/*
* gistSplit -- split a page in the tree.
*/
static IndexTuple *
gistSplit(Relation r,
Buffer buffer,
IndexTuple *itup, /* contains compressed entry */
int *len,
GISTSTATE *giststate,
InsertIndexResult *res)
{
Page p;
Buffer leftbuf,
rightbuf;
Page left,
right;
IndexTuple *lvectup,
*rvectup,
*newtup;
BlockNumber lbknum,
rbknum;
GISTPageOpaque opaque;
GIST_SPLITVEC v;
GistEntryVector *entryvec;
bool *decompvec;
int i,
j,
nlen;
int MaxGrpId = 1;
Datum datum;
bool IsNull;
p = (Page) BufferGetPage(buffer);
opaque = (GISTPageOpaque) PageGetSpecialPointer(p);
/*
* The root of the tree is the first block in the relation. If we're
* about to split the root, we need to do some hocus-pocus to enforce
* this guarantee.
*/
if (BufferGetBlockNumber(buffer) == GISTP_ROOT)
{
leftbuf = ReadBuffer(r, P_NEW);
GISTInitBuffer(leftbuf, opaque->flags);
lbknum = BufferGetBlockNumber(leftbuf);
left = (Page) BufferGetPage(leftbuf);
}
else
{
leftbuf = buffer;
IncrBufferRefCount(buffer);
lbknum = BufferGetBlockNumber(buffer);
left = (Page) PageGetTempPage(p, sizeof(GISTPageOpaqueData));
}
rightbuf = ReadBuffer(r, P_NEW);
GISTInitBuffer(rightbuf, opaque->flags);
rbknum = BufferGetBlockNumber(rightbuf);
right = (Page) BufferGetPage(rightbuf);
/* generate the item array */
entryvec = palloc(GEVHDRSZ + (*len + 1) * sizeof(GISTENTRY));
entryvec->n = *len + 1;
decompvec = (bool *) palloc((*len + 1) * sizeof(bool));
for (i = 1; i <= *len; i++)
{
datum = index_getattr(itup[i - 1], 1, giststate->tupdesc, &IsNull);
gistdentryinit(giststate, 0, &(entryvec->vector[i]),
datum, r, p, i,
ATTSIZE(datum, giststate->tupdesc, 1, IsNull), FALSE, IsNull);
if ((!isAttByVal(giststate, 0)) && entryvec->vector[i].key != datum)
decompvec[i] = TRUE;
else
decompvec[i] = FALSE;
}
/*
* now let the user-defined picksplit function set up the split
* vector; in entryvec have no null value!!
*/
FunctionCall2(&giststate->picksplitFn[0],
PointerGetDatum(entryvec),
PointerGetDatum(&v));
/* compatibility with old code */
if (v.spl_left[v.spl_nleft - 1] == InvalidOffsetNumber)
v.spl_left[v.spl_nleft - 1] = (OffsetNumber) *len;
if (v.spl_right[v.spl_nright - 1] == InvalidOffsetNumber)
v.spl_right[v.spl_nright - 1] = (OffsetNumber) *len;
v.spl_lattr[0] = v.spl_ldatum;
v.spl_rattr[0] = v.spl_rdatum;
v.spl_lisnull[0] = false;
v.spl_risnull[0] = false;
/*
* if index is multikey, then we must to try get smaller bounding box
* for subkey(s)
*/
if (r->rd_att->natts > 1)
{
v.spl_idgrp = (int *) palloc0(sizeof(int) * (*len + 1));
v.spl_grpflag = (char *) palloc0(sizeof(char) * (*len + 1));
v.spl_ngrp = (int *) palloc(sizeof(int) * (*len + 1));
MaxGrpId = gistfindgroup(giststate, entryvec->vector, &v);
/* form union of sub keys for each page (l,p) */
gistunionsubkey(r, giststate, itup, &v);
/*
* if possible, we insert equivalent tuples with control by
* penalty for a subkey(s)
*/
if (MaxGrpId > 1)
gistadjsubkey(r, itup, len, &v, giststate);
pfree(v.spl_idgrp);
pfree(v.spl_grpflag);
pfree(v.spl_ngrp);
}
/* clean up the entry vector: its keys need to be deleted, too */
for (i = 1; i <= *len; i++)
if (decompvec[i])
pfree(DatumGetPointer(entryvec->vector[i].key));
pfree(entryvec);
pfree(decompvec);
/* form left and right vector */
lvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * v.spl_nleft);
rvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * v.spl_nright);
for (i = 0; i < v.spl_nleft; i++)
lvectup[i] = itup[v.spl_left[i] - 1];
for (i = 0; i < v.spl_nright; i++)
rvectup[i] = itup[v.spl_right[i] - 1];
/* write on disk (may be need another split) */
if (gistnospace(right, rvectup, v.spl_nright))
{
nlen = v.spl_nright;
newtup = gistSplit(r, rightbuf, rvectup, &nlen, giststate,
(res && rvectup[nlen - 1] == itup[*len - 1]) ? res : NULL);
ReleaseBuffer(rightbuf);
for (j = 1; j < r->rd_att->natts; j++)
if ((!isAttByVal(giststate, j)) && !v.spl_risnull[j])
pfree(DatumGetPointer(v.spl_rattr[j]));
}
else
{
OffsetNumber l;
l = gistwritebuffer(r, right, rvectup, v.spl_nright, FirstOffsetNumber);
WriteBuffer(rightbuf);
if (res)
ItemPointerSet(&((*res)->pointerData), rbknum, l);
nlen = 1;
newtup = (IndexTuple *) palloc(sizeof(IndexTuple) * 1);
newtup[0] = gistFormTuple(giststate, r, v.spl_rattr, v.spl_rattrsize, v.spl_risnull);
ItemPointerSet(&(newtup[0]->t_tid), rbknum, 1);
}
if (gistnospace(left, lvectup, v.spl_nleft))
{
int llen = v.spl_nleft;
IndexTuple *lntup;
lntup = gistSplit(r, leftbuf, lvectup, &llen, giststate,
(res && lvectup[llen - 1] == itup[*len - 1]) ? res : NULL);
ReleaseBuffer(leftbuf);
for (j = 1; j < r->rd_att->natts; j++)
if ((!isAttByVal(giststate, j)) && !v.spl_lisnull[j])
pfree(DatumGetPointer(v.spl_lattr[j]));
newtup = gistjoinvector(newtup, &nlen, lntup, llen);
pfree(lntup);
}
else
{
OffsetNumber l;
l = gistwritebuffer(r, left, lvectup, v.spl_nleft, FirstOffsetNumber);
if (BufferGetBlockNumber(buffer) != GISTP_ROOT)
PageRestoreTempPage(left, p);
WriteBuffer(leftbuf);
if (res)
ItemPointerSet(&((*res)->pointerData), lbknum, l);
nlen += 1;
newtup = (IndexTuple *) repalloc((void *) newtup, sizeof(IndexTuple) * nlen);
newtup[nlen - 1] = gistFormTuple(giststate, r, v.spl_lattr, v.spl_lattrsize, v.spl_lisnull);
ItemPointerSet(&(newtup[nlen - 1]->t_tid), lbknum, 1);
}
/* !!! pfree */
pfree(rvectup);
pfree(lvectup);
pfree(v.spl_left);
pfree(v.spl_right);
*len = nlen;
return newtup;
}
/*
* Calls user picksplit method for attno columns to split vector to
* two vectors. May use attno+n columns data to
* get better split.
* Returns TRUE and v->spl_equiv = NULL if left and right unions of attno columns are the same,
* so caller may find better split
* Returns TRUE and v->spl_equiv != NULL if there is tuples which may be freely moved
*/
static bool
gistUserPicksplit(Relation r, GistEntryVector *entryvec, int attno, GistSplitVector *v,
IndexTuple *itup, int len, GISTSTATE *giststate)
{
GIST_SPLITVEC *sv = &v->splitVector;
/*
* now let the user-defined picksplit function set up the split vector; in
* entryvec there is no null value!!
*/
sv->spl_ldatum_exists = (v->spl_lisnull[attno]) ? false : true;
sv->spl_rdatum_exists = (v->spl_risnull[attno]) ? false : true;
sv->spl_ldatum = v->spl_lattr[attno];
sv->spl_rdatum = v->spl_rattr[attno];
FunctionCall2(&giststate->picksplitFn[attno],
PointerGetDatum(entryvec),
PointerGetDatum(sv));
if ( sv->spl_nleft == 0 || sv->spl_nright == 0 )
{
ereport(DEBUG1,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("picksplit method for column %d of index \"%s\" failed",
attno+1, RelationGetRelationName(r)),
errhint("The index is not optimal. To optimize it, contact a developer, or try to use the column as the second one in the CREATE INDEX command.")));
/*
* Reinit GIST_SPLITVEC. Although that fields are not used
* by genericPickSplit(), let us set up it for further processing
*/
sv->spl_ldatum_exists = (v->spl_lisnull[attno]) ? false : true;
sv->spl_rdatum_exists = (v->spl_risnull[attno]) ? false : true;
sv->spl_ldatum = v->spl_lattr[attno];
sv->spl_rdatum = v->spl_rattr[attno];
genericPickSplit(giststate, entryvec, sv, attno);
if (sv->spl_ldatum_exists || sv->spl_rdatum_exists)
supportSecondarySplit(r, giststate, attno, sv, v->spl_lattr[attno], v->spl_rattr[attno]);
}
else
{
/* compatibility with old code */
if (sv->spl_left[sv->spl_nleft - 1] == InvalidOffsetNumber)
sv->spl_left[sv->spl_nleft - 1] = (OffsetNumber) (entryvec->n - 1);
if (sv->spl_right[sv->spl_nright - 1] == InvalidOffsetNumber)
sv->spl_right[sv->spl_nright - 1] = (OffsetNumber) (entryvec->n - 1);
if (sv->spl_ldatum_exists || sv->spl_rdatum_exists)
{
elog(LOG, "PickSplit method of %d columns of index '%s' doesn't support secondary split",
attno + 1, RelationGetRelationName(r));
supportSecondarySplit(r, giststate, attno, sv, v->spl_lattr[attno], v->spl_rattr[attno]);
}
}
v->spl_lattr[attno] = sv->spl_ldatum;
v->spl_rattr[attno] = sv->spl_rdatum;
v->spl_lisnull[attno] = false;
v->spl_risnull[attno] = false;
/*
* if index is multikey, then we must to try get smaller bounding box for
* subkey(s)
*/
v->spl_equiv = NULL;
if (giststate->tupdesc->natts > 1 && attno + 1 != giststate->tupdesc->natts)
{
if (gistKeyIsEQ(giststate, attno, sv->spl_ldatum, sv->spl_rdatum))
{
/*
* Left and right key's unions are equial, so we can get better
* split by following columns. Note, unions for attno columns are
* already done.
*/
return true;
}
else
{
int LenEquiv;
v->spl_equiv = (bool *) palloc0(sizeof(bool) * (entryvec->n + 1));
LenEquiv = gistfindgroup(r, giststate, entryvec->vector, v, attno);
/*
* if possible, we should distribute equivalent tuples
*/
if (LenEquiv == 0)
{
gistunionsubkey(giststate, itup, v, attno + 1);
}
else
{
cleanupOffsets(sv->spl_left, &sv->spl_nleft, v->spl_equiv, &LenEquiv);
cleanupOffsets(sv->spl_right, &sv->spl_nright, v->spl_equiv, &LenEquiv);
gistunionsubkey(giststate, itup, v, attno + 1);
if (LenEquiv == 1)
{
/*
* In case with one tuple we just choose left-right by
* penalty. It's simplify user-defined pickSplit
*/
OffsetNumber toMove = InvalidOffsetNumber;
for (toMove = FirstOffsetNumber; toMove < entryvec->n; toMove++)
if (v->spl_equiv[toMove])
break;
Assert(toMove < entryvec->n);
placeOne(r, giststate, v, itup[toMove - 1], toMove, attno + 1);
/*
* redo gistunionsubkey(): it will not degradate
* performance, because it's very rarely
*/
v->spl_equiv = NULL;
gistunionsubkey(giststate, itup, v, attno + 1);
return false;
}
else if (LenEquiv > 1)
return true;
}
}
}
return false;
}