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/*------------------------------------------------------------------------- * * tupdesc.h * POSTGRES tuple descriptor definitions. * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/access/tupdesc.h * *------------------------------------------------------------------------- */ #ifndef TUPDESC_H #define TUPDESC_H #include "access/attnum.h" #include "catalog/pg_attribute.h" #include "nodes/pg_list.h" typedef struct attrDefault { AttrNumber adnum; char *adbin; /* nodeToString representation of expr */ } AttrDefault; typedef struct constrCheck { char *ccname; char *ccbin; /* nodeToString representation of expr */ bool ccvalid; bool ccnoinherit; /* this is a non-inheritable constraint */ } ConstrCheck; /* This structure contains constraints of a tuple */ typedef struct tupleConstr { AttrDefault *defval; /* array */ ConstrCheck *check; /* array */ uint16 num_defval; uint16 num_check; bool has_not_null; } TupleConstr; /* * This struct is passed around within the backend to describe the structure * of tuples. For tuples coming from on-disk relations, the information is * collected from the pg_attribute, pg_attrdef, and pg_constraint catalogs. * Transient row types (such as the result of a join query) have anonymous * TupleDesc structs that generally omit any constraint info; therefore the * structure is designed to let the constraints be omitted efficiently. * * Note that only user attributes, not system attributes, are mentioned in * TupleDesc; with the exception that tdhasoid indicates if OID is present. * * If the tupdesc is known to correspond to a named rowtype (such as a table's * rowtype) then tdtypeid identifies that type and tdtypmod is -1. Otherwise * tdtypeid is RECORDOID, and tdtypmod can be either -1 for a fully anonymous * row type, or a value >= 0 to allow the rowtype to be looked up in the * typcache.c type cache. * * Tuple descriptors that live in caches (relcache or typcache, at present) * are reference-counted: they can be deleted when their reference count goes * to zero. Tuple descriptors created by the executor need no reference * counting, however: they are simply created in the appropriate memory * context and go away when the context is freed. We set the tdrefcount * field of such a descriptor to -1, while reference-counted descriptors * always have tdrefcount >= 0. */ typedef struct tupleDesc { int natts; /* number of attributes in the tuple */ Form_pg_attribute *attrs; /* attrs[N] is a pointer to the description of Attribute Number N+1 */ TupleConstr *constr; /* constraints, or NULL if none */ Oid tdtypeid; /* composite type ID for tuple type */ int32 tdtypmod; /* typmod for tuple type */ bool tdhasoid; /* tuple has oid attribute in its header */ int tdrefcount; /* reference count, or -1 if not counting */ } *TupleDesc; /* Accessor for the i'th attribute of tupdesc. */ #define TupleDescAttr(tupdesc, i) ((tupdesc)->attrs[(i)]) extern TupleDesc CreateTemplateTupleDesc(int natts, bool hasoid); extern TupleDesc CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs); extern TupleDesc CreateTupleDescCopy(TupleDesc tupdesc); extern TupleDesc CreateTupleDescCopyConstr(TupleDesc tupdesc); extern void FreeTupleDesc(TupleDesc tupdesc); extern void IncrTupleDescRefCount(TupleDesc tupdesc); extern void DecrTupleDescRefCount(TupleDesc tupdesc); #define PinTupleDesc(tupdesc) \ do { \ if ((tupdesc)->tdrefcount >= 0) \ IncrTupleDescRefCount(tupdesc); \ } while (0) #define ReleaseTupleDesc(tupdesc) \ do { \ if ((tupdesc)->tdrefcount >= 0) \ DecrTupleDescRefCount(tupdesc); \ } while (0) extern bool equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2); extern void TupleDescInitEntry(TupleDesc desc, AttrNumber attributeNumber, const char *attributeName, Oid oidtypeid, int32 typmod, int attdim); extern void TupleDescInitEntryCollation(TupleDesc desc, AttrNumber attributeNumber, Oid collationid); extern TupleDesc BuildDescForRelation(List *schema); extern TupleDesc BuildDescFromLists(List *names, List *types, List *typmods, List *collations); #endif /* TUPDESC_H */