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When doing coverage analysis of a btree page for pragma integrity_check,

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make the first entry (that covers the header, cell index, and gap) implied,
for a performance boost and size reduction.

FossilOrigin-Name: e53d497c2d2fbc5014b39f5624b52ce207800698
This commit is contained in:
drh
2015-07-02 19:47:08 +00:00
parent 6544b8643f
commit d2dc87f6d5
3 changed files with 21 additions and 15 deletions
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20
src/btree.c
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@@ -8955,7 +8955,7 @@ static int checkTreePage(
u32 usableSize; /* Usable size of the page */
u32 contentOffset; /* Offset to the start of the cell content area */
u32 *heap = 0; /* Min-heap used for checking cell coverage */
u32 x, prev = 0;
u32 x, prev = 0; /* Next and previous entry on the min-heap */
const char *saved_zPfx = pCheck->zPfx;
int saved_v1 = pCheck->v1;
int saved_v2 = pCheck->v2;
@@ -9018,7 +9018,6 @@ static int checkTreePage(
** as the other cell checks, so initialize the heap. */
heap = pCheck->heap;
heap[0] = 0;
btreeHeapInsert(heap, contentOffset-1);
}
/* EVIDENCE-OF: R-02776-14802 The cell pointer array consists of K 2-byte
@@ -9099,7 +9098,6 @@ static int checkTreePage(
if( !pPage->leaf ){
heap = pCheck->heap;
heap[0] = 0;
btreeHeapInsert(heap, contentOffset-1);
for(i=nCell-1; i>=0; i--){
u32 size;
pc = get2byteAligned(&data[cellStart+i*2]);
@@ -9133,13 +9131,21 @@ static int checkTreePage(
}
/* Analyze the min-heap looking for overlap between cells and/or
** freeblocks, and counting the number of untracked bytes in nFrag.
**
** Each min-heap entry is of the form: (start_address<<16)|end_address.
** There is an implied first entry the covers the page header, the cell
** pointer index, and the gap between the cell pointer index and the start
** of cell content.
**
** The loop below pulls entries from the min-heap in order and compares
** the start_address against the previous end_address. If there is an
** overlap, that means bytes are used multiple times. If there is a gap,
** that gap is added to the fragmentation count.
*/
nFrag = 0;
assert( heap[0]>0 );
assert( (heap[1]>>16)==0 );
btreeHeapPull(heap,&prev);
prev = contentOffset - 1; /* Implied first min-heap entry */
while( btreeHeapPull(heap,&x) ){
if( (prev&0xffff)+1>(x>>16) ){
if( (prev&0xffff)>=(x>>16) ){
checkAppendMsg(pCheck,
"Multiple uses for byte %u of page %d", x>>16, iPage);
break;