From d326064e0d144584320218beee587bd5b5da4b24 Mon Sep 17 00:00:00 2001 From: danielk1977 Date: Fri, 26 Sep 2008 17:31:55 +0000 Subject: [PATCH] Performance enhancement: avoid calling reparentChildPages() from balance_nonroot(). (CVS 5743) FossilOrigin-Name: 28fd0a50ca8529892f5b1ababd38d494889eed6d --- manifest | 12 ++++++------ manifest.uuid | 2 +- src/btree.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 55 insertions(+), 9 deletions(-) diff --git a/manifest b/manifest index 3dbba4bc66..d52ce8976e 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C On\swindows,\savoid\srunning\sthose\stests\sin\sexclusive.test\sthat\srequire\sthe\sjournal\sfile\sto\sbe\sexternally\saccessed\swhile\sSQLite\sis\sholding\sit\sopen.\sThis\sdoesn't\swork\son\swindows.\s(CVS\s5742) -D 2008-09-24T14:03:43 +C Performance\senhancement:\savoid\scalling\sreparentChildPages()\sfrom\sbalance_nonroot().\s(CVS\s5743) +D 2008-09-26T17:31:55 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0 F Makefile.in e4ab842f9a64ef61d57093539a8aab76b12810db F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654 @@ -99,7 +99,7 @@ F src/attach.c db3f4a60538733c1e4dcb9d0217a6e0d6ccd615b F src/auth.c c8b2ab5c8bad4bd90ed7c294694f48269162c627 F src/bitvec.c 95c86bd18d8fedf0533f5af196192546e10a7e7d F src/btmutex.c 709cad2cdca0afd013f0f612363810e53f59ec53 -F src/btree.c 4d642d23fc4507089f702eb24b506be2ce7e0efd +F src/btree.c 850d7ede7fe58f8bfad78131278ceff83817abf5 F src/btree.h 6371c5e599fab391a150c96afbc10062b276d107 F src/btreeInt.h e36f77e6621d671beb19ae581af1eba116cdfdc4 F src/build.c 160c71acca8f643f436ed6c1ee2f684c88df4dfe @@ -637,7 +637,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff F tool/speedtest8.c 1dbced29de5f59ba2ebf877edcadf171540374d1 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e -P 0acca5842f83943228d4225b60dc7e8a42bae577 -R 9eb08ed19a8499580c1afb4ad41aa2b7 +P 5debf12fa46520946ac5da44c03448fffbc9940c +R ad8baa95733fbb9a312a15654e608ce1 U danielk1977 -Z 7daec82c5a8b96a531bdb9c3bccd5b3b +Z 410e2e4a76b6dc0451fd1f6a24aebc75 diff --git a/manifest.uuid b/manifest.uuid index bbb10a515e..2f22cb8c72 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -5debf12fa46520946ac5da44c03448fffbc9940c \ No newline at end of file +28fd0a50ca8529892f5b1ababd38d494889eed6d \ No newline at end of file diff --git a/src/btree.c b/src/btree.c index 2a0b048bef..9e105326b7 100644 --- a/src/btree.c +++ b/src/btree.c @@ -9,7 +9,7 @@ ** May you share freely, never taking more than you give. ** ************************************************************************* -** $Id: btree.c,v 1.516 2008/09/19 16:39:38 danielk1977 Exp $ +** $Id: btree.c,v 1.517 2008/09/26 17:31:55 danielk1977 Exp $ ** ** This file implements a external (disk-based) database using BTrees. ** See the header comment on "btreeInt.h" for additional information. @@ -5586,14 +5586,46 @@ static int balance_nonroot(MemPage *pPage){ } /* - ** Reparent children of all cells. + ** At this point we used to call reparentChildPages() to make sure that + ** the MemPage.pParent and MemPage.idxParent variables are correct for + ** all children of the pages modified by this balance operation. Even + ** if this is an auto-vacuum database there is no need to update the + ** pointer-map entries for child pages - that has already been done + ** by the block above. + ** + ** However, this is no longer necessary because the MemPage.pParent and + ** MemPage.idxParent variables are only assumed to be valid when there + ** are one or more references to the page (when isInit==PAGE_ISINIT_FULL). + ** At this point we can account for all references to the pages + ** manipulated by this function and deduce that it is not necessary to + ** update these two variables because: + ** + ** a) it must have been called, directly or indirectly, from BtreeInsert() + ** or BtreeDelete(). Both these functions call saveAllCursors(), so + ** we can be sure that there exactly one write-cursor (and no + ** read-cursors) open on the b-tree being manipulated. No other + ** cursor may be holding references to any pages in the b-tree. + ** + ** b) After this function returns, the one open write-cursor will be + ** moved to point at the root of the table using moveToRoot(). The + ** code that does this (see BtreeInsert() and BtreeDelete()) ensures + ** that the MemPage.pParent variables are not used to find the root + ** page of the b-tree, it is located using BtCursor.pgnoRoot. + ** + ** c) the other page references are those held by this function, on + ** the pages in apNew[] and apOld[]. They are about to be released. + ** + ** Therefore, no need to call reparentChildPages(). This can be a + ** significant performance boost. */ +#if 0 for(i=0; ipPage); + pCur->pPage = 0; moveToRoot(pCur); } end_insert: @@ -6089,6 +6128,13 @@ int sqlite3BtreeDelete(BtCursor *pCur){ rc = balance(pPage, 0); } if( rc==SQLITE_OK ){ + /* balance() may have messed up the chain of MemPage.pParent pointers. + ** To prevent moveToRoot() from trying to use them to locate the root + ** page of this table, release the reference to the current page before + ** calling it. + */ + releasePage(pCur->pPage); + pCur->pPage = 0; moveToRoot(pCur); } return rc;