database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-11-12 13:01:09 +03:00
Code Activity

Minor cleanup of the sqlite3Select() procedure.

Browse Source 
FossilOrigin-Name: f4c90d06bb941453d8110680c7b279e471e8f034
This commit is contained in:
drh
2015-06-06 00:18:01 +00:00
parent 4490c40b90
commit adc57f6834
3 changed files with 35 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
src/select.c
View File

@@ -4814,12 +4814,11 @@ int sqlite3Select(
memset(&sSort, 0, sizeof(sSort));
sSort.pOrderBy = p->pOrderBy;
pTabList = p->pSrc;
pEList = p->pEList;
if( pParse->nErr || db->mallocFailed ){
goto select_end;
}
assert( p->pEList!=0 );
isAgg = (p->selFlags & SF_Aggregate)!=0;
assert( pEList!=0 );
#if SELECTTRACE_ENABLED
if( sqlite3SelectTrace & 0x100 ){
SELECTTRACE(0x100,pParse,p, ("after name resolution:\n"));
@@ -4828,21 +4827,16 @@ int sqlite3Select(
#endif
/* Begin generating code.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto select_end;
/* If writing to memory or generating a set
** only a single column may be output.
*/
#ifndef SQLITE_OMIT_SUBQUERY
if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
if( checkForMultiColumnSelectError(pParse, pDest, p->pEList->nExpr) ){
goto select_end;
}
#endif
/* Try to flatten subqueries in the FROM clause into the main query
/* Try to flatten subqueries in the FROM clause up into the main query
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
@@ -4867,6 +4861,10 @@ int sqlite3Select(
}
#endif
/* Get a pointer the VDBE under construction, allocating a new VDBE if one
** does not already exist */
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto select_end;
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/* Handle compound SELECT statements using the separate multiSelect()
@@ -4890,7 +4888,6 @@ int sqlite3Select(
struct SrcList_item *pItem = &pTabList->a[i];
SelectDest dest;
Select *pSub = pItem->pSelect;
if( pSub==0 ) continue;
/* Sometimes the code for a subquery will be generated more than
@@ -4915,6 +4912,9 @@ int sqlite3Select(
*/
pParse->nHeight += sqlite3SelectExprHeight(p);
/* Make copies of constant WHERE-clause terms in the outer query down
** inside the subquery. This can help the subquery to run more efficiently.
*/
if( (pItem->jointype & JT_OUTER)==0
&& pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor)
){
@@ -4925,6 +4925,9 @@ int sqlite3Select(
}
#endif
}
/* Generate code to implement the subquery
*/
if( pTabList->nSrc==1
&& (p->selFlags & SF_All)==0
&& OptimizationEnabled(db, SQLITE_SubqCoroutine)
@@ -4978,13 +4981,13 @@ int sqlite3Select(
sqlite3VdbeChangeP1(v, topAddr, retAddr);
sqlite3ClearTempRegCache(pParse);
}
if( db->mallocFailed ){
goto select_end;
}
if( db->mallocFailed ) goto select_end;
pParse->nHeight -= sqlite3SelectExprHeight(p);
}
pEList = p->pEList;
#endif
/* Various elements of the SELECT copied into local variables for convenience */
pEList = p->pEList;
pWhere = p->pWhere;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
@@ -5013,23 +5016,23 @@ int sqlite3Select(
** BY and DISTINCT, and an index or separate temp-table for the other.
*/
if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct
&& sqlite3ExprListCompare(sSort.pOrderBy, p->pEList, -1)==0
&& sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0
){
p->selFlags &= ~SF_Distinct;
p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
pGroupBy = p->pGroupBy;
pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0);
/* Notice that even thought SF_Distinct has been cleared from p->selFlags,
** the sDistinct.isTnct is still set. Hence, isTnct represents the
** original setting of the SF_Distinct flag, not the current setting */
assert( sDistinct.isTnct );
}
/* If there is an ORDER BY clause, then this sorting
** index might end up being unused if the data can be
** extracted in pre-sorted order. If that is the case, then the
** OP_OpenEphemeral instruction will be changed to an OP_Noop once
** we figure out that the sorting index is not needed. The addrSortIndex
** variable is used to facilitate that change.
/* If there is an ORDER BY clause, then create an ephemeral index to
** do the sorting. But this sorting ephemeral index might end up
** being unused if the data can be extracted in pre-sorted order.
** If that is the case, then the OP_OpenEphemeral instruction will be
** changed to an OP_Noop once we figure out that the sorting index is
** not needed. The sSort.addrSortIndex variable is used to facilitate
** that change.
*/
if( sSort.pOrderBy ){
KeyInfo *pKeyInfo;
@@ -5060,7 +5063,7 @@ int sqlite3Select(
sSort.sortFlags |= SORTFLAG_UseSorter;
}
/* Open a virtual index to use for the distinct set.
/* Open an ephemeral index to use for the distinct set.
*/
if( p->selFlags & SF_Distinct ){
sDistinct.tabTnct = pParse->nTab++;
@@ -5145,11 +5148,10 @@ int sqlite3Select(
p->nSelectRow = 1;
}
/* If there is both a GROUP BY and an ORDER BY clause and they are
** identical, then it may be possible to disable the ORDER BY clause
** on the grounds that the GROUP BY will cause elements to come out
** in the correct order. It also may not - the GROUP BY may use a
** in the correct order. It also may not - the GROUP BY might use a
** database index that causes rows to be grouped together as required
** but not actually sorted. Either way, record the fact that the
** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp