index.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * index.c
 *	  code to create and destroy POSTGRES index relations
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/catalog/index.c,v 1.81.2.1 1999/08/02 05:56:54 scrappy Exp $
 *
 *
 * INTERFACE ROUTINES
 *		index_create()			- Create a cataloged index relation
 *		index_destroy()			- Removes index relation from catalogs
 *
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"


#include "access/genam.h"
#include "access/heapam.h"
#include "access/istrat.h"
#include "bootstrap/bootstrap.h"
#include "catalog/catname.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/pg_index.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
#include "optimizer/prep.h"
#include "parser/parse_func.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
#include "utils/temprel.h"

/*
 * macros used in guessing how many tuples are on a page.
 */
#define AVG_ATTR_SIZE 8
#define NTUPLES_PER_PAGE(natts) \
	((BLCKSZ - MAXALIGN(sizeof (PageHeaderData))) / \
	((natts) * AVG_ATTR_SIZE + MAXALIGN(sizeof(HeapTupleHeaderData))))

/* non-export function prototypes */
static Oid GetHeapRelationOid(char *heapRelationName, char *indexRelationName,
				   bool istemp);
static TupleDesc BuildFuncTupleDesc(FuncIndexInfo *funcInfo);
static TupleDesc ConstructTupleDescriptor(Oid heapoid, Relation heapRelation,
						 List *attributeList,
						 int numatts, AttrNumber *attNums);

static void ConstructIndexReldesc(Relation indexRelation, Oid amoid);
static Oid	UpdateRelationRelation(Relation indexRelation, char *temp_relname);
static void InitializeAttributeOids(Relation indexRelation,
						int numatts,
						Oid indexoid);
static void
			AppendAttributeTuples(Relation indexRelation, int numatts);
static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
					FuncIndexInfo *funcInfo, int natts,
					AttrNumber *attNums, Oid *classOids, Node *predicate,
		   List *attributeList, bool islossy, bool unique, bool primary);
static void DefaultBuild(Relation heapRelation, Relation indexRelation,
			 int numberOfAttributes, AttrNumber *attributeNumber,
			 IndexStrategy indexStrategy, uint16 parameterCount,
		Datum *parameter, FuncIndexInfoPtr funcInfo, PredInfo *predInfo);

/* ----------------------------------------------------------------
 *	  sysatts is a structure containing attribute tuple forms
 *	  for system attributes (numbered -1, -2, ...).  This really
 *	  should be generated or eliminated or moved elsewhere. -cim 1/19/91
 *
 * typedef struct FormData_pg_attribute {
 *		Oid				attrelid;
 *		NameData		attname;
 *		Oid				atttypid;
 *		uint32			attnvals;
 *		int16			attlen;
 *		AttrNumber		attnum;
 *		uint32			attnelems;
 *		int32			attcacheoff;
 *		int32			atttypmod;
 *		bool			attbyval;
 *		bool			attisset;
 *		char			attalign;
 *		bool			attnotnull;
 *		bool			atthasdef;
 * } FormData_pg_attribute;
 *
 * ----------------------------------------------------------------
 */
static FormData_pg_attribute sysatts[] = {
	{0, {"ctid"}, TIDOID, 0, 6, -1, 0, -1, -1, '\0', '\0', 'i', '\0', '\0'},
	{0, {"oid"}, OIDOID, 0, 4, -2, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'},
	{0, {"xmin"}, XIDOID, 0, 4, -3, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'},
	{0, {"cmin"}, CIDOID, 0, 4, -4, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'},
	{0, {"xmax"}, XIDOID, 0, 4, -5, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'},
	{0, {"cmax"}, CIDOID, 0, 4, -6, 0, -1, -1, '\001', '\0', 'i', '\0', '\0'},
};

/* ----------------------------------------------------------------
 *		GetHeapRelationOid
 * ----------------------------------------------------------------
 */
static Oid
GetHeapRelationOid(char *heapRelationName, char *indexRelationName, bool istemp)
{
	Oid			indoid;
	Oid			heapoid;


	indoid = RelnameFindRelid(indexRelationName);

	if ((!istemp && OidIsValid(indoid)) ||
		(istemp && get_temp_rel_by_name(indexRelationName) != NULL))
		elog(ERROR, "Cannot create index: '%s' already exists",
			 indexRelationName);

	heapoid = RelnameFindRelid(heapRelationName);

	if (!OidIsValid(heapoid))
		elog(ERROR, "Cannot create index on '%s': relation does not exist",
			 heapRelationName);

	return heapoid;
}

static TupleDesc
BuildFuncTupleDesc(FuncIndexInfo *funcInfo)
{
	HeapTuple	tuple;
	TupleDesc	funcTupDesc;
	Oid			retType;
	char	   *funcname;
	int4		nargs;
	Oid		   *argtypes;

	/*
	 * Allocate and zero a tuple descriptor.
	 */
	funcTupDesc = CreateTemplateTupleDesc(1);
	funcTupDesc->attrs[0] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);
	MemSet(funcTupDesc->attrs[0], 0, ATTRIBUTE_TUPLE_SIZE);

	/*
	 * Lookup the function for the return type.
	 */
	funcname = FIgetname(funcInfo);
	nargs = FIgetnArgs(funcInfo);
	argtypes = FIgetArglist(funcInfo);
	tuple = SearchSysCacheTuple(PRONAME,
								PointerGetDatum(funcname),
								Int32GetDatum(nargs),
								PointerGetDatum(argtypes),
								0);

	if (!HeapTupleIsValid(tuple))
		func_error("BuildFuncTupleDesc", funcname, nargs, argtypes, NULL);

	retType = ((Form_pg_proc) GETSTRUCT(tuple))->prorettype;

	/*
	 * Look up the return type in pg_type for the type length.
	 */
	tuple = SearchSysCacheTuple(TYPOID,
								ObjectIdGetDatum(retType),
								0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "Function %s return type does not exist", FIgetname(funcInfo));

	/*
	 * Assign some of the attributes values. Leave the rest as 0.
	 */
	funcTupDesc->attrs[0]->attlen = ((Form_pg_type) GETSTRUCT(tuple))->typlen;
	funcTupDesc->attrs[0]->atttypid = retType;
	funcTupDesc->attrs[0]->attnum = 1;
	funcTupDesc->attrs[0]->attbyval = ((Form_pg_type) GETSTRUCT(tuple))->typbyval;
	funcTupDesc->attrs[0]->attcacheoff = -1;
	funcTupDesc->attrs[0]->atttypmod = -1;
	funcTupDesc->attrs[0]->attalign = ((Form_pg_type) GETSTRUCT(tuple))->typalign;

	/*
	 * make the attributes name the same as the functions
	 */
	namestrcpy(&funcTupDesc->attrs[0]->attname, funcname);

	return funcTupDesc;
}

/* ----------------------------------------------------------------
 *		ConstructTupleDescriptor
 * ----------------------------------------------------------------
 */
static TupleDesc
ConstructTupleDescriptor(Oid heapoid,
						 Relation heapRelation,
						 List *attributeList,
						 int numatts,
						 AttrNumber *attNums)
{
	TupleDesc	heapTupDesc;
	TupleDesc	indexTupDesc;
	IndexElem  *IndexKey;
	TypeName   *IndexKeyType;
	AttrNumber	atnum;			/* attributeNumber[attributeOffset] */
	AttrNumber	atind;
	int			natts;			/* Form_pg_class->relnatts */
	char	   *from;			/* used to simplify memcpy below */
	char	   *to;				/* used to simplify memcpy below */
	int			i;

	/* ----------------
	 *	allocate the new tuple descriptor
	 * ----------------
	 */
	natts = RelationGetForm(heapRelation)->relnatts;

	indexTupDesc = CreateTemplateTupleDesc(numatts);

	/* ----------------
	 *
	 * ----------------
	 */

	/* ----------------
	 *	  for each attribute we are indexing, obtain its attribute
	 *	  tuple form from either the static table of system attribute
	 *	  tuple forms or the relation tuple descriptor
	 * ----------------
	 */
	for (i = 0; i < numatts; i += 1)
	{

		/* ----------------
		 *	 get the attribute number and make sure it's valid
		 * ----------------
		 */
		atnum = attNums[i];
		if (atnum > natts)
			elog(ERROR, "Cannot create index: attribute %d does not exist",
				 atnum);
		if (attributeList)
		{
			IndexKey = (IndexElem *) lfirst(attributeList);
			IndexKeyType = IndexKey->typename;
			attributeList = lnext(attributeList);
		}
		else
			IndexKeyType = NULL;

		indexTupDesc->attrs[i] = (Form_pg_attribute) palloc(ATTRIBUTE_TUPLE_SIZE);

		/* ----------------
		 *	 determine which tuple descriptor to copy
		 * ----------------
		 */
		if (!AttrNumberIsForUserDefinedAttr(atnum))
		{

			/* ----------------
			 *	  here we are indexing on a system attribute (-1...-12)
			 *	  so we convert atnum into a usable index 0...11 so we can
			 *	  use it to dereference the array sysatts[] which stores
			 *	  tuple descriptor information for system attributes.
			 * ----------------
			 */
			if (atnum <= FirstLowInvalidHeapAttributeNumber || atnum >= 0)
				elog(ERROR, "Cannot create index on system attribute: attribute number out of range (%d)", atnum);
			atind = (-atnum) - 1;

			from = (char *) (&sysatts[atind]);

		}
		else
		{
			/* ----------------
			 *	  here we are indexing on a normal attribute (1...n)
			 * ----------------
			 */
			heapTupDesc = RelationGetDescr(heapRelation);
			atind = AttrNumberGetAttrOffset(atnum);

			from = (char *) (heapTupDesc->attrs[atind]);
		}

		/* ----------------
		 *	 now that we've determined the "from", let's copy
		 *	 the tuple desc data...
		 * ----------------
		 */

		to = (char *) (indexTupDesc->attrs[i]);
		memcpy(to, from, ATTRIBUTE_TUPLE_SIZE);

		((Form_pg_attribute) to)->attnum = i + 1;

		((Form_pg_attribute) to)->attnotnull = false;
		((Form_pg_attribute) to)->atthasdef = false;
		((Form_pg_attribute) to)->attcacheoff = -1;
		((Form_pg_attribute) to)->atttypmod = -1;
		((Form_pg_attribute) to)->attalign = 'i';

		/*
		 * if the keytype is defined, we need to change the tuple form's
		 * atttypid & attlen field to match that of the key's type
		 */
		if (IndexKeyType != NULL)
		{
			HeapTuple	tup;

			tup = SearchSysCacheTuple(TYPNAME,
									  PointerGetDatum(IndexKeyType->name),
									  0, 0, 0);
			if (!HeapTupleIsValid(tup))
				elog(ERROR, "create index: type '%s' undefined",
					 IndexKeyType->name);
			((Form_pg_attribute) to)->atttypid = tup->t_data->t_oid;
			((Form_pg_attribute) to)->attbyval =
				((Form_pg_type) GETSTRUCT(tup))->typbyval;
			((Form_pg_attribute) to)->attlen =
				((Form_pg_type) GETSTRUCT(tup))->typlen;
			((Form_pg_attribute) to)->attalign =
				((Form_pg_type) GETSTRUCT(tup))->typalign;
			((Form_pg_attribute) to)->atttypmod = IndexKeyType->typmod;
		}


		/* ----------------
		 *	  now we have to drop in the proper relation descriptor
		 *	  into the copied tuple form's attrelid and we should be
		 *	  all set.
		 * ----------------
		 */
		((Form_pg_attribute) to)->attrelid = heapoid;
	}

	return indexTupDesc;
}

/* ----------------------------------------------------------------
 * AccessMethodObjectIdGetForm
 *		Returns the formated access method tuple given its object identifier.
 *
 * XXX ADD INDEXING
 *
 * Note:
 *		Assumes object identifier is valid.
 * ----------------------------------------------------------------
 */
Form_pg_am
AccessMethodObjectIdGetForm(Oid accessMethodObjectId)
{
	Relation	pg_am_desc;
	HeapScanDesc pg_am_scan;
	HeapTuple	pg_am_tuple;
	ScanKeyData key;
	Form_pg_am	aform;

	/* ----------------
	 *	form a scan key for the pg_am relation
	 * ----------------
	 */
	ScanKeyEntryInitialize(&key, 0, ObjectIdAttributeNumber,
						   F_OIDEQ,
						   ObjectIdGetDatum(accessMethodObjectId));

	/* ----------------
	 *	fetch the desired access method tuple
	 * ----------------
	 */
	pg_am_desc = heap_openr(AccessMethodRelationName);
	pg_am_scan = heap_beginscan(pg_am_desc, 0, SnapshotNow, 1, &key);

	pg_am_tuple = heap_getnext(pg_am_scan, 0);

	/* ----------------
	 *	return NULL if not found
	 * ----------------
	 */
	if (!HeapTupleIsValid(pg_am_tuple))
	{
		heap_endscan(pg_am_scan);
		heap_close(pg_am_desc);
		return NULL;
	}

	/* ----------------
	 *	if found am tuple, then copy the form and return the copy
	 * ----------------
	 */
	aform = (Form_pg_am) palloc(sizeof *aform);
	memcpy(aform, GETSTRUCT(pg_am_tuple), sizeof *aform);

	heap_endscan(pg_am_scan);
	heap_close(pg_am_desc);

	return aform;
}

/* ----------------------------------------------------------------
 *		ConstructIndexReldesc
 * ----------------------------------------------------------------
 */
static void
ConstructIndexReldesc(Relation indexRelation, Oid amoid)
{
	extern GlobalMemory CacheCxt;
	MemoryContext oldcxt;

	/* ----------------
	 *	  here we make certain to allocate the access method
	 *	  tuple within the cache context lest it vanish when the
	 *	  context changes
	 * ----------------
	 */
	if (!CacheCxt)
		CacheCxt = CreateGlobalMemory("Cache");

	oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);

	indexRelation->rd_am = AccessMethodObjectIdGetForm(amoid);

	MemoryContextSwitchTo(oldcxt);

	/* ----------------
	 *	 XXX missing the initialization of some other fields