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Change the way that balance_nonroot() partitions cells between the sibling

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pages such that a scan of the cell size array is not required.

FossilOrigin-Name: 168728715156d756ac8c0df45710d054eee027ec
This commit is contained in:
drh
2015-06-22 20:02:04 +00:00
parent 82c4f9b407
commit 658873bdb3
3 changed files with 70 additions and 28 deletions
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81
src/btree.c
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@@ -3206,6 +3206,7 @@ static int setChildPtrmaps(MemPage *pPage){
if( !pPage->leaf ){
Pgno childPgno = get4byte(pCell);
ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno, &rc);
if( rc ) return rc;
}
}
@@ -6295,7 +6296,7 @@ static void insertCell(
** The MemPage.nFree field is invalidated by this function. It is the
** responsibility of the caller to set it correctly.
*/
static void rebuildPage(
static int rebuildPage(
MemPage *pPg, /* Edit this page */
int nCell, /* Final number of cells on page */
u8 **apCell, /* Array of cells */
@@ -6320,9 +6321,10 @@ static void rebuildPage(
pCell = &pTmp[pCell - aData];
}
pData -= szCell[i];
memcpy(pData, pCell, szCell[i]);
put2byte(pCellptr, (pData - aData));
pCellptr += 2;
if( pData < pCellptr ) return SQLITE_CORRUPT_BKPT;
memcpy(pData, pCell, szCell[i]);
assert( szCell[i]==pPg->xCellSize(pPg, pCell) || CORRUPT_DB );
testcase( szCell[i]==pPg->xCellSize(pPg,pCell) );
}
@@ -6335,6 +6337,7 @@ static void rebuildPage(
put2byte(&aData[hdr+3], pPg->nCell);
put2byte(&aData[hdr+5], pData - aData);
aData[hdr+7] = 0x00;
return SQLITE_OK;
}
/*
@@ -6454,7 +6457,7 @@ static int pageFreeArray(
** The pPg->nFree field is invalid when this function returns. It is the
** responsibility of the caller to set it correctly.
*/
static void editPage(
static int editPage(
MemPage *pPg, /* Edit this page */
int iOld, /* Index of first cell currently on page */
int iNew, /* Index of new first cell on page */
@@ -6545,10 +6548,10 @@ static void editPage(
}
#endif
return;
return SQLITE_OK;
editpage_fail:
/* Unable to edit this page. Rebuild it from scratch instead. */
rebuildPage(pPg, nNew, &apCell[iNew], &szCell[iNew]);
return rebuildPage(pPg, nNew, &apCell[iNew], &szCell[iNew]);
}
/*
@@ -6620,7 +6623,8 @@ static int balance_quick(MemPage *pParent, MemPage *pPage, u8 *pSpace){
assert( sqlite3PagerIswriteable(pNew->pDbPage) );
assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
rebuildPage(pNew, 1, &pCell, &szCell);
rc = rebuildPage(pNew, 1, &pCell, &szCell);
if( rc ) return rc;
pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;
/* If this is an auto-vacuum database, update the pointer map
@@ -6835,7 +6839,6 @@ static int balance_nonroot(
int leafData; /* True if pPage is a leaf of a LEAFDATA tree */
int usableSpace; /* Bytes in pPage beyond the header */
int pageFlags; /* Value of pPage->aData[0] */
int subtotal; /* Subtotal of bytes in cells on one page */
int iSpace1 = 0; /* First unused byte of aSpace1[] */
int iOvflSpace = 0; /* First unused byte of aOvflSpace[] */
int szScratch; /* Size of scratch memory requested */
@@ -7081,21 +7084,50 @@ static int balance_nonroot(
**
*/
usableSpace = pBt->usableSize - 12 + leafCorrection;
for(subtotal=k=i=0; i<nCell; i++){
assert( i<nMaxCells );
subtotal += szCell[i] + 2;
if( subtotal > usableSpace ){
szNew[k] = subtotal - szCell[i] - 2;
cntNew[k] = i;
if( leafData ){ i--; }
subtotal = 0;
k++;
if( k>NB+1 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
for(i=0; i<nOld; i++){
MemPage *p = apOld[i];
szNew[i] = usableSpace - p->nFree;
if( szNew[i]<0 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
for(j=0; j<p->nOverflow; j++){
szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]);
}
cntNew[i] = cntOld[i];
}
k = nOld;
for(i=0; i<k; i++){
int sz;
while( szNew[i]>usableSpace ){
if( i+1>=k ){
k = i+2;
if( k>NB+2 ){ rc = SQLITE_CORRUPT_BKPT; goto balance_cleanup; }
szNew[k-1] = 0;
cntNew[k-1] = nCell;
}
sz = 2+szCell[cntNew[i]-1];
szNew[i] -= sz;
if( !leafData ){
sz = cntNew[i]<nCell ? 2+szCell[cntNew[i]] : 0;
}
szNew[i+1] += sz;
cntNew[i]--;
}
while( cntNew[i]<nCell ){
sz = 2+szCell[cntNew[i]];
if( szNew[i]+sz>usableSpace ) break;
szNew[i] += sz;
cntNew[i]++;
if( !leafData ){
sz = cntNew[i]<nCell ? 2+szCell[cntNew[i]] : 0;
}
szNew[i+1] -= sz;
}
if( cntNew[i]>=nCell ){
k = i+1;
}else if( cntNew[i] - (i>0 ? cntNew[i-1] : 0) <= 0 ){
rc = SQLITE_CORRUPT_BKPT;
goto balance_cleanup;
}
}
szNew[k] = subtotal;
cntNew[k] = nCell;
k++;
/*
** The packing computed by the previous block is biased toward the siblings
@@ -7124,6 +7156,10 @@ static int balance_nonroot(
szRight += szCell[d] + 2;
szLeft -= szCell[r] + 2;
cntNew[i-1]--;
if( cntNew[i-1] <= 0 ){
rc = SQLITE_CORRUPT_BKPT;
goto balance_cleanup;
}
r = cntNew[i-1] - 1;
d = r + 1 - leafData;
}
@@ -7294,9 +7330,11 @@ static int balance_nonroot(
){
if( !leafCorrection ){
ptrmapPut(pBt, get4byte(pCell), PTRMAP_BTREE, pNew->pgno, &rc);
if( rc ) goto balance_cleanup;
}
if( szCell[i]>pNew->minLocal ){
ptrmapPutOvflPtr(pNew, pCell, &rc);
if( rc ) goto balance_cleanup;
}
}
}
@@ -7404,7 +7442,8 @@ static int balance_nonroot(
nNewCell = cntNew[iPg] - iNew;
}
editPage(apNew[iPg], iOld, iNew, nNewCell, apCell, szCell);
rc = editPage(apNew[iPg], iOld, iNew, nNewCell, apCell, szCell);
if( rc ) goto balance_cleanup;
abDone[iPg]++;
apNew[iPg]->nFree = usableSpace-szNew[iPg];
assert( apNew[iPg]->nOverflow==0 );