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authorUlrich Drepper <drepper@redhat.com>2000-01-02 06:01:06 +0000
committerUlrich Drepper <drepper@redhat.com>2000-01-02 06:01:06 +0000
commit8d6f1731fcd082e4f744ba9cb4bde4be7c08f1b3 (patch)
tree099a250d7366aef2ab028fdb24f0d692cd784b4a /db/btree/bt_split.c
parent9a6450d578556c11e7c173d2f28362345b8f1258 (diff)
downloadglibc-8d6f1731fcd082e4f744ba9cb4bde4be7c08f1b3.tar.gz
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Update.
	* Makeconfig (all-subdirs): Remove db and db2.
	* db/*: Removed.
	* db2/*: Removed.
Diffstat (limited to 'db/btree/bt_split.c')
-rw-r--r--db/btree/bt_split.c829
1 files changed, 0 insertions, 829 deletions
diff --git a/db/btree/bt_split.c b/db/btree/bt_split.c
deleted file mode 100644
index 4119ccbf79..0000000000
--- a/db/btree/bt_split.c
+++ /dev/null
@@ -1,829 +0,0 @@
-/*-
- * Copyright (c) 1990, 1993, 1994
- *	The Regents of the University of California.  All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Mike Olson.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *	This product includes software developed by the University of
- *	California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)bt_split.c	8.9 (Berkeley) 7/26/94";
-#endif /* LIBC_SCCS and not lint */
-
-#include <sys/types.h>
-
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <db.h>
-#include "btree.h"
-
-static int	 bt_broot __P((BTREE *, PAGE *, PAGE *, PAGE *));
-static PAGE	*bt_page
-		    __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t));
-static int	 bt_preserve __P((BTREE *, pgno_t));
-static PAGE	*bt_psplit
-		    __P((BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t));
-static PAGE	*bt_root
-		    __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t));
-static int	 bt_rroot __P((BTREE *, PAGE *, PAGE *, PAGE *));
-static recno_t	 rec_total __P((PAGE *));
-
-#ifdef STATISTICS
-u_long	bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved;
-#endif
-
-/*
- * __BT_SPLIT -- Split the tree.
- *
- * Parameters:
- *	t:	tree
- *	sp:	page to split
- *	key:	key to insert
- *	data:	data to insert
- *	flags:	BIGKEY/BIGDATA flags
- *	ilen:	insert length
- *	skip:	index to leave open
- *
- * Returns:
- *	RET_ERROR, RET_SUCCESS
- */
-int
-__bt_split(t, sp, key, data, flags, ilen, argskip)
-	BTREE *t;
-	PAGE *sp;
-	const DBT *key, *data;
-	int flags;
-	size_t ilen;
-	u_int32_t argskip;
-{
-	BINTERNAL *bi;
-	BLEAF *bl, *tbl;
-	DBT a, b;
-	EPGNO *parent;
-	PAGE *h, *l, *r, *lchild, *rchild;
-	indx_t nxtindex;
-	u_int16_t skip;
-	u_int32_t n, nbytes, nksize;
-	int parentsplit;
-	char *dest;
-
-	/*
-	 * Split the page into two pages, l and r.  The split routines return
-	 * a pointer to the page into which the key should be inserted and with
-	 * skip set to the offset which should be used.  Additionally, l and r
-	 * are pinned.
-	 */
-	skip = argskip;
-	h = sp->pgno == P_ROOT ?
-	    bt_root(t, sp, &l, &r, &skip, ilen) :
-	    bt_page(t, sp, &l, &r, &skip, ilen);
-	if (h == NULL)
-		return (RET_ERROR);
-
-	/*
-	 * Insert the new key/data pair into the leaf page.  (Key inserts
-	 * always cause a leaf page to split first.)
-	 */
-	h->linp[skip] = h->upper -= ilen;
-	dest = (char *)h + h->upper;
-	if (F_ISSET(t, R_RECNO))
-		WR_RLEAF(dest, data, flags)
-	else
-		WR_BLEAF(dest, key, data, flags)
-
-	/* If the root page was split, make it look right. */
-	if (sp->pgno == P_ROOT &&
-	    (F_ISSET(t, R_RECNO) ?
-	    bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
-		goto err2;
-
-	/*
-	 * Now we walk the parent page stack -- a LIFO stack of the pages that
-	 * were traversed when we searched for the page that split.  Each stack
-	 * entry is a page number and a page index offset.  The offset is for
-	 * the page traversed on the search.  We've just split a page, so we
-	 * have to insert a new key into the parent page.
-	 *
-	 * If the insert into the parent page causes it to split, may have to
-	 * continue splitting all the way up the tree.  We stop if the root
-	 * splits or the page inserted into didn't have to split to hold the
-	 * new key.  Some algorithms replace the key for the old page as well
-	 * as the new page.  We don't, as there's no reason to believe that the
-	 * first key on the old page is any better than the key we have, and,
-	 * in the case of a key being placed at index 0 causing the split, the
-	 * key is unavailable.
-	 *
-	 * There are a maximum of 5 pages pinned at any time.  We keep the left
-	 * and right pages pinned while working on the parent.   The 5 are the
-	 * two children, left parent and right parent (when the parent splits)
-	 * and the root page or the overflow key page when calling bt_preserve.
-	 * This code must make sure that all pins are released other than the
-	 * root page or overflow page which is unlocked elsewhere.
-	 */
-	while ((parent = BT_POP(t)) != NULL) {
-		lchild = l;
-		rchild = r;
-
-		/* Get the parent page. */
-		if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
-			goto err2;
-
-	 	/*
-		 * The new key goes ONE AFTER the index, because the split
-		 * was to the right.
-		 */
-		skip = parent->index + 1;
-
-		/*
-		 * Calculate the space needed on the parent page.
-		 *
-		 * Prefix trees: space hack when inserting into BINTERNAL
-		 * pages.  Retain only what's needed to distinguish between
-		 * the new entry and the LAST entry on the page to its left.
-		 * If the keys compare equal, retain the entire key.  Note,
-		 * we don't touch overflow keys, and the entire key must be
-		 * retained for the next-to-left most key on the leftmost
-		 * page of each level, or the search will fail.  Applicable
-		 * ONLY to internal pages that have leaf pages as children.
-		 * Further reduction of the key between pairs of internal
-		 * pages loses too much information.
-		 */
-		switch (rchild->flags & P_TYPE) {
-		case P_BINTERNAL:
-			bi = GETBINTERNAL(rchild, 0);
-			nbytes = NBINTERNAL(bi->ksize);
-			break;
-		case P_BLEAF:
-			bl = GETBLEAF(rchild, 0);
-			nbytes = NBINTERNAL(bl->ksize);
-			if (t->bt_pfx && !(bl->flags & P_BIGKEY) &&
-			    (h->prevpg != P_INVALID || skip > 1)) {
-				tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1);
-				a.size = tbl->ksize;
-				a.data = tbl->bytes;
-				b.size = bl->ksize;
-				b.data = bl->bytes;
-				nksize = t->bt_pfx(&a, &b);
-				n = NBINTERNAL(nksize);
-				if (n < nbytes) {
-#ifdef STATISTICS
-					bt_pfxsaved += nbytes - n;
-#endif
-					nbytes = n;
-				} else
-					nksize = 0;
-			} else
-				nksize = 0;
-			break;
-		case P_RINTERNAL:
-		case P_RLEAF:
-			nbytes = NRINTERNAL;
-			break;
-		default:
-			abort();
-		}
-
-		/* Split the parent page if necessary or shift the indices. */
-		if ((u_int32_t) (h->upper - h->lower)
-		    < nbytes + sizeof(indx_t)) {
-			sp = h;
-			h = h->pgno == P_ROOT ?
-			    bt_root(t, h, &l, &r, &skip, nbytes) :
-			    bt_page(t, h, &l, &r, &skip, nbytes);
-			if (h == NULL)
-				goto err1;
-			parentsplit = 1;
-		} else {
-			if (skip < (nxtindex = NEXTINDEX(h)))
-				memmove(h->linp + skip + 1, h->linp + skip,
-				    (nxtindex - skip) * sizeof(indx_t));
-			h->lower += sizeof(indx_t);
-			parentsplit = 0;
-		}
-
-		/* Insert the key into the parent page. */
-		switch (rchild->flags & P_TYPE) {
-		case P_BINTERNAL:
-			h->linp[skip] = h->upper -= nbytes;
-			dest = (char *)h + h->linp[skip];
-			memmove(dest, bi, nbytes);
-			((BINTERNAL *)dest)->pgno = rchild->pgno;
-			break;
-		case P_BLEAF:
-			h->linp[skip] = h->upper -= nbytes;
-			dest = (char *)h + h->linp[skip];
-			WR_BINTERNAL(dest, nksize ? nksize : bl->ksize,
-			    rchild->pgno, bl->flags & P_BIGKEY);
-			memmove(dest, bl->bytes, nksize ? nksize : bl->ksize);
-			if (bl->flags & P_BIGKEY &&
-			    bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
-				goto err1;
-			break;
-		case P_RINTERNAL:
-			/*
-			 * Update the left page count.  If split
-			 * added at index 0, fix the correct page.
-			 */
-			if (skip > 0)
-				dest = (char *)h + h->linp[skip - 1];
-			else
-				dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
-			((RINTERNAL *)dest)->nrecs = rec_total(lchild);
-			((RINTERNAL *)dest)->pgno = lchild->pgno;
-
-			/* Update the right page count. */
-			h->linp[skip] = h->upper -= nbytes;
-			dest = (char *)h + h->linp[skip];
-			((RINTERNAL *)dest)->nrecs = rec_total(rchild);
-			((RINTERNAL *)dest)->pgno = rchild->pgno;
-			break;
-		case P_RLEAF:
-			/*
-			 * Update the left page count.  If split
-			 * added at index 0, fix the correct page.
-			 */
-			if (skip > 0)
-				dest = (char *)h + h->linp[skip - 1];
-			else
-				dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
-			((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild);
-			((RINTERNAL *)dest)->pgno = lchild->pgno;
-
-			/* Update the right page count. */
-			h->linp[skip] = h->upper -= nbytes;
-			dest = (char *)h + h->linp[skip];
-			((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild);
-			((RINTERNAL *)dest)->pgno = rchild->pgno;
-			break;
-		default:
-			abort();
-		}
-
-		/* Unpin the held pages. */
-		if (!parentsplit) {
-			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
-			break;
-		}
-
-		/* If the root page was split, make it look right. */
-		if (sp->pgno == P_ROOT &&
-		    (F_ISSET(t, R_RECNO) ?
-		    bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
-			goto err1;
-
-		mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
-		mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
-	}
-
-	/* Unpin the held pages. */
-	mpool_put(t->bt_mp, l, MPOOL_DIRTY);
-	mpool_put(t->bt_mp, r, MPOOL_DIRTY);
-
-	/* Clear any pages left on the stack. */
-	return (RET_SUCCESS);
-
-	/*
-	 * If something fails in the above loop we were already walking back
-	 * up the tree and the tree is now inconsistent.  Nothing much we can
-	 * do about it but release any memory we're holding.
-	 */
-err1:	mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
-	mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
-
-err2:	mpool_put(t->bt_mp, l, 0);
-	mpool_put(t->bt_mp, r, 0);
-	__dbpanic(t->bt_dbp);
-	return (RET_ERROR);
-}
-
-/*
- * BT_PAGE -- Split a non-root page of a btree.
- *
- * Parameters:
- *	t:	tree
- *	h:	root page
- *	lp:	pointer to left page pointer
- *	rp:	pointer to right page pointer
- *	skip:	pointer to index to leave open
- *	ilen:	insert length
- *
- * Returns:
- *	Pointer to page in which to insert or NULL on error.
- */
-static PAGE *
-bt_page(t, h, lp, rp, skip, ilen)
-	BTREE *t;
-	PAGE *h, **lp, **rp;
-	indx_t *skip;
-	size_t ilen;
-{
-	PAGE *l, *r, *tp;
-	pgno_t npg;
-
-#ifdef STATISTICS
-	++bt_split;
-#endif
-	/* Put the new right page for the split into place. */
-	if ((r = __bt_new(t, &npg)) == NULL)
-		return (NULL);
-	r->pgno = npg;
-	r->lower = BTDATAOFF;
-	r->upper = t->bt_psize;
-	r->nextpg = h->nextpg;
-	r->prevpg = h->pgno;
-	r->flags = h->flags & P_TYPE;
-
-	/*
-	 * If we're splitting the last page on a level because we're appending
-	 * a key to it (skip is NEXTINDEX()), it's likely that the data is
-	 * sorted.  Adding an empty page on the side of the level is less work
-	 * and can push the fill factor much higher than normal.  If we're
-	 * wrong it's no big deal, we'll just do the split the right way next
-	 * time.  It may look like it's equally easy to do a similar hack for
-	 * reverse sorted data, that is, split the tree left, but it's not.
-	 * Don't even try.
-	 */
-	if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) {
-#ifdef STATISTICS
-		++bt_sortsplit;
-#endif
-		h->nextpg = r->pgno;
-		r->lower = BTDATAOFF + sizeof(indx_t);
-		*skip = 0;
-		*lp = h;
-		*rp = r;
-		return (r);
-	}
-
-	/* Put the new left page for the split into place. */
-	if ((l = (PAGE *)malloc(t->bt_psize)) == NULL) {
-		mpool_put(t->bt_mp, r, 0);
-		return (NULL);
-	}
-#ifdef PURIFY
-	memset(l, 0xff, t->bt_psize);
-#endif
-	l->pgno = h->pgno;
-	l->nextpg = r->pgno;
-	l->prevpg = h->prevpg;
-	l->lower = BTDATAOFF;
-	l->upper = t->bt_psize;
-	l->flags = h->flags & P_TYPE;
-
-	/* Fix up the previous pointer of the page after the split page. */
-	if (h->nextpg != P_INVALID) {
-		if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) {
-			free(l);
-			/* XXX mpool_free(t->bt_mp, r->pgno); */
-			return (NULL);
-		}
-		tp->prevpg = r->pgno;
-		mpool_put(t->bt_mp, tp, MPOOL_DIRTY);
-	}
-
-	/*
-	 * Split right.  The key/data pairs aren't sorted in the btree page so
-	 * it's simpler to copy the data from the split page onto two new pages
-	 * instead of copying half the data to the right page and compacting
-	 * the left page in place.  Since the left page can't change, we have
-	 * to swap the original and the allocated left page after the split.
-	 */
-	tp = bt_psplit(t, h, l, r, skip, ilen);
-
-	/* Move the new left page onto the old left page. */
-	memmove(h, l, t->bt_psize);
-	if (tp == l)
-		tp = h;
-	free(l);
-
-	*lp = h;
-	*rp = r;
-	return (tp);
-}
-
-/*
- * BT_ROOT -- Split the root page of a btree.
- *
- * Parameters:
- *	t:	tree
- *	h:	root page
- *	lp:	pointer to left page pointer
- *	rp:	pointer to right page pointer
- *	skip:	pointer to index to leave open
- *	ilen:	insert length
- *
- * Returns:
- *	Pointer to page in which to insert or NULL on error.
- */
-static PAGE *
-bt_root(t, h, lp, rp, skip, ilen)
-	BTREE *t;
-	PAGE *h, **lp, **rp;
-	indx_t *skip;
-	size_t ilen;
-{
-	PAGE *l, *r, *tp;
-	pgno_t lnpg, rnpg;
-
-#ifdef STATISTICS
-	++bt_split;
-	++bt_rootsplit;
-#endif
-	/* Put the new left and right pages for the split into place. */
-	if ((l = __bt_new(t, &lnpg)) == NULL ||
-	    (r = __bt_new(t, &rnpg)) == NULL)
-		return (NULL);
-	l->pgno = lnpg;
-	r->pgno = rnpg;
-	l->nextpg = r->pgno;
-	r->prevpg = l->pgno;
-	l->prevpg = r->nextpg = P_INVALID;
-	l->lower = r->lower = BTDATAOFF;
-	l->upper = r->upper = t->bt_psize;
-	l->flags = r->flags = h->flags & P_TYPE;
-
-	/* Split the root page. */
-	tp = bt_psplit(t, h, l, r, skip, ilen);
-
-	*lp = l;
-	*rp = r;
-	return (tp);
-}
-
-/*
- * BT_RROOT -- Fix up the recno root page after it has been split.
- *
- * Parameters:
- *	t:	tree
- *	h:	root page
- *	l:	left page
- *	r:	right page
- *
- * Returns:
- *	RET_ERROR, RET_SUCCESS
- */
-static int
-bt_rroot(t, h, l, r)
-	BTREE *t;
-	PAGE *h, *l, *r;
-{
-	char *dest;
-
-	/* Insert the left and right keys, set the header information. */
-	h->linp[0] = h->upper = t->bt_psize - NRINTERNAL;
-	dest = (char *)h + h->upper;
-	WR_RINTERNAL(dest,
-	    l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno);
-
-	h->linp[1] = h->upper -= NRINTERNAL;
-	dest = (char *)h + h->upper;
-	WR_RINTERNAL(dest,
-	    r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno);
-
-	h->lower = BTDATAOFF + 2 * sizeof(indx_t);
-
-	/* Unpin the root page, set to recno internal page. */
-	h->flags &= ~P_TYPE;
-	h->flags |= P_RINTERNAL;
-	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
-
-	return (RET_SUCCESS);
-}
-
-/*
- * BT_BROOT -- Fix up the btree root page after it has been split.
- *
- * Parameters:
- *	t:	tree
- *	h:	root page
- *	l:	left page
- *	r:	right page
- *
- * Returns:
- *	RET_ERROR, RET_SUCCESS
- */
-static int
-bt_broot(t, h, l, r)
-	BTREE *t;
-	PAGE *h, *l, *r;
-{
-	BINTERNAL *bi;
-	BLEAF *bl;
-	u_int32_t nbytes;
-	char *dest;
-
-	/*
-	 * If the root page was a leaf page, change it into an internal page.
-	 * We copy the key we split on (but not the key's data, in the case of
-	 * a leaf page) to the new root page.
-	 *
-	 * The btree comparison code guarantees that the left-most key on any
-	 * level of the tree is never used, so it doesn't need to be filled in.
-	 */
-	nbytes = NBINTERNAL(0);
-	h->linp[0] = h->upper = t->bt_psize - nbytes;
-	dest = (char *)h + h->upper;
-	WR_BINTERNAL(dest, 0, l->pgno, 0);
-
-	switch (h->flags & P_TYPE) {
-	case P_BLEAF:
-		bl = GETBLEAF(r, 0);
-		nbytes = NBINTERNAL(bl->ksize);
-		h->linp[1] = h->upper -= nbytes;
-		dest = (char *)h + h->upper;
-		WR_BINTERNAL(dest, bl->ksize, r->pgno, 0);
-		memmove(dest, bl->bytes, bl->ksize);
-
-		/*
-		 * If the key is on an overflow page, mark the overflow chain
-		 * so it isn't deleted when the leaf copy of the key is deleted.
-		 */
-		if (bl->flags & P_BIGKEY &&
-		    bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
-			return (RET_ERROR);
-		break;
-	case P_BINTERNAL:
-		bi = GETBINTERNAL(r, 0);
-		nbytes = NBINTERNAL(bi->ksize);
-		h->linp[1] = h->upper -= nbytes;
-		dest = (char *)h + h->upper;
-		memmove(dest, bi, nbytes);
-		((BINTERNAL *)dest)->pgno = r->pgno;
-		break;
-	default:
-		abort();
-	}
-
-	/* There are two keys on the page. */
-	h->lower = BTDATAOFF + 2 * sizeof(indx_t);
-
-	/* Unpin the root page, set to btree internal page. */
-	h->flags &= ~P_TYPE;
-	h->flags |= P_BINTERNAL;
-	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
-
-	return (RET_SUCCESS);
-}
-
-/*
- * BT_PSPLIT -- Do the real work of splitting the page.
- *
- * Parameters:
- *	t:	tree
- *	h:	page to be split
- *	l:	page to put lower half of data
- *	r:	page to put upper half of data
- *	pskip:	pointer to index to leave open
- *	ilen:	insert length
- *
- * Returns:
- *	Pointer to page in which to insert.
- */
-static PAGE *
-bt_psplit(t, h, l, r, pskip, ilen)
-	BTREE *t;
-	PAGE *h, *l, *r;
-	indx_t *pskip;
-	size_t ilen;
-{
-	BINTERNAL *bi;
-	BLEAF *bl;
-	CURSOR *c;
-	RLEAF *rl;
-	PAGE *rval;
-	void *src;
-	indx_t full, half, nxt, off, skip, top, used;
-	u_int32_t nbytes;
-	int bigkeycnt, isbigkey;
-
-	/*
-	 * Split the data to the left and right pages.  Leave the skip index
-	 * open.  Additionally, make some effort not to split on an overflow
-	 * key.  This makes internal page processing faster and can save
-	 * space as overflow keys used by internal pages are never deleted.
-	 */
-	bigkeycnt = 0;
-	skip = *pskip;
-	full = t->bt_psize - BTDATAOFF;
-	half = full / 2;
-	used = 0;
-	for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) {
-		if (skip == off) {
-			nbytes = ilen;
-			isbigkey = 0;		/* XXX: not really known. */
-		} else
-			switch (h->flags & P_TYPE) {
-			case P_BINTERNAL:
-				src = bi = GETBINTERNAL(h, nxt);
-				nbytes = NBINTERNAL(bi->ksize);
-				isbigkey = bi->flags & P_BIGKEY;
-				break;
-			case P_BLEAF:
-				src = bl = GETBLEAF(h, nxt);
-				nbytes = NBLEAF(bl);
-				isbigkey = bl->flags & P_BIGKEY;
-				break;
-			case P_RINTERNAL:
-				src = GETRINTERNAL(h, nxt);
-				nbytes = NRINTERNAL;
-				isbigkey = 0;
-				break;
-			case P_RLEAF:
-				src = rl = GETRLEAF(h, nxt);
-				nbytes = NRLEAF(rl);
-				isbigkey = 0;
-				break;
-			default:
-				abort();
-			}
-
-		/*
-		 * If the key/data pairs are substantial fractions of the max
-		 * possible size for the page, it's possible to get situations
-		 * where we decide to try and copy too much onto the left page.
-		 * Make sure that doesn't happen.
-		 */
-		if ((skip <= off && used + nbytes + sizeof(indx_t) >= full)
-		    || nxt == top - 1) {
-			--off;
-			break;
-		}
-
-		/* Copy the key/data pair, if not the skipped index. */
-		if (skip != off) {
-			++nxt;
-
-			l->linp[off] = l->upper -= nbytes;
-			memmove((char *)l + l->upper, src, nbytes);
-		}
-
-		used += nbytes + sizeof(indx_t);
-		if (used >= half) {
-			if (!isbigkey || bigkeycnt == 3)
-				break;
-			else
-				++bigkeycnt;
-		}
-	}
-
-	/*
-	 * Off is the last offset that's valid for the left page.
-	 * Nxt is the first offset to be placed on the right page.
-	 */
-	l->lower += (off + 1) * sizeof(indx_t);
-
-	/*
-	 * If splitting the page that the cursor was on, the cursor has to be
-	 * adjusted to point to the same record as before the split.  If the
-	 * cursor is at or past the skipped slot, the cursor is incremented by
-	 * one.  If the cursor is on the right page, it is decremented by the
-	 * number of records split to the left page.
-	 */
-	c = &t->bt_cursor;
-	if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) {
-		if (c->pg.index >= skip)
-			++c->pg.index;
-		if (c->pg.index < nxt)			/* Left page. */
-			c->pg.pgno = l->pgno;
-		else {					/* Right page. */
-			c->pg.pgno = r->pgno;
-			c->pg.index -= nxt;
-		}
-	}
-
-	/*
-	 * If the skipped index was on the left page, just return that page.
-	 * Otherwise, adjust the skip index to reflect the new position on
-	 * the right page.
-	 */
-	if (skip <= off) {
-		skip = 0;
-		rval = l;
-	} else {
-		rval = r;
-		*pskip -= nxt;
-	}
-
-	for (off = 0; nxt < top; ++off) {
-		if (skip == nxt) {
-			++off;
-			skip = 0;
-		}
-		switch (h->flags & P_TYPE) {
-		case P_BINTERNAL:
-			src = bi = GETBINTERNAL(h, nxt);
-			nbytes = NBINTERNAL(bi->ksize);
-			break;
-		case P_BLEAF:
-			src = bl = GETBLEAF(h, nxt);
-			nbytes = NBLEAF(bl);
-			break;
-		case P_RINTERNAL:
-			src = GETRINTERNAL(h, nxt);
-			nbytes = NRINTERNAL;
-			break;
-		case P_RLEAF:
-			src = rl = GETRLEAF(h, nxt);
-			nbytes = NRLEAF(rl);
-			break;
-		default:
-			abort();
-		}
-		++nxt;
-		r->linp[off] = r->upper -= nbytes;
-		memmove((char *)r + r->upper, src, nbytes);
-	}
-	r->lower += off * sizeof(indx_t);
-
-	/* If the key is being appended to the page, adjust the index. */
-	if (skip == top)
-		r->lower += sizeof(indx_t);
-
-	return (rval);
-}
-
-/*
- * BT_PRESERVE -- Mark a chain of pages as used by an internal node.
- *
- * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the
- * record that references them gets deleted.  Chains pointed to by internal
- * pages never get deleted.  This routine marks a chain as pointed to by an
- * internal page.
- *
- * Parameters:
- *	t:	tree
- *	pg:	page number of first page in the chain.
- *
- * Returns:
- *	RET_SUCCESS, RET_ERROR.
- */
-static int
-bt_preserve(t, pg)
-	BTREE *t;
-	pgno_t pg;
-{
-	PAGE *h;
-
-	if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
-		return (RET_ERROR);
-	h->flags |= P_PRESERVE;
-	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
-	return (RET_SUCCESS);
-}
-
-/*
- * REC_TOTAL -- Return the number of recno entries below a page.
- *
- * Parameters:
- *	h:	page
- *
- * Returns:
- *	The number of recno entries below a page.
- *
- * XXX
- * These values could be set by the bt_psplit routine.  The problem is that the
- * entry has to be popped off of the stack etc. or the values have to be passed
- * all the way back to bt_split/bt_rroot and it's not very clean.
- */
-static recno_t
-rec_total(h)
-	PAGE *h;
-{
-	recno_t recs;
-	indx_t nxt, top;
-
-	for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt)
-		recs += GETRINTERNAL(h, nxt)->nrecs;
-	return (recs);
-}