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Overview
| Comment: | Must faster computation of estimated logarithm. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | nextgen-query-plan-exp |
| Files: | files | file ages | folders |
| SHA1: | dfbca3acaeb862f24f25e7810a16ff20 |
| User & Date: | drh 2013-06-07 02:04:19 |
Context
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2013-06-10
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| 12:17 | Add a high-speed bypass for the NGQP for the common case of a simply query with quality constraints that outputs a single row. check-in: 8d1ba309 user: drh tags: nextgen-query-plan-exp | |
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2013-06-09
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| 17:21 | High-speed version of NGQP. Still has some minor problems. check-in: db2415fa user: drh tags: nextgen-query-plan-fast | |
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2013-06-07
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| 02:04 | Must faster computation of estimated logarithm. check-in: dfbca3ac user: drh tags: nextgen-query-plan-exp | |
| 00:29 | Further prepare-time performance improvements. check-in: 02741d17 user: drh tags: nextgen-query-plan-exp | |
Changes
Changes to src/where.c.
1827 1827 ** Prepare a crude estimate of the logarithm of the input value. 1828 1828 ** The results need not be exact. This is only used for estimating 1829 1829 ** the total cost of performing operations with O(logN) or O(NlogN) 1830 1830 ** complexity. Because N is just a guess, it is no great tragedy if 1831 1831 ** logN is a little off. 1832 1832 */ 1833 1833 static WhereCost estLog(WhereCost N){ 1834 - WhereCost logN = 1; 1835 - WhereCost x = 10; 1836 - while( N>x ){ 1837 - logN += 1; 1838 - x *= 10; 1839 - } 1840 - return logN; 1834 + u32 a; 1835 + assert( sizeof(WhereCost)==4 ); /* 32-bit float input */ 1836 + if( N<=0.0 ) return 0.0; 1837 + memcpy(&a, &N, 4); 1838 + return ((a >>= 23)-127)*0.3; 1841 1839 } 1842 1840 1843 1841 /* 1844 1842 ** Two routines for printing the content of an sqlite3_index_info 1845 1843 ** structure. Used for testing and debugging only. If neither 1846 1844 ** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines 1847 1845 ** are no-ops. ................................................................................ 5394 5392 if( pDistinct && isDistinctRedundant(pParse,pTabList,&pWInfo->sWC,pDistinct) ){ 5395 5393 pDistinct = 0; 5396 5394 pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; 5397 5395 } 5398 5396 5399 5397 /* Construct the WhereLoop objects */ 5400 5398 WHERETRACE(("*** Optimizer Start ***\n")); 5399 + /* TBD: if( nTablist==1 ) whereCommonCase(&sWLB); */ 5401 5400 rc = whereLoopAddAll(&sWLB); 5402 5401 if( rc ) goto whereBeginError; 5403 5402 5404 5403 /* Display all of the WhereLoop objects if wheretrace is enabled */ 5405 5404 #ifdef WHERETRACE_ENABLED 5406 5405 if( sqlite3WhereTrace ){ 5407 5406 WhereLoop *p;