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04011cc970
postgresql/src/include/miscadmin.h
Tom Lane 04011cc970 Allow backends to start up without use of the flat-file copy of pg_database. 
To make this work in the base case, pg_database now has a nailed-in-cache
relation descriptor that is initialized using hardwired knowledge in
relcache.c.  This means pg_database is added to the set of relations that
need to have a Schema_pg_xxx macro maintained in pg_attribute.h.  When this
path is taken, we'll have to do a seqscan of pg_database to find the row
we need.

In the normal case, we are able to do an indexscan to find the database's row
by name.  This is made possible by storing a global relcache init file that
describes only the shared catalogs and their indexes (and therefore is usable
by all backends in any database).  A new backend loads this cache file,
finds its database OID after an indexscan on pg_database, and then loads
the local relcache init file for that database.

This change should effectively eliminate number of databases as a factor
in backend startup time, even with large numbers of databases.  However,
the real reason for doing it is as a first step towards getting rid of
the flat files altogether.  There are still several other sub-projects
to be tackled before that can happen.
2009-08-12 20:53:31 +00:00

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/*-------------------------------------------------------------------------
*
* miscadmin.h
* This file contains general postgres administration and initialization
* stuff that used to be spread out between the following files:
* globals.h global variables
* pdir.h directory path crud
* pinit.h postgres initialization
* pmod.h processing modes
* Over time, this has also become the preferred place for widely known
* resource-limitation stuff, such as work_mem and check_stack_depth().
*
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.212 2009/08/12 20:53:30 tgl Exp $
*
* NOTES
* some of the information in this file should be moved to other files.
*
*-------------------------------------------------------------------------
*/
#ifndef MISCADMIN_H
#define MISCADMIN_H
#include "pgtime.h" /* for pg_time_t */
#define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
/*****************************************************************************
* System interrupt and critical section handling
*
* There are two types of interrupts that a running backend needs to accept
* without messing up its state: QueryCancel (SIGINT) and ProcDie (SIGTERM).
* In both cases, we need to be able to clean up the current transaction
* gracefully, so we can't respond to the interrupt instantaneously ---
* there's no guarantee that internal data structures would be self-consistent
* if the code is interrupted at an arbitrary instant. Instead, the signal
* handlers set flags that are checked periodically during execution.
*
* The CHECK_FOR_INTERRUPTS() macro is called at strategically located spots
* where it is normally safe to accept a cancel or die interrupt. In some
* cases, we invoke CHECK_FOR_INTERRUPTS() inside low-level subroutines that
* might sometimes be called in contexts that do *not* want to allow a cancel
* or die interrupt. The HOLD_INTERRUPTS() and RESUME_INTERRUPTS() macros
* allow code to ensure that no cancel or die interrupt will be accepted,
* even if CHECK_FOR_INTERRUPTS() gets called in a subroutine. The interrupt
* will be held off until CHECK_FOR_INTERRUPTS() is done outside any
* HOLD_INTERRUPTS() ... RESUME_INTERRUPTS() section.
*
* Special mechanisms are used to let an interrupt be accepted when we are
* waiting for a lock or when we are waiting for command input (but, of
* course, only if the interrupt holdoff counter is zero). See the
* related code for details.
*
* A related, but conceptually distinct, mechanism is the "critical section"
* mechanism. A critical section not only holds off cancel/die interrupts,
* but causes any ereport(ERROR) or ereport(FATAL) to become ereport(PANIC)
* --- that is, a system-wide reset is forced. Needless to say, only really
* *critical* code should be marked as a critical section! Currently, this
* mechanism is only used for XLOG-related code.
*
*****************************************************************************/
/* in globals.c */
/* these are marked volatile because they are set by signal handlers: */
extern PGDLLIMPORT volatile bool InterruptPending;
extern volatile bool QueryCancelPending;
extern volatile bool ProcDiePending;
/* these are marked volatile because they are examined by signal handlers: */
extern volatile bool ImmediateInterruptOK;
extern PGDLLIMPORT volatile uint32 InterruptHoldoffCount;
extern PGDLLIMPORT volatile uint32 CritSectionCount;
/* in tcop/postgres.c */
extern void ProcessInterrupts(void);
#ifndef WIN32
#define CHECK_FOR_INTERRUPTS() \
do { \
if (InterruptPending) \
ProcessInterrupts(); \
} while(0)
#else /* WIN32 */
#define CHECK_FOR_INTERRUPTS() \
do { \
if (UNBLOCKED_SIGNAL_QUEUE()) \
pgwin32_dispatch_queued_signals(); \
if (InterruptPending) \
ProcessInterrupts(); \
} while(0)
#endif /* WIN32 */
#define HOLD_INTERRUPTS() (InterruptHoldoffCount++)
#define RESUME_INTERRUPTS() \
do { \
Assert(InterruptHoldoffCount > 0); \
InterruptHoldoffCount--; \
} while(0)
#define START_CRIT_SECTION() (CritSectionCount++)
#define END_CRIT_SECTION() \
do { \
Assert(CritSectionCount > 0); \
CritSectionCount--; \
} while(0)
/*****************************************************************************
* globals.h -- *
*****************************************************************************/
/*
* from utils/init/globals.c
*/
extern pid_t PostmasterPid;
extern bool IsPostmasterEnvironment;
extern PGDLLIMPORT bool IsUnderPostmaster;
extern bool ExitOnAnyError;
extern PGDLLIMPORT char *DataDir;
extern PGDLLIMPORT int NBuffers;
extern int MaxBackends;
extern int MaxConnections;
extern PGDLLIMPORT int MyProcPid;
extern PGDLLIMPORT pg_time_t MyStartTime;
extern PGDLLIMPORT struct Port *MyProcPort;
extern long MyCancelKey;
extern int MyPMChildSlot;
extern char OutputFileName[];
extern PGDLLIMPORT char my_exec_path[];
extern char pkglib_path[];
#ifdef EXEC_BACKEND
extern char postgres_exec_path[];
#endif
/*
* done in storage/backendid.h for now.
*
* extern BackendId MyBackendId;
*/
extern PGDLLIMPORT Oid MyDatabaseId;
extern PGDLLIMPORT Oid MyDatabaseTableSpace;
/*
* Date/Time Configuration
*
* DateStyle defines the output formatting choice for date/time types:
* USE_POSTGRES_DATES specifies traditional Postgres format
* USE_ISO_DATES specifies ISO-compliant format
* USE_SQL_DATES specifies Oracle/Ingres-compliant format
* USE_GERMAN_DATES specifies German-style dd.mm/yyyy
*
* DateOrder defines the field order to be assumed when reading an
* ambiguous date (anything not in YYYY-MM-DD format, with a four-digit
* year field first, is taken to be ambiguous):
* DATEORDER_YMD specifies field order yy-mm-dd
* DATEORDER_DMY specifies field order dd-mm-yy ("European" convention)
* DATEORDER_MDY specifies field order mm-dd-yy ("US" convention)
*
* In the Postgres and SQL DateStyles, DateOrder also selects output field
* order: day comes before month in DMY style, else month comes before day.
*
* The user-visible "DateStyle" run-time parameter subsumes both of these.
*/
/* valid DateStyle values */
#define USE_POSTGRES_DATES 0
#define USE_ISO_DATES 1
#define USE_SQL_DATES 2
#define USE_GERMAN_DATES 3
#define USE_XSD_DATES 4
/* valid DateOrder values */
#define DATEORDER_YMD 0
#define DATEORDER_DMY 1
#define DATEORDER_MDY 2
extern int DateStyle;
extern int DateOrder;
/*
* IntervalStyles
* INTSTYLE_POSTGRES Like Postgres < 8.4 when DateStyle = 'iso'
* INTSTYLE_POSTGRES_VERBOSE Like Postgres < 8.4 when DateStyle != 'iso'
* INTSTYLE_SQL_STANDARD SQL standard interval literals
* INTSTYLE_ISO_8601 ISO-8601-basic formatted intervals
*/
#define INTSTYLE_POSTGRES 0
#define INTSTYLE_POSTGRES_VERBOSE 1
#define INTSTYLE_SQL_STANDARD 2
#define INTSTYLE_ISO_8601 3
extern int IntervalStyle;
/*
* HasCTZSet is true if user has set timezone as a numeric offset from UTC.
* If so, CTimeZone is the timezone offset in seconds (using the Unix-ish
* sign convention, ie, positive offset is west of UTC, rather than the
* SQL-ish convention that positive is east of UTC).
*/
extern bool HasCTZSet;
extern int CTimeZone;
#define MAXTZLEN 10 /* max TZ name len, not counting tr. null */
extern bool enableFsync;
extern bool allowSystemTableMods;
extern PGDLLIMPORT int work_mem;
extern PGDLLIMPORT int maintenance_work_mem;
extern int VacuumCostPageHit;
extern int VacuumCostPageMiss;
extern int VacuumCostPageDirty;
extern int VacuumCostLimit;
extern int VacuumCostDelay;
extern int VacuumCostBalance;
extern bool VacuumCostActive;
/* in tcop/postgres.c */
extern void check_stack_depth(void);
/*****************************************************************************
* pdir.h -- *
* POSTGRES directory path definitions. *
*****************************************************************************/
extern char *DatabasePath;
/* now in utils/init/miscinit.c */
extern void SetDatabasePath(const char *path);
extern char *GetUserNameFromId(Oid roleid);
extern Oid GetUserId(void);
extern Oid GetOuterUserId(void);
extern Oid GetSessionUserId(void);
extern void GetUserIdAndContext(Oid *userid, bool *sec_def_context);
extern void SetUserIdAndContext(Oid userid, bool sec_def_context);
extern bool InSecurityDefinerContext(void);
extern void InitializeSessionUserId(const char *rolename);
extern void InitializeSessionUserIdStandalone(void);
extern void SetSessionAuthorization(Oid userid, bool is_superuser);
extern Oid GetCurrentRoleId(void);
extern void SetCurrentRoleId(Oid roleid, bool is_superuser);
extern void SetDataDir(const char *dir);
extern void ChangeToDataDir(void);
extern char *make_absolute_path(const char *path);
/* in utils/misc/superuser.c */
extern bool superuser(void); /* current user is superuser */
extern bool superuser_arg(Oid roleid); /* given user is superuser */
/*****************************************************************************
* pmod.h -- *
* POSTGRES processing mode definitions. *
*****************************************************************************/
/*
* Description:
* There are three processing modes in POSTGRES. They are
* BootstrapProcessing or "bootstrap," InitProcessing or
* "initialization," and NormalProcessing or "normal."
*
* The first two processing modes are used during special times. When the
* system state indicates bootstrap processing, transactions are all given
* transaction id "one" and are consequently guaranteed to commit. This mode
* is used during the initial generation of template databases.
*
* Initialization mode: used while starting a backend, until all normal
* initialization is complete. Some code behaves differently when executed
* in this mode to enable system bootstrapping.
*
* If a POSTGRES binary is in normal mode, then all code may be executed
* normally.
*/
typedef enum ProcessingMode
{
BootstrapProcessing, /* bootstrap creation of template database */
InitProcessing, /* initializing system */
NormalProcessing /* normal processing */
} ProcessingMode;
extern ProcessingMode Mode;
#define IsBootstrapProcessingMode() ((bool)(Mode == BootstrapProcessing))
#define IsInitProcessingMode() ((bool)(Mode == InitProcessing))
#define IsNormalProcessingMode() ((bool)(Mode == NormalProcessing))
#define SetProcessingMode(mode) \
do { \
AssertArg((mode) == BootstrapProcessing || \
(mode) == InitProcessing || \
(mode) == NormalProcessing); \
Mode = (mode); \
} while(0)
#define GetProcessingMode() Mode
/*****************************************************************************
* pinit.h -- *
* POSTGRES initialization and cleanup definitions. *
*****************************************************************************/
/* in utils/init/postinit.c */
extern bool InitPostgres(const char *in_dbname, Oid dboid, const char *username,
char *out_dbname);
extern void BaseInit(void);
/* in utils/init/miscinit.c */
extern bool IgnoreSystemIndexes;
extern PGDLLIMPORT bool process_shared_preload_libraries_in_progress;
extern char *shared_preload_libraries_string;
extern char *local_preload_libraries_string;
extern void SetReindexProcessing(Oid heapOid, Oid indexOid);
extern void ResetReindexProcessing(void);
extern bool ReindexIsProcessingHeap(Oid heapOid);
extern bool ReindexIsProcessingIndex(Oid indexOid);
extern void CreateDataDirLockFile(bool amPostmaster);
extern void CreateSocketLockFile(const char *socketfile, bool amPostmaster);
extern void TouchSocketLockFile(void);
extern void RecordSharedMemoryInLockFile(unsigned long id1,
unsigned long id2);
extern void ValidatePgVersion(const char *path);
extern void process_shared_preload_libraries(void);
extern void process_local_preload_libraries(void);
extern void pg_bindtextdomain(const char *domain);
/* in access/transam/xlog.c */
extern bool BackupInProgress(void);
extern void CancelBackup(void);
#endif /* MISCADMIN_H */
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