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Avoid loading large intkey rows when VACUUMing, even if the page-size is changing.

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FossilOrigin-Name: 0d2c3776065dc94119899ae4164995193b82fca7ac31868f3141b729d0b65ab9
This commit is contained in:
dan
2020-12-09 16:32:11 +00:00
parent 036e0675e6
commit ebbf36878c
5 changed files with 200 additions and 73 deletions
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157
src/btree.c
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@@ -1143,6 +1143,24 @@ static SQLITE_NOINLINE void btreeParseCellAdjustSizeForOverflow(
pInfo->nSize = (u16)(&pInfo->pPayload[pInfo->nLocal] - pCell) + 4;
}
/*
** Given a record with nPayload bytes of payload stored within btree
** page pPage, return the number of bytes of payload stored locally.
*/
static int btreePayloadToLocal(MemPage *pPage, int nPayload){
int maxLocal; /* Maximum amount of payload held locally */
maxLocal = pPage->maxLocal;
if( nPayload<=maxLocal ){
return nPayload;
}else{
int minLocal; /* Minimum amount of payload held locally */
int surplus; /* Overflow payload available for local storage */
minLocal = pPage->minLocal;
surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize-4);
return ( surplus <= maxLocal ) ? surplus : minLocal;
}
}
/*
** The following routines are implementations of the MemPage.xParseCell()
** method.
@@ -6500,7 +6518,7 @@ static int fillInCell(
/* Fill in the header. */
nHeader = pPage->childPtrSize;
if( pPage->intKey ){
if( pX->pData==(const void*)pPage->pBt->pTmpSpace ){
if( pX->nZero<0 ){
*pnSize = pX->nData;
return SQLITE_OK;
}
@@ -8924,72 +8942,89 @@ int sqlite3BtreeTransfer(
){
int rc = SQLITE_OK;
BtreePayload x;
Pager *pSrcPager = pSrc->pBt->pPager;
u8 *pCell = pDest->pBt->pTmpSpace;
u8 *aOut; /* Pointer to next output buffer */
int nOut; /* Size of output buffer aOut[] */
const u8 *aIn; /* Pointer to next input buffer */
int nIn; /* Size of input buffer aIn[] */
int nRem; /* Bytes of data still to copy */
u8 *pPgnoOut = 0;
Pgno ovflIn = 0;
DbPage *pPageIn = 0;
MemPage *pPageOut = 0;
memset(&x, 0, sizeof(x));
x.nKey = iKey;
getCellInfo(pSrc);
if( pDest->pBt->usableSize!=pSrc->pBt->usableSize ){
void *pFree = 0;
x.nData = pSrc->info.nPayload;
if( pSrc->info.nLocal==pSrc->info.nPayload ){
x.pData = pSrc->info.pPayload;
}else{
x.pData = pFree = sqlite3_malloc(pSrc->info.nPayload);
if( pFree==0 ){
rc = SQLITE_NOMEM_BKPT;
}else{
rc = sqlite3BtreePayload(pSrc, 0, x.nData, pFree);
x.pData = pCell;
x.nData = putVarint32(pCell, pSrc->info.nPayload);
x.nData += putVarint(&pCell[x.nData], iKey);
x.nZero = -1;
nOut = btreePayloadToLocal(pDest->pPage, pSrc->info.nPayload);
aOut = &pCell[x.nData];
nIn = pSrc->info.nLocal;
aIn = pSrc->info.pPayload;
nRem = pSrc->info.nPayload;
x.nData += nOut;
if( nOut<pSrc->info.nPayload ){
pPgnoOut = &pCell[x.nData];
x.nData += 4;
}
if( nRem>nIn ){
ovflIn = get4byte(&pSrc->info.pPayload[nIn]);
}
do {
nRem -= nOut;
do{
assert( nOut>0 );
if( nIn>0 ){
int nCopy = MIN(nOut, nIn);
memcpy(aOut, aIn, nCopy);
nOut -= nCopy;
nIn -= nCopy;
aOut += nCopy;
aIn += nCopy;
}
if( nOut>0 ){
sqlite3PagerUnref(pPageIn);
pPageIn = 0;
rc = sqlite3PagerGet(pSrcPager, ovflIn, &pPageIn, PAGER_GET_READONLY);
if( rc==SQLITE_OK ){
aIn = (const u8*)sqlite3PagerGetData(pPageIn);
ovflIn = get4byte(aIn);
aIn += 4;
nIn = pSrc->pBt->usableSize - 4;
}
}
}while( rc==SQLITE_OK && nOut>0 );
if( rc==SQLITE_OK && nRem>0 ){
Pgno pgnoNew;
MemPage *pNew = 0;
rc = allocateBtreePage(pDest->pBt, &pNew, &pgnoNew, 0, 0);
put4byte(pPgnoOut, pgnoNew);
releasePage(pPageOut);
pPageOut = pNew;
if( pPageOut ){
pPgnoOut = pPageOut->aData;
put4byte(pPgnoOut, 0);
aOut = &pPgnoOut[4];
nOut = MIN(pDest->pBt->usableSize - 4, nRem);
}
}
if( rc==SQLITE_OK ){
rc = sqlite3BtreeInsert(pDest, &x, OPFLAG_APPEND, seekResult);
}
sqlite3_free(pFree);
}else{
/* Page sizes match. This means each overflow page (if any) and the
** cell itself can be copied verbatim. */
u8 *pCell = pDest->pBt->pTmpSpace;
x.pData = pCell;
x.nData = putVarint32(pCell, pSrc->info.nPayload);
x.nData += putVarint(&pCell[x.nData], iKey);
memcpy(&pCell[x.nData], pSrc->info.pPayload, pSrc->info.nLocal);
x.nData += pSrc->info.nLocal;
assert( pSrc->info.nLocal<=pSrc->info.nPayload );
if( pSrc->info.nLocal<pSrc->info.nPayload ){
Pager *pSrcPager = pSrc->pBt->pPager;
u8 *pPgno = &pCell[x.nData];
Pgno ovfl;
x.nData += 4;
ovfl = get4byte(pSrc->info.pPayload + pSrc->info.nLocal);
do{
MemPage *pNew = 0;
Pgno pgnoNew = 0;
if( rc==SQLITE_OK ){
rc = allocateBtreePage(pDest->pBt, &pNew, &pgnoNew, 0, 0);
put4byte(pPgno, pgnoNew);
}
if( rc==SQLITE_OK ){
pPgno = pNew->aData;
rc = sqlite3PagerWrite(pNew->pDbPage);
}
if( rc==SQLITE_OK ){
DbPage *pOrig = 0;
void *pOrigData;
rc = sqlite3PagerGet(pSrcPager, ovfl, &pOrig, PAGER_GET_READONLY);
if( rc==SQLITE_OK ){
pOrigData = sqlite3PagerGetData(pOrig);
memcpy(pNew->aData, pOrigData, pDest->pBt->usableSize);
put4byte(pNew->aData, 0);
ovfl = get4byte(pOrigData);
}
sqlite3PagerUnref(pOrig);
}
releasePage(pNew);
}while( rc==SQLITE_OK && ovfl>0 );
}
if( rc==SQLITE_OK ){
rc = sqlite3BtreeInsert(pDest, &x, OPFLAG_APPEND, seekResult);
}
}while( nRem>0 && rc==SQLITE_OK );
releasePage(pPageOut);
sqlite3PagerUnref(pPageIn);
if( rc==SQLITE_OK ){
rc = sqlite3BtreeInsert(pDest, &x, OPFLAG_APPEND, seekResult);
}
return rc;