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postgresql/src/backend/access/gist/gistutil.c

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/*-------------------------------------------------------------------------
*
* gistutil.c
* utilities routines for the postgres GiST index access method.
*
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/gist/gistutil.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/gist_private.h"
#include "access/reloptions.h"
#include "storage/freespace.h"
#include "storage/indexfsm.h"
#include "storage/lmgr.h"
#include "storage/bufmgr.h"
#include "utils/rel.h"
/*
* static *S used for temrorary storage (saves stack and palloc() call)
*/
static Datum attrS[INDEX_MAX_KEYS];
static bool isnullS[INDEX_MAX_KEYS];
/*
* Write itup vector to page, has no control of free space.
*/
void
gistfillbuffer(Page page, IndexTuple *itup, int len, OffsetNumber off)
{
OffsetNumber l = InvalidOffsetNumber;
int i;
if (off == InvalidOffsetNumber)
off = (PageIsEmpty(page)) ? FirstOffsetNumber :
OffsetNumberNext(PageGetMaxOffsetNumber(page));
for (i = 0; i < len; i++)
{
Size sz = IndexTupleSize(itup[i]);
l = PageAddItem(page, (Item) itup[i], sz, off, false, false);
if (l == InvalidOffsetNumber)
elog(ERROR, "failed to add item to GiST index page, item %d out of %d, size %d bytes",
i, len, (int) sz);
off++;
}
}
/*
* Check space for itup vector on page
*/
bool
gistnospace(Page page, IndexTuple *itvec, int len, OffsetNumber todelete, Size freespace)
{
unsigned int size = freespace,
deleted = 0;
int i;
for (i = 0; i < len; i++)
size += IndexTupleSize(itvec[i]) + sizeof(ItemIdData);
if (todelete != InvalidOffsetNumber)
{
IndexTuple itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, todelete));
deleted = IndexTupleSize(itup) + sizeof(ItemIdData);
}
return (PageGetFreeSpace(page) + deleted < size);
}
bool
gistfitpage(IndexTuple *itvec, int len)
{
int i;
Size size = 0;
for (i = 0; i < len; i++)
size += IndexTupleSize(itvec[i]) + sizeof(ItemIdData);
/* TODO: Consider fillfactor */
return (size <= GiSTPageSize);
}
/*
* Read buffer into itup vector
*/
IndexTuple *
gistextractpage(Page page, int *len /* out */ )
{
OffsetNumber i,
maxoff;
IndexTuple *itvec;
maxoff = PageGetMaxOffsetNumber(page);
*len = maxoff;
itvec = palloc(sizeof(IndexTuple) * maxoff);
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
itvec[i - FirstOffsetNumber] = (IndexTuple) PageGetItem(page, PageGetItemId(page, i));
return itvec;
}
/*
* join two vectors into one
*/
IndexTuple *
gistjoinvector(IndexTuple *itvec, int *len, IndexTuple *additvec, int addlen)
{
itvec = (IndexTuple *) repalloc((void *) itvec, sizeof(IndexTuple) * ((*len) + addlen));
memmove(&itvec[*len], additvec, sizeof(IndexTuple) * addlen);
*len += addlen;
return itvec;
}
/*
* make plain IndexTupleVector
*/
IndexTupleData *
gistfillitupvec(IndexTuple *vec, int veclen, int *memlen)
{
char *ptr,
*ret;
int i;
*memlen = 0;
for (i = 0; i < veclen; i++)
*memlen += IndexTupleSize(vec[i]);
ptr = ret = palloc(*memlen);
for (i = 0; i < veclen; i++)
{
memcpy(ptr, vec[i], IndexTupleSize(vec[i]));
ptr += IndexTupleSize(vec[i]);
}
return (IndexTupleData *) ret;
}
/*
* Make unions of keys in IndexTuple vector, return FALSE if itvec contains
* invalid tuple. Resulting Datums aren't compressed.
*/
void
gistMakeUnionItVec(GISTSTATE *giststate, IndexTuple *itvec, int len, int startkey,
Datum *attr, bool *isnull)
{
int i;
GistEntryVector *evec;
int attrsize;
evec = (GistEntryVector *) palloc((len + 2) * sizeof(GISTENTRY) + GEVHDRSZ);
for (i = startkey; i < giststate->tupdesc->natts; i++)
{
int j;
evec->n = 0;
if (!isnull[i])
{
gistentryinit(evec->vector[evec->n], attr[i],
NULL, NULL, (OffsetNumber) 0,
FALSE);
evec->n++;
}
for (j = 0; j < len; j++)
{
Datum datum;
bool IsNull;
datum = index_getattr(itvec[j], i + 1, giststate->tupdesc, &IsNull);
if (IsNull)
continue;
gistdentryinit(giststate, i,
evec->vector + evec->n,
datum,
NULL, NULL, (OffsetNumber) 0,
FALSE, IsNull);
evec->n++;
}
/* If this tuple vector was all NULLs, the union is NULL */
if (evec->n == 0)
{
attr[i] = (Datum) 0;
isnull[i] = TRUE;
}
else
{
if (evec->n == 1)
{
evec->n = 2;
evec->vector[1] = evec->vector[0];
}
/* Make union and store in attr array */
attr[i] = FunctionCall2(&giststate->unionFn[i],
PointerGetDatum(evec),
PointerGetDatum(&attrsize));
isnull[i] = FALSE;
}
}
}
/*
* Return an IndexTuple containing the result of applying the "union"
* method to the specified IndexTuple vector.
*/
IndexTuple
gistunion(Relation r, IndexTuple *itvec, int len, GISTSTATE *giststate)
{
memset(isnullS, TRUE, sizeof(bool) * giststate->tupdesc->natts);
gistMakeUnionItVec(giststate, itvec, len, 0, attrS, isnullS);
return gistFormTuple(giststate, r, attrS, isnullS, false);
}
/*
* makes union of two key
*/
void
gistMakeUnionKey(GISTSTATE *giststate, int attno,
GISTENTRY *entry1, bool isnull1,
GISTENTRY *entry2, bool isnull2,
Datum *dst, bool *dstisnull)
{
int dstsize;
static char storage[2 * sizeof(GISTENTRY) + GEVHDRSZ];
GistEntryVector *evec = (GistEntryVector *) storage;
evec->n = 2;
if (isnull1 && isnull2)
{
*dstisnull = TRUE;
*dst = (Datum) 0;
}
else
{
if (isnull1 == FALSE && isnull2 == FALSE)
{
evec->vector[0] = *entry1;
evec->vector[1] = *entry2;
}
else if (isnull1 == FALSE)
{
evec->vector[0] = *entry1;
evec->vector[1] = *entry1;
}
else
{
evec->vector[0] = *entry2;
evec->vector[1] = *entry2;
}
*dstisnull = FALSE;
*dst = FunctionCall2(&giststate->unionFn[attno],
PointerGetDatum(evec),
PointerGetDatum(&dstsize));
}
}
bool
gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b)
{
bool result;
FunctionCall3(&giststate->equalFn[attno],
a, b,
PointerGetDatum(&result));
return result;
}
/*
* Decompress all keys in tuple
*/
void
gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p,
OffsetNumber o, GISTENTRY *attdata, bool *isnull)
{
int i;
for (i = 0; i < r->rd_att->natts; i++)
{
Datum datum = index_getattr(tuple, i + 1, giststate->tupdesc, &isnull[i]);
gistdentryinit(giststate, i, &attdata[i],
datum, r, p, o,
FALSE, isnull[i]);
}
}
/*
* Forms union of oldtup and addtup, if union == oldtup then return NULL
*/
IndexTuple
gistgetadjusted(Relation r, IndexTuple oldtup, IndexTuple addtup, GISTSTATE *giststate)
{
bool neednew = FALSE;
GISTENTRY oldentries[INDEX_MAX_KEYS],
addentries[INDEX_MAX_KEYS];
bool oldisnull[INDEX_MAX_KEYS],
addisnull[INDEX_MAX_KEYS];
IndexTuple newtup = NULL;
int i;
gistDeCompressAtt(giststate, r, oldtup, NULL,
(OffsetNumber) 0, oldentries, oldisnull);
gistDeCompressAtt(giststate, r, addtup, NULL,
(OffsetNumber) 0, addentries, addisnull);
for (i = 0; i < r->rd_att->natts; i++)
{
gistMakeUnionKey(giststate, i,
oldentries + i, oldisnull[i],
addentries + i, addisnull[i],
attrS + i, isnullS + i);
if (neednew)
/* we already need new key, so we can skip check */
continue;
if (isnullS[i])
/* union of key may be NULL if and only if both keys are NULL */
continue;
if (!addisnull[i])
{
if (oldisnull[i] || gistKeyIsEQ(giststate, i, oldentries[i].key, attrS[i]) == false)
neednew = true;
}
}
if (neednew)
{
/* need to update key */
newtup = gistFormTuple(giststate, r, attrS, isnullS, false);
newtup->t_tid = oldtup->t_tid;
}
return newtup;
}
/*
* find entry with lowest penalty
*/
OffsetNumber
gistchoose(Relation r, Page p, IndexTuple it, /* it has compressed entry */
GISTSTATE *giststate)
{
OffsetNumber maxoff;
OffsetNumber i;
OffsetNumber which;
float sum_grow,
which_grow[INDEX_MAX_KEYS];
GISTENTRY entry,
identry[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
maxoff = PageGetMaxOffsetNumber(p);
*which_grow = -1.0;
which = InvalidOffsetNumber;
sum_grow = 1;
gistDeCompressAtt(giststate, r,
it, NULL, (OffsetNumber) 0,
identry, isnull);
Assert(maxoff >= FirstOffsetNumber);
Assert(!GistPageIsLeaf(p));
for (i = FirstOffsetNumber; i <= maxoff && sum_grow; i = OffsetNumberNext(i))
{
int j;
IndexTuple itup = (IndexTuple) PageGetItem(p, PageGetItemId(p, i));
sum_grow = 0;
for (j = 0; j < r->rd_att->natts; j++)
{
Datum datum;
float usize;
bool IsNull;
datum = index_getattr(itup, j + 1, giststate->tupdesc, &IsNull);
gistdentryinit(giststate, j, &entry, datum, r, p, i,
FALSE, IsNull);
usize = gistpenalty(giststate, j, &entry, IsNull,
&identry[j], isnull[j]);
if (which_grow[j] < 0 || usize < which_grow[j])
{
which = i;
which_grow[j] = usize;
if (j < r->rd_att->natts - 1 && i == FirstOffsetNumber)
which_grow[j + 1] = -1;
sum_grow += which_grow[j];
}
else if (which_grow[j] == usize)
sum_grow += usize;
else
{
sum_grow = 1;
break;
}
}
}
if (which == InvalidOffsetNumber)
which = FirstOffsetNumber;
return which;
}
/*
* initialize a GiST entry with a decompressed version of key
*/
void
gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e,
Datum k, Relation r, Page pg, OffsetNumber o,
bool l, bool isNull)
{
if (!isNull)
{
GISTENTRY *dep;
gistentryinit(*e, k, r, pg, o, l);
dep = (GISTENTRY *)
DatumGetPointer(FunctionCall1(&giststate->decompressFn[nkey],
PointerGetDatum(e)));
/* decompressFn may just return the given pointer */
if (dep != e)
gistentryinit(*e, dep->key, dep->rel, dep->page, dep->offset,
dep->leafkey);
}
else
gistentryinit(*e, (Datum) 0, r, pg, o, l);
}
/*
* initialize a GiST entry with a compressed version of key
*/
void
gistcentryinit(GISTSTATE *giststate, int nkey,
GISTENTRY *e, Datum k, Relation r,
Page pg, OffsetNumber o, bool l, bool isNull)
{
if (!isNull)
{
GISTENTRY *cep;
gistentryinit(*e, k, r, pg, o, l);
cep = (GISTENTRY *)
DatumGetPointer(FunctionCall1(&giststate->compressFn[nkey],
PointerGetDatum(e)));
/* compressFn may just return the given pointer */
if (cep != e)
gistentryinit(*e, cep->key, cep->rel, cep->page, cep->offset,
cep->leafkey);
}
else
gistentryinit(*e, (Datum) 0, r, pg, o, l);
}
IndexTuple
gistFormTuple(GISTSTATE *giststate, Relation r,
Datum attdata[], bool isnull[], bool newValues)
{
GISTENTRY centry[INDEX_MAX_KEYS];
Datum compatt[INDEX_MAX_KEYS];
int i;
IndexTuple res;
for (i = 0; i < r->rd_att->natts; i++)
{
if (isnull[i])
compatt[i] = (Datum) 0;
else
{
gistcentryinit(giststate, i, &centry[i], attdata[i],
r, NULL, (OffsetNumber) 0,
newValues,
FALSE);
compatt[i] = centry[i].key;
}
}
res = index_form_tuple(giststate->tupdesc, compatt, isnull);
/*
* The offset number on tuples on internal pages is unused. For historical
* reasons, it is set 0xffff.
*/
ItemPointerSetOffsetNumber( &(res->t_tid), 0xffff);
return res;
}
float
gistpenalty(GISTSTATE *giststate, int attno,
GISTENTRY *orig, bool isNullOrig,
GISTENTRY *add, bool isNullAdd)
{
float penalty = 0.0;
if (giststate->penaltyFn[attno].fn_strict == FALSE || (isNullOrig == FALSE && isNullAdd == FALSE))
FunctionCall3(&giststate->penaltyFn[attno],
PointerGetDatum(orig),
PointerGetDatum(add),
PointerGetDatum(&penalty));
else if (isNullOrig && isNullAdd)
penalty = 0.0;
else
penalty = 1e10; /* try to prevent to mix null and non-null
* value */
return penalty;
}
/*
* Initialize a new index page
*/
void
GISTInitBuffer(Buffer b, uint32 f)
{
GISTPageOpaque opaque;
Page page;
Size pageSize;
pageSize = BufferGetPageSize(b);
page = BufferGetPage(b);
PageInit(page, pageSize, sizeof(GISTPageOpaqueData));
opaque = GistPageGetOpaque(page);
/* page was already zeroed by PageInit, so this is not needed: */
/* memset(&(opaque->nsn), 0, sizeof(GistNSN)); */
opaque->rightlink = InvalidBlockNumber;
opaque->flags = f;
opaque->gist_page_id = GIST_PAGE_ID;
}
/*
* Verify that a freshly-read page looks sane.
*/
void
gistcheckpage(Relation rel, Buffer buf)
{
Page page = BufferGetPage(buf);
/*
* ReadBuffer verifies that every newly-read page passes
* PageHeaderIsValid, which means it either contains a reasonably sane
* page header or is all-zero. We have to defend against the all-zero
* case, however.
*/
if (PageIsNew(page))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains unexpected zero page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
/*
* Additionally check that the special area looks sane.
*/
if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GISTPageOpaqueData)))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
}
/*
* Allocate a new page (either by recycling, or by extending the index file)
*
* The returned buffer is already pinned and exclusive-locked
*
* Caller is responsible for initializing the page by calling GISTInitBuffer
*/
Buffer
gistNewBuffer(Relation r)
{
Buffer buffer;
bool needLock;
/* First, try to get a page from FSM */
for (;;)
{
BlockNumber blkno = GetFreeIndexPage(r);
if (blkno == InvalidBlockNumber)
break; /* nothing left in FSM */
buffer = ReadBuffer(r, blkno);
/*
* We have to guard against the possibility that someone else already
* recycled this page; the buffer may be locked if so.
*/
if (ConditionalLockBuffer(buffer))
{
Page page = BufferGetPage(buffer);
if (PageIsNew(page))
return buffer; /* OK to use, if never initialized */
gistcheckpage(r, buffer);
if (GistPageIsDeleted(page))
return buffer; /* OK to use */
LockBuffer(buffer, GIST_UNLOCK);
}
/* Can't use it, so release buffer and try again */
ReleaseBuffer(buffer);
}
/* Must extend the file */
needLock = !RELATION_IS_LOCAL(r);
if (needLock)
LockRelationForExtension(r, ExclusiveLock);
buffer = ReadBuffer(r, P_NEW);
LockBuffer(buffer, GIST_EXCLUSIVE);
if (needLock)
UnlockRelationForExtension(r, ExclusiveLock);
return buffer;
}
Datum
gistoptions(PG_FUNCTION_ARGS)
{
Datum reloptions = PG_GETARG_DATUM(0);
bool validate = PG_GETARG_BOOL(1);
bytea *result;
result = default_reloptions(reloptions, validate, RELOPT_KIND_GIST);
if (result)
PG_RETURN_BYTEA_P(result);
PG_RETURN_NULL();
}
/*
* Temporary GiST indexes are not WAL-logged, but we need LSNs to detect
* concurrent page splits anyway. GetXLogRecPtrForTemp() provides a fake
* sequence of LSNs for that purpose. Each call generates an LSN that is
* greater than any previous value returned by this function in the same
* session.
*/
XLogRecPtr
GetXLogRecPtrForTemp(void)
{
static XLogRecPtr counter = {0, 1};
counter.xrecoff++;
if (counter.xrecoff == 0)
{
counter.xlogid++;
counter.xrecoff++;
}
return counter;
}
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