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diff --git a/src/backend/access/gist/gistsplit.c b/src/backend/access/gist/gistsplit.c
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+/*-------------------------------------------------------------------------
+ *
+ * gistsplit.c
+ * Multi-column page splitting algorithm
+ *
+ * This file is concerned with making good page-split decisions in multi-column
+ * GiST indexes. The opclass-specific picksplit functions can only be expected
+ * to produce answers based on a single column. We first run the picksplit
+ * function for column 1; then, if there are more columns, we check if any of
+ * the tuples are "don't cares" so far as the column 1 split is concerned
+ * (that is, they could go to either side for no additional penalty). If so,
+ * we try to redistribute those tuples on the basis of the next column.
+ * Repeat till we're out of columns.
+ *
+ * gistSplitByKey() is the entry point to this file.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/backend/access/gist/gistsplit.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "utils/rel.h"
+
+typedef struct
+{
+ OffsetNumber *entries;
+ int len;
+ Datum *attr;
+ bool *isnull;
+ bool *dontcare;
+} GistSplitUnion;
+
+
+/*
+ * Form unions of subkeys in itvec[] entries listed in gsvp->entries[],
+ * ignoring any tuples that are marked in gsvp->dontcare[]. Subroutine for
+ * gistunionsubkey.
+ */
+static void
+gistunionsubkeyvec(GISTSTATE *giststate, IndexTuple *itvec,
+ GistSplitUnion *gsvp)
+{
+ IndexTuple *cleanedItVec;
+ int i,
+ cleanedLen = 0;
+
+ cleanedItVec = (IndexTuple *) palloc(sizeof(IndexTuple) * gsvp->len);
+
+ for (i = 0; i < gsvp->len; i++)
+ {
+ if (gsvp->dontcare && gsvp->dontcare[gsvp->entries[i]])
+ continue;
+
+ cleanedItVec[cleanedLen++] = itvec[gsvp->entries[i] - 1];
+ }
+
+ gistMakeUnionItVec(giststate, cleanedItVec, cleanedLen,
+ gsvp->attr, gsvp->isnull);
+
+ pfree(cleanedItVec);
+}
+
+/*
+ * Recompute unions of left- and right-side subkeys after a page split,
+ * ignoring any tuples that are marked in spl->spl_dontcare[].
+ *
+ * Note: we always recompute union keys for all index columns. In some cases
+ * this might represent duplicate work for the leftmost column(s), but it's
+ * not safe to assume that "zero penalty to move a tuple" means "the union
+ * key doesn't change at all". Penalty functions aren't 100% accurate.
+ */
+static void
+gistunionsubkey(GISTSTATE *giststate, IndexTuple *itvec, GistSplitVector *spl)
+{
+ GistSplitUnion gsvp;
+
+ gsvp.dontcare = spl->spl_dontcare;
+
+ gsvp.entries = spl->splitVector.spl_left;
+ gsvp.len = spl->splitVector.spl_nleft;
+ gsvp.attr = spl->spl_lattr;
+ gsvp.isnull = spl->spl_lisnull;
+
+ gistunionsubkeyvec(giststate, itvec, &gsvp);
+
+ gsvp.entries = spl->splitVector.spl_right;
+ gsvp.len = spl->splitVector.spl_nright;
+ gsvp.attr = spl->spl_rattr;
+ gsvp.isnull = spl->spl_risnull;
+
+ gistunionsubkeyvec(giststate, itvec, &gsvp);
+}
+
+/*
+ * Find tuples that are "don't cares", that is could be moved to the other
+ * side of the split with zero penalty, so far as the attno column is
+ * concerned.
+ *
+ * Don't-care tuples are marked by setting the corresponding entry in
+ * spl->spl_dontcare[] to "true". Caller must have initialized that array
+ * to zeroes.
+ *
+ * Returns number of don't-cares found.
+ */
+static int
+findDontCares(Relation r, GISTSTATE *giststate, GISTENTRY *valvec,
+ GistSplitVector *spl, int attno)
+{
+ int i;
+ GISTENTRY entry;
+ int NumDontCare = 0;
+
+ /*
+ * First, search the left-side tuples to see if any have zero penalty to
+ * be added to the right-side union key.
+ *
+ * attno column is known all-not-null (see gistSplitByKey), so we need not
+ * check for nulls
+ */
+ gistentryinit(entry, spl->splitVector.spl_rdatum, r, NULL,
+ (OffsetNumber) 0, false);
+ for (i = 0; i < spl->splitVector.spl_nleft; i++)
+ {
+ int j = spl->splitVector.spl_left[i];
+ float penalty = gistpenalty(giststate, attno, &entry, false,
+ &valvec[j], false);
+
+ if (penalty == 0.0)
+ {
+ spl->spl_dontcare[j] = true;
+ NumDontCare++;
+ }
+ }
+
+ /* And conversely for the right-side tuples */
+ gistentryinit(entry, spl->splitVector.spl_ldatum, r, NULL,
+ (OffsetNumber) 0, false);
+ for (i = 0; i < spl->splitVector.spl_nright; i++)
+ {
+ int j = spl->splitVector.spl_right[i];
+ float penalty = gistpenalty(giststate, attno, &entry, false,
+ &valvec[j], false);
+
+ if (penalty == 0.0)
+ {
+ spl->spl_dontcare[j] = true;
+ NumDontCare++;
+ }
+ }
+
+ return NumDontCare;
+}
+
+/*
+ * Remove tuples that are marked don't-cares from the tuple index array a[]
+ * of length *len. This is applied separately to the spl_left and spl_right
+ * arrays.
+ */
+static void
+removeDontCares(OffsetNumber *a, int *len, const bool *dontcare)
+{
+ int origlen,
+ newlen,
+ i;
+ OffsetNumber *curwpos;
+
+ origlen = newlen = *len;
+ curwpos = a;
+ for (i = 0; i < origlen; i++)
+ {
+ OffsetNumber ai = a[i];
+
+ if (dontcare[ai] == false)
+ {
+ /* re-emit item into a[] */
+ *curwpos = ai;
+ curwpos++;
+ }
+ else
+ newlen--;
+ }
+
+ *len = newlen;
+}
+
+/*
+ * Place a single don't-care tuple into either the left or right side of the
+ * split, according to which has least penalty for merging the tuple into
+ * the previously-computed union keys. We need consider only columns starting
+ * at attno.
+ */
+static void
+placeOne(Relation r, GISTSTATE *giststate, GistSplitVector *v,
+ IndexTuple itup, OffsetNumber off, int attno)
+{
+ GISTENTRY identry[INDEX_MAX_KEYS];
+ bool isnull[INDEX_MAX_KEYS];
+ bool toLeft = true;
+
+ gistDeCompressAtt(giststate, r, itup, NULL, (OffsetNumber) 0,
+ identry, isnull);
+
+ for (; attno < giststate->nonLeafTupdesc->natts; attno++)
+ {
+ float lpenalty,
+ rpenalty;
+ GISTENTRY entry;
+
+ gistentryinit(entry, v->spl_lattr[attno], r, NULL, 0, false);
+ lpenalty = gistpenalty(giststate, attno, &entry, v->spl_lisnull[attno],
+ identry + attno, isnull[attno]);
+ gistentryinit(entry, v->spl_rattr[attno], r, NULL, 0, false);
+ rpenalty = gistpenalty(giststate, attno, &entry, v->spl_risnull[attno],
+ identry + attno, isnull[attno]);
+
+ if (lpenalty != rpenalty)
+ {
+ if (lpenalty > rpenalty)
+ toLeft = false;
+ break;
+ }
+ }
+
+ if (toLeft)
+ v->splitVector.spl_left[v->splitVector.spl_nleft++] = off;
+ else
+ v->splitVector.spl_right[v->splitVector.spl_nright++] = off;
+}
+
+#define SWAPVAR( s, d, t ) \
+do { \
+ (t) = (s); \
+ (s) = (d); \
+ (d) = (t); \
+} while(0)
+
+/*
+ * Clean up when we did a secondary split but the user-defined PickSplit
+ * method didn't support it (leaving spl_ldatum_exists or spl_rdatum_exists
+ * true).
+ *
+ * We consider whether to swap the left and right outputs of the secondary
+ * split; this can be worthwhile if the penalty for merging those tuples into
+ * the previously chosen sets is less that way.
+ *
+ * In any case we must update the union datums for the current column by
+ * adding in the previous union keys (oldL/oldR), since the user-defined
+ * PickSplit method didn't do so.
+ */
+static void
+supportSecondarySplit(Relation r, GISTSTATE *giststate, int attno,
+ GIST_SPLITVEC *sv, Datum oldL, Datum oldR)
+{
+ bool leaveOnLeft = true,
+ tmpBool;
+ GISTENTRY entryL,
+ entryR,
+ entrySL,
+ entrySR;
+
+ gistentryinit(entryL, oldL, r, NULL, 0, false);
+ gistentryinit(entryR, oldR, r, NULL, 0, false);
+ gistentryinit(entrySL, sv->spl_ldatum, r, NULL, 0, false);
+ gistentryinit(entrySR, sv->spl_rdatum, r, NULL, 0, false);
+
+ if (sv->spl_ldatum_exists && sv->spl_rdatum_exists)
+ {
+ float penalty1,
+ penalty2;
+
+ penalty1 = gistpenalty(giststate, attno, &entryL, false, &entrySL, false) +
+ gistpenalty(giststate, attno, &entryR, false, &entrySR, false);
+ penalty2 = gistpenalty(giststate, attno, &entryL, false, &entrySR, false) +
+ gistpenalty(giststate, attno, &entryR, false, &entrySL, false);
+
+ if (penalty1 > penalty2)
+ leaveOnLeft = false;
+ }
+ else
+ {
+ GISTENTRY *entry1 = (sv->spl_ldatum_exists) ? &entryL : &entryR;
+ float penalty1,
+ penalty2;
+
+ /*
+ * There is only one previously defined union, so we just choose swap
+ * or not by lowest penalty for that side. We can only get here if a
+ * secondary split happened to have all NULLs in its column in the
+ * tuples that the outer recursion level had assigned to one side.
+ * (Note that the null checks in gistSplitByKey don't prevent the
+ * case, because they'll only be checking tuples that were considered
+ * don't-cares at the outer recursion level, not the tuples that went
+ * into determining the passed-down left and right union keys.)
+ */
+ penalty1 = gistpenalty(giststate, attno, entry1, false, &entrySL, false);
+ penalty2 = gistpenalty(giststate, attno, entry1, false, &entrySR, false);
+
+ if (penalty1 < penalty2)
+ leaveOnLeft = (sv->spl_ldatum_exists) ? true : false;
+ else
+ leaveOnLeft = (sv->spl_rdatum_exists) ? true : false;
+ }
+
+ if (leaveOnLeft == false)
+ {
+ /*
+ * swap left and right
+ */
+ OffsetNumber *off,
+ noff;
+ Datum datum;
+
+ SWAPVAR(sv->spl_left, sv->spl_right, off);
+ SWAPVAR(sv->spl_nleft, sv->spl_nright, noff);
+ SWAPVAR(sv->spl_ldatum, sv->spl_rdatum, datum);
+ gistentryinit(entrySL, sv->spl_ldatum, r, NULL, 0, false);
+ gistentryinit(entrySR, sv->spl_rdatum, r, NULL, 0, false);
+ }
+
+ if (sv->spl_ldatum_exists)
+ gistMakeUnionKey(giststate, attno, &entryL, false, &entrySL, false,
+ &sv->spl_ldatum, &tmpBool);
+
+ if (sv->spl_rdatum_exists)
+ gistMakeUnionKey(giststate, attno, &entryR, false, &entrySR, false,
+ &sv->spl_rdatum, &tmpBool);
+
+ sv->spl_ldatum_exists = sv->spl_rdatum_exists = false;
+}
+
+/*
+ * Trivial picksplit implementation. Function called only
+ * if user-defined picksplit puts all keys on the same side of the split.
+ * That is a bug of user-defined picksplit but we don't want to fail.
+ */
+static void
+genericPickSplit(GISTSTATE *giststate, GistEntryVector *entryvec, GIST_SPLITVEC *v, int attno)
+{
+ OffsetNumber i,
+ maxoff;
+ int nbytes;
+ GistEntryVector *evec;
+
+ maxoff = entryvec->n - 1;
+
+ nbytes = (maxoff + 2) * sizeof(OffsetNumber);
+
+ v->spl_left = (OffsetNumber *) palloc(nbytes);
+ v->spl_right = (OffsetNumber *) palloc(nbytes);
+ v->spl_nleft = v->spl_nright = 0;
+
+ for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+ {
+ if (i <= (maxoff - FirstOffsetNumber + 1) / 2)
+ {
+ v->spl_left[v->spl_nleft] = i;
+ v->spl_nleft++;
+ }
+ else
+ {
+ v->spl_right[v->spl_nright] = i;
+ v->spl_nright++;
+ }
+ }
+
+ /*
+ * Form union datums for each side
+ */
+ evec = palloc(sizeof(GISTENTRY) * entryvec->n + GEVHDRSZ);
+
+ evec->n = v->spl_nleft;
+ memcpy(evec->vector, entryvec->vector + FirstOffsetNumber,
+ sizeof(GISTENTRY) * evec->n);
+ v->spl_ldatum = FunctionCall2Coll(&giststate->unionFn[attno],
+ giststate->supportCollation[attno],
+ PointerGetDatum(evec),
+ PointerGetDatum(&nbytes));
+
+ evec->n = v->spl_nright;
+ memcpy(evec->vector, entryvec->vector + FirstOffsetNumber + v->spl_nleft,
+ sizeof(GISTENTRY) * evec->n);
+ v->spl_rdatum = FunctionCall2Coll(&giststate->unionFn[attno],
+ giststate->supportCollation[attno],
+ PointerGetDatum(evec),
+ PointerGetDatum(&nbytes));
+}
+
+/*
+ * Calls user picksplit method for attno column to split tuples into
+ * two vectors.
+ *
+ * Returns false if split is complete (there are no more index columns, or
+ * there is no need to consider them because split is optimal already).
+ *
+ * Returns true and v->spl_dontcare = NULL if the picksplit result is
+ * degenerate (all tuples seem to be don't-cares), so we should just
+ * disregard this column and split on the next column(s) instead.
+ *
+ * Returns true and v->spl_dontcare != NULL if there are don't-care tuples
+ * that could be relocated based on the next column(s). The don't-care
+ * tuples have been removed from the split and must be reinserted by caller.
+ * There is at least one non-don't-care tuple on each side of the split,
+ * and union keys for all columns are updated to include just those tuples.
+ *
+ * A true result implies there is at least one more index column.
+ */
+static bool
+gistUserPicksplit(Relation r, GistEntryVector *entryvec, int attno, GistSplitVector *v,
+ IndexTuple *itup, int len, GISTSTATE *giststate)
+{
+ GIST_SPLITVEC *sv = &v->splitVector;
+
+ /*
+ * Prepare spl_ldatum/spl_rdatum/spl_ldatum_exists/spl_rdatum_exists in
+ * case we are doing a secondary split (see comments in gist.h).
+ */
+ 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];
+
+ /*
+ * Let the opclass-specific PickSplit method do its thing. Note that at
+ * this point we know there are no null keys in the entryvec.
+ */
+ FunctionCall2Coll(&giststate->picksplitFn[attno],
+ giststate->supportCollation[attno],
+ PointerGetDatum(entryvec),
+ PointerGetDatum(sv));
+
+ if (sv->spl_nleft == 0 || sv->spl_nright == 0)
+ {
+ /*
+ * User-defined picksplit failed to create an actual split, ie it put
+ * everything on the same side. Complain but cope.
+ */
+ 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 these fields are not used by
+ * genericPickSplit(), set them up 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];
+
+ /* Do a generic split */
+ genericPickSplit(giststate, entryvec, sv, attno);
+ }
+ else
+ {
+ /* hack for compatibility with old picksplit API */
+ 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);
+ }
+
+ /* Clean up if PickSplit didn't take care of a secondary split */
+ if (sv->spl_ldatum_exists || sv->spl_rdatum_exists)
+ supportSecondarySplit(r, giststate, attno, sv,
+ v->spl_lattr[attno], v->spl_rattr[attno]);
+
+ /* emit union datums computed by PickSplit back to v arrays */
+ 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 columns remain, then consider whether we can improve the split
+ * by using them.
+ */
+ v->spl_dontcare = NULL;
+
+ if (attno + 1 < giststate->nonLeafTupdesc->natts)
+ {
+ int NumDontCare;
+
+ /*
+ * Make a quick check to see if left and right union keys are equal;
+ * if so, the split is certainly degenerate, so tell caller to
+ * re-split with the next column.
+ */
+ if (gistKeyIsEQ(giststate, attno, sv->spl_ldatum, sv->spl_rdatum))
+ return true;
+
+ /*
+ * Locate don't-care tuples, if any. If there are none, the split is
+ * optimal, so just fall out and return false.
+ */
+ v->spl_dontcare = (bool *) palloc0(sizeof(bool) * (entryvec->n + 1));
+
+ NumDontCare = findDontCares(r, giststate, entryvec->vector, v, attno);
+
+ if (NumDontCare > 0)
+ {
+ /*
+ * Remove don't-cares from spl_left[] and spl_right[].
+ */
+ removeDontCares(sv->spl_left, &sv->spl_nleft, v->spl_dontcare);
+ removeDontCares(sv->spl_right, &sv->spl_nright, v->spl_dontcare);
+
+ /*
+ * If all tuples on either side were don't-cares, the split is
+ * degenerate, and we're best off to ignore it and split on the
+ * next column. (We used to try to press on with a secondary
+ * split by forcing a random tuple on each side to be treated as
+ * non-don't-care, but it seems unlikely that that technique
+ * really gives a better result. Note that we don't want to try a
+ * secondary split with empty left or right primary split sides,
+ * because then there is no union key on that side for the
+ * PickSplit function to try to expand, so it can have no good
+ * figure of merit for what it's doing. Also note that this check
+ * ensures we can't produce a bogus one-side-only split in the
+ * NumDontCare == 1 special case below.)
+ */
+ if (sv->spl_nleft == 0 || sv->spl_nright == 0)
+ {
+ v->spl_dontcare = NULL;
+ return true;
+ }
+
+ /*
+ * Recompute union keys, considering only non-don't-care tuples.
+ * NOTE: this will set union keys for remaining index columns,
+ * which will cause later calls of gistUserPicksplit to pass those
+ * values down to user-defined PickSplit methods with
+ * spl_ldatum_exists/spl_rdatum_exists set true.
+ */
+ gistunionsubkey(giststate, itup, v);
+
+ if (NumDontCare == 1)
+ {
+ /*
+ * If there's only one don't-care tuple then we can't do a
+ * PickSplit on it, so just choose whether to send it left or
+ * right by comparing penalties. We needed the
+ * gistunionsubkey step anyway so that we have appropriate
+ * union keys for figuring the penalties.
+ */
+ OffsetNumber toMove;
+
+ /* find it ... */
+ for (toMove = FirstOffsetNumber; toMove < entryvec->n; toMove++)
+ {
+ if (v->spl_dontcare[toMove])
+ break;
+ }
+ Assert(toMove < entryvec->n);
+
+ /* ... and assign it to cheaper side */
+ placeOne(r, giststate, v, itup[toMove - 1], toMove, attno + 1);
+
+ /*
+ * At this point the union keys are wrong, but we don't care
+ * because we're done splitting. The outermost recursion
+ * level of gistSplitByKey will fix things before returning.
+ */
+ }
+ else
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/*
+ * simply split page in half
+ */
+static void
+gistSplitHalf(GIST_SPLITVEC *v, int len)
+{
+ int i;
+
+ v->spl_nright = v->spl_nleft = 0;
+ v->spl_left = (OffsetNumber *) palloc(len * sizeof(OffsetNumber));
+ v->spl_right = (OffsetNumber *) palloc(len * sizeof(OffsetNumber));
+ for (i = 1; i <= len; i++)
+ if (i < len / 2)
+ v->spl_right[v->spl_nright++] = i;
+ else
+ v->spl_left[v->spl_nleft++] = i;
+
+ /* we need not compute union keys, caller took care of it */
+}
+
+/*
+ * gistSplitByKey: main entry point for page-splitting algorithm
+ *
+ * r: index relation
+ * page: page being split
+ * itup: array of IndexTuples to be processed
+ * len: number of IndexTuples to be processed (must be at least 2)
+ * giststate: additional info about index
+ * v: working state and output area
+ * attno: column we are working on (zero-based index)
+ *
+ * Outside caller must initialize v->spl_lisnull and v->spl_risnull arrays
+ * to all-true. On return, spl_left/spl_nleft contain indexes of tuples
+ * to go left, spl_right/spl_nright contain indexes of tuples to go right,
+ * spl_lattr/spl_lisnull contain left-side union key values, and
+ * spl_rattr/spl_risnull contain right-side union key values. Other fields
+ * in this struct are workspace for this file.
+ *
+ * Outside caller must pass zero for attno. The function may internally
+ * recurse to the next column by passing attno+1.
+ */
+void
+gistSplitByKey(Relation r, Page page, IndexTuple *itup, int len,
+ GISTSTATE *giststate, GistSplitVector *v, int attno)
+{
+ GistEntryVector *entryvec;
+ OffsetNumber *offNullTuples;
+ int nOffNullTuples = 0;
+ int i;
+
+ /* generate the item array, and identify tuples with null keys */
+ /* note that entryvec->vector[0] goes unused in this code */
+ entryvec = palloc(GEVHDRSZ + (len + 1) * sizeof(GISTENTRY));
+ entryvec->n = len + 1;
+ offNullTuples = (OffsetNumber *) palloc(len * sizeof(OffsetNumber));
+
+ for (i = 1; i <= len; i++)
+ {
+ Datum datum;
+ bool IsNull;
+
+ datum = index_getattr(itup[i - 1], attno + 1, giststate->leafTupdesc,
+ &IsNull);
+ gistdentryinit(giststate, attno, &(entryvec->vector[i]),
+ datum, r, page, i,
+ false, IsNull);
+ if (IsNull)
+ offNullTuples[nOffNullTuples++] = i;
+ }
+
+ if (nOffNullTuples == len)
+ {
+ /*
+ * Corner case: All keys in attno column are null, so just transfer
+ * our attention to the next column. If there's no next column, just
+ * split page in half.
+ */
+ v->spl_risnull[attno] = v->spl_lisnull[attno] = true;
+
+ if (attno + 1 < giststate->nonLeafTupdesc->natts)
+ gistSplitByKey(r, page, itup, len, giststate, v, attno + 1);
+ else
+ gistSplitHalf(&v->splitVector, len);
+ }
+ else if (nOffNullTuples > 0)
+ {
+ int j = 0;
+
+ /*
+ * We don't want to mix NULL and not-NULL keys on one page, so split
+ * nulls to right page and not-nulls to left.
+ */
+ v->splitVector.spl_right = offNullTuples;
+ v->splitVector.spl_nright = nOffNullTuples;
+ v->spl_risnull[attno] = true;
+
+ v->splitVector.spl_left = (OffsetNumber *) palloc(len * sizeof(OffsetNumber));
+ v->splitVector.spl_nleft = 0;
+ for (i = 1; i <= len; i++)
+ if (j < v->splitVector.spl_nright && offNullTuples[j] == i)
+ j++;
+ else
+ v->splitVector.spl_left[v->splitVector.spl_nleft++] = i;
+
+ /* Compute union keys, unless outer recursion level will handle it */
+ if (attno == 0 && giststate->nonLeafTupdesc->natts == 1)
+ {
+ v->spl_dontcare = NULL;
+ gistunionsubkey(giststate, itup, v);
+ }
+ }
+ else
+ {
+ /*
+ * All keys are not-null, so apply user-defined PickSplit method
+ */
+ if (gistUserPicksplit(r, entryvec, attno, v, itup, len, giststate))
+ {
+ /*
+ * Splitting on attno column is not optimal, so consider
+ * redistributing don't-care tuples according to the next column
+ */
+ Assert(attno + 1 < giststate->nonLeafTupdesc->natts);
+
+ if (v->spl_dontcare == NULL)
+ {
+ /*
+ * This split was actually degenerate, so ignore it altogether
+ * and just split according to the next column.
+ */
+ gistSplitByKey(r, page, itup, len, giststate, v, attno + 1);
+ }
+ else
+ {
+ /*
+ * Form an array of just the don't-care tuples to pass to a
+ * recursive invocation of this function for the next column.
+ */
+ IndexTuple *newitup = (IndexTuple *) palloc(len * sizeof(IndexTuple));
+ OffsetNumber *map = (OffsetNumber *) palloc(len * sizeof(OffsetNumber));
+ int newlen = 0;
+ GIST_SPLITVEC backupSplit;
+
+ for (i = 0; i < len; i++)
+ {
+ if (v->spl_dontcare[i + 1])
+ {
+ newitup[newlen] = itup[i];
+ map[newlen] = i + 1;
+ newlen++;
+ }
+ }
+
+ Assert(newlen > 0);
+
+ /*
+ * Make a backup copy of v->splitVector, since the recursive
+ * call will overwrite that with its own result.
+ */
+ backupSplit = v->splitVector;
+ backupSplit.spl_left = (OffsetNumber *) palloc(sizeof(OffsetNumber) * len);
+ memcpy(backupSplit.spl_left, v->splitVector.spl_left, sizeof(OffsetNumber) * v->splitVector.spl_nleft);
+ backupSplit.spl_right = (OffsetNumber *) palloc(sizeof(OffsetNumber) * len);
+ memcpy(backupSplit.spl_right, v->splitVector.spl_right, sizeof(OffsetNumber) * v->splitVector.spl_nright);
+
+ /* Recursively decide how to split the don't-care tuples */
+ gistSplitByKey(r, page, newitup, newlen, giststate, v, attno + 1);
+
+ /* Merge result of subsplit with non-don't-care tuples */
+ for (i = 0; i < v->splitVector.spl_nleft; i++)
+ backupSplit.spl_left[backupSplit.spl_nleft++] = map[v->splitVector.spl_left[i] - 1];
+ for (i = 0; i < v->splitVector.spl_nright; i++)
+ backupSplit.spl_right[backupSplit.spl_nright++] = map[v->splitVector.spl_right[i] - 1];
+
+ v->splitVector = backupSplit;
+ }
+ }
+ }
+
+ /*
+ * If we're handling a multicolumn index, at the end of the recursion
+ * recompute the left and right union datums for all index columns. This
+ * makes sure we hand back correct union datums in all corner cases,
+ * including when we haven't processed all columns to start with, or when
+ * a secondary split moved "don't care" tuples from one side to the other
+ * (we really shouldn't assume that that didn't change the union datums).
+ *
+ * Note: when we're in an internal recursion (attno > 0), we do not worry
+ * about whether the union datums we return with are sensible, since
+ * calling levels won't care. Also, in a single-column index, we expect
+ * that PickSplit (or the special cases above) produced correct union
+ * datums.
+ */
+ if (attno == 0 && giststate->nonLeafTupdesc->natts > 1)
+ {
+ v->spl_dontcare = NULL;
+ gistunionsubkey(giststate, itup, v);
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 08:23:28 +0000