}
}
+/*
+** The following parameters determine how many adjacent pages get involved
+** in a balancing operation. NN is the number of neighbors on either side
+** of the page that participate in the balancing operation. NB is the
+** total number of pages that participate, including the target page and
+** NN neighbors on either side.
+**
+** The minimum value of NN is 1 (of course). Increasing NN above 1
+** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
+** in exchange for a larger degradation in INSERT and UPDATE performance.
+** The value of NN appears to give the best results overall.
+**
+** (Later:) The description above makes it seem as if these values are
+** tunable - as if you could change them and recompile and it would all work.
+** But that is unlikely. NB has been 3 since the inception of SQLite and
+** we have never tested any other value.
+*/
+#define NN 1 /* Number of neighbors on either side of pPage */
+#define NB 3 /* (NN*2+1): Total pages involved in the balance */
+
/*
** A CellArray object contains a cache of pointers and sizes for a
** consecutive sequence of cells that might be held on multiple pages.
+**
+** The cells in this array are the divider cell or cells from the pParent
+** page plus up to three child pages. There are a total of nCell cells.
+**
+** pRef is a pointer to one of the pages that contributes cells. This is
+** used to access information such as MemPage.intKey and MemPage.pBt->pageSize
+** which should be common to all pages that contribute cells to this array.
+**
+** apCell[] and szCell[] hold, respectively, pointers to the start of each
+** cell and the size of each cell. Some of the apCell[] pointers might refer
+** to overflow cells. In other words, some apCel[] pointers might not point
+** to content area of the pages.
+**
+** A szCell[] of zero means the size of that cell has not yet been computed.
+**
+** The cells come from as many as four different pages:
+**
+** -----------
+** | Parent |
+** -----------
+** / | \
+** / | \
+** --------- --------- ---------
+** |Child-1| |Child-2| |Child-3|
+** --------- --------- ---------
+**
+** The order of cells is in the array is:
+**
+** 1. All cells from Child-1 in order
+** 2. The first divider cell from Parent
+** 3. All cells from Child-2 in order
+** 4. The second divider cell from Parent
+** 5. All cells from Child-3 in order
+**
+** The apEnd[] array holds pointer to the end of page for Child-1, the
+** Parent, Child-2, the Parent (again), and Child-3. The ixNx[] array
+** holds the number of cells contained in each of these 5 stages, and
+** all stages to the left. Hence:
+** ixNx[0] = Number of cells in Child-1.
+** ixNx[1] = Number of cells in Child-1 plus 1 for first divider.
+** ixNx[2] = Number of cells in Child-1 and Child-2 + 1 for 1st divider.
+** ixNx[3] = Number of cells in Child-1 and Child-2 + both divider cells
+** ixNx[4] = Total number of cells.
*/
typedef struct CellArray CellArray;
struct CellArray {
MemPage *pRef; /* Reference page */
u8 **apCell; /* All cells begin balanced */
u16 *szCell; /* Local size of all cells in apCell[] */
+ u8 *apEnd[NB*2]; /* MemPage.aDataEnd values */
+ int ixNx[NB*2]; /* Index of at which we move to the next apEnd[] */
};
/*
** responsibility of the caller to set it correctly.
*/
static int rebuildPage(
- MemPage *pPg, /* Edit this page */
+ CellArray *pCArray, /* Content to be added to page pPg */
+ int iFirst, /* First cell in pCArray to use */
int nCell, /* Final number of cells on page */
- u8 **apCell, /* Array of cells */
- u16 *szCell /* Array of cell sizes */
+ MemPage *pPg /* The page to be reconstructed */
){
const int hdr = pPg->hdrOffset; /* Offset of header on pPg */
u8 * const aData = pPg->aData; /* Pointer to data for pPg */
const int usableSize = pPg->pBt->usableSize;
u8 * const pEnd = &aData[usableSize];
- int i;
+ int i = iFirst; /* Which cell to copy from pCArray*/
+ int j; /* Start of cell content area */
+ int iEnd = i+nCell; /* Loop terminator */
u8 *pCellptr = pPg->aCellIdx;
u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
u8 *pData;
+ int k; /* Current slot in pCArray->apEnd[] */
+ u8 *pSrcEnd; /* Current pCArray->apEnd[k] value */
+
+ assert( i<iEnd );
+ j = get2byte(&aData[hdr+5]);
+ memcpy(&pTmp[j], &aData[j], usableSize - j);
- i = get2byte(&aData[hdr+5]);
- memcpy(&pTmp[i], &aData[i], usableSize - i);
+ for(k=0; pCArray->ixNx[k]<=i && ALWAYS(k<NB*2); k++){}
+ pSrcEnd = pCArray->apEnd[k];
pData = pEnd;
- for(i=0; i<nCell; i++){
- u8 *pCell = apCell[i];
+ while( 1/*exit by break*/ ){
+ u8 *pCell = pCArray->apCell[i];
+ u16 sz = pCArray->szCell[i];
+ assert( sz>0 );
if( SQLITE_WITHIN(pCell,aData,pEnd) ){
- if( ((uptr)(pCell+szCell[i]))>(uptr)pEnd ) return SQLITE_CORRUPT_BKPT;
+ if( ((uptr)(pCell+sz))>(uptr)pEnd ) return SQLITE_CORRUPT_BKPT;
pCell = &pTmp[pCell - aData];
+ }else if( (uptr)(pCell+sz)>(uptr)pSrcEnd
+ && (uptr)(pCell)<(uptr)pSrcEnd
+ ){
+ return SQLITE_CORRUPT_BKPT;
}
- pData -= szCell[i];
+
+ pData -= sz;
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) );
+ memcpy(pData, pCell, sz);
+ assert( sz==pPg->xCellSize(pPg, pCell) || CORRUPT_DB );
+ testcase( sz!=pPg->xCellSize(pPg,pCell) );
+ i++;
+ if( i>=iEnd ) break;
+ if( pCArray->ixNx[k]<=i ){
+ k++;
+ pSrcEnd = pCArray->apEnd[k];
+ }
}
/* The pPg->nFree field is now set incorrectly. The caller will fix it. */
}
/*
-** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
-** contains the size in bytes of each such cell. This function attempts to
-** add the cells stored in the array to page pPg. If it cannot (because
-** the page needs to be defragmented before the cells will fit), non-zero
-** is returned. Otherwise, if the cells are added successfully, zero is
-** returned.
+** The pCArray objects contains pointers to b-tree cells and the cell sizes.
+** This function attempts to add the cells stored in the array to page pPg.
+** If it cannot (because the page needs to be defragmented before the cells
+** will fit), non-zero is returned. Otherwise, if the cells are added
+** successfully, zero is returned.
**
** Argument pCellptr points to the first entry in the cell-pointer array
** (part of page pPg) to populate. After cell apCell[0] is written to the
static int pageInsertArray(
MemPage *pPg, /* Page to add cells to */
u8 *pBegin, /* End of cell-pointer array */
- u8 **ppData, /* IN/OUT: Page content -area pointer */
+ u8 **ppData, /* IN/OUT: Page content-area pointer */
u8 *pCellptr, /* Pointer to cell-pointer area */
int iFirst, /* Index of first cell to add */
int nCell, /* Number of cells to add to pPg */
CellArray *pCArray /* Array of cells */
){
- int i;
- u8 *aData = pPg->aData;
- u8 *pData = *ppData;
- int iEnd = iFirst + nCell;
+ int i = iFirst; /* Loop counter - cell index to insert */
+ u8 *aData = pPg->aData; /* Complete page */
+ u8 *pData = *ppData; /* Content area. A subset of aData[] */
+ int iEnd = iFirst + nCell; /* End of loop. One past last cell to ins */
+ int k; /* Current slot in pCArray->apEnd[] */
+ u8 *pEnd; /* Maximum extent of cell data */
assert( CORRUPT_DB || pPg->hdrOffset==0 ); /* Never called on page 1 */
- for(i=iFirst; i<iEnd; i++){
+ if( iEnd<=iFirst ) return 0;
+ for(k=0; pCArray->ixNx[k]<=i && ALWAYS(k<NB*2); k++){}
+ pEnd = pCArray->apEnd[k];
+ while( 1 /*Exit by break*/ ){
int sz, rc;
u8 *pSlot;
sz = cachedCellSize(pCArray, i);
assert( (pSlot+sz)<=pCArray->apCell[i]
|| pSlot>=(pCArray->apCell[i]+sz)
|| CORRUPT_DB );
+ if( (uptr)(pCArray->apCell[i]+sz)>(uptr)pEnd
+ && (uptr)(pCArray->apCell[i])<(uptr)pEnd
+ ){
+ assert( CORRUPT_DB );
+ (void)SQLITE_CORRUPT_BKPT;
+ return 1;
+ }
memmove(pSlot, pCArray->apCell[i], sz);
put2byte(pCellptr, (pSlot - aData));
pCellptr += 2;
+ i++;
+ if( i>=iEnd ) break;
+ if( pCArray->ixNx[k]<=i ){
+ k++;
+ pEnd = pCArray->apEnd[k];
+ }
}
*ppData = pData;
return 0;
}
/*
-** Array apCell[] contains nCell pointers to b-tree cells. Array szCell
-** contains the size in bytes of each such cell. This function adds the
-** space associated with each cell in the array that is currently stored
-** within the body of pPg to the pPg free-list. The cell-pointers and other
-** fields of the page are not updated.
+** The pCArray object contains pointers to b-tree cells and their sizes.
+**
+** This function adds the space associated with each cell in the array
+** that is currently stored within the body of pPg to the pPg free-list.
+** The cell-pointers and other fields of the page are not updated.
**
** This function returns the total number of cells added to the free-list.
*/
}
/*
-** apCell[] and szCell[] contains pointers to and sizes of all cells in the
-** pages being balanced. The current page, pPg, has pPg->nCell cells starting
-** with apCell[iOld]. After balancing, this page should hold nNew cells
+** pCArray contains pointers to and sizes of all cells in the pages being
+** balanced. The current page, pPg, has pPg->nCell cells starting with
+** pCArray->apCell[iOld]. After balancing, this page should hold nNew cells
** starting at apCell[iNew].
**
** This routine makes the necessary adjustments to pPg so that it contains
editpage_fail:
/* Unable to edit this page. Rebuild it from scratch instead. */
populateCellCache(pCArray, iNew, nNew);
- return rebuildPage(pPg, nNew, &pCArray->apCell[iNew], &pCArray->szCell[iNew]);
+ return rebuildPage(pCArray, iNew, nNew, pPg);
}
-/*
-** The following parameters determine how many adjacent pages get involved
-** in a balancing operation. NN is the number of neighbors on either side
-** of the page that participate in the balancing operation. NB is the
-** total number of pages that participate, including the target page and
-** NN neighbors on either side.
-**
-** The minimum value of NN is 1 (of course). Increasing NN above 1
-** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
-** in exchange for a larger degradation in INSERT and UPDATE performance.
-** The value of NN appears to give the best results overall.
-*/
-#define NN 1 /* Number of neighbors on either side of pPage */
-#define NB (NN*2+1) /* Total pages involved in the balance */
-
#ifndef SQLITE_OMIT_QUICKBALANCE
/*
u8 *pCell = pPage->apOvfl[0];
u16 szCell = pPage->xCellSize(pPage, pCell);
u8 *pStop;
+ CellArray b;
assert( sqlite3PagerIswriteable(pNew->pDbPage) );
assert( pPage->aData[0]==(PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF) );
zeroPage(pNew, PTF_INTKEY|PTF_LEAFDATA|PTF_LEAF);
- rc = rebuildPage(pNew, 1, &pCell, &szCell);
- if( NEVER(rc) ) return rc;
+ b.nCell = 1;
+ b.pRef = pPage;
+ b.apCell = &pCell;
+ b.szCell = &szCell;
+ b.apEnd[0] = pPage->aDataEnd;
+ b.ixNx[0] = 2;
+ rc = rebuildPage(&b, 0, 1, pNew);
+ if( NEVER(rc) ){
+ releasePage(pNew);
+ return rc;
+ }
pNew->nFree = pBt->usableSize - pNew->cellOffset - 2 - szCell;
/* If this is an auto-vacuum database, update the pointer map
usableSpace = pBt->usableSize - 12 + leafCorrection;
for(i=0; i<nOld; i++){
MemPage *p = apOld[i];
+ b.apEnd[i*2] = p->aDataEnd;
+ b.apEnd[i*2+1] = pParent->aDataEnd;
+ b.ixNx[i*2] = cntOld[i];
+ b.ixNx[i*2+1] = cntOld[i]+1;
szNew[i] = usableSpace - p->nFree;
for(j=0; j<p->nOverflow; j++){
szNew[i] += 2 + p->xCellSize(p, p->apOvfl[j]);
projects / thirdparty / sqlite.git / commitdiff
