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Overview
| Comment: | Improve performance of sqlite3VdbeRecordCompare() by using an approximation that might give false negatives and only running the more expensive exact subexpression if the approximation fails. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
28979dcd16f53e0ddca8eed74b668834 |
| User & Date: | drh 2013-08-05 15:32:09 |
Context
|
2013-08-05
| ||
| 19:11 | Factor all KeyInfo object allocations into a single function: sqlite3KeyInfoAlloc(). Always allocate enough space so that sqlite3VdbeRecordCompare() can avoid checking boundaries and hence run faster. check-in: 7301bedd user: drh tags: trunk | |
| 15:32 | Improve performance of sqlite3VdbeRecordCompare() by using an approximation that might give false negatives and only running the more expensive exact subexpression if the approximation fails. check-in: 28979dcd user: drh tags: trunk | |
| 12:31 | Add a missing '#include "tcl.h"' to test_rtree.c. check-in: 4b8b426f user: drh tags: trunk | |
Changes
Changes to src/vdbeaux.c.
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nField = pKeyInfo->nField;
assert( pKeyInfo->aSortOrder!=0 );
while( idx1<szHdr1 && i<pPKey2->nField ){
u32 serial_type1;
/* Read the serial types for the next element in each key. */
idx1 += getVarint32( aKey1+idx1, serial_type1 );
if( d1+sqlite3VdbeSerialTypeLen(serial_type1)>(u32)nKey1 ) break;
/* Extract the values to be compared.
*/
d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
/* Do the comparison
*/
|
> > > > > > > > | > > > |
3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 |
nField = pKeyInfo->nField;
assert( pKeyInfo->aSortOrder!=0 );
while( idx1<szHdr1 && i<pPKey2->nField ){
u32 serial_type1;
/* Read the serial types for the next element in each key. */
idx1 += getVarint32( aKey1+idx1, serial_type1 );
/* Verify that there is enough key space remaining to avoid
** a buffer overread. The "d1+serial_type1+2" subexpression will
** always be greater than or equal to the amount of required key space.
** Use that approximation to avoid the more expensive call to
** sqlite3VdbeSerialTypeLen() in the common case.
*/
if( d1+serial_type1+2>(u32)nKey1
&& d1+sqlite3VdbeSerialTypeLen(serial_type1)>(u32)nKey1
){
break;
}
/* Extract the values to be compared.
*/
d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
/* Do the comparison
*/
|