heap.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * heap.c
 *	  code to create and destroy POSTGRES heap relations
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/catalog/heap.c,v 1.89 1999/07/08 02:46:37 momjian Exp $
 *
 *
 * INTERFACE ROUTINES
 *		heap_create()			- Create an uncataloged heap relation
 *		heap_create_with_catalog() - Create a cataloged relation
 *		heap_destroy_with_catalog() - Removes named relation from catalogs
 *
 * NOTES
 *	  this code taken from access/heap/create.c, which contains
 *	  the old heap_create_with_catalog, amcreate, and amdestroy.
 *	  those routines will soon call these routines using the function
 *	  manager,
 *	  just like the poorly named "NewXXX" routines do.	The
 *	  "New" routines are all going to die soon, once and for all!
 *		-cim 1/13/91
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
#include "miscadmin.h"

#include "access/heapam.h"
#include "catalog/catalog.h"
#include "catalog/catname.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_index.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_ipl.h"
#include "catalog/pg_relcheck.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "fmgr.h"
#include "nodes/plannodes.h"
#include "optimizer/tlist.h"
#include "parser/parse_expr.h"
#include "parser/parse_node.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "parser/parse_coerce.h"
#include "rewrite/rewriteRemove.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
#include "tcop/tcopprot.h"
#include "utils/catcache.h"
#include "utils/builtins.h"
#include "utils/mcxt.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
#include "utils/tqual.h"
#include "utils/temprel.h"

#ifndef HAVE_MEMMOVE
#include <regex/utils.h>
#else
#include <string.h>
#endif

static void AddNewRelationTuple(Relation pg_class_desc,
				  Relation new_rel_desc, Oid new_rel_oid, unsigned natts,
					char relkind, char *temp_relname);
static void AddToNoNameRelList(Relation r);
static void DeleteAttributeTuples(Relation rel);
static void DeleteRelationTuple(Relation rel);
static void DeleteTypeTuple(Relation rel);
static void RelationRemoveIndexes(Relation relation);
static void RelationRemoveInheritance(Relation relation);
static void RemoveFromNoNameRelList(Relation r);
static void AddNewRelationType(char *typeName, Oid new_rel_oid);
static void StoreConstraints(Relation rel);
static void RemoveConstraints(Relation rel);


/* ----------------------------------------------------------------
 *				XXX UGLY HARD CODED BADNESS FOLLOWS XXX
 *
 *		these should all be moved to someplace in the lib/catalog
 *		module, if not obliterated first.
 * ----------------------------------------------------------------
 */


/*
 * Note:
 *		Should the executor special case these attributes in the future?
 *		Advantage:	consume 1/2 the space in the ATTRIBUTE relation.
 *		Disadvantage:  having rules to compute values in these tuples may
 *				be more difficult if not impossible.
 */

static FormData_pg_attribute a1 = {
	0xffffffff, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
	SelfItemPointerAttributeNumber, 0, -1, -1, '\0', '\0', 'i', '\0', '\0'
};

static FormData_pg_attribute a2 = {
	0xffffffff, {"oid"}, OIDOID, 0, sizeof(Oid),
	ObjectIdAttributeNumber, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'
};

static FormData_pg_attribute a3 = {
	0xffffffff, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
	MinTransactionIdAttributeNumber, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'
};

static FormData_pg_attribute a4 = {
	0xffffffff, {"cmin"}, CIDOID, 0, sizeof(CommandId),
	MinCommandIdAttributeNumber, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'
};

static FormData_pg_attribute a5 = {
	0xffffffff, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
	MaxTransactionIdAttributeNumber, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'
};

static FormData_pg_attribute a6 = {
	0xffffffff, {"cmax"}, CIDOID, 0, sizeof(CommandId),
	MaxCommandIdAttributeNumber, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'
};

static Form_pg_attribute HeapAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6};

/* ----------------------------------------------------------------
 *				XXX END OF UGLY HARD CODED BADNESS XXX
 * ----------------------------------------------------------------
 */

/* the tempRelList holds
   the list of temporary uncatalogued relations that are created.
   these relations should be destroyed at the end of transactions
*/
typedef struct tempRelList
{
	Relation   *rels;			/* array of relation descriptors */
	int			num;			/* number of temporary relations */
	int			size;			/* size of space allocated for the rels
								 * array */
} TempRelList;

#define NONAME_REL_LIST_SIZE	32

static TempRelList *tempRels = NULL;


/* ----------------------------------------------------------------
 *		heap_create		- Create an uncataloged heap relation
 *
 *		Fields relpages, reltuples, reltuples, relkeys, relhistory,
 *		relisindexed, and relkind of rel->rd_rel are initialized
 *		to all zeros, as are rd_last and rd_hook.  Rd_refcnt is set to 1.
 *
 *		Remove the system relation specific code to elsewhere eventually.
 *
 *		Eventually, must place information about this temporary relation
 *		into the transaction context block.
 *
 *
 * if heap_create is called with "" as the name, then heap_create will create
 * a temporary name "pg_noname.$PID.$SEQUENCE" for the relation
 * ----------------------------------------------------------------
 */
Relation
heap_create(char *relname,
			TupleDesc tupDesc,
			bool isnoname,
			bool istemp)
{
	unsigned	i;
	Oid			relid;
	Relation	rel;
	int			len;
	bool		nailme = false;
	int			natts = tupDesc->natts;
	static unsigned int uniqueId = 0;

	extern GlobalMemory CacheCxt;
	MemoryContext oldcxt;


	/* ----------------
	 *	sanity checks
	 * ----------------
	 */
	AssertArg(natts > 0);

	if (relname && !allowSystemTableMods && IsSystemRelationName(relname) && IsNormalProcessingMode())
	{
		elog(ERROR, "Illegal class name '%s'"
			 "\n\tThe 'pg_' name prefix is reserved for system catalogs",
			 relname);
	}

	/* ----------------
	 *	switch to the cache context so that we don't lose
	 *	allocations at the end of this transaction, I guess.
	 *	-cim 6/14/90
	 * ----------------
	 */
	if (!CacheCxt)
		CacheCxt = CreateGlobalMemory("Cache");

	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	/* ----------------
	 *	real ugly stuff to assign the proper relid in the relation
	 *	descriptor follows.
	 * ----------------
	 */
	if (relname && !strcmp(RelationRelationName, relname))
	{
		relid = RelOid_pg_class;
		nailme = true;
	}
	else if (relname && !strcmp(AttributeRelationName, relname))
	{
		relid = RelOid_pg_attribute;
		nailme = true;
	}
	else if (relname && !strcmp(ProcedureRelationName, relname))
	{
		relid = RelOid_pg_proc;
		nailme = true;
	}
	else if (relname && !strcmp(TypeRelationName, relname))
	{
		relid = RelOid_pg_type;
		nailme = true;
	}
	else
		relid = newoid();

	if (isnoname)
	{
		Assert(!relname);
		relname = palloc(NAMEDATALEN);
		snprintf(relname, NAMEDATALEN, "pg_noname.%d.%u",
				 (int) MyProcPid, uniqueId++);
	}

	if (istemp)
	{
		/* replace relname of caller */
		snprintf(relname, NAMEDATALEN, "pg_temp.%d.%u",
				 MyProcPid, uniqueId++);
	}

	/* ----------------
	 *	allocate a new relation descriptor.
	 *
	 *	XXX the length computation may be incorrect, handle elsewhere
	 * ----------------
	 */
	len = sizeof(RelationData);

	rel = (Relation) palloc(len);
	MemSet((char *) rel, 0, len);

	/*
	 * create a new tuple descriptor from the one passed in
	 */
	rel->rd_att = CreateTupleDescCopyConstr(tupDesc);

	/* ----------------
	 *	nail the reldesc if this is a bootstrap create reln and
	 *	we may need it in the cache later on in the bootstrap
	 *	process so we don't ever want it kicked out.  e.g. pg_attribute!!!
	 * ----------------
	 */
	if (nailme)
		rel->rd_isnailed = true;

	RelationSetReferenceCount(rel, 1);

	rel->rd_rel = (Form_pg_class) palloc(sizeof *rel->rd_rel);

	/* ----------------
	 *	initialize the fields of our new relation descriptor
	 * ----------------
	 */
	MemSet((char *) rel->rd_rel, 0, sizeof *rel->rd_rel);
	namestrcpy(&(rel->rd_rel->relname), relname);
	rel->rd_rel->relkind = RELKIND_UNCATALOGED;
	rel->rd_rel->relnatts = natts;
	if (tupDesc->constr)
		rel->rd_rel->relchecks = tupDesc->constr->num_check;

	for (i = 0; i < natts; i++)
		rel->rd_att->attrs[i]->attrelid = relid;

	RelationGetRelid(rel) = relid;

	if (nailme)
	{
		/* for system relations, set the reltype field here */
		rel->rd_rel->reltype = relid;
	}

	/* ----------------
	 *	remember if this is a noname relation
	 * ----------------
	 */
	rel->rd_isnoname = isnoname;

	/* ----------------
	 *	have the storage manager create the relation.
	 * ----------------
	 */

	rel->rd_nonameunlinked = TRUE;		/* change once table is created */
	rel->rd_fd = (File) smgrcreate(DEFAULT_SMGR, rel);
	rel->rd_nonameunlinked = FALSE;

	RelationRegisterRelation(rel);

	MemoryContextSwitchTo(oldcxt);

	/*
	 * add all noname relations to the tempRels list so they can be
	 * properly disposed of at the end of transaction
	 */
	if (isnoname)
		AddToNoNameRelList(rel);

	return rel;
}


/* ----------------------------------------------------------------
 *		heap_create_with_catalog		- Create a cataloged relation
 *
 *		this is done in 6 steps:
 *
 *		1) CheckAttributeNames() is used to make certain the tuple
 *		   descriptor contains a valid set of attribute names
 *
 *		2) pg_class is opened and RelationFindRelid()
 *		   preforms a scan to ensure that no relation with the
 *		   same name already exists.
 *
 *		3) heap_create_with_catalog() is called to create the new relation
 *		   on disk.
 *
 *		4) TypeDefine() is called to define a new type corresponding
 *		   to the new relation.
 *
 *		5) AddNewAttributeTuples() is called to register the
 *		   new relation's schema in pg_attribute.
 *
 *		6) AddNewRelationTuple() is called to register the
 *		   relation itself in the catalogs.
 *
 *		7) StoreConstraints is called ()		- vadim 08/22/97
 *
 *		8) the relations are closed and the new relation's oid
 *		   is returned.
 *
 * old comments:
 *		A new relation is inserted into the RELATION relation
 *		with the specified attribute(s) (newly inserted into
 *		the ATTRIBUTE relation).  How does concurrency control
 *		work?  Is it automatic now?  Expects the caller to have
 *		attname, atttypid, atttyparg, attproc, and attlen domains filled.
 *		Create fills the attnum domains sequentually from zero,
 *		fills the attdisbursion domains with zeros, and fills the
 *		attrelid fields with the relid.
 *
 *		scan relation catalog for name conflict
 *		scan type catalog for typids (if not arg)
 *		create and insert attribute(s) into attribute catalog
 *		create new relation
 *		insert new relation into attribute catalog
 *
 *		Should coordinate with heap_create_with_catalog(). Either
 *		it should not be called or there should be a way to prevent
 *		the relation from being removed at the end of the
 *		transaction if it is successful ('u'/'r' may be enough).
 *		Also, if the transaction does not commit, then the
 *		relation should be removed.
 *
 *		XXX amcreate ignores "off" when inserting (for now).
 *		XXX amcreate (like the other utilities) needs to understand indexes.
 *
 * ----------------------------------------------------------------
 */

/* --------------------------------
 *		CheckAttributeNames
 *
 *		this is used to make certain the tuple descriptor contains a
 *		valid set of attribute names.  a problem simply generates
 *		elog(ERROR) which aborts the current transaction.
 * --------------------------------
 */
static void
CheckAttributeNames(TupleDesc tupdesc)
{
	unsigned	i;
	unsigned	j;
	int			natts = tupdesc->natts;

	/* ----------------
	 *	first check for collision with system attribute names
	 * ----------------
	 *
	 *	 also, warn user if attribute to be created has
	 *	 an unknown typid  (usually as a result of a 'retrieve into'
	 *	  - jolly
	 */
	for (i = 0; i < natts; i += 1)
	{
		for (j = 0; j < sizeof HeapAtt / sizeof HeapAtt[0]; j += 1)
		{
			if (nameeq(&(HeapAtt[j]->attname),
					   &(tupdesc->attrs[i]->attname)))
			{
				elog(ERROR, "Attribute '%s' has a name conflict"
					 "\n\tName matches an existing system attribute",
					 HeapAtt[j]->attname.data);
			}
		}
		if (tupdesc->attrs[i]->atttypid == UNKNOWNOID)
		{
			elog(NOTICE, "Attribute '%s' has an unknown type"
				 "\n\tRelation created; continue",
				 tupdesc->attrs[i]->attname.data);
		}
	}

	/* ----------------
	 *	next check for repeated attribute names
	 * ----------------
	 */
	for (i = 1; i < natts; i += 1)
	{
		for (j = 0; j < i; j += 1)
		{
			if (nameeq(&(tupdesc->attrs[j]->attname),
					   &(tupdesc->attrs[i]->attname)))
			{
				elog(ERROR, "Attribute '%s' is repeated",
					 tupdesc->attrs[j]->attname.data);
			}
		}
	}
}

/* --------------------------------
 *		RelnameFindRelid
 *
 *		this preforms a scan of pg_class to ensure that
 *		no relation with the same name already exists.
 * --------------------------------
 */
Oid
RelnameFindRelid(char *relname)
{
	HeapTuple	tuple;
	Oid			relid;

	/*
	 * If this is not bootstrap (initdb) time, use the catalog index on
	 * pg_class.
	 */
	if (!IsBootstrapProcessingMode())
	{
		tuple = SearchSysCacheTuple(RELNAME,
									PointerGetDatum(relname),
									0, 0, 0);
		if (HeapTupleIsValid(tuple))
			relid = tuple->t_data->t_oid;
		else
			relid = InvalidOid;
	}
	else
	{
		Relation	pg_class_desc;
		ScanKeyData key;
		HeapScanDesc pg_class_scan;

		pg_class_desc = heap_openr(RelationRelationName);

		/* ----------------
		 *	At bootstrap time, we have to do this the hard way.  Form the
		 *	scan key.
		 * ----------------
		 */
		ScanKeyEntryInitialize(&key,
							   0,
							   (AttrNumber) Anum_pg_class_relname,
							   (RegProcedure) F_NAMEEQ,
							   (Datum) relname);

		/* ----------------
		 *	begin the scan
		 * ----------------
		 */
		pg_class_scan = heap_beginscan(pg_class_desc,
									   0,
									   SnapshotNow,
									   1,
									   &key);

		/* ----------------
		 *	get a tuple.  if the tuple is NULL then it means we
		 *	didn't find an existing relation.
		 * ----------------
		 */
		tuple = heap_getnext(pg_class_scan, 0);

		if (HeapTupleIsValid(tuple))
			relid = tuple->t_data->t_oid;
		else
			relid = InvalidOid;

		heap_endscan(pg_class_scan);

		heap_close(pg_class_desc);
	}
	return relid;
}

/* --------------------------------
 *		AddNewAttributeTuples
 *
 *		this registers the new relation's schema by adding
 *		tuples to pg_attribute.
 * --------------------------------
 */
static void
AddNewAttributeTuples(Oid new_rel_oid,
					  TupleDesc tupdesc)
{
	Form_pg_attribute *dpp;
	unsigned	i;
	HeapTuple	tup;
	Relation	rel;
	bool		hasindex;
	Relation	idescs[Num_pg_attr_indices];
	int			natts = tupdesc->natts;

	/* ----------------
	 *	open pg_attribute
	 * ----------------
	 */
	rel = heap_openr(AttributeRelationName);

	/* -----------------
	 * Check if we have any indices defined on pg_attribute.
	 * -----------------
	 */
	Assert(rel);
	Assert(rel->rd_rel);
	hasindex = RelationGetForm(rel)->relhasindex;
	if (hasindex)
		CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs);

	/* ----------------
	 *	initialize tuple descriptor.  Note we use setheapoverride()
	 *	so that we can see the effects of our TypeDefine() done
	 *	previously.
	 * ----------------
	 */
	setheapoverride(true);
	fillatt(tupdesc);
	setheapoverride(false);