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ecae097252
Because we assume that int64 and double have the same alignment requirement, AIX's default behavior that alignof(double) = 4 while alignof(int64) = 8 is a headache. There are two issues: 1. We align both int8 and float8 tuple columns per ALIGNOF_DOUBLE, which is an ancient choice that can't be undone without breaking pg_upgrade and creating some subtle SQL-level compatibility issues too. However, the cost of that is just some marginal inefficiency in fetching int8 values, which can't be too awful if the platform architects were willing to pay the same costs for fetching float8s. So our decision is to leave that alone. This patch makes our alignment choices the same as they were pre-v17, namely that ALIGNOF_DOUBLE and ALIGNOF_INT64_T are whatever the compiler prefers and then MAXIMUM_ALIGNOF is the larger of the two. (On all supported platforms other than AIX, all three values will be the same.) 2. We need to overlay C structs onto catalog tuples, and int8 fields in those struct declarations may not be aligned to match this rule. In the old branches we had some annoying rules about ordering catalog columns to avoid alignment problems, but nobody wants to resurrect those. However, there's a better answer: make the compiler construe those struct declarations the way we need it to by using the pack(N) pragma. This requires no manual effort to maintain going forward; we only have to insert the pragma into all the catalog *.h files. (As the catalogs stand at this writing, nothing actually changes because we've not moved any affected columns since v16; hence no catversion bump is required. The point of this is to not have to worry about the issue going forward.) We did not have this option when the AIX port was first made. This patch depends on the C99 feature _Pragma(), as well as the pack(N) pragma which dates to somewhere around gcc 4.0, and probably doesn't exist in xlc at all. But now that we've agreed to toss xlc support out the window, there doesn't seem to be a reason not to go this way. In passing, I got rid of LONGALIGN[_DOWN] along with the configure probes for ALIGNOF_LONG. We were not using those anywhere and it seems highly unlikely that we'd do so in future. Instead supply INT64ALIGN[_DOWN], which isn't used either but at least could have a good reason to be used. Discussion: https://postgr.es/m/1127261.1769649624@sss.pgh.pa.us
134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_database.h
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* definition of the "database" system catalog (pg_database)
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*
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*
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* Portions Copyright (c) 1996-2026, 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_database.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_DATABASE_H
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#define PG_DATABASE_H
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#include "catalog/genbki.h"
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#include "catalog/pg_database_d.h" /* IWYU pragma: export */
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/* ----------------
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* pg_database definition. cpp turns this into
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* typedef struct FormData_pg_database
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* ----------------
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*/
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BEGIN_CATALOG_STRUCT
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CATALOG(pg_database,1262,DatabaseRelationId) BKI_SHARED_RELATION BKI_ROWTYPE_OID(1248,DatabaseRelation_Rowtype_Id) BKI_SCHEMA_MACRO
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{
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/* oid */
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Oid oid;
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/* database name */
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NameData datname;
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/* owner of database */
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Oid datdba BKI_DEFAULT(POSTGRES) BKI_LOOKUP(pg_authid);
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/* character encoding */
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int32 encoding;
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/* locale provider, see pg_collation.collprovider */
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char datlocprovider;
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/* allowed as CREATE DATABASE template? */
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bool datistemplate;
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/* new connections allowed? */
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bool datallowconn;
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/* database has login event triggers? */
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bool dathasloginevt;
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/*
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* Max connections allowed. Negative values have special meaning, see
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* DATCONNLIMIT_* defines below.
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*/
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int32 datconnlimit;
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/* all Xids < this are frozen in this DB */
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TransactionId datfrozenxid;
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/* all multixacts in the DB are >= this */
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TransactionId datminmxid;
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/* default table space for this DB */
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Oid dattablespace BKI_LOOKUP(pg_tablespace);
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#ifdef CATALOG_VARLEN /* variable-length fields start here */
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/* LC_COLLATE setting */
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text datcollate BKI_FORCE_NOT_NULL;
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/* LC_CTYPE setting */
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text datctype BKI_FORCE_NOT_NULL;
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/* ICU locale ID */
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text datlocale;
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/* ICU collation rules */
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text daticurules;
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/* provider-dependent version of collation data */
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text datcollversion BKI_DEFAULT(_null_);
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/* access permissions */
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aclitem datacl[1];
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#endif
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} FormData_pg_database;
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END_CATALOG_STRUCT
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/* ----------------
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* Form_pg_database corresponds to a pointer to a tuple with
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* the format of pg_database relation.
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* ----------------
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*/
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typedef FormData_pg_database *Form_pg_database;
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DECLARE_TOAST_WITH_MACRO(pg_database, 4177, 4178, PgDatabaseToastTable, PgDatabaseToastIndex);
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DECLARE_UNIQUE_INDEX(pg_database_datname_index, 2671, DatabaseNameIndexId, pg_database, btree(datname name_ops));
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DECLARE_UNIQUE_INDEX_PKEY(pg_database_oid_index, 2672, DatabaseOidIndexId, pg_database, btree(oid oid_ops));
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MAKE_SYSCACHE(DATABASEOID, pg_database_oid_index, 4);
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/*
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* pg_database.dat contains an entry for template1, but not for the template0
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* or postgres databases, because those are created later in initdb.
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* However, we still want to manually assign the OIDs for template0 and
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* postgres, so declare those here.
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*/
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DECLARE_OID_DEFINING_MACRO(Template0DbOid, 4);
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DECLARE_OID_DEFINING_MACRO(PostgresDbOid, 5);
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/*
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* Special values for pg_database.datconnlimit. Normal values are >= 0.
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*/
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#define DATCONNLIMIT_UNLIMITED -1 /* no limit */
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/*
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* A database is set to invalid partway through being dropped. Using
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* datconnlimit=-2 for this purpose isn't particularly clean, but is
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* backpatchable.
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*/
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#define DATCONNLIMIT_INVALID_DB -2
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extern Oid get_database_oid(const char *dbname, bool missing_ok);
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extern bool database_is_invalid_form(Form_pg_database datform);
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extern bool database_is_invalid_oid(Oid dboid);
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#endif /* PG_DATABASE_H */
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