database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-08-07 02:42:48 +03:00
Code Activity

Simplification to the insertCell() routine in btree.c, resulting in a

Browse Source 
performance boost and a very small size decrease.  It turns out that the
extra work involved in sometimes avoiding an memcpy() of the first four bytes
of a record takes more time than just unconditionally copying those
four bytes.

FossilOrigin-Name: 66de15580d3c289601e67debfe1edee286f4db5f
This commit is contained in:
drh
2014-10-11 17:22:55 +00:00
parent 8683e08676
commit d6176c4131
3 changed files with 9 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/btree.c
View File

@@ -5845,11 +5845,6 @@ static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
** in pTemp or the original pCell) and also record its index.
** Allocating a new entry in pPage->aCell[] implies that
** pPage->nOverflow is incremented.
**
** If nSkip is non-zero, then do not copy the first nSkip bytes of the
** cell. The caller will overwrite them after this function returns. If
** nSkip is non-zero, then pCell may not point to an invalid memory location
** (but pCell+nSkip is always valid).
*/
static void insertCell(
MemPage *pPage, /* Page into which we are copying */
@@ -5866,7 +5861,6 @@ static void insertCell(
int ins; /* Index in data[] where new cell pointer is inserted */
int cellOffset; /* Address of first cell pointer in data[] */
u8 *data; /* The content of the whole page */
int nSkip = (iChild ? 4 : 0);
if( *pRC ) return;
@@ -5884,7 +5878,7 @@ static void insertCell(
assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) );
if( pPage->nOverflow || sz+2>pPage->nFree ){
if( pTemp ){
memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
memcpy(pTemp, pCell, sz);
pCell = pTemp;
}
if( iChild ){
@@ -5913,7 +5907,7 @@ static void insertCell(
assert( idx+sz <= (int)pPage->pBt->usableSize );
pPage->nCell++;
pPage->nFree -= (u16)(2 + sz);
memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
memcpy(&data[idx], pCell, sz);
if( iChild ){
put4byte(&data[idx], iChild);
}