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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
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_shdepend.h
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* definition of the "shared dependency" system catalog (pg_shdepend)
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*
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* pg_shdepend has no preloaded contents, so there is no pg_shdepend.dat
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* file; system-defined dependencies are loaded into it during a late stage
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* of the initdb process.
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*
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* NOTE: we do not represent all possible dependency pairs in pg_shdepend;
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* for example, there's not much value in creating an explicit dependency
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* from a relation to its database. Currently, only dependencies on roles
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* are explicitly stored in pg_shdepend.
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*
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* Portions Copyright (c) 1996-2021, 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/catalog/pg_shdepend.h
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*
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* NOTES
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* The Catalog.pm module reads this file and derives schema
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* information.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_SHDEPEND_H
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#define PG_SHDEPEND_H
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#include "catalog/genbki.h"
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#include "catalog/pg_shdepend_d.h"
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/* ----------------
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* pg_shdepend definition. cpp turns this into
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* typedef struct FormData_pg_shdepend
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* ----------------
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*/
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CATALOG(pg_shdepend,1214,SharedDependRelationId) BKI_SHARED_RELATION
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{
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/*
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* Identification of the dependent (referencing) object.
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*
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* These fields are all zeroes for a DEPENDENCY_PIN entry. Also, dbid can
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* be zero to denote a shared object.
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*/
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Oid dbid BKI_LOOKUP_OPT(pg_database); /* OID of database
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* containing object */
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Oid classid BKI_LOOKUP_OPT(pg_class); /* OID of table containing
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* object */
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Oid objid; /* OID of object itself */
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int32 objsubid; /* column number, or 0 if not used */
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/*
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* Identification of the independent (referenced) object. This is always
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* a shared object, so we need no database ID field. We don't bother with
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* a sub-object ID either.
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*/
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Oid refclassid BKI_LOOKUP(pg_class); /* OID of table containing
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* object */
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Oid refobjid; /* OID of object itself */
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/*
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* Precise semantics of the relationship are specified by the deptype
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* field. See SharedDependencyType in catalog/dependency.h.
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*/
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char deptype; /* see codes in dependency.h */
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} FormData_pg_shdepend;
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/* ----------------
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* Form_pg_shdepend corresponds to a pointer to a row with
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* the format of pg_shdepend relation.
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* ----------------
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*/
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typedef FormData_pg_shdepend *Form_pg_shdepend;
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DECLARE_INDEX(pg_shdepend_depender_index, 1232, on pg_shdepend using btree(dbid oid_ops, classid oid_ops, objid oid_ops, objsubid int4_ops));
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#define SharedDependDependerIndexId 1232
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DECLARE_INDEX(pg_shdepend_reference_index, 1233, on pg_shdepend using btree(refclassid oid_ops, refobjid oid_ops));
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#define SharedDependReferenceIndexId 1233
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#endif /* PG_SHDEPEND_H */
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