mirror of
https://github.com/postgres/postgres.git
synced 2026-03-20 17:44:08 -04:00
62f34097c8
This follows in the spirit of commit dfb75e478, which created primary
key and uniqueness constraints to improve the visibility of constraints
imposed on the system catalogs. While our catalogs contain many
foreign-key-like relationships, they don't quite follow SQL semantics,
in that the convention for an omitted reference is to write zero not
NULL. Plus, we have some cases in which there are arrays each of whose
elements is supposed to be an FK reference; SQL has no way to model that.
So we can't create actual foreign key constraints to describe the
situation. Nonetheless, we can collect and use knowledge about these
relationships.
This patch therefore adds annotations to the catalog header files to
declare foreign-key relationships. (The BKI_LOOKUP annotations cover
simple cases, but we weren't previously distinguishing which such
columns are allowed to contain zeroes; we also need new markings for
multi-column FK references.) Then, Catalog.pm and genbki.pl are
taught to collect this information into a table in a new generated
header "system_fk_info.h". The only user of that at the moment is
a new SQL function pg_get_catalog_foreign_keys(), which exposes the
table to SQL. The oidjoins regression test is rewritten to use
pg_get_catalog_foreign_keys() to find out which columns to check.
Aside from removing the need for manual maintenance of that test
script, this allows it to cover numerous relationships that were not
checked by the old implementation based on findoidjoins. (As of this
commit, 217 relationships are checked by the test, versus 181 before.)
Discussion: https://postgr.es/m/3240355.1612129197@sss.pgh.pa.us
68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* pg_shdescription.h
|
|
* definition of the "shared description" system catalog
|
|
* (pg_shdescription)
|
|
*
|
|
* Because the contents of this table are taken from the *.dat files
|
|
* of other catalogs, there is no pg_shdescription.dat file. The initial
|
|
* contents are assembled by genbki.pl and loaded during initdb.
|
|
*
|
|
* NOTE: an object is identified by the OID of the row that primarily
|
|
* defines the object, plus the OID of the table that that row appears in.
|
|
* For example, a database is identified by the OID of its pg_database row
|
|
* plus the pg_class OID of table pg_database. This allows unique
|
|
* identification of objects without assuming that OIDs are unique
|
|
* across tables.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/catalog/pg_shdescription.h
|
|
*
|
|
* NOTES
|
|
* The Catalog.pm module reads this file and derives schema
|
|
* information.
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef PG_SHDESCRIPTION_H
|
|
#define PG_SHDESCRIPTION_H
|
|
|
|
#include "catalog/genbki.h"
|
|
#include "catalog/pg_shdescription_d.h"
|
|
|
|
/* ----------------
|
|
* pg_shdescription definition. cpp turns this into
|
|
* typedef struct FormData_pg_shdescription
|
|
* ----------------
|
|
*/
|
|
CATALOG(pg_shdescription,2396,SharedDescriptionRelationId) BKI_SHARED_RELATION
|
|
{
|
|
Oid objoid; /* OID of object itself */
|
|
Oid classoid; /* OID of table containing object */
|
|
|
|
#ifdef CATALOG_VARLEN /* variable-length fields start here */
|
|
text description BKI_FORCE_NOT_NULL; /* description of object */
|
|
#endif
|
|
} FormData_pg_shdescription;
|
|
|
|
/* ----------------
|
|
* Form_pg_shdescription corresponds to a pointer to a tuple with
|
|
* the format of pg_shdescription relation.
|
|
* ----------------
|
|
*/
|
|
typedef FormData_pg_shdescription * Form_pg_shdescription;
|
|
|
|
DECLARE_TOAST(pg_shdescription, 2846, 2847);
|
|
#define PgShdescriptionToastTable 2846
|
|
#define PgShdescriptionToastIndex 2847
|
|
|
|
DECLARE_UNIQUE_INDEX_PKEY(pg_shdescription_o_c_index, 2397, on pg_shdescription using btree(objoid oid_ops, classoid oid_ops));
|
|
#define SharedDescriptionObjIndexId 2397
|
|
|
|
/* We do not use BKI_LOOKUP here because it causes problems for genbki.pl */
|
|
DECLARE_FOREIGN_KEY((classoid), pg_class, (oid));
|
|
|
|
#endif /* PG_SHDESCRIPTION_H */
|