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Avoid moving pages more than once in an incremental vacuum operation.

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FossilOrigin-Name: c3939d249119b47bd57baa11a5ed7cc6014fc795
This commit is contained in:
dan
2013-02-22 20:16:34 +00:00
parent d5d0f6432c
commit 51f0b6d568
3 changed files with 102 additions and 62 deletions
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145
src/btree.c
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@@ -2909,26 +2909,28 @@ static int relocatePage(
/* Forward declaration required by incrVacuumStep(). */
static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
#define BTALLOC_ANY 0 /* Allocate any page */
#define BTALLOC_EXACT 1 /* Allocate exact page if possible */
#define BTALLOC_LE 2 /* Allocate any page <= the parameter */
/*
** Perform a single step of an incremental-vacuum. If successful,
** return SQLITE_OK. If there is no work to do (and therefore no
** point in calling this function again), return SQLITE_DONE.
** Perform a single step of an incremental-vacuum. If successful, return
** SQLITE_OK. If there is no work to do (and therefore no point in
** calling this function again), return SQLITE_DONE. Or, if an error
** occurs, return some other error code.
**
** More specificly, this function attempts to re-organize the
** database so that the last page of the file currently in use
** is no longer in use.
** More specificly, this function attempts to re-organize the database so
** that the last page of the file currently in use is no longer in use.
**
** If the nFin parameter is non-zero, this function assumes
** that the caller will keep calling incrVacuumStep() until
** it returns SQLITE_DONE or an error, and that nFin is the
** number of pages the database file will contain after this
** process is complete. If nFin is zero, it is assumed that
** incrVacuumStep() will be called a finite amount of times
** which may or may not empty the freelist. A full autovacuum
** has nFin>0. A "PRAGMA incremental_vacuum" has nFin==0.
** Parameter nFin is the number of pages that this database would contain
** were this function called until it returns SQLITE_DONE.
**
** If the bCommit parameter is non-zero, this function assumes that the
** caller will keep calling incrVacuumStep() until it returns SQLITE_DONE
** or an error. bCommit is passed true for an auto-vacuum-on-commmit
** operation, or false for an incremental vacuum.
*/
static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg, int bCommit){
Pgno nFreeList; /* Number of pages still on the free-list */
int rc;
@@ -2953,15 +2955,15 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
}
if( eType==PTRMAP_FREEPAGE ){
if( nFin==0 ){
if( bCommit==0 ){
/* Remove the page from the files free-list. This is not required
** if nFin is non-zero. In that case, the free-list will be
** if bCommit is non-zero. In that case, the free-list will be
** truncated to zero after this function returns, so it doesn't
** matter if it still contains some garbage entries.
*/
Pgno iFreePg;
MemPage *pFreePg;
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, 1);
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, BTALLOC_EXACT);
if( rc!=SQLITE_OK ){
return rc;
}
@@ -2971,28 +2973,34 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
} else {
Pgno iFreePg; /* Index of free page to move pLastPg to */
MemPage *pLastPg;
u8 eMode = BTALLOC_ANY; /* Mode parameter for allocateBtreePage() */
Pgno iNear = 0; /* nearby parameter for allocateBtreePage() */
rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
if( rc!=SQLITE_OK ){
return rc;
}
/* If nFin is zero, this loop runs exactly once and page pLastPg
/* If bCommit is zero, this loop runs exactly once and page pLastPg
** is swapped with the first free page pulled off the free list.
**
** On the other hand, if nFin is greater than zero, then keep
** On the other hand, if bCommit is greater than zero, then keep
** looping until a free-page located within the first nFin pages
** of the file is found.
*/
if( bCommit==0 ){
eMode = BTALLOC_LE;
iNear = nFin;
}
do {
MemPage *pFreePg;
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, 0, 0);
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iNear, eMode);
if( rc!=SQLITE_OK ){
releasePage(pLastPg);
return rc;
}
releasePage(pFreePg);
}while( nFin!=0 && iFreePg>nFin );
}while( bCommit && iFreePg>nFin );
assert( iFreePg<iLastPg );
rc = sqlite3PagerWrite(pLastPg->pDbPage);
@@ -3006,7 +3014,7 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
}
}
if( nFin==0 ){
if( bCommit==0 ){
iLastPg--;
while( iLastPg==PENDING_BYTE_PAGE(pBt)||PTRMAP_ISPAGE(pBt, iLastPg) ){
if( PTRMAP_ISPAGE(pBt, iLastPg) ){
@@ -3029,6 +3037,30 @@ static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
return SQLITE_OK;
}
/*
** The database opened by the first argument is an auto-vacuum database
** nOrig pages in size containing nFree free pages. Return the expected
** size of the database in pages following an auto-vacuum operation.
*/
static Pgno finalDbSize(BtShared *pBt, Pgno nOrig, Pgno nFree){
int nEntry; /* Number of entries on one ptrmap page */
Pgno nPtrmap; /* Number of PtrMap pages to be freed */
Pgno nFin; /* Return value */
nEntry = pBt->usableSize/5;
nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
nFin = nOrig - nFree - nPtrmap;
if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
return nFin;
}
/*
** A write-transaction must be opened before calling this function.
** It performs a single unit of work towards an incremental vacuum.
@@ -3046,11 +3078,19 @@ int sqlite3BtreeIncrVacuum(Btree *p){
if( !pBt->autoVacuum ){
rc = SQLITE_DONE;
}else{
invalidateAllOverflowCache(pBt);
rc = incrVacuumStep(pBt, 0, btreePagecount(pBt));
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
put4byte(&pBt->pPage1->aData[28], pBt->nPage);
Pgno nOrig = btreePagecount(pBt);
Pgno nFree = get4byte(&pBt->pPage1->aData[36]);
Pgno nFin = finalDbSize(pBt, nOrig, nFree);
if( nFin<nOrig ){
invalidateAllOverflowCache(pBt);
rc = incrVacuumStep(pBt, nFin, nOrig, 0);
if( rc==SQLITE_OK ){
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
put4byte(&pBt->pPage1->aData[28], pBt->nPage);
}
}else{
rc = SQLITE_DONE;
}
}
sqlite3BtreeLeave(p);
@@ -3077,9 +3117,7 @@ static int autoVacuumCommit(BtShared *pBt){
if( !pBt->incrVacuum ){
Pgno nFin; /* Number of pages in database after autovacuuming */
Pgno nFree; /* Number of pages on the freelist initially */
Pgno nPtrmap; /* Number of PtrMap pages to be freed */
Pgno iFree; /* The next page to be freed */
int nEntry; /* Number of entries on one ptrmap page */
Pgno nOrig; /* Database size before freeing */
nOrig = btreePagecount(pBt);
@@ -3092,19 +3130,11 @@ static int autoVacuumCommit(BtShared *pBt){
}
nFree = get4byte(&pBt->pPage1->aData[36]);
nEntry = pBt->usableSize/5;
nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
nFin = nOrig - nFree - nPtrmap;
if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
nFin = finalDbSize(pBt, nOrig, nFree);
if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
rc = incrVacuumStep(pBt, nFin, iFree);
rc = incrVacuumStep(pBt, nFin, iFree, 1);
}
if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
@@ -4867,7 +4897,7 @@ static int allocateBtreePage(
MemPage **ppPage,
Pgno *pPgno,
Pgno nearby,
u8 exact
u8 eMode
){
MemPage *pPage1;
int rc;
@@ -4895,16 +4925,19 @@ static int allocateBtreePage(
** the entire-list will be searched for that page.
*/
#ifndef SQLITE_OMIT_AUTOVACUUM
if( exact && nearby<=mxPage ){
u8 eType;
assert( nearby>0 );
assert( pBt->autoVacuum );
rc = ptrmapGet(pBt, nearby, &eType, 0);
if( rc ) return rc;
if( eType==PTRMAP_FREEPAGE ){
searchList = 1;
if( eMode==BTALLOC_EXACT ){
if( nearby<=mxPage ){
u8 eType;
assert( nearby>0 );
assert( pBt->autoVacuum );
rc = ptrmapGet(pBt, nearby, &eType, 0);
if( rc ) return rc;
if( eType==PTRMAP_FREEPAGE ){
searchList = 1;
}
}
*pPgno = nearby;
}else if( eMode==BTALLOC_LE ){
searchList = 1;
}
#endif
@@ -4959,11 +4992,13 @@ static int allocateBtreePage(
rc = SQLITE_CORRUPT_BKPT;
goto end_allocate_page;
#ifndef SQLITE_OMIT_AUTOVACUUM
}else if( searchList && nearby==iTrunk ){
}else if( searchList
&& (nearby==iTrunk || (iTrunk<nearby && eMode==BTALLOC_LE))
){
/* The list is being searched and this trunk page is the page
** to allocate, regardless of whether it has leaves.
*/
assert( *pPgno==iTrunk );
*pPgno = iTrunk;
*ppPage = pTrunk;
searchList = 0;
rc = sqlite3PagerWrite(pTrunk->pDbPage);
@@ -5047,7 +5082,9 @@ static int allocateBtreePage(
goto end_allocate_page;
}
testcase( iPage==mxPage );
if( !searchList || iPage==nearby ){
if( !searchList
|| (iPage==nearby || (iPage<nearby && eMode==BTALLOC_LE))
){
int noContent;
*pPgno = iPage;
TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
@@ -7119,7 +7156,7 @@ static int btreeCreateTable(Btree *p, int *piTable, int createTabFlags){
** be moved to the allocated page (unless the allocated page happens
** to reside at pgnoRoot).
*/
rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, 1);
rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, BTALLOC_EXACT);
if( rc!=SQLITE_OK ){
return rc;
}