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Overview
| Comment: | Performance optimization and very slight size reduction for OP_Column. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
869c30e45cc87063be423c650f16b99e |
| User & Date: | drh 2014-10-11 23:31:52.159 |
Context
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2014-10-12
| ||
| 22:37 | Remove the VdbeCursor.lastRowid cache of the current rowid, since maintaining the correct cache value uses more CPU cycles than just recomputing the rowid on the occasions when it is actually needed. Replace it with the VdbeCursor.aOffset field which used to be computed from VdbeCursor.aType when needed. Saves 100 bytes of code space and runs 0.2% faster. (check-in: 91384a7d72 user: drh tags: trunk) | |
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2014-10-11
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| 23:31 | Performance optimization and very slight size reduction for OP_Column. (check-in: 869c30e45c user: drh tags: trunk) | |
| 17:22 | Simplification to the insertCell() routine in btree.c, resulting in a 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. (check-in: 66de15580d user: drh tags: trunk) | |
Changes
Changes to src/vdbe.c.
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2328 2329 2330 2331 2332 2333 2334 |
goto too_big;
}
}
pC->cacheStatus = p->cacheCtr;
pC->iHdrOffset = getVarint32(pC->aRow, offset);
pC->nHdrParsed = 0;
aOffset[0] = offset;
| < < < < < < < < > > > > > > > > > > > > > > > > > | 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 |
goto too_big;
}
}
pC->cacheStatus = p->cacheCtr;
pC->iHdrOffset = getVarint32(pC->aRow, offset);
pC->nHdrParsed = 0;
aOffset[0] = offset;
/* Make sure a corrupt database has not given us an oversize header.
** Do this now to avoid an oversize memory allocation.
**
** Type entries can be between 1 and 5 bytes each. But 4 and 5 byte
** types use so much data space that there can only be 4096 and 32 of
** them, respectively. So the maximum header length results from a
** 3-byte type for each of the maximum of 32768 columns plus three
** extra bytes for the header length itself. 32768*3 + 3 = 98307.
*/
if( offset > 98307 || offset > pC->payloadSize ){
rc = SQLITE_CORRUPT_BKPT;
goto op_column_error;
}
if( avail<offset ){
/* pC->aRow does not have to hold the entire row, but it does at least
** need to cover the header of the record. If pC->aRow does not contain
** the complete header, then set it to zero, forcing the header to be
** dynamically allocated. */
pC->aRow = 0;
pC->szRow = 0;
}
/* The following goto is an optimization. It can be omitted and
** everything will still work. But OP_Column is measurably faster
** by skipping the subsequent conditional, which is always true.
*/
assert( pC->nHdrParsed<=p2 ); /* Conditional skipped */
goto op_column_read_header;
}
/* Make sure at least the first p2+1 entries of the header have been
** parsed and valid information is in aOffset[] and pC->aType[].
*/
if( pC->nHdrParsed<=p2 ){
/* If there is more header available for parsing in the record, try
** to extract additional fields up through the p2+1-th field
*/
op_column_read_header:
if( pC->iHdrOffset<aOffset[0] ){
/* Make sure zData points to enough of the record to cover the header. */
if( pC->aRow==0 ){
memset(&sMem, 0, sizeof(sMem));
rc = sqlite3VdbeMemFromBtree(pCrsr, 0, aOffset[0],
!pC->isTable, &sMem);
if( rc!=SQLITE_OK ){
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