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Overview
Comment: | Fix the count-of-view optimization so that it is (correctly) disabled for a query that includes a WHERE clause or a GROUP BY clause. Cherrypick of [05897ca48a40c6771]. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | branch-3.28 |
Files: | files | file ages | folders |
SHA3-256: |
583e5a0ab6bdf3ce3d76852089160a8d |
User & Date: | mistachkin 2019-06-03 13:53:29.317 |
Context
2019-06-03
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15:10 | Fix harmless compiler warning in lemon. (check-in: 3a05242953 user: mistachkin tags: branch-3.28) | |
13:53 | Fix the count-of-view optimization so that it is (correctly) disabled for a query that includes a WHERE clause or a GROUP BY clause. Cherrypick of [05897ca48a40c6771]. (check-in: 583e5a0ab6 user: mistachkin tags: branch-3.28) | |
2019-05-15
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18:42 | Fix the count-of-view optimization so that it is (correctly) disabled for a query that includes a WHERE clause or a GROUP BY clause. (check-in: 05897ca48a user: drh tags: trunk) | |
2019-04-23
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15:21 | Minor simplification of NULL value handling for STAT4. Cherrypick of [69bad9257f8db6a2] from trunk. (check-in: 442c177dc4 user: mistachkin tags: branch-3.28) | |
Changes
Changes to src/select.c.
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5502 5503 5504 5505 5506 5507 5508 | ** SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2) ** ** The transformation only works if all of the following are true: ** ** * The subquery is a UNION ALL of two or more terms ** * The subquery does not have a LIMIT clause ** * There is no WHERE or GROUP BY or HAVING clauses on the subqueries | | > > > | 5502 5503 5504 5505 5506 5507 5508 5509 5510 5511 5512 5513 5514 5515 5516 5517 5518 5519 5520 5521 5522 5523 5524 5525 5526 5527 5528 5529 | ** SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2) ** ** The transformation only works if all of the following are true: ** ** * The subquery is a UNION ALL of two or more terms ** * The subquery does not have a LIMIT clause ** * There is no WHERE or GROUP BY or HAVING clauses on the subqueries ** * The outer query is a simple count(*) with no WHERE clause or other ** extraneous syntax. ** ** Return TRUE if the optimization is undertaken. */ static int countOfViewOptimization(Parse *pParse, Select *p){ Select *pSub, *pPrior; Expr *pExpr; Expr *pCount; sqlite3 *db; if( (p->selFlags & SF_Aggregate)==0 ) return 0; /* This is an aggregate */ if( p->pEList->nExpr!=1 ) return 0; /* Single result column */ if( p->pWhere ) return 0; if( p->pGroupBy ) return 0; pExpr = p->pEList->a[0].pExpr; if( pExpr->op!=TK_AGG_FUNCTION ) return 0; /* Result is an aggregate */ if( sqlite3_stricmp(pExpr->u.zToken,"count") ) return 0; /* Is count() */ if( pExpr->x.pList!=0 ) return 0; /* Must be count(*) */ if( p->pSrc->nSrc!=1 ) return 0; /* One table in FROM */ pSub = p->pSrc->a[0].pSelect; if( pSub==0 ) return 0; /* The FROM is a subquery */ |
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Changes to test/countofview.test.
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35 36 37 38 39 40 41 42 43 | } {1} do_execsql_test 1.3 { select count(*) from ( select c from t2 union all select f from t3 ) } {3} finish_test | > > > > > > > > > > > > > | 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | } {1} do_execsql_test 1.3 { select count(*) from ( select c from t2 union all select f from t3 ) } {3} # 2019-05-15 do_execsql_test 2.0 { CREATE TABLE t1(x); INSERT INTO t1 VALUES(1),(99),('abc'); CREATE VIEW v1(x,y) AS SELECT x,1 FROM t1 UNION ALL SELECT x,2 FROM t1; SELECT count(*) FROM v1 WHERE x<>1; } {4} do_execsql_test 2.1 { SELECT count(*) FROM v1 GROUP BY y; } {3 3} finish_test |