-C Merge\sthe\squery\sflattener\scomment\simprovements\sfrom\strunk.
-D 2017-09-29T16:08:46.956
+C Always\srender\sa\ssubquery\sthat\sis\snot\spart\sof\sa\sjoin\sas\sa\sco-routine.
+D 2017-09-29T22:13:24.684
F Makefile.in 4bc36d913c2e3e2d326d588d72f618ac9788b2fd4b7efda61102611a6495c3ff
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 6033b51b6aea702ea059f6ab2d47b1d3cef648695f787247dd4fb395fe60673f
F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
F src/resolve.c 4324a94573b1e29286f8121e4881db59eaedc014afeb274c8d3e07ed282e0e20
F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
-F src/select.c 73fa1cc03a325dd5f3e84bc6c4c975000028f96f85025ae2fe0b6eb0c30c2fe0
+F src/select.c 8e8e9965af11f7ca54a44fc2cea9e8d162a6ffa1ccd2e840c69ff4468e0d08e0
F src/shell.c c1206a23d9239f8f51751d3be9b8c3b02fa4103546bea1add7f864d84a8276ab
F src/shell.c.in bb9720a8c5c98d3984b16ab7540e7142bcae959666ecf248bfc523a1d44220ee
F src/sqlite.h.in ab4f8a29d1580dfaeb6891fa1b83cff8229ba0daa56994707ceaca71495d9ab7
F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
F src/sqlite3ext.h a1fd3aa82f967da436164e0728a7d6841651fd0c6e27b9044e0eb9f6c8462e47
-F src/sqliteInt.h 954fed875c59d283870f13010bbbb96d8b25cf3db0683843403c36e9dfcf1bdd
+F src/sqliteInt.h d51b1b549b6f64a44b0f5f5620aeb5bba414cf07704978238885b273ce2aa84f
F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
F src/status.c 9737ed017279a9e0c5da748701c3c7bf1e8ae0dae459aad20dd64fcff97a7e35
F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
F src/tclsqlite.c 487951d81f9704800fd9f0ffdaa2f935a83ccb6be3575c2c4ef83e4789b4c828
-F src/test1.c a947b2554fa77d0ef2dd21d1ef08e37e5d91b17af83de923a4e3c7f10957a2eb
+F src/test1.c 8ef15f7a357f85dfc41c6c748ce9c947b4f676e01bb5ae6a45bee4923dff8b51
F src/test2.c 3efb99ab7f1fc8d154933e02ae1378bac9637da5
F src/test3.c b8434949dfb8aff8dfa082c8b592109e77844c2135ed3c492113839b6956255b
F src/test4.c 18ec393bb4d0ad1de729f0b94da7267270f3d8e6
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 06f432fb7c979f1bb7f01f5c90716ce5c0248f73f70b78a9870b9de5c9bf7ef4 0840f9f824c16212ce3fd6c859e501176eb0a58924ea1728a54d5bdfd0c25c86
-R 4be3453c15fd85db566735e226eb00f9
+P f62cd4d940506c39db82e83ff3df8ab1856f1fb91ffda835ae2d727263ee9b0b
+R 5c67a1a4877d581279b4ed945a250449
U drh
-Z be149bf809ee0d7792ea4e04a36ef7f0
+Z 6d48696ae0bb75b33e85df88734665c6
**
** Flattening is subject to the following constraints:
**
-** (1) The subquery and the outer query cannot both be aggregates.
+** (**) We no longer attempt to flatten aggregate subqueries. Was:
+** The subquery and the outer query cannot both be aggregates.
**
-** (2) If the subquery is an aggregate then
+** (**) We no longer attempt to flatten aggregate subqueries. Was:
+** (2) If the subquery is an aggregate then
** (2a) the outer query must not be a join and
** (2b) the outer query must not use subqueries
** other than the one FROM-clause subquery that is a candidate
** sub-queries that were excluded from this optimization. Restriction
** (4) has since been expanded to exclude all DISTINCT subqueries.
**
-** (6) If the subquery is aggregate, the outer query may not be DISTINCT.
+** (**) We no longer attempt to flatten aggregate subqueries. Was:
+** If the subquery is aggregate, the outer query may not be DISTINCT.
**
** (7) The subquery must have a FROM clause. TODO: For subqueries without
** A FROM clause, consider adding a FROM clause with the special
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
-** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
+** uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
Parse *pParse, /* Parsing context */
Select *p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
- int isAgg, /* True if outer SELECT uses aggregate functions */
- int subqueryIsAgg /* True if the subquery uses aggregate functions */
+ int isAgg /* True if outer SELECT uses aggregate functions */
){
const char *zSavedAuthContext = pParse->zAuthContext;
Select *pParent; /* Current UNION ALL term of the other query */
iParent = pSubitem->iCursor;
pSub = pSubitem->pSelect;
assert( pSub!=0 );
- if( subqueryIsAgg ){
- if( isAgg ) return 0; /* Restriction (1) */
- if( pSrc->nSrc>1 ) return 0; /* Restriction (2a) */
- if( (p->pWhere && ExprHasProperty(p->pWhere,EP_Subquery))
- || (sqlite3ExprListFlags(p->pEList) & EP_Subquery)!=0
- || (sqlite3ExprListFlags(p->pOrderBy) & EP_Subquery)!=0
- ){
- return 0; /* Restriction (2b) */
- }
- }
pSubSrc = pSub->pSrc;
assert( pSubSrc );
if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
return 0; /* Restrictions (8)(9) */
}
- if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){
- return 0; /* Restriction (6) */
- }
if( p->pOrderBy && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isLeftJoin>0 ){
setJoinExpr(pWhere, iNewParent);
}
- if( subqueryIsAgg ){
- assert( pParent->pHaving==0 );
- pParent->pHaving = pParent->pWhere;
- pParent->pWhere = pWhere;
- pParent->pHaving = sqlite3ExprAnd(db,
- sqlite3ExprDup(db, pSub->pHaving, 0), pParent->pHaving
- );
- assert( pParent->pGroupBy==0 );
- pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0);
- }else{
- pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere);
- }
+ pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere);
if( db->mallocFailed==0 ){
SubstContext x;
x.pParse = pParse;
**
** Do not attempt this optimization if:
**
-** (1) The inner query is an aggregate. (In that case, we'd really want
-** to copy the outer WHERE-clause terms onto the HAVING clause of the
-** inner query. But they probably won't help there so do not bother.)
+** (1) (** This restriction was removed on 2017-09-29. We used to
+** disallow this optimization for aggregate subqueries, but now
+** it is allowed by putting the extra terms on the HAVING clause **)
**
** (2) The inner query is the recursive part of a common table expression.
**
Select *pX; /* For looping over compound SELECTs in pSubq */
if( pWhere==0 ) return 0;
for(pX=pSubq; pX; pX=pX->pPrior){
- if( (pX->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){
- testcase( pX->selFlags & SF_Aggregate );
- testcase( pX->selFlags & SF_Recursive );
+ if( (pX->selFlags & (SF_Recursive))!=0 ){
testcase( pX!=pSubq );
- return 0; /* restrictions (1) and (2) */
+ return 0; /* restriction (2) */
}
}
if( pSubq->pLimit!=0 ){
nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, iCursor);
pWhere = pWhere->pLeft;
}
- if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */
+ if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction (5) */
if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){
nChng++;
while( pSubq ){
x.isLeftJoin = 0;
x.pEList = pSubq->pEList;
pNew = substExpr(&x, pNew);
- pSubq->pWhere = sqlite3ExprAnd(pParse->db, pSubq->pWhere, pNew);
+ if( pSubq->selFlags & SF_Aggregate ){
+ pSubq->pHaving = sqlite3ExprAnd(pParse->db, pSubq->pHaving, pNew);
+ }else{
+ pSubq->pWhere = sqlite3ExprAnd(pParse->db, pSubq->pWhere, pNew);
+ }
pSubq = pSubq->pPrior;
}
}
for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
struct SrcList_item *pItem = &pTabList->a[i];
Select *pSub = pItem->pSelect;
- int isAggSub;
Table *pTab = pItem->pTab;
if( pSub==0 ) continue;
goto select_end;
}
- /* If the subquery contains an ORDER BY or GROUP BY clause and if
+ /* Do not try to flatten an aggregate subquery.
+ **
+ ** Flattening an aggregate subquery is only possible if the outer query
+ ** is not a join. But if the outer query is not a join, then the subquery
+ ** will be implemented as a co-routine and there is no advantage to
+ ** flattening in that case.
+ */
+ if( (pSub->selFlags & SF_Aggregate)!=0 ) continue;
+ assert( pSub->pGroupBy==0 );
+
+ /* If the subquery contains an ORDER BY clause and if
** it will be implemented as a co-routine, then do not flatten. This
** restriction allows SQL constructs like this:
**
** The expensive_function() is only computed on the 10 rows that
** are output, rather than every row of the table.
*/
- if( (pSub->pOrderBy!=0 || pSub->pGroupBy!=0)
+ if( pSub->pOrderBy!=0
&& i==0
&& (pTabList->nSrc==1
|| (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0)
- && OptimizationEnabled(db, SQLITE_SubqCoroutine)
){
continue;
}
- isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
- if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
+ if( flattenSubquery(pParse, p, i, isAgg) ){
/* This subquery can be absorbed into its parent. */
- if( isAggSub ){
- isAgg = 1;
- p->selFlags |= SF_Aggregate;
- }
i = -1;
}
pTabList = p->pSrc;
/* Generate code to implement the subquery
**
- ** The subquery is implemented as a co-routine if all of these are true:
- ** (1) The subquery is guaranteed to be the outer loop (so that it
- ** does not need to be computed more than once)
- ** (2) REMOVED (2017-09-28): The ALL keyword after SELECT is omitted.
- ** (3) Co-routines are not disabled using sqlite3_test_control()
- ** with SQLITE_TESTCTRL_OPTIMIZATIONS.
+ ** The subquery is implemented as a co-routine if the subquery is
+ ** guaranteed to be the outer loop (so that it does not need to be
+ ** computed more than once)
**
** TODO: Are there other reasons beside (1) to use a co-routine
** implementation?
if( i==0
&& (pTabList->nSrc==1
|| (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0) /* (1) */
- /*** constraint removed: && (p->selFlags & SF_All)==0 (2) */
- && OptimizationEnabled(db, SQLITE_SubqCoroutine) /* (3) */
){
/* Implement a co-routine that will return a single row of the result
** set on each invocation.
projects / thirdparty / sqlite.git / commitdiff
