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Overview
Comment: | Performance improvement in the OP_Column opcode. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
dc98a92f32511ee322b0207bd286e967 |
User & Date: | drh 2017-08-16 11:04:22.469 |
Context
2017-08-16
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14:16 | Remove an unnecessary local variable from OP_Column, for a small size reduction and performance increase. (check-in: 3954390328 user: drh tags: trunk) | |
11:04 | Performance improvement in the OP_Column opcode. (check-in: dc98a92f32 user: drh tags: trunk) | |
2017-08-15
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14:14 | Small size and performance improvement in the OP_Column opcode. (check-in: 2cf3f3de8a user: drh tags: trunk) | |
Changes
Changes to src/vdbe.c.
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2460 2461 2462 2463 2464 2465 2466 | ** 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 abort_due_to_error; } | | | > | < > > > > > > > > > > | 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 | ** 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 abort_due_to_error; } }else{ /* This is an optimization. By skipping over the first few tests ** (ex: pC->nHdrParsed<=p2) in the next section, we achieve a ** measurable performance gain. ** ** This branch is taken even if offset==0. Such a record is never ** generated by SQLite, and could be considered corruption, but we ** accept it for historical reasons. When offset==0, the code this ** branch jumps to reads past the end of the record, but never more ** than a few bytes. Even if the record occurs at the end of the page ** content area, the "page header" comes after the page content and so ** this overread is harmless. Similar overreads can occur for a corrupt ** database file. */ zData = pC->aRow; assert( pC->nHdrParsed<=p2 ); /* Conditional skipped */ testcase( offset==0 ); 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[]. */ |
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2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 | /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */ op_column_read_header: i = pC->nHdrParsed; offset64 = aOffset[i]; zHdr = zData + pC->iHdrOffset; zEndHdr = zData + aOffset[0]; do{ if( (t = zHdr[0])<0x80 ){ zHdr++; offset64 += sqlite3VdbeOneByteSerialTypeLen(t); }else{ zHdr += sqlite3GetVarint32(zHdr, &t); offset64 += sqlite3VdbeSerialTypeLen(t); } pC->aType[i++] = t; aOffset[i] = (u32)(offset64 & 0xffffffff); }while( i<=p2 && zHdr<zEndHdr ); /* The record is corrupt if any of the following are true: ** (1) the bytes of the header extend past the declared header size ** (2) the entire header was used but not all data was used ** (3) the end of the data extends beyond the end of the record. */ if( (zHdr>=zEndHdr && (zHdr>zEndHdr || offset64!=pC->payloadSize)) || (offset64 > pC->payloadSize) ){ | > > > > > | | | > | 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 | /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */ op_column_read_header: i = pC->nHdrParsed; offset64 = aOffset[i]; zHdr = zData + pC->iHdrOffset; zEndHdr = zData + aOffset[0]; testcase( zHdr>=zEndHdr ); do{ if( (t = zHdr[0])<0x80 ){ zHdr++; offset64 += sqlite3VdbeOneByteSerialTypeLen(t); }else{ zHdr += sqlite3GetVarint32(zHdr, &t); offset64 += sqlite3VdbeSerialTypeLen(t); } pC->aType[i++] = t; aOffset[i] = (u32)(offset64 & 0xffffffff); }while( i<=p2 && zHdr<zEndHdr ); /* The record is corrupt if any of the following are true: ** (1) the bytes of the header extend past the declared header size ** (2) the entire header was used but not all data was used ** (3) the end of the data extends beyond the end of the record. */ if( (zHdr>=zEndHdr && (zHdr>zEndHdr || offset64!=pC->payloadSize)) || (offset64 > pC->payloadSize) ){ if( aOffset[0]==0 ){ i = 0; zHdr = zEndHdr; }else{ if( pC->aRow==0 ) sqlite3VdbeMemRelease(&sMem); rc = SQLITE_CORRUPT_BKPT; goto abort_due_to_error; } } pC->nHdrParsed = i; pC->iHdrOffset = (u32)(zHdr - zData); if( pC->aRow==0 ) sqlite3VdbeMemRelease(&sMem); }else{ t = 0; |
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