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Overview
Comment: | Remove an unnecessary local variable from OP_Column, for a small size reduction and performance increase. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
39543903282409ad3f139f8a0bb37666 |
User & Date: | drh 2017-08-16 14:16:19.879 |
Context
2017-08-16
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19:20 | Avoid a test for CURTYPE_BTREE in sqlite3VdbeCursorMoveto() in order to reduce the size and improve the performance of OP_Column. (check-in: f078deb251 user: drh tags: trunk) | |
17:06 | Update this branch with the latest changes from trunk. (check-in: 380a7b7a45 user: dan tags: server-process-edition) | |
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) | |
Changes
Changes to src/vdbe.c.
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2382 2383 2384 2385 2386 2387 2388 | int len; /* The length of the serialized data for the column */ int i; /* Loop counter */ Mem *pDest; /* Where to write the extracted value */ Mem sMem; /* For storing the record being decoded */ const u8 *zData; /* Part of the record being decoded */ const u8 *zHdr; /* Next unparsed byte of the header */ const u8 *zEndHdr; /* Pointer to first byte after the header */ | < | 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 | int len; /* The length of the serialized data for the column */ int i; /* Loop counter */ Mem *pDest; /* Where to write the extracted value */ Mem sMem; /* For storing the record being decoded */ const u8 *zData; /* Part of the record being decoded */ const u8 *zHdr; /* Next unparsed byte of the header */ const u8 *zEndHdr; /* Pointer to first byte after the header */ u64 offset64; /* 64-bit offset */ u32 t; /* A type code from the record header */ Mem *pReg; /* PseudoTable input register */ pC = p->apCsr[pOp->p1]; p2 = pOp->p2; |
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2434 2435 2436 2437 2438 2439 2440 | assert( pC->szRow<=pC->payloadSize ); assert( pC->szRow<=65536 ); /* Maximum page size is 64KiB */ if( pC->payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){ goto too_big; } } pC->cacheStatus = p->cacheCtr; | | < | | | | | | 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 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 | assert( pC->szRow<=pC->payloadSize ); assert( pC->szRow<=65536 ); /* Maximum page size is 64KiB */ if( pC->payloadSize > (u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){ goto too_big; } } pC->cacheStatus = p->cacheCtr; pC->iHdrOffset = getVarint32(pC->aRow, aOffset[0]); pC->nHdrParsed = 0; if( pC->szRow<aOffset[0] ){ /*OPTIMIZATION-IF-FALSE*/ /* 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; /* 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( aOffset[0] > 98307 || aOffset[0] > 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 aOffset[0]==0. Such a record is never ** generated by SQLite, and could be considered corruption, but we ** accept it for historical reasons. When aOffset[0]==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( aOffset[0]==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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