relcache.c

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/*-------------------------------------------------------------------------
 *
 * relcache.c
 *	  POSTGRES relation descriptor cache code
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.190 2003/09/25 06:58:05 petere Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 * INTERFACE ROUTINES
 *		RelationCacheInitialize			- initialize relcache
 *		RelationCacheInitializePhase2	- finish initializing relcache
 *		RelationIdGetRelation			- get a reldesc by relation id
 *		RelationSysNameGetRelation		- get a reldesc by system rel name
 *		RelationIdCacheGetRelation		- get a cached reldesc by relid
 *		RelationClose					- close an open relation
 *
 * NOTES
 *		The following code contains many undocumented hacks.  Please be
 *		careful....
 */
#include "postgres.h"

#include <errno.h>
#include <sys/file.h>
#include <fcntl.h>
#include <unistd.h>

#include "access/genam.h"
#include "access/heapam.h"
#include "access/istrat.h"
#include "catalog/catalog.h"
#include "catalog/catname.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_amproc.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_attribute.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_index.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_rewrite.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/relcache.h"
#include "utils/syscache.h"


/*
 * name of relcache init file, used to speed up backend startup
 */
#define RELCACHE_INIT_FILENAME	"pg_internal.init"

/*
 *		hardcoded tuple descriptors.  see include/catalog/pg_attribute.h
 */
static FormData_pg_attribute Desc_pg_class[Natts_pg_class] = {Schema_pg_class};
static FormData_pg_attribute Desc_pg_attribute[Natts_pg_attribute] = {Schema_pg_attribute};
static FormData_pg_attribute Desc_pg_proc[Natts_pg_proc] = {Schema_pg_proc};
static FormData_pg_attribute Desc_pg_type[Natts_pg_type] = {Schema_pg_type};

/*
 *		Hash tables that index the relation cache
 *
 *		Relations are looked up two ways, by OID and by name,
 *		thus there are two hash tables for referencing them.
 *
 *		The OID index covers all relcache entries.	The name index
 *		covers *only* system relations (only those in PG_CATALOG_NAMESPACE).
 */
static HTAB *RelationIdCache;
static HTAB *RelationSysNameCache;

/*
 * Bufmgr uses RelFileNode for lookup. Actually, I would like to do
 * not pass Relation to bufmgr & beyond at all and keep some cache
 * in smgr, but no time to do it right way now.		-- vadim 10/22/2000
 */
static HTAB *RelationNodeCache;

/*
 * This flag is false until we have prepared the critical relcache entries
 * that are needed to do indexscans on the tables read by relcache building.
 */
bool		criticalRelcachesBuilt = false;

/*
 * This flag is set if we discover that we need to write a new relcache
 * cache file at the end of startup.
 */
static bool needNewCacheFile = false;

/*
 * This counter counts relcache inval events received since backend startup
 * (but only for rels that are actually in cache).	Presently, we use it only
 * to detect whether data about to be written by write_relcache_init_file()
 * might already be obsolete.
 */
static long relcacheInvalsReceived = 0L;

/*
 * This list remembers the OIDs of the relations cached in the relcache
 * init file.
 */
static List *initFileRelationIds = NIL;

/*
 *		RelationBuildDescInfo exists so code can be shared
 *		between RelationIdGetRelation() and RelationSysNameGetRelation()
 */
typedef struct RelationBuildDescInfo
{
	int			infotype;		/* lookup by id or by name */
#define INFO_RELID 1
#define INFO_RELNAME 2
	union
	{
		Oid			info_id;	/* relation object id */
		char	   *info_name;	/* system relation name */
	}			i;
} RelationBuildDescInfo;

typedef struct relidcacheent
{
	Oid			reloid;
	Relation	reldesc;
} RelIdCacheEnt;

typedef struct relnamecacheent
{
	NameData	relname;
	Relation	reldesc;
} RelNameCacheEnt;

typedef struct relnodecacheent
{
	RelFileNode relnode;
	Relation	reldesc;
} RelNodeCacheEnt;

/*
 *		macros to manipulate the lookup hashtables
 */
#define RelationCacheInsert(RELATION)	\
do { \
	RelIdCacheEnt *idhentry; RelNodeCacheEnt *nodentry; bool found; \
	idhentry = (RelIdCacheEnt*)hash_search(RelationIdCache, \
										   (void *) &(RELATION->rd_id), \
										   HASH_ENTER, \
										   &found); \
	if (idhentry == NULL) \
		ereport(ERROR, \
				(errcode(ERRCODE_OUT_OF_MEMORY), \
				 errmsg("out of memory"))); \
	/* used to give notice if found -- now just keep quiet */ \
	idhentry->reldesc = RELATION; \
	nodentry = (RelNodeCacheEnt*)hash_search(RelationNodeCache, \
										   (void *) &(RELATION->rd_node), \
										   HASH_ENTER, \
										   &found); \
	if (nodentry == NULL) \
		ereport(ERROR, \
				(errcode(ERRCODE_OUT_OF_MEMORY), \
				 errmsg("out of memory"))); \
	/* used to give notice if found -- now just keep quiet */ \
	nodentry->reldesc = RELATION; \
	if (IsSystemNamespace(RelationGetNamespace(RELATION))) \
	{ \
		char *relname = RelationGetRelationName(RELATION); \
		RelNameCacheEnt *namehentry; \
		namehentry = (RelNameCacheEnt*)hash_search(RelationSysNameCache, \
												   relname, \
												   HASH_ENTER, \
												   &found); \
		if (namehentry == NULL) \
			ereport(ERROR, \
					(errcode(ERRCODE_OUT_OF_MEMORY), \
					 errmsg("out of memory"))); \
		/* used to give notice if found -- now just keep quiet */ \
		namehentry->reldesc = RELATION; \
	} \
} while(0)

#define RelationIdCacheLookup(ID, RELATION) \
do { \
	RelIdCacheEnt *hentry; \
	hentry = (RelIdCacheEnt*)hash_search(RelationIdCache, \
										 (void *)&(ID), HASH_FIND,NULL); \
	if (hentry) \
		RELATION = hentry->reldesc; \
	else \
		RELATION = NULL; \
} while(0)

#define RelationSysNameCacheLookup(NAME, RELATION) \
do { \
	RelNameCacheEnt *hentry; \
	hentry = (RelNameCacheEnt*)hash_search(RelationSysNameCache, \
										   (void *) (NAME), HASH_FIND,NULL); \
	if (hentry) \
		RELATION = hentry->reldesc; \
	else \
		RELATION = NULL; \
} while(0)

#define RelationNodeCacheLookup(NODE, RELATION) \
do { \
	RelNodeCacheEnt *hentry; \
	hentry = (RelNodeCacheEnt*)hash_search(RelationNodeCache, \
										   (void *)&(NODE), HASH_FIND,NULL); \
	if (hentry) \
		RELATION = hentry->reldesc; \
	else \
		RELATION = NULL; \
} while(0)

#define RelationCacheDelete(RELATION) \
do { \
	RelIdCacheEnt *idhentry; RelNodeCacheEnt *nodentry; \
	idhentry = (RelIdCacheEnt*)hash_search(RelationIdCache, \
										   (void *)&(RELATION->rd_id), \
										   HASH_REMOVE, NULL); \
	if (idhentry == NULL) \
		elog(WARNING, "trying to delete a rd_id reldesc that does not exist"); \
	nodentry = (RelNodeCacheEnt*)hash_search(RelationNodeCache, \
										   (void *)&(RELATION->rd_node), \
										   HASH_REMOVE, NULL); \
	if (nodentry == NULL) \
		elog(WARNING, "trying to delete a rd_node reldesc that does not exist"); \
	if (IsSystemNamespace(RelationGetNamespace(RELATION))) \
	{ \
		char *relname = RelationGetRelationName(RELATION); \
		RelNameCacheEnt *namehentry; \
		namehentry = (RelNameCacheEnt*)hash_search(RelationSysNameCache, \
												   relname, \
												   HASH_REMOVE, NULL); \
		if (namehentry == NULL) \
			elog(WARNING, "trying to delete a relname reldesc that does not exist"); \
	} \
} while(0)


/*
 * Special cache for opclass-related information
 */
typedef struct opclasscacheent
{
	Oid			opclassoid;		/* lookup key: OID of opclass */
	bool		valid;			/* set TRUE after successful fill-in */
	StrategyNumber numStrats;	/* max # of strategies (from pg_am) */
	StrategyNumber numSupport;	/* max # of support procs (from pg_am) */
	Oid		   *operatorOids;	/* strategy operators' OIDs */
	RegProcedure *operatorProcs;	/* strategy operators' procs */
	RegProcedure *supportProcs; /* support procs */
} OpClassCacheEnt;

static HTAB *OpClassCache = NULL;


/* non-export function prototypes */

static void RelationClearRelation(Relation relation, bool rebuild);

static void RelationReloadClassinfo(Relation relation);
static void RelationFlushRelation(Relation relation);
static Relation RelationSysNameCacheGetRelation(const char *relationName);
static bool load_relcache_init_file(void);
static void write_relcache_init_file(void);

static void formrdesc(const char *relationName, int natts,
		  FormData_pg_attribute *att);

static HeapTuple ScanPgRelation(RelationBuildDescInfo buildinfo, bool indexOK);
static Relation AllocateRelationDesc(Relation relation, Form_pg_class relp);
static void RelationBuildTupleDesc(RelationBuildDescInfo buildinfo,
					   Relation relation);
static Relation RelationBuildDesc(RelationBuildDescInfo buildinfo,
				  Relation oldrelation);
static void AttrDefaultFetch(Relation relation);
static void CheckConstraintFetch(Relation relation);
static List *insert_ordered_oid(List *list, Oid datum);
static void IndexSupportInitialize(Form_pg_index iform,
					   IndexStrategy indexStrategy,
					   Oid *indexOperator,
					   RegProcedure *indexSupport,
					   StrategyNumber maxStrategyNumber,
					   StrategyNumber maxSupportNumber,
					   AttrNumber maxAttributeNumber);
static OpClassCacheEnt *LookupOpclassInfo(Oid operatorClassOid,
				  StrategyNumber numStrats,
				  StrategyNumber numSupport);


/*
 *		ScanPgRelation
 *
 *		this is used by RelationBuildDesc to find a pg_class
 *		tuple matching either a relation name or a relation id
 *		as specified in buildinfo.
 *
 *		NB: the returned tuple has been copied into palloc'd storage
 *		and must eventually be freed with heap_freetuple.
 */
static HeapTuple
ScanPgRelation(RelationBuildDescInfo buildinfo, bool indexOK)
{
	HeapTuple	pg_class_tuple;
	Relation	pg_class_desc;
	const char *indexRelname;
	SysScanDesc pg_class_scan;
	ScanKeyData key[2];
	int			nkeys;

	/*
	 * form a scan key
	 */
	switch (buildinfo.infotype)
	{
		case INFO_RELID:
			ScanKeyEntryInitialize(&key[0], 0,
								   ObjectIdAttributeNumber,
								   F_OIDEQ,
								   ObjectIdGetDatum(buildinfo.i.info_id));
			nkeys = 1;
			indexRelname = ClassOidIndex;
			break;

		case INFO_RELNAME:
			ScanKeyEntryInitialize(&key[0], 0,
								   Anum_pg_class_relname,
								   F_NAMEEQ,
								   NameGetDatum(buildinfo.i.info_name));
			ScanKeyEntryInitialize(&key[1], 0,
								   Anum_pg_class_relnamespace,
								   F_OIDEQ,
								 ObjectIdGetDatum(PG_CATALOG_NAMESPACE));
			nkeys = 2;
			indexRelname = ClassNameNspIndex;
			break;

		default:
			elog(ERROR, "unrecognized buildinfo type: %d",
				 buildinfo.infotype);
			return NULL;		/* keep compiler quiet */
	}

	/*
	 * Open pg_class and fetch a tuple.  Force heap scan if we haven't yet
	 * built the critical relcache entries (this includes initdb and
	 * startup without a pg_internal.init file).  The caller can also
	 * force a heap scan by setting indexOK == false.
	 */
	pg_class_desc = heap_openr(RelationRelationName, AccessShareLock);
	pg_class_scan = systable_beginscan(pg_class_desc, indexRelname,
									   indexOK && criticalRelcachesBuilt,
									   SnapshotNow,
									   nkeys, key);

	pg_class_tuple = systable_getnext(pg_class_scan);

	/*
	 * Must copy tuple before releasing buffer.
	 */
	if (HeapTupleIsValid(pg_class_tuple))
		pg_class_tuple = heap_copytuple(pg_class_tuple);

	/* all done */
	systable_endscan(pg_class_scan);
	heap_close(pg_class_desc, AccessShareLock);

	return pg_class_tuple;
}

/*
 *		AllocateRelationDesc
 *
 *		This is used to allocate memory for a new relation descriptor
 *		and initialize the rd_rel field.
 *
 *		If 'relation' is NULL, allocate a new RelationData object.
 *		If not, reuse the given object (that path is taken only when
 *		we have to rebuild a relcache entry during RelationClearRelation).
 */
static Relation
AllocateRelationDesc(Relation relation, Form_pg_class relp)
{
	MemoryContext oldcxt;
	Form_pg_class relationForm;

	/* Relcache entries must live in CacheMemoryContext */
	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

	/*
	 * allocate space for new relation descriptor, if needed
	 */
	if (relation == NULL)
		relation = (Relation) palloc(sizeof(RelationData));

	/*
	 * clear all fields of reldesc
	 */
	MemSet((char *) relation, 0, sizeof(RelationData));
	relation->rd_targblock = InvalidBlockNumber;

	/* make sure relation is marked as having no open file yet */
	relation->rd_fd = -1;

	/*
	 * Copy the relation tuple form
	 *
	 * We only allocate space for the fixed fields, ie, CLASS_TUPLE_SIZE.
	 * relacl is NOT stored in the relcache --- there'd be little point in
	 * it, since we don't copy the tuple's nullvalues bitmap and hence
	 * wouldn't know if the value is valid ... bottom line is that relacl
	 * *cannot* be retrieved from the relcache.  Get it from the syscache
	 * if you need it.
	 */
	relationForm = (Form_pg_class) palloc(CLASS_TUPLE_SIZE);

	memcpy((char *) relationForm, (char *) relp, CLASS_TUPLE_SIZE);

	/* initialize relation tuple form */
	relation->rd_rel = relationForm;

	/* and allocate attribute tuple form storage */
	relation->rd_att = CreateTemplateTupleDesc(relationForm->relnatts,
											   relationForm->relhasoids);

	MemoryContextSwitchTo(oldcxt);

	return relation;
}

/*
 *		RelationBuildTupleDesc
 *
 *		Form the relation's tuple descriptor from information in
 *		the pg_attribute, pg_attrdef & pg_constraint system catalogs.
 */