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Replace TupleTableSlot convention for whole-row variables and function
results with tuples as ordinary varlena Datums. This commit does not in itself do much for us, except eliminate the horrid memory leak associated with evaluation of whole-row variables. However, it lays the groundwork for allowing composite types as table columns, and perhaps some other useful features as well. Per my proposal of a few days ago.
This commit is contained in:
Tom Lane
@ -9,7 +9,7 @@
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*
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* Copyright (c) 2002-2003, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/include/funcapi.h,v 1.10 2003/11/29 22:40:53 pgsql Exp $
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* $PostgreSQL: pgsql/src/include/funcapi.h,v 1.11 2004/04/01 21:28:46 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -57,7 +57,7 @@ typedef struct AttInMetadata
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typedef struct FuncCallContext
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{
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/*
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* Number of times we've been called before.
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* Number of times we've been called before
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*
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* call_cntr is initialized to 0 for you by SRF_FIRSTCALL_INIT(), and
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* incremented for you every time SRF_RETURN_NEXT() is called.
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@ -67,7 +67,7 @@ typedef struct FuncCallContext
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/*
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* OPTIONAL maximum number of calls
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*
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* max_calls is here for convenience ONLY and setting it is OPTIONAL. If
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* max_calls is here for convenience only and setting it is optional. If
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* not set, you must provide alternative means to know when the
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* function is done.
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*/
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@ -76,41 +76,50 @@ typedef struct FuncCallContext
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/*
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* OPTIONAL pointer to result slot
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*
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* slot is for use when returning tuples (i.e. composite data types) and
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* is not needed when returning base (i.e. scalar) data types.
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* This is obsolete and only present for backwards compatibility, viz,
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* user-defined SRFs that use the deprecated TupleDescGetSlot().
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*/
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TupleTableSlot *slot;
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/*
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* OPTIONAL pointer to misc user provided context info
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* OPTIONAL pointer to miscellaneous user-provided context information
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*
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* user_fctx is for use as a pointer to your own struct to retain
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* arbitrary context information between calls for your function.
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* arbitrary context information between calls of your function.
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*/
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void *user_fctx;
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/*
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* OPTIONAL pointer to struct containing arrays of attribute type
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* input metainfo
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* OPTIONAL pointer to struct containing attribute type input metadata
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*
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* attinmeta is for use when returning tuples (i.e. composite data types)
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* and is not needed when returning base (i.e. scalar) data types. It
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* is ONLY needed if you intend to use BuildTupleFromCStrings() to
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* create the return tuple.
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* and is not used when returning base data types. It is only needed
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* if you intend to use BuildTupleFromCStrings() to create the return
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* tuple.
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*/
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AttInMetadata *attinmeta;
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/*
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* memory context used for structures which must live for multiple
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* calls
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* memory context used for structures that must live for multiple calls
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*
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* multi_call_memory_ctx is set by SRF_FIRSTCALL_INIT() for you, and used
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* by SRF_RETURN_DONE() for cleanup. It is the most appropriate memory
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* context for any memory that is to be re-used across multiple calls
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* context for any memory that is to be reused across multiple calls
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* of the SRF.
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*/
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MemoryContext multi_call_memory_ctx;
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/*
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* OPTIONAL pointer to struct containing tuple description
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*
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* tuple_desc is for use when returning tuples (i.e. composite data types)
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* and is only needed if you are going to build the tuples with
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* heap_formtuple() rather than with BuildTupleFromCStrings(). Note that
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* the TupleDesc pointer stored here should usually have been run through
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* BlessTupleDesc() first.
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*/
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TupleDesc tuple_desc;
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} FuncCallContext;
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/*----------
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@ -122,38 +131,43 @@ typedef struct FuncCallContext
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* TupleDesc TypeGetTupleDesc(Oid typeoid, List *colaliases) - Use to get a
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* TupleDesc based on a 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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* TupleDesc BlessTupleDesc(TupleDesc tupdesc) - "Bless" a completed tuple
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* descriptor so that it can be used to return properly labeled tuples.
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* You need to call this if you are going to use heap_formtuple directly.
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* TupleDescGetAttInMetadata does it for you, however, so no need to call
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* it if you call TupleDescGetAttInMetadata.
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* AttInMetadata *TupleDescGetAttInMetadata(TupleDesc tupdesc) - Build an
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* AttInMetadata struct based on the given 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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* tuple.
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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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* HeapTupleGetDatum(HeapTuple tuple) - convert a HeapTuple to a Datum.
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*
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* Obsolete routines and macros:
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* TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc) - Builds a
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* TupleTableSlot, which is not needed anymore.
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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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*/
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#define HeapTupleGetDatum(_tuple) PointerGetDatum((_tuple)->t_data)
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/* obsolete version of above */
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#define TupleGetDatum(_slot, _tuple) PointerGetDatum((_tuple)->t_data)
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/* from tupdesc.c */
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extern TupleDesc RelationNameGetTupleDesc(const 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 TupleDesc BlessTupleDesc(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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/*
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* Note we pass shouldFree = false; this is needed because the tuple will
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* typically be in a shorter-lived memory context than the TupleTableSlot.
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*/
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#define TupleGetDatum(_slot, _tuple) \
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PointerGetDatum(ExecStoreTuple(_tuple, _slot, InvalidBuffer, false))
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extern TupleTableSlot *TupleDescGetSlot(TupleDesc tupdesc);
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/*----------
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@ -176,8 +190,7 @@ extern HeapTuple BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values)
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* oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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* <user defined code>
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* <if returning composite>
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* <obtain slot>
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* funcctx->slot = slot;
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* <build TupleDesc, and perhaps AttInMetaData>
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* <endif returning composite>
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* <user defined code>
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* // return to original context when allocating transient memory
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