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Overview
Comment: | Enhance the query flattener to handle subqueries that are joins. All regressions pass but new tests need to be added before release. Ticket #272. (CVS 948) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
ad57693e9f1b83a8cc4d028264b35018 |
User & Date: | drh 2003-05-02 16:04:17.000 |
Context
2003-05-02
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16:44 | Additional tests of the new flattener added. Ticket #272. (CVS 949) (check-in: 8d9ee45ab4 user: drh tags: trunk) | |
16:04 | Enhance the query flattener to handle subqueries that are joins. All regressions pass but new tests need to be added before release. Ticket #272. (CVS 948) (check-in: ad57693e9f user: drh tags: trunk) | |
14:32 | VDBE cursors numbers for tables in a join do not have to be consecutive. This is one step on the road to fixing ticket #272. (CVS 947) (check-in: be7aed2011 user: drh tags: trunk) | |
Changes
Changes to src/select.c.
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8 9 10 11 12 13 14 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file contains C code routines that are called by the parser ** to handle SELECT statements in SQLite. ** | | | 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file contains C code routines that are called by the parser ** to handle SELECT statements in SQLite. ** ** $Id: select.c,v 1.137 2003/05/02 16:04:17 drh Exp $ */ #include "sqliteInt.h" /* ** Allocate a new Select structure and return a pointer to that ** structure. |
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1551 1552 1553 1554 1555 1556 1557 | ** ** Flattening is only attempted if all of the following are true: ** ** (1) The subquery and the outer query do not both use aggregates. ** ** (2) The subquery is not an aggregate or the outer query is not a join. ** | | | 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 | ** ** Flattening is only attempted if all of the following are true: ** ** (1) The subquery and the outer query do not both use aggregates. ** ** (2) The subquery is not an aggregate or the outer query is not a join. ** ** (3) (No longer a restriction) ** ** (4) The subquery is not DISTINCT or the outer query is not a join. ** ** (5) The subquery is not DISTINCT or the outer query does not use ** aggregates. ** ** (6) The subquery does not use aggregates or the outer query is not |
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1609 1610 1611 1612 1613 1614 1615 | assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc ); pSub = pSrc->a[iFrom].pSelect; assert( pSub!=0 ); if( isAgg && subqueryIsAgg ) return 0; if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; pSubSrc = pSub->pSrc; assert( pSubSrc ); | | > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 | assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc ); pSub = pSrc->a[iFrom].pSelect; assert( pSub!=0 ); if( isAgg && subqueryIsAgg ) return 0; if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; pSubSrc = pSub->pSrc; assert( pSubSrc ); if( pSubSrc->nSrc==0 ) return 0; if( (pSub->isDistinct || pSub->nLimit>=0) && (pSrc->nSrc>1 || isAgg) ){ return 0; } if( (p->isDistinct || p->nLimit>=0) && subqueryIsAgg ) return 0; if( p->pOrderBy && pSub->pOrderBy ) return 0; /* If we reach this point, it means flattening is permitted for the ** iFrom-th entry of the FROM clause in the outer query. */ /* Move all of the FROM elements of the subquery into the ** the FROM clause of the outer query. Before doing this, remember ** the cursor number for the original outer query FROM element in ** iParent. The iParent cursor will never be used. Subsequent code ** will scan expressions looking for iParent references and replace ** those references with expressions that resolve to the subquery FROM ** elements we are now copying in. */ iParent = pSrc->a[iFrom].iCursor; { int nSubSrc = pSubSrc->nSrc; if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){ sqliteDeleteTable(0, pSrc->a[iFrom].pTab); } sqliteFree(pSrc->a[iFrom].zName); sqliteFree(pSrc->a[iFrom].zAlias); if( nSubSrc>1 ){ int extra = nSubSrc - 1; for(i=1; i<nSubSrc; i++){ pSrc = sqliteSrcListAppend(pSrc, 0, 0); } p->pSrc = pSrc; for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){ pSrc->a[i] = pSrc->a[i-extra]; } } for(i=0; i<nSubSrc; i++){ pSrc->a[i+iFrom] = pSubSrc->a[i]; memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); } } /* Now begin substituting subquery result set expressions for ** references to the iParent in the outer query. ** ** Example: ** ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b; ** \ \_____________ subquery __________/ / ** \_____________________ outer query ______________________________/ ** ** We look at every expression in the outer query and every place we see ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10". */ substExprList(p->pEList, iParent, pSub->pEList); pList = p->pEList; for(i=0; i<pList->nExpr; i++){ Expr *pExpr; if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){ pList->a[i].zName = sqliteStrNDup(pExpr->span.z, pExpr->span.n); } |
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1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 | p->pWhere = pWhere; }else{ substExpr(p->pWhere, iParent, pSub->pEList); if( pWhere ){ p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0); } } p->isDistinct = p->isDistinct || pSub->isDistinct; if( pSub->nLimit>=0 ){ if( p->nLimit<0 ){ p->nLimit = pSub->nLimit; }else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){ p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset; } } p->nOffset += pSub->nOffset; | > > > > > > > < | < < < < < < > > | 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 | p->pWhere = pWhere; }else{ substExpr(p->pWhere, iParent, pSub->pEList); if( pWhere ){ p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0); } } /* The flattened query is distinct if either the inner or the ** outer query is distinct. */ p->isDistinct = p->isDistinct || pSub->isDistinct; /* Transfer the limit expression from the subquery to the outer ** query. */ if( pSub->nLimit>=0 ){ if( p->nLimit<0 ){ p->nLimit = pSub->nLimit; }else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){ p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset; } } p->nOffset += pSub->nOffset; /* Finially, delete what is left of the subquery and return ** success. */ sqliteSelectDelete(pSub); return 1; } /* ** Analyze the SELECT statement passed in as an argument to see if it ** is a simple min() or max() query. If it is and this query can be |
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2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 | } } /* Generate code for all sub-queries in the FROM clause */ for(i=0; i<pTabList->nSrc; i++){ const char *zSavedAuthContext; if( pTabList->a[i].pSelect==0 ) continue; if( pTabList->a[i].zName!=0 ){ zSavedAuthContext = pParse->zAuthContext; pParse->zAuthContext = pTabList->a[i].zName; } sqliteSelect(pParse, pTabList->a[i].pSelect, SRT_TempTable, pTabList->a[i].iCursor, p, i, &isAgg); | > > > > > | | | 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 | } } /* Generate code for all sub-queries in the FROM clause */ for(i=0; i<pTabList->nSrc; i++){ const char *zSavedAuthContext; int needRestoreContext; if( pTabList->a[i].pSelect==0 ) continue; if( pTabList->a[i].zName!=0 ){ zSavedAuthContext = pParse->zAuthContext; pParse->zAuthContext = pTabList->a[i].zName; needRestoreContext = 1; }else{ needRestoreContext = 0; } sqliteSelect(pParse, pTabList->a[i].pSelect, SRT_TempTable, pTabList->a[i].iCursor, p, i, &isAgg); if( needRestoreContext ){ pParse->zAuthContext = zSavedAuthContext; } pTabList = p->pSrc; pWhere = p->pWhere; if( eDest!=SRT_Union && eDest!=SRT_Except && eDest!=SRT_Discard ){ pOrderBy = p->pOrderBy; } pGroupBy = p->pGroupBy; pHaving = p->pHaving; isDistinct = p->isDistinct; } |
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Changes to test/view.test.
1 2 3 4 5 6 7 8 9 10 11 12 13 | # 2002 February 26 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # This file implements regression tests for SQLite library. The # focus of this file is testing VIEW statements. # | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | # 2002 February 26 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # This file implements regression tests for SQLite library. The # focus of this file is testing VIEW statements. # # $Id: view.test,v 1.15 2003/05/02 16:04:17 drh Exp $ set testdir [file dirname $argv0] source $testdir/tester.tcl do_test view-1.0 { execsql { CREATE TABLE t1(a,b,c); INSERT INTO t1 VALUES(1,2,3); |
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193 194 195 196 197 198 199 | INSERT INTO t2 VALUES(55,5); SELECT * FROM t2; } } {22 2 33 3 44 4 55 5} do_test view-5.2 { execsql { CREATE VIEW v5 AS | | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 | INSERT INTO t2 VALUES(55,5); SELECT * FROM t2; } } {22 2 33 3 44 4 55 5} do_test view-5.2 { execsql { CREATE VIEW v5 AS SELECT t1.x AS v, t2.y AS w FROM t1 JOIN t2 USING(a); SELECT * FROM v5; } } {1 22 4 55} # Verify that the view v5 gets flattened. see sqliteFlattenSubquery(). # Ticket #272 do_test view-5.3 { lsearch [execsql { EXPLAIN SELECT * FROM v5; }] OpenTemp } {-1} do_test view-5.4 { execsql { SELECT * FROM v5 AS a, t2 AS b WHERE a.w=b.y; } } {1 22 22 2 4 55 55 5} do_test view-5.5 { lsearch [execsql { EXPLAIN SELECT * FROM v5 AS a, t2 AS b WHERE a.w=b.y; }] OpenTemp } {-1} do_test view-5.6 { execsql { SELECT * FROM t2 AS b, v5 AS a WHERE a.w=b.y; } } {22 2 1 22 55 5 4 55} do_test view-5.7 { lsearch [execsql { EXPLAIN SELECT * FROM t2 AS b, v5 AS a WHERE a.w=b.y; }] OpenTemp } {-1} do_test view-5.8 { execsql { SELECT * FROM t1 AS a, v5 AS b, t2 AS c WHERE a.x=b.v AND b.w=c.y; } } {1 2 3 4 1 22 22 2 4 5 6 7 4 55 55 5} do_test view-5.9 { lsearch [execsql { EXPLAIN SELECT * FROM t1 AS a, v5 AS b, t2 AS c WHERE a.x=b.v AND b.w=c.y; }] OpenTemp } {-1} do_test view-6.1 { execsql { SELECT min(x), min(a), min(b), min(c), min(a+b+c) FROM v2; } } {7 8 9 10 27} do_test view-6.2 { |
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