pg_constraint.h

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/*-------------------------------------------------------------------------
 *
 * pg_constraint.h
 *    definition of the "constraint" system catalog (pg_constraint)
 *
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/catalog/pg_constraint.h
 *
 * NOTES
 *    The Catalog.pm module reads this file and derives schema
 *    information.
 *
 *-------------------------------------------------------------------------
 */
#ifndef PG_CONSTRAINT_H
#define PG_CONSTRAINT_H

#include "catalog/dependency.h"
#include "catalog/genbki.h"
#include "catalog/pg_constraint_d.h"
#include "nodes/pg_list.h"

/* ----------------
 *      pg_constraint definition.  cpp turns this into
 *      typedef struct FormData_pg_constraint
 * ----------------
 */
CATALOG(pg_constraint,2606,ConstraintRelationId)
{
    Oid         oid;            /* oid */

    /*
     * conname + connamespace is deliberately not unique; we allow, for
     * example, the same name to be used for constraints of different
     * relations.  This is partly for backwards compatibility with past
     * Postgres practice, and partly because we don't want to have to obtain a
     * global lock to generate a globally unique name for a nameless
     * constraint.  We associate a namespace with constraint names only for
     * SQL-spec compatibility.
     *
     * However, we do require conname to be unique among the constraints of a
     * single relation or domain.  This is enforced by a unique index on
     * conrelid + contypid + conname.
     */
    NameData    conname;        /* name of this constraint */
    Oid         connamespace BKI_LOOKUP(pg_namespace);  /* OID of namespace
                                                         * containing constraint */
    char        contype;        /* constraint type; see codes below */
    bool        condeferrable;  /* deferrable constraint? */
    bool        condeferred;    /* deferred by default? */
    bool        convalidated;   /* constraint has been validated? */

    /*
     * conrelid and conkey are only meaningful if the constraint applies to a
     * specific relation (this excludes domain constraints and assertions).
     * Otherwise conrelid is 0 and conkey is NULL.
     */
    Oid         conrelid BKI_LOOKUP_OPT(pg_class);  /* relation this
                                                     * constraint constrains */

    /*
     * contypid links to the pg_type row for a domain if this is a domain
     * constraint.  Otherwise it's 0.
     *
     * For SQL-style global ASSERTIONs, both conrelid and contypid would be
     * zero. This is not presently supported, however.
     */
    Oid         contypid BKI_LOOKUP_OPT(pg_type);   /* domain this constraint
                                                     * constrains */

    /*
     * conindid links to the index supporting the constraint, if any;
     * otherwise it's 0.  This is used for unique, primary-key, and exclusion
     * constraints, and less obviously for foreign-key constraints (where the
     * index is a unique index on the referenced relation's referenced
     * columns).  Notice that the index is on conrelid in the first case but
     * confrelid in the second.
     */
    Oid         conindid BKI_LOOKUP_OPT(pg_class);  /* index supporting this
                                                     * constraint */

    /*
     * If this constraint is on a partition inherited from a partitioned
     * table, this is the OID of the corresponding constraint in the parent.
     */
    Oid         conparentid BKI_LOOKUP_OPT(pg_constraint);

    /*
     * These fields, plus confkey, are only meaningful for a foreign-key
     * constraint.  Otherwise confrelid is 0 and the char fields are spaces.
     */
    Oid         confrelid BKI_LOOKUP_OPT(pg_class); /* relation referenced by
                                                     * foreign key */
    char        confupdtype;    /* foreign key's ON UPDATE action */
    char        confdeltype;    /* foreign key's ON DELETE action */
    char        confmatchtype;  /* foreign key's match type */

    /* Has a local definition (hence, do not drop when coninhcount is 0) */
    bool        conislocal;

    /* Number of times inherited from direct parent relation(s) */
    int32       coninhcount;

    /* Has a local definition and cannot be inherited */
    bool        connoinherit;

#ifdef CATALOG_VARLEN           /* variable-length fields start here */

    /*
     * Columns of conrelid that the constraint applies to, if known (this is
     * NULL for trigger constraints)
     */
    int16       conkey[1];

    /*
     * If a foreign key, the referenced columns of confrelid
     */
    int16       confkey[1];

    /*
     * If a foreign key, the OIDs of the PK = FK equality operators for each
     * column of the constraint
     */
    Oid         conpfeqop[1] BKI_LOOKUP(pg_operator);

    /*
     * If a foreign key, the OIDs of the PK = PK equality operators for each
     * column of the constraint (i.e., equality for the referenced columns)
     */
    Oid         conppeqop[1] BKI_LOOKUP(pg_operator);

    /*
     * If a foreign key, the OIDs of the FK = FK equality operators for each
     * column of the constraint (i.e., equality for the referencing columns)
     */
    Oid         conffeqop[1] BKI_LOOKUP(pg_operator);

    /*
     * If an exclusion constraint, the OIDs of the exclusion operators for
     * each column of the constraint
     */
    Oid         conexclop[1] BKI_LOOKUP(pg_operator);

    /*
     * If a check constraint, nodeToString representation of expression
     */
    pg_node_tree conbin;
#endif
} FormData_pg_constraint;

/* ----------------
 *      Form_pg_constraint corresponds to a pointer to a tuple with
 *      the format of pg_constraint relation.
 * ----------------
 */
typedef FormData_pg_constraint *Form_pg_constraint;

DECLARE_TOAST(pg_constraint, 2832, 2833);

DECLARE_INDEX(pg_constraint_conname_nsp_index, 2664, ConstraintNameNspIndexId, on pg_constraint using btree(conname name_ops, connamespace oid_ops));
DECLARE_UNIQUE_INDEX(pg_constraint_conrelid_contypid_conname_index, 2665, ConstraintRelidTypidNameIndexId, on pg_constraint using btree(conrelid oid_ops, contypid oid_ops, conname name_ops));
DECLARE_INDEX(pg_constraint_contypid_index, 2666, ConstraintTypidIndexId, on pg_constraint using btree(contypid oid_ops));
DECLARE_UNIQUE_INDEX_PKEY(pg_constraint_oid_index, 2667, ConstraintOidIndexId, on pg_constraint using btree(oid oid_ops));
DECLARE_INDEX(pg_constraint_conparentid_index, 2579, ConstraintParentIndexId, on pg_constraint using btree(conparentid oid_ops));

/* conkey can contain zero (InvalidAttrNumber) if a whole-row Var is used */
DECLARE_ARRAY_FOREIGN_KEY_OPT((conrelid, conkey), pg_attribute, (attrelid, attnum));
DECLARE_ARRAY_FOREIGN_KEY((confrelid, confkey), pg_attribute, (attrelid, attnum));

#ifdef EXPOSE_TO_CLIENT_CODE

/* Valid values for contype */
#define CONSTRAINT_CHECK            'c'
#define CONSTRAINT_FOREIGN          'f'
#define CONSTRAINT_PRIMARY          'p'
#define CONSTRAINT_UNIQUE           'u'
#define CONSTRAINT_TRIGGER          't'
#define CONSTRAINT_EXCLUSION        'x'

/*
 * Valid values for confupdtype and confdeltype are the FKCONSTR_ACTION_xxx
 * constants defined in parsenodes.h.  Valid values for confmatchtype are
 * the FKCONSTR_MATCH_xxx constants defined in parsenodes.h.
 */

#endif                          /* EXPOSE_TO_CLIENT_CODE */

/*
 * Identify constraint type for lookup purposes
 */
typedef enum ConstraintCategory
{
    CONSTRAINT_RELATION,
    CONSTRAINT_DOMAIN,
    CONSTRAINT_ASSERTION        /* for future expansion */
} ConstraintCategory;


extern Oid  CreateConstraintEntry(const char *constraintName,
                                  Oid constraintNamespace,
                                  char constraintType,
                                  bool isDeferrable,
                                  bool isDeferred,
                                  bool isValidated,
                                  Oid parentConstrId,
                                  Oid relId,
                                  const int16 *constraintKey,
                                  int constraintNKeys,
                                  int constraintNTotalKeys,
                                  Oid domainId,
                                  Oid indexRelId,
                                  Oid foreignRelId,
                                  const int16 *foreignKey,
                                  const Oid *pfEqOp,
                                  const Oid *ppEqOp,
                                  const Oid *ffEqOp,
                                  int foreignNKeys,
                                  char foreignUpdateType,
                                  char foreignDeleteType,
                                  char foreignMatchType,
                                  const Oid *exclOp,
                                  Node *conExpr,
                                  const char *conBin,
                                  bool conIsLocal,
                                  int conInhCount,
                                  bool conNoInherit,
                                  bool is_internal);

extern void RemoveConstraintById(Oid conId);
extern void RenameConstraintById(Oid conId, const char *newname);

extern bool ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,
                                 const char *conname);
extern bool ConstraintNameExists(const char *conname, Oid namespaceid);
extern char *ChooseConstraintName(const char *name1, const char *name2,
                                  const char *label, Oid namespaceid,
                                  List *others);

extern void AlterConstraintNamespaces(Oid ownerId, Oid oldNspId,
                                      Oid newNspId, bool isType, ObjectAddresses *objsMoved);
extern void ConstraintSetParentConstraint(Oid childConstrId,
                                          Oid parentConstrId,
                                          Oid childTableId);
extern Oid  get_relation_constraint_oid(Oid relid, const char *conname, bool missing_ok);
extern Bitmapset *get_relation_constraint_attnos(Oid relid, const char *conname,
                                                 bool missing_ok, Oid *constraintOid);
extern Oid  get_domain_constraint_oid(Oid typid, const char *conname, bool missing_ok);
extern Oid  get_relation_idx_constraint_oid(Oid relationId, Oid indexId);

extern Bitmapset *get_primary_key_attnos(Oid relid, bool deferrableOk,
                                         Oid *constraintOid);
extern void DeconstructFkConstraintRow(HeapTuple tuple, int *numfks,
                                       AttrNumber *conkey, AttrNumber *confkey,
                                       Oid *pf_eq_oprs, Oid *pp_eq_oprs, Oid *ff_eq_oprs);

extern bool check_functional_grouping(Oid relid,
                                      Index varno, Index varlevelsup,
                                      List *grouping_columns,
                                      List **constraintDeps);

#endif                          /* PG_CONSTRAINT_H */