bt_split.c revision 14272
11573Srgrimes/*- 214272Spst * Copyright (c) 1990, 1993, 1994 31573Srgrimes * The Regents of the University of California. All rights reserved. 41573Srgrimes * 51573Srgrimes * This code is derived from software contributed to Berkeley by 61573Srgrimes * Mike Olson. 71573Srgrimes * 81573Srgrimes * Redistribution and use in source and binary forms, with or without 91573Srgrimes * modification, are permitted provided that the following conditions 101573Srgrimes * are met: 111573Srgrimes * 1. Redistributions of source code must retain the above copyright 121573Srgrimes * notice, this list of conditions and the following disclaimer. 131573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer in the 151573Srgrimes * documentation and/or other materials provided with the distribution. 161573Srgrimes * 3. All advertising materials mentioning features or use of this software 171573Srgrimes * must display the following acknowledgement: 181573Srgrimes * This product includes software developed by the University of 191573Srgrimes * California, Berkeley and its contributors. 201573Srgrimes * 4. Neither the name of the University nor the names of its contributors 211573Srgrimes * may be used to endorse or promote products derived from this software 221573Srgrimes * without specific prior written permission. 231573Srgrimes * 241573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341573Srgrimes * SUCH DAMAGE. 351573Srgrimes */ 361573Srgrimes 371573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 3814272Spststatic char sccsid[] = "@(#)bt_split.c 8.9 (Berkeley) 7/26/94"; 391573Srgrimes#endif /* LIBC_SCCS and not lint */ 401573Srgrimes 411573Srgrimes#include <sys/types.h> 421573Srgrimes 431573Srgrimes#include <limits.h> 441573Srgrimes#include <stdio.h> 451573Srgrimes#include <stdlib.h> 461573Srgrimes#include <string.h> 471573Srgrimes 481573Srgrimes#include <db.h> 491573Srgrimes#include "btree.h" 501573Srgrimes 511573Srgrimesstatic int bt_broot __P((BTREE *, PAGE *, PAGE *, PAGE *)); 521573Srgrimesstatic PAGE *bt_page 531573Srgrimes __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t)); 541573Srgrimesstatic int bt_preserve __P((BTREE *, pgno_t)); 551573Srgrimesstatic PAGE *bt_psplit 561573Srgrimes __P((BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t)); 571573Srgrimesstatic PAGE *bt_root 581573Srgrimes __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t)); 591573Srgrimesstatic int bt_rroot __P((BTREE *, PAGE *, PAGE *, PAGE *)); 601573Srgrimesstatic recno_t rec_total __P((PAGE *)); 611573Srgrimes 621573Srgrimes#ifdef STATISTICS 631573Srgrimesu_long bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved; 641573Srgrimes#endif 651573Srgrimes 661573Srgrimes/* 671573Srgrimes * __BT_SPLIT -- Split the tree. 681573Srgrimes * 691573Srgrimes * Parameters: 701573Srgrimes * t: tree 711573Srgrimes * sp: page to split 721573Srgrimes * key: key to insert 731573Srgrimes * data: data to insert 741573Srgrimes * flags: BIGKEY/BIGDATA flags 751573Srgrimes * ilen: insert length 761573Srgrimes * skip: index to leave open 771573Srgrimes * 781573Srgrimes * Returns: 791573Srgrimes * RET_ERROR, RET_SUCCESS 801573Srgrimes */ 811573Srgrimesint 8214272Spst__bt_split(t, sp, key, data, flags, ilen, argskip) 831573Srgrimes BTREE *t; 841573Srgrimes PAGE *sp; 851573Srgrimes const DBT *key, *data; 861573Srgrimes int flags; 871573Srgrimes size_t ilen; 8814272Spst u_int32_t argskip; 891573Srgrimes{ 901573Srgrimes BINTERNAL *bi; 911573Srgrimes BLEAF *bl, *tbl; 921573Srgrimes DBT a, b; 931573Srgrimes EPGNO *parent; 941573Srgrimes PAGE *h, *l, *r, *lchild, *rchild; 951573Srgrimes indx_t nxtindex; 9614272Spst u_int16_t skip; 9714272Spst u_int32_t n, nbytes, nksize; 981573Srgrimes int parentsplit; 991573Srgrimes char *dest; 1001573Srgrimes 1011573Srgrimes /* 1021573Srgrimes * Split the page into two pages, l and r. The split routines return 1031573Srgrimes * a pointer to the page into which the key should be inserted and with 1041573Srgrimes * skip set to the offset which should be used. Additionally, l and r 1051573Srgrimes * are pinned. 1061573Srgrimes */ 10714272Spst skip = argskip; 1081573Srgrimes h = sp->pgno == P_ROOT ? 1091573Srgrimes bt_root(t, sp, &l, &r, &skip, ilen) : 1101573Srgrimes bt_page(t, sp, &l, &r, &skip, ilen); 1111573Srgrimes if (h == NULL) 1121573Srgrimes return (RET_ERROR); 1131573Srgrimes 1141573Srgrimes /* 1151573Srgrimes * Insert the new key/data pair into the leaf page. (Key inserts 1161573Srgrimes * always cause a leaf page to split first.) 1171573Srgrimes */ 1181573Srgrimes h->linp[skip] = h->upper -= ilen; 1191573Srgrimes dest = (char *)h + h->upper; 12014272Spst if (F_ISSET(t, R_RECNO)) 1211573Srgrimes WR_RLEAF(dest, data, flags) 1221573Srgrimes else 1231573Srgrimes WR_BLEAF(dest, key, data, flags) 1241573Srgrimes 1251573Srgrimes /* If the root page was split, make it look right. */ 1261573Srgrimes if (sp->pgno == P_ROOT && 12714272Spst (F_ISSET(t, R_RECNO) ? 1281573Srgrimes bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 1291573Srgrimes goto err2; 1301573Srgrimes 1311573Srgrimes /* 1321573Srgrimes * Now we walk the parent page stack -- a LIFO stack of the pages that 1331573Srgrimes * were traversed when we searched for the page that split. Each stack 1341573Srgrimes * entry is a page number and a page index offset. The offset is for 1351573Srgrimes * the page traversed on the search. We've just split a page, so we 1361573Srgrimes * have to insert a new key into the parent page. 1371573Srgrimes * 1381573Srgrimes * If the insert into the parent page causes it to split, may have to 1391573Srgrimes * continue splitting all the way up the tree. We stop if the root 1401573Srgrimes * splits or the page inserted into didn't have to split to hold the 1411573Srgrimes * new key. Some algorithms replace the key for the old page as well 1421573Srgrimes * as the new page. We don't, as there's no reason to believe that the 1431573Srgrimes * first key on the old page is any better than the key we have, and, 1441573Srgrimes * in the case of a key being placed at index 0 causing the split, the 1451573Srgrimes * key is unavailable. 1461573Srgrimes * 1471573Srgrimes * There are a maximum of 5 pages pinned at any time. We keep the left 1481573Srgrimes * and right pages pinned while working on the parent. The 5 are the 1491573Srgrimes * two children, left parent and right parent (when the parent splits) 1501573Srgrimes * and the root page or the overflow key page when calling bt_preserve. 1511573Srgrimes * This code must make sure that all pins are released other than the 1521573Srgrimes * root page or overflow page which is unlocked elsewhere. 1531573Srgrimes */ 1541573Srgrimes while ((parent = BT_POP(t)) != NULL) { 1551573Srgrimes lchild = l; 1561573Srgrimes rchild = r; 1571573Srgrimes 1581573Srgrimes /* Get the parent page. */ 1591573Srgrimes if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL) 1601573Srgrimes goto err2; 1611573Srgrimes 1621573Srgrimes /* 1631573Srgrimes * The new key goes ONE AFTER the index, because the split 1641573Srgrimes * was to the right. 1651573Srgrimes */ 1661573Srgrimes skip = parent->index + 1; 1671573Srgrimes 1681573Srgrimes /* 1691573Srgrimes * Calculate the space needed on the parent page. 1701573Srgrimes * 1711573Srgrimes * Prefix trees: space hack when inserting into BINTERNAL 1721573Srgrimes * pages. Retain only what's needed to distinguish between 1731573Srgrimes * the new entry and the LAST entry on the page to its left. 1741573Srgrimes * If the keys compare equal, retain the entire key. Note, 1751573Srgrimes * we don't touch overflow keys, and the entire key must be 1761573Srgrimes * retained for the next-to-left most key on the leftmost 1771573Srgrimes * page of each level, or the search will fail. Applicable 1781573Srgrimes * ONLY to internal pages that have leaf pages as children. 1791573Srgrimes * Further reduction of the key between pairs of internal 1801573Srgrimes * pages loses too much information. 1811573Srgrimes */ 1821573Srgrimes switch (rchild->flags & P_TYPE) { 1831573Srgrimes case P_BINTERNAL: 1841573Srgrimes bi = GETBINTERNAL(rchild, 0); 1851573Srgrimes nbytes = NBINTERNAL(bi->ksize); 1861573Srgrimes break; 1871573Srgrimes case P_BLEAF: 1881573Srgrimes bl = GETBLEAF(rchild, 0); 1891573Srgrimes nbytes = NBINTERNAL(bl->ksize); 1901573Srgrimes if (t->bt_pfx && !(bl->flags & P_BIGKEY) && 1911573Srgrimes (h->prevpg != P_INVALID || skip > 1)) { 1921573Srgrimes tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1); 1931573Srgrimes a.size = tbl->ksize; 1941573Srgrimes a.data = tbl->bytes; 1951573Srgrimes b.size = bl->ksize; 1961573Srgrimes b.data = bl->bytes; 1971573Srgrimes nksize = t->bt_pfx(&a, &b); 1981573Srgrimes n = NBINTERNAL(nksize); 1991573Srgrimes if (n < nbytes) { 2001573Srgrimes#ifdef STATISTICS 2011573Srgrimes bt_pfxsaved += nbytes - n; 2021573Srgrimes#endif 2031573Srgrimes nbytes = n; 2041573Srgrimes } else 2051573Srgrimes nksize = 0; 2061573Srgrimes } else 2071573Srgrimes nksize = 0; 2081573Srgrimes break; 2091573Srgrimes case P_RINTERNAL: 2101573Srgrimes case P_RLEAF: 2111573Srgrimes nbytes = NRINTERNAL; 2121573Srgrimes break; 2131573Srgrimes default: 2141573Srgrimes abort(); 2151573Srgrimes } 2161573Srgrimes 2171573Srgrimes /* Split the parent page if necessary or shift the indices. */ 2181573Srgrimes if (h->upper - h->lower < nbytes + sizeof(indx_t)) { 2191573Srgrimes sp = h; 2201573Srgrimes h = h->pgno == P_ROOT ? 2211573Srgrimes bt_root(t, h, &l, &r, &skip, nbytes) : 2221573Srgrimes bt_page(t, h, &l, &r, &skip, nbytes); 2231573Srgrimes if (h == NULL) 2241573Srgrimes goto err1; 2251573Srgrimes parentsplit = 1; 2261573Srgrimes } else { 2271573Srgrimes if (skip < (nxtindex = NEXTINDEX(h))) 2281573Srgrimes memmove(h->linp + skip + 1, h->linp + skip, 2291573Srgrimes (nxtindex - skip) * sizeof(indx_t)); 2301573Srgrimes h->lower += sizeof(indx_t); 2311573Srgrimes parentsplit = 0; 2321573Srgrimes } 2331573Srgrimes 2341573Srgrimes /* Insert the key into the parent page. */ 23514272Spst switch (rchild->flags & P_TYPE) { 2361573Srgrimes case P_BINTERNAL: 2371573Srgrimes h->linp[skip] = h->upper -= nbytes; 2381573Srgrimes dest = (char *)h + h->linp[skip]; 2391573Srgrimes memmove(dest, bi, nbytes); 2401573Srgrimes ((BINTERNAL *)dest)->pgno = rchild->pgno; 2411573Srgrimes break; 2421573Srgrimes case P_BLEAF: 2431573Srgrimes h->linp[skip] = h->upper -= nbytes; 2441573Srgrimes dest = (char *)h + h->linp[skip]; 2451573Srgrimes WR_BINTERNAL(dest, nksize ? nksize : bl->ksize, 2461573Srgrimes rchild->pgno, bl->flags & P_BIGKEY); 2471573Srgrimes memmove(dest, bl->bytes, nksize ? nksize : bl->ksize); 2481573Srgrimes if (bl->flags & P_BIGKEY && 2491573Srgrimes bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR) 2501573Srgrimes goto err1; 2511573Srgrimes break; 2521573Srgrimes case P_RINTERNAL: 2531573Srgrimes /* 2541573Srgrimes * Update the left page count. If split 2551573Srgrimes * added at index 0, fix the correct page. 2561573Srgrimes */ 2571573Srgrimes if (skip > 0) 2581573Srgrimes dest = (char *)h + h->linp[skip - 1]; 2591573Srgrimes else 2601573Srgrimes dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 2611573Srgrimes ((RINTERNAL *)dest)->nrecs = rec_total(lchild); 2621573Srgrimes ((RINTERNAL *)dest)->pgno = lchild->pgno; 2631573Srgrimes 2641573Srgrimes /* Update the right page count. */ 2651573Srgrimes h->linp[skip] = h->upper -= nbytes; 2661573Srgrimes dest = (char *)h + h->linp[skip]; 2671573Srgrimes ((RINTERNAL *)dest)->nrecs = rec_total(rchild); 2681573Srgrimes ((RINTERNAL *)dest)->pgno = rchild->pgno; 2691573Srgrimes break; 2701573Srgrimes case P_RLEAF: 2711573Srgrimes /* 2721573Srgrimes * Update the left page count. If split 2731573Srgrimes * added at index 0, fix the correct page. 2741573Srgrimes */ 2751573Srgrimes if (skip > 0) 2761573Srgrimes dest = (char *)h + h->linp[skip - 1]; 2771573Srgrimes else 2781573Srgrimes dest = (char *)l + l->linp[NEXTINDEX(l) - 1]; 2791573Srgrimes ((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild); 2801573Srgrimes ((RINTERNAL *)dest)->pgno = lchild->pgno; 2811573Srgrimes 2821573Srgrimes /* Update the right page count. */ 2831573Srgrimes h->linp[skip] = h->upper -= nbytes; 2841573Srgrimes dest = (char *)h + h->linp[skip]; 2851573Srgrimes ((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild); 2861573Srgrimes ((RINTERNAL *)dest)->pgno = rchild->pgno; 2871573Srgrimes break; 2881573Srgrimes default: 2891573Srgrimes abort(); 2901573Srgrimes } 2911573Srgrimes 2921573Srgrimes /* Unpin the held pages. */ 2931573Srgrimes if (!parentsplit) { 2941573Srgrimes mpool_put(t->bt_mp, h, MPOOL_DIRTY); 2951573Srgrimes break; 2961573Srgrimes } 2971573Srgrimes 2981573Srgrimes /* If the root page was split, make it look right. */ 2991573Srgrimes if (sp->pgno == P_ROOT && 30014272Spst (F_ISSET(t, R_RECNO) ? 3011573Srgrimes bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR) 3021573Srgrimes goto err1; 3031573Srgrimes 3041573Srgrimes mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 3051573Srgrimes mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 3061573Srgrimes } 3071573Srgrimes 3081573Srgrimes /* Unpin the held pages. */ 3091573Srgrimes mpool_put(t->bt_mp, l, MPOOL_DIRTY); 3101573Srgrimes mpool_put(t->bt_mp, r, MPOOL_DIRTY); 3111573Srgrimes 3121573Srgrimes /* Clear any pages left on the stack. */ 3131573Srgrimes return (RET_SUCCESS); 3141573Srgrimes 3151573Srgrimes /* 3161573Srgrimes * If something fails in the above loop we were already walking back 3171573Srgrimes * up the tree and the tree is now inconsistent. Nothing much we can 3181573Srgrimes * do about it but release any memory we're holding. 3191573Srgrimes */ 3201573Srgrimeserr1: mpool_put(t->bt_mp, lchild, MPOOL_DIRTY); 3211573Srgrimes mpool_put(t->bt_mp, rchild, MPOOL_DIRTY); 3221573Srgrimes 3231573Srgrimeserr2: mpool_put(t->bt_mp, l, 0); 3241573Srgrimes mpool_put(t->bt_mp, r, 0); 3251573Srgrimes __dbpanic(t->bt_dbp); 3261573Srgrimes return (RET_ERROR); 3271573Srgrimes} 3281573Srgrimes 3291573Srgrimes/* 3301573Srgrimes * BT_PAGE -- Split a non-root page of a btree. 3311573Srgrimes * 3321573Srgrimes * Parameters: 3331573Srgrimes * t: tree 3341573Srgrimes * h: root page 3351573Srgrimes * lp: pointer to left page pointer 3361573Srgrimes * rp: pointer to right page pointer 3371573Srgrimes * skip: pointer to index to leave open 3381573Srgrimes * ilen: insert length 3391573Srgrimes * 3401573Srgrimes * Returns: 3411573Srgrimes * Pointer to page in which to insert or NULL on error. 3421573Srgrimes */ 3431573Srgrimesstatic PAGE * 3441573Srgrimesbt_page(t, h, lp, rp, skip, ilen) 3451573Srgrimes BTREE *t; 3461573Srgrimes PAGE *h, **lp, **rp; 3471573Srgrimes indx_t *skip; 3481573Srgrimes size_t ilen; 3491573Srgrimes{ 3501573Srgrimes PAGE *l, *r, *tp; 3511573Srgrimes pgno_t npg; 3521573Srgrimes 3531573Srgrimes#ifdef STATISTICS 3541573Srgrimes ++bt_split; 3551573Srgrimes#endif 3561573Srgrimes /* Put the new right page for the split into place. */ 3571573Srgrimes if ((r = __bt_new(t, &npg)) == NULL) 3581573Srgrimes return (NULL); 3591573Srgrimes r->pgno = npg; 3601573Srgrimes r->lower = BTDATAOFF; 3611573Srgrimes r->upper = t->bt_psize; 3621573Srgrimes r->nextpg = h->nextpg; 3631573Srgrimes r->prevpg = h->pgno; 3641573Srgrimes r->flags = h->flags & P_TYPE; 3651573Srgrimes 3661573Srgrimes /* 3671573Srgrimes * If we're splitting the last page on a level because we're appending 3681573Srgrimes * a key to it (skip is NEXTINDEX()), it's likely that the data is 3691573Srgrimes * sorted. Adding an empty page on the side of the level is less work 3701573Srgrimes * and can push the fill factor much higher than normal. If we're 3711573Srgrimes * wrong it's no big deal, we'll just do the split the right way next 3721573Srgrimes * time. It may look like it's equally easy to do a similar hack for 3731573Srgrimes * reverse sorted data, that is, split the tree left, but it's not. 3741573Srgrimes * Don't even try. 3751573Srgrimes */ 3761573Srgrimes if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) { 3771573Srgrimes#ifdef STATISTICS 3781573Srgrimes ++bt_sortsplit; 3791573Srgrimes#endif 3801573Srgrimes h->nextpg = r->pgno; 3811573Srgrimes r->lower = BTDATAOFF + sizeof(indx_t); 3821573Srgrimes *skip = 0; 3831573Srgrimes *lp = h; 3841573Srgrimes *rp = r; 3851573Srgrimes return (r); 3861573Srgrimes } 3871573Srgrimes 3881573Srgrimes /* Put the new left page for the split into place. */ 3891573Srgrimes if ((l = (PAGE *)malloc(t->bt_psize)) == NULL) { 3901573Srgrimes mpool_put(t->bt_mp, r, 0); 3911573Srgrimes return (NULL); 3921573Srgrimes } 39314272Spst#ifdef PURIFY 39414272Spst memset(l, 0xff, t->bt_psize); 39514272Spst#endif 3961573Srgrimes l->pgno = h->pgno; 3971573Srgrimes l->nextpg = r->pgno; 3981573Srgrimes l->prevpg = h->prevpg; 3991573Srgrimes l->lower = BTDATAOFF; 4001573Srgrimes l->upper = t->bt_psize; 4011573Srgrimes l->flags = h->flags & P_TYPE; 4021573Srgrimes 4031573Srgrimes /* Fix up the previous pointer of the page after the split page. */ 4041573Srgrimes if (h->nextpg != P_INVALID) { 4051573Srgrimes if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) { 4061573Srgrimes free(l); 4071573Srgrimes /* XXX mpool_free(t->bt_mp, r->pgno); */ 4081573Srgrimes return (NULL); 4091573Srgrimes } 4101573Srgrimes tp->prevpg = r->pgno; 41114272Spst mpool_put(t->bt_mp, tp, MPOOL_DIRTY); 4121573Srgrimes } 4131573Srgrimes 4141573Srgrimes /* 4151573Srgrimes * Split right. The key/data pairs aren't sorted in the btree page so 4161573Srgrimes * it's simpler to copy the data from the split page onto two new pages 4171573Srgrimes * instead of copying half the data to the right page and compacting 4181573Srgrimes * the left page in place. Since the left page can't change, we have 4191573Srgrimes * to swap the original and the allocated left page after the split. 4201573Srgrimes */ 4211573Srgrimes tp = bt_psplit(t, h, l, r, skip, ilen); 4221573Srgrimes 4231573Srgrimes /* Move the new left page onto the old left page. */ 4241573Srgrimes memmove(h, l, t->bt_psize); 4251573Srgrimes if (tp == l) 4261573Srgrimes tp = h; 4271573Srgrimes free(l); 4281573Srgrimes 4291573Srgrimes *lp = h; 4301573Srgrimes *rp = r; 4311573Srgrimes return (tp); 4321573Srgrimes} 4331573Srgrimes 4341573Srgrimes/* 4351573Srgrimes * BT_ROOT -- Split the root page of a btree. 4361573Srgrimes * 4371573Srgrimes * Parameters: 4381573Srgrimes * t: tree 4391573Srgrimes * h: root page 4401573Srgrimes * lp: pointer to left page pointer 4411573Srgrimes * rp: pointer to right page pointer 4421573Srgrimes * skip: pointer to index to leave open 4431573Srgrimes * ilen: insert length 4441573Srgrimes * 4451573Srgrimes * Returns: 4461573Srgrimes * Pointer to page in which to insert or NULL on error. 4471573Srgrimes */ 4481573Srgrimesstatic PAGE * 4491573Srgrimesbt_root(t, h, lp, rp, skip, ilen) 4501573Srgrimes BTREE *t; 4511573Srgrimes PAGE *h, **lp, **rp; 4521573Srgrimes indx_t *skip; 4531573Srgrimes size_t ilen; 4541573Srgrimes{ 4551573Srgrimes PAGE *l, *r, *tp; 4561573Srgrimes pgno_t lnpg, rnpg; 4571573Srgrimes 4581573Srgrimes#ifdef STATISTICS 4591573Srgrimes ++bt_split; 4601573Srgrimes ++bt_rootsplit; 4611573Srgrimes#endif 4621573Srgrimes /* Put the new left and right pages for the split into place. */ 4631573Srgrimes if ((l = __bt_new(t, &lnpg)) == NULL || 4641573Srgrimes (r = __bt_new(t, &rnpg)) == NULL) 4651573Srgrimes return (NULL); 4661573Srgrimes l->pgno = lnpg; 4671573Srgrimes r->pgno = rnpg; 4681573Srgrimes l->nextpg = r->pgno; 4691573Srgrimes r->prevpg = l->pgno; 4701573Srgrimes l->prevpg = r->nextpg = P_INVALID; 4711573Srgrimes l->lower = r->lower = BTDATAOFF; 4721573Srgrimes l->upper = r->upper = t->bt_psize; 4731573Srgrimes l->flags = r->flags = h->flags & P_TYPE; 4741573Srgrimes 4751573Srgrimes /* Split the root page. */ 4761573Srgrimes tp = bt_psplit(t, h, l, r, skip, ilen); 4771573Srgrimes 4781573Srgrimes *lp = l; 4791573Srgrimes *rp = r; 4801573Srgrimes return (tp); 4811573Srgrimes} 4821573Srgrimes 4831573Srgrimes/* 4841573Srgrimes * BT_RROOT -- Fix up the recno root page after it has been split. 4851573Srgrimes * 4861573Srgrimes * Parameters: 4871573Srgrimes * t: tree 4881573Srgrimes * h: root page 4891573Srgrimes * l: left page 4901573Srgrimes * r: right page 4911573Srgrimes * 4921573Srgrimes * Returns: 4931573Srgrimes * RET_ERROR, RET_SUCCESS 4941573Srgrimes */ 4951573Srgrimesstatic int 4961573Srgrimesbt_rroot(t, h, l, r) 4971573Srgrimes BTREE *t; 4981573Srgrimes PAGE *h, *l, *r; 4991573Srgrimes{ 5001573Srgrimes char *dest; 5011573Srgrimes 5021573Srgrimes /* Insert the left and right keys, set the header information. */ 5031573Srgrimes h->linp[0] = h->upper = t->bt_psize - NRINTERNAL; 5041573Srgrimes dest = (char *)h + h->upper; 5051573Srgrimes WR_RINTERNAL(dest, 5061573Srgrimes l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno); 5071573Srgrimes 5081573Srgrimes h->linp[1] = h->upper -= NRINTERNAL; 5091573Srgrimes dest = (char *)h + h->upper; 5101573Srgrimes WR_RINTERNAL(dest, 5111573Srgrimes r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno); 5121573Srgrimes 5131573Srgrimes h->lower = BTDATAOFF + 2 * sizeof(indx_t); 5141573Srgrimes 5151573Srgrimes /* Unpin the root page, set to recno internal page. */ 5161573Srgrimes h->flags &= ~P_TYPE; 5171573Srgrimes h->flags |= P_RINTERNAL; 5181573Srgrimes mpool_put(t->bt_mp, h, MPOOL_DIRTY); 5191573Srgrimes 5201573Srgrimes return (RET_SUCCESS); 5211573Srgrimes} 5221573Srgrimes 5231573Srgrimes/* 5241573Srgrimes * BT_BROOT -- Fix up the btree root page after it has been split. 5251573Srgrimes * 5261573Srgrimes * Parameters: 5271573Srgrimes * t: tree 5281573Srgrimes * h: root page 5291573Srgrimes * l: left page 5301573Srgrimes * r: right page 5311573Srgrimes * 5321573Srgrimes * Returns: 5331573Srgrimes * RET_ERROR, RET_SUCCESS 5341573Srgrimes */ 5351573Srgrimesstatic int 5361573Srgrimesbt_broot(t, h, l, r) 5371573Srgrimes BTREE *t; 5381573Srgrimes PAGE *h, *l, *r; 5391573Srgrimes{ 5401573Srgrimes BINTERNAL *bi; 5411573Srgrimes BLEAF *bl; 54214272Spst u_int32_t nbytes; 5431573Srgrimes char *dest; 5441573Srgrimes 5451573Srgrimes /* 5461573Srgrimes * If the root page was a leaf page, change it into an internal page. 5471573Srgrimes * We copy the key we split on (but not the key's data, in the case of 5481573Srgrimes * a leaf page) to the new root page. 5491573Srgrimes * 5501573Srgrimes * The btree comparison code guarantees that the left-most key on any 5511573Srgrimes * level of the tree is never used, so it doesn't need to be filled in. 5521573Srgrimes */ 5531573Srgrimes nbytes = NBINTERNAL(0); 5541573Srgrimes h->linp[0] = h->upper = t->bt_psize - nbytes; 5551573Srgrimes dest = (char *)h + h->upper; 5561573Srgrimes WR_BINTERNAL(dest, 0, l->pgno, 0); 5571573Srgrimes 55814272Spst switch (h->flags & P_TYPE) { 5591573Srgrimes case P_BLEAF: 5601573Srgrimes bl = GETBLEAF(r, 0); 5611573Srgrimes nbytes = NBINTERNAL(bl->ksize); 5621573Srgrimes h->linp[1] = h->upper -= nbytes; 5631573Srgrimes dest = (char *)h + h->upper; 5641573Srgrimes WR_BINTERNAL(dest, bl->ksize, r->pgno, 0); 5651573Srgrimes memmove(dest, bl->bytes, bl->ksize); 5661573Srgrimes 5671573Srgrimes /* 5681573Srgrimes * If the key is on an overflow page, mark the overflow chain 5691573Srgrimes * so it isn't deleted when the leaf copy of the key is deleted. 5701573Srgrimes */ 5711573Srgrimes if (bl->flags & P_BIGKEY && 5721573Srgrimes bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR) 5731573Srgrimes return (RET_ERROR); 5741573Srgrimes break; 5751573Srgrimes case P_BINTERNAL: 5761573Srgrimes bi = GETBINTERNAL(r, 0); 5771573Srgrimes nbytes = NBINTERNAL(bi->ksize); 5781573Srgrimes h->linp[1] = h->upper -= nbytes; 5791573Srgrimes dest = (char *)h + h->upper; 5801573Srgrimes memmove(dest, bi, nbytes); 5811573Srgrimes ((BINTERNAL *)dest)->pgno = r->pgno; 5821573Srgrimes break; 5831573Srgrimes default: 5841573Srgrimes abort(); 5851573Srgrimes } 5861573Srgrimes 5871573Srgrimes /* There are two keys on the page. */ 5881573Srgrimes h->lower = BTDATAOFF + 2 * sizeof(indx_t); 5891573Srgrimes 5901573Srgrimes /* Unpin the root page, set to btree internal page. */ 5911573Srgrimes h->flags &= ~P_TYPE; 5921573Srgrimes h->flags |= P_BINTERNAL; 5931573Srgrimes mpool_put(t->bt_mp, h, MPOOL_DIRTY); 5941573Srgrimes 5951573Srgrimes return (RET_SUCCESS); 5961573Srgrimes} 5971573Srgrimes 5981573Srgrimes/* 5991573Srgrimes * BT_PSPLIT -- Do the real work of splitting the page. 6001573Srgrimes * 6011573Srgrimes * Parameters: 6021573Srgrimes * t: tree 6031573Srgrimes * h: page to be split 6041573Srgrimes * l: page to put lower half of data 6051573Srgrimes * r: page to put upper half of data 6061573Srgrimes * pskip: pointer to index to leave open 6071573Srgrimes * ilen: insert length 6081573Srgrimes * 6091573Srgrimes * Returns: 6101573Srgrimes * Pointer to page in which to insert. 6111573Srgrimes */ 6121573Srgrimesstatic PAGE * 6131573Srgrimesbt_psplit(t, h, l, r, pskip, ilen) 6141573Srgrimes BTREE *t; 6151573Srgrimes PAGE *h, *l, *r; 6161573Srgrimes indx_t *pskip; 6171573Srgrimes size_t ilen; 6181573Srgrimes{ 6191573Srgrimes BINTERNAL *bi; 6201573Srgrimes BLEAF *bl; 62114272Spst CURSOR *c; 6221573Srgrimes RLEAF *rl; 6231573Srgrimes PAGE *rval; 6241573Srgrimes void *src; 6251573Srgrimes indx_t full, half, nxt, off, skip, top, used; 62614272Spst u_int32_t nbytes; 6271573Srgrimes int bigkeycnt, isbigkey; 6281573Srgrimes 6291573Srgrimes /* 6301573Srgrimes * Split the data to the left and right pages. Leave the skip index 6311573Srgrimes * open. Additionally, make some effort not to split on an overflow 6321573Srgrimes * key. This makes internal page processing faster and can save 6331573Srgrimes * space as overflow keys used by internal pages are never deleted. 6341573Srgrimes */ 6351573Srgrimes bigkeycnt = 0; 6361573Srgrimes skip = *pskip; 6371573Srgrimes full = t->bt_psize - BTDATAOFF; 6381573Srgrimes half = full / 2; 6391573Srgrimes used = 0; 6401573Srgrimes for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) { 6411573Srgrimes if (skip == off) { 6421573Srgrimes nbytes = ilen; 6431573Srgrimes isbigkey = 0; /* XXX: not really known. */ 6441573Srgrimes } else 6451573Srgrimes switch (h->flags & P_TYPE) { 6461573Srgrimes case P_BINTERNAL: 6471573Srgrimes src = bi = GETBINTERNAL(h, nxt); 6481573Srgrimes nbytes = NBINTERNAL(bi->ksize); 6491573Srgrimes isbigkey = bi->flags & P_BIGKEY; 6501573Srgrimes break; 6511573Srgrimes case P_BLEAF: 6521573Srgrimes src = bl = GETBLEAF(h, nxt); 6531573Srgrimes nbytes = NBLEAF(bl); 6541573Srgrimes isbigkey = bl->flags & P_BIGKEY; 6551573Srgrimes break; 6561573Srgrimes case P_RINTERNAL: 6571573Srgrimes src = GETRINTERNAL(h, nxt); 6581573Srgrimes nbytes = NRINTERNAL; 6591573Srgrimes isbigkey = 0; 6601573Srgrimes break; 6611573Srgrimes case P_RLEAF: 6621573Srgrimes src = rl = GETRLEAF(h, nxt); 6631573Srgrimes nbytes = NRLEAF(rl); 6641573Srgrimes isbigkey = 0; 6651573Srgrimes break; 6661573Srgrimes default: 6671573Srgrimes abort(); 6681573Srgrimes } 6691573Srgrimes 6701573Srgrimes /* 6711573Srgrimes * If the key/data pairs are substantial fractions of the max 6721573Srgrimes * possible size for the page, it's possible to get situations 6731573Srgrimes * where we decide to try and copy too much onto the left page. 6741573Srgrimes * Make sure that doesn't happen. 6751573Srgrimes */ 6761573Srgrimes if (skip <= off && used + nbytes >= full) { 6771573Srgrimes --off; 6781573Srgrimes break; 6791573Srgrimes } 6801573Srgrimes 6811573Srgrimes /* Copy the key/data pair, if not the skipped index. */ 6821573Srgrimes if (skip != off) { 6831573Srgrimes ++nxt; 6841573Srgrimes 6851573Srgrimes l->linp[off] = l->upper -= nbytes; 6861573Srgrimes memmove((char *)l + l->upper, src, nbytes); 6871573Srgrimes } 6881573Srgrimes 6891573Srgrimes used += nbytes; 6901573Srgrimes if (used >= half) { 6911573Srgrimes if (!isbigkey || bigkeycnt == 3) 6921573Srgrimes break; 6931573Srgrimes else 6941573Srgrimes ++bigkeycnt; 6951573Srgrimes } 6961573Srgrimes } 6971573Srgrimes 6981573Srgrimes /* 6991573Srgrimes * Off is the last offset that's valid for the left page. 7001573Srgrimes * Nxt is the first offset to be placed on the right page. 7011573Srgrimes */ 7021573Srgrimes l->lower += (off + 1) * sizeof(indx_t); 7031573Srgrimes 7041573Srgrimes /* 7051573Srgrimes * If splitting the page that the cursor was on, the cursor has to be 7061573Srgrimes * adjusted to point to the same record as before the split. If the 7071573Srgrimes * cursor is at or past the skipped slot, the cursor is incremented by 7081573Srgrimes * one. If the cursor is on the right page, it is decremented by the 7091573Srgrimes * number of records split to the left page. 7101573Srgrimes */ 71114272Spst c = &t->bt_cursor; 71214272Spst if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) { 71314272Spst if (c->pg.index >= skip) 71414272Spst ++c->pg.index; 71514272Spst if (c->pg.index < nxt) /* Left page. */ 71614272Spst c->pg.pgno = l->pgno; 7171573Srgrimes else { /* Right page. */ 71814272Spst c->pg.pgno = r->pgno; 71914272Spst c->pg.index -= nxt; 7201573Srgrimes } 7211573Srgrimes } 7221573Srgrimes 7231573Srgrimes /* 7241573Srgrimes * If the skipped index was on the left page, just return that page. 7251573Srgrimes * Otherwise, adjust the skip index to reflect the new position on 7261573Srgrimes * the right page. 7271573Srgrimes */ 7281573Srgrimes if (skip <= off) { 7291573Srgrimes skip = 0; 7301573Srgrimes rval = l; 7311573Srgrimes } else { 7321573Srgrimes rval = r; 7331573Srgrimes *pskip -= nxt; 7341573Srgrimes } 7351573Srgrimes 7361573Srgrimes for (off = 0; nxt < top; ++off) { 7371573Srgrimes if (skip == nxt) { 7381573Srgrimes ++off; 7391573Srgrimes skip = 0; 7401573Srgrimes } 7411573Srgrimes switch (h->flags & P_TYPE) { 7421573Srgrimes case P_BINTERNAL: 7431573Srgrimes src = bi = GETBINTERNAL(h, nxt); 7441573Srgrimes nbytes = NBINTERNAL(bi->ksize); 7451573Srgrimes break; 7461573Srgrimes case P_BLEAF: 7471573Srgrimes src = bl = GETBLEAF(h, nxt); 7481573Srgrimes nbytes = NBLEAF(bl); 7491573Srgrimes break; 7501573Srgrimes case P_RINTERNAL: 7511573Srgrimes src = GETRINTERNAL(h, nxt); 7521573Srgrimes nbytes = NRINTERNAL; 7531573Srgrimes break; 7541573Srgrimes case P_RLEAF: 7551573Srgrimes src = rl = GETRLEAF(h, nxt); 7561573Srgrimes nbytes = NRLEAF(rl); 7571573Srgrimes break; 7581573Srgrimes default: 7591573Srgrimes abort(); 7601573Srgrimes } 7611573Srgrimes ++nxt; 7621573Srgrimes r->linp[off] = r->upper -= nbytes; 7631573Srgrimes memmove((char *)r + r->upper, src, nbytes); 7641573Srgrimes } 7651573Srgrimes r->lower += off * sizeof(indx_t); 7661573Srgrimes 7671573Srgrimes /* If the key is being appended to the page, adjust the index. */ 7681573Srgrimes if (skip == top) 7691573Srgrimes r->lower += sizeof(indx_t); 7701573Srgrimes 7711573Srgrimes return (rval); 7721573Srgrimes} 7731573Srgrimes 7741573Srgrimes/* 7751573Srgrimes * BT_PRESERVE -- Mark a chain of pages as used by an internal node. 7761573Srgrimes * 7771573Srgrimes * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the 7781573Srgrimes * record that references them gets deleted. Chains pointed to by internal 7791573Srgrimes * pages never get deleted. This routine marks a chain as pointed to by an 7801573Srgrimes * internal page. 7811573Srgrimes * 7821573Srgrimes * Parameters: 7831573Srgrimes * t: tree 7841573Srgrimes * pg: page number of first page in the chain. 7851573Srgrimes * 7861573Srgrimes * Returns: 7871573Srgrimes * RET_SUCCESS, RET_ERROR. 7881573Srgrimes */ 7891573Srgrimesstatic int 7901573Srgrimesbt_preserve(t, pg) 7911573Srgrimes BTREE *t; 7921573Srgrimes pgno_t pg; 7931573Srgrimes{ 7941573Srgrimes PAGE *h; 7951573Srgrimes 7961573Srgrimes if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) 7971573Srgrimes return (RET_ERROR); 7981573Srgrimes h->flags |= P_PRESERVE; 7991573Srgrimes mpool_put(t->bt_mp, h, MPOOL_DIRTY); 8001573Srgrimes return (RET_SUCCESS); 8011573Srgrimes} 8021573Srgrimes 8031573Srgrimes/* 8041573Srgrimes * REC_TOTAL -- Return the number of recno entries below a page. 8051573Srgrimes * 8061573Srgrimes * Parameters: 8071573Srgrimes * h: page 8081573Srgrimes * 8091573Srgrimes * Returns: 8101573Srgrimes * The number of recno entries below a page. 8111573Srgrimes * 8121573Srgrimes * XXX 8131573Srgrimes * These values could be set by the bt_psplit routine. The problem is that the 8141573Srgrimes * entry has to be popped off of the stack etc. or the values have to be passed 8151573Srgrimes * all the way back to bt_split/bt_rroot and it's not very clean. 8161573Srgrimes */ 8171573Srgrimesstatic recno_t 8181573Srgrimesrec_total(h) 8191573Srgrimes PAGE *h; 8201573Srgrimes{ 8211573Srgrimes recno_t recs; 8221573Srgrimes indx_t nxt, top; 8231573Srgrimes 8241573Srgrimes for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt) 8251573Srgrimes recs += GETRINTERNAL(h, nxt)->nrecs; 8261573Srgrimes return (recs); 8271573Srgrimes} 828