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125 lines
4.1 KiB
C
125 lines
4.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* tupdesc.h
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* POSTGRES tuple descriptor definitions.
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*
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*
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/tupdesc.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPDESC_H
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#define TUPDESC_H
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#include "access/attnum.h"
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#include "catalog/pg_attribute.h"
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#include "nodes/pg_list.h"
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typedef struct attrDefault
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{
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AttrNumber adnum;
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char *adbin; /* nodeToString representation of expr */
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} AttrDefault;
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typedef struct constrCheck
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{
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char *ccname;
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char *ccbin; /* nodeToString representation of expr */
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} ConstrCheck;
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/* This structure contains constraints of a tuple */
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typedef struct tupleConstr
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{
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AttrDefault *defval; /* array */
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ConstrCheck *check; /* array */
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uint16 num_defval;
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uint16 num_check;
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bool has_not_null;
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} TupleConstr;
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/*
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* This struct is passed around within the backend to describe the structure
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* of tuples. For tuples coming from on-disk relations, the information is
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* collected from the pg_attribute, pg_attrdef, and pg_constraint catalogs.
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* Transient row types (such as the result of a join query) have anonymous
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* TupleDesc structs that generally omit any constraint info; therefore the
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* structure is designed to let the constraints be omitted efficiently.
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*
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* Note that only user attributes, not system attributes, are mentioned in
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* TupleDesc; with the exception that tdhasoid indicates if OID is present.
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*
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* If the tupdesc is known to correspond to a named rowtype (such as a table's
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* rowtype) then tdtypeid identifies that type and tdtypmod is -1. Otherwise
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* tdtypeid is RECORDOID, and tdtypmod can be either -1 for a fully anonymous
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* row type, or a value >= 0 to allow the rowtype to be looked up in the
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* typcache.c type cache.
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*
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* Tuple descriptors that live in caches (relcache or typcache, at present)
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* are reference-counted: they can be deleted when their reference count goes
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* to zero. Tuple descriptors created by the executor need no reference
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* counting, however: they are simply created in the appropriate memory
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* context and go away when the context is freed. We set the tdrefcount
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* field of such a descriptor to -1, while reference-counted descriptors
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* always have tdrefcount >= 0.
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*/
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typedef struct tupleDesc
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{
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int natts; /* number of attributes in the tuple */
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Form_pg_attribute *attrs;
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/* attrs[N] is a pointer to the description of Attribute Number N+1 */
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TupleConstr *constr; /* constraints, or NULL if none */
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Oid tdtypeid; /* composite type ID for tuple type */
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int32 tdtypmod; /* typmod for tuple type */
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bool tdhasoid; /* tuple has oid attribute in its header */
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int tdrefcount; /* reference count, or -1 if not counting */
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} *TupleDesc;
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extern TupleDesc CreateTemplateTupleDesc(int natts, bool hasoid);
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extern TupleDesc CreateTupleDesc(int natts, bool hasoid,
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Form_pg_attribute *attrs);
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extern TupleDesc CreateTupleDescCopy(TupleDesc tupdesc);
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extern TupleDesc CreateTupleDescCopyConstr(TupleDesc tupdesc);
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extern void FreeTupleDesc(TupleDesc tupdesc);
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extern void IncrTupleDescRefCount(TupleDesc tupdesc);
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extern void DecrTupleDescRefCount(TupleDesc tupdesc);
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#define PinTupleDesc(tupdesc) \
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do { \
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if ((tupdesc)->tdrefcount >= 0) \
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IncrTupleDescRefCount(tupdesc); \
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} while (0)
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#define ReleaseTupleDesc(tupdesc) \
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do { \
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if ((tupdesc)->tdrefcount >= 0) \
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DecrTupleDescRefCount(tupdesc); \
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} while (0)
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extern bool equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2);
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extern void TupleDescInitEntry(TupleDesc desc,
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AttrNumber attributeNumber,
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const char *attributeName,
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Oid oidtypeid,
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int32 typmod,
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int attdim);
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extern void TupleDescInitEntryCollation(TupleDesc desc,
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AttrNumber attributeNumber,
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Oid collationid);
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extern TupleDesc BuildDescForRelation(List *schema);
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extern TupleDesc BuildDescFromLists(List *names, List *types, List *typmods, List *collations);
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#endif /* TUPDESC_H */
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