Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Changes In Branch defragmentpage-opt Excluding Merge-Ins
This is equivalent to a diff from a8fd705258 to f9863b39d9
2017-02-25
| ||
17:47 | Optimize defragmentPage() in the case where the page contains either one or two free-blocks and a small number of fragmented bytes. (check-in: 4cd2a9672c user: dan tags: trunk) | |
16:24 | Tweak the code on this branch to detect b-tree page corruption in the same cases as the trunk. (Closed-Leaf check-in: f9863b39d9 user: dan tags: defragmentpage-opt) | |
2017-02-24
| ||
19:58 | Optimize defragmentPage() in the case where the page contains either one or two free-blocks and a small number of fragmented bytes. (check-in: 202b1c0276 user: dan tags: defragmentpage-opt) | |
2017-02-23
| ||
16:30 | Save a few bytes and a few cycles by setting Vdbe.expmask to zero for statements prepared using legacy interface sqlite3_prepare(). (check-in: a8fd705258 user: dan tags: trunk) | |
2017-02-22
| ||
19:41 | Move a branch condition in analyze.c inside an #ifdef SQLITE_ENABLE_STAT4 block. (check-in: d6afd98de3 user: dan tags: trunk) | |
Changes to src/btree.c.
︙ | ︙ | |||
1313 1314 1315 1316 1317 1318 1319 | ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC); } } #endif /* | | | | | > | < > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > < > | 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 | ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno, pRC); } } #endif /* ** Defragment the page given. This routine reorganizes cells within the ** page so that there are no free-blocks on the free-block list. ** ** Parameter nMaxFrag is the maximum amount of fragmented space that may be ** present in the page after this routine returns. ** ** EVIDENCE-OF: R-44582-60138 SQLite may from time to time reorganize a ** b-tree page so that there are no freeblocks or fragment bytes, all ** unused bytes are contained in the unallocated space region, and all ** cells are packed tightly at the end of the page. */ static int defragmentPage(MemPage *pPage, int nMaxFrag){ int i; /* Loop counter */ int pc; /* Address of the i-th cell */ int hdr; /* Offset to the page header */ int size; /* Size of a cell */ int usableSize; /* Number of usable bytes on a page */ int cellOffset; /* Offset to the cell pointer array */ int cbrk; /* Offset to the cell content area */ int nCell; /* Number of cells on the page */ unsigned char *data; /* The page data */ unsigned char *temp; /* Temp area for cell content */ unsigned char *src; /* Source of content */ int iCellFirst; /* First allowable cell index */ int iCellLast; /* Last possible cell index */ assert( sqlite3PagerIswriteable(pPage->pDbPage) ); assert( pPage->pBt!=0 ); assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE ); assert( pPage->nOverflow==0 ); assert( sqlite3_mutex_held(pPage->pBt->mutex) ); temp = 0; src = data = pPage->aData; hdr = pPage->hdrOffset; cellOffset = pPage->cellOffset; nCell = pPage->nCell; assert( nCell==get2byte(&data[hdr+3]) ); iCellFirst = cellOffset + 2*nCell; /* This block handles pages with two or fewer free blocks and nMaxFrag ** or fewer fragmented bytes. In this case it is faster to move the ** two (or one) blocks of cells using memmove() and add the required ** offsets to each pointer in the cell-pointer array than it is to ** reconstruct the entire page. */ if( (int)data[hdr+7]<=nMaxFrag ){ int iFree = get2byte(&data[hdr+1]); if( iFree ){ int iFree2 = get2byte(&data[iFree]); if( 0==iFree2 || (data[iFree2]==0 && data[iFree2+1]==0) ){ u8 *pEnd = &data[cellOffset + nCell*2]; u8 *pAddr; int sz2 = 0; int sz = get2byte(&data[iFree+2]); int top = get2byte(&data[hdr+5]); if( iFree2 ){ sz2 = get2byte(&data[iFree2+2]); memmove(&data[iFree+sz+sz2], &data[iFree+sz], iFree2-(iFree+sz)); sz += sz2; } cbrk = top+sz; memmove(&data[cbrk], &data[top], iFree-top); for(pAddr=&data[cellOffset]; pAddr<pEnd; pAddr+=2){ pc = get2byte(pAddr); if( pc<iFree ){ put2byte(pAddr, pc+sz); } else if( pc<iFree2 ){ put2byte(pAddr, pc+sz2); } } goto defragment_out; } } } usableSize = pPage->pBt->usableSize; cbrk = usableSize; iCellLast = usableSize - 4; for(i=0; i<nCell; i++){ u8 *pAddr; /* The i-th cell pointer */ pAddr = &data[cellOffset + i*2]; pc = get2byte(pAddr); testcase( pc==iCellFirst ); testcase( pc==iCellLast ); /* These conditions have already been verified in btreeInitPage() |
︙ | ︙ | |||
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 | temp = sqlite3PagerTempSpace(pPage->pBt->pPager); x = get2byte(&data[hdr+5]); memcpy(&temp[x], &data[x], (cbrk+size) - x); src = temp; } memcpy(&data[cbrk], &src[pc], size); } assert( cbrk>=iCellFirst ); put2byte(&data[hdr+5], cbrk); data[hdr+1] = 0; data[hdr+2] = 0; | > > > > > > < < < < | 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 | temp = sqlite3PagerTempSpace(pPage->pBt->pPager); x = get2byte(&data[hdr+5]); memcpy(&temp[x], &data[x], (cbrk+size) - x); src = temp; } memcpy(&data[cbrk], &src[pc], size); } data[hdr+7] = 0; defragment_out: if( data[hdr+7]+cbrk-iCellFirst!=pPage->nFree ){ return SQLITE_CORRUPT_BKPT; } assert( cbrk>=iCellFirst ); put2byte(&data[hdr+5], cbrk); data[hdr+1] = 0; data[hdr+2] = 0; memset(&data[iCellFirst], 0, cbrk-iCellFirst); assert( sqlite3PagerIswriteable(pPage->pDbPage) ); return SQLITE_OK; } /* ** Search the free-list on page pPg for space to store a cell nByte bytes in ** size. If one can be found, return a pointer to the space and remove it ** from the free-list. |
︙ | ︙ | |||
1533 1534 1535 1536 1537 1538 1539 | /* The request could not be fulfilled using a freelist slot. Check ** to see if defragmentation is necessary. */ testcase( gap+2+nByte==top ); if( gap+2+nByte>top ){ assert( pPage->nCell>0 || CORRUPT_DB ); | | | | 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 | /* The request could not be fulfilled using a freelist slot. Check ** to see if defragmentation is necessary. */ testcase( gap+2+nByte==top ); if( gap+2+nByte>top ){ assert( pPage->nCell>0 || CORRUPT_DB ); rc = defragmentPage(pPage, MIN(4, pPage->nFree - (2+nByte))); if( rc ) return rc; top = get2byteNotZero(&data[hdr+5]); assert( gap+2+nByte<=top ); } /* Allocate memory from the gap in between the cell pointer array ** and the cell content area. The btreeInitPage() call has already ** validated the freelist. Given that the freelist is valid, there ** is no way that the allocation can extend off the end of the page. |
︙ | ︙ | |||
7685 7686 7687 7688 7689 7690 7691 | ** ** It is critical that the child page be defragmented before being ** copied into the parent, because if the parent is page 1 then it will ** by smaller than the child due to the database header, and so all the ** free space needs to be up front. */ assert( nNew==1 || CORRUPT_DB ); | | | 7721 7722 7723 7724 7725 7726 7727 7728 7729 7730 7731 7732 7733 7734 7735 | ** ** It is critical that the child page be defragmented before being ** copied into the parent, because if the parent is page 1 then it will ** by smaller than the child due to the database header, and so all the ** free space needs to be up front. */ assert( nNew==1 || CORRUPT_DB ); rc = defragmentPage(apNew[0], -1); testcase( rc!=SQLITE_OK ); assert( apNew[0]->nFree == (get2byte(&apNew[0]->aData[5])-apNew[0]->cellOffset-apNew[0]->nCell*2) || rc!=SQLITE_OK ); copyNodeContent(apNew[0], pParent, &rc); freePage(apNew[0], &rc); |
︙ | ︙ |