcinfo->flinfo->fn_extra; \
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if(_funcctx->slot != NULL) \
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ExecClearTuple(_funcctx->slot)
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#define SRF_RETURN_NEXT(_funcctx, _result) \
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do { \
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ReturnSetInfo *rsi; \
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_funcctx->call_cntr++; \
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rsi = (ReturnSetInfo *) fcinfo->resultinfo; \
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rsi->isDone = ExprMultipleResult; \
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PG_RETURN_DATUM(_result); \
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} while (0)
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#define SRF_RETURN_DONE(_funcctx) \
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do { \
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ReturnSetInfo *rsi; \
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end_MultiFuncCall(fcinfo, _funcctx); \
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rsi = (ReturnSetInfo *) fcinfo->resultinfo; \
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rsi->isDone = ExprEndResult; \
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_funcctx->slot = NULL; \
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PG_RETURN_NULL(); \
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} while (0)
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#endif /* FUNCAPI_H */
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