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Overview
Comment: | Simplify the interface to the subst() routines that are part of the query flattener by collecting common parameters into the SubstContext object and passing around a pointer to that object. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
e651074be28b2077b8a298f513e2e699 |
User & Date: | drh 2017-04-14 12:39:37.290 |
Context
2017-04-14
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14:02 | Enhance the sqlite3TreeView() display for Expr objects so that it shows the iRightJoinTable value for Expr nodes that have the EP_FromJoin property. (check-in: 5159cb8f2b user: drh tags: trunk) | |
12:39 | Simplify the interface to the subst() routines that are part of the query flattener by collecting common parameters into the SubstContext object and passing around a pointer to that object. (check-in: e651074be2 user: drh tags: trunk) | |
12:27 | Remove an incorrect ALWAYS(). (check-in: f956f6ae6b user: drh tags: trunk) | |
Changes
Changes to src/select.c.
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3140 3141 3142 3143 3144 3145 3146 3147 | **** subqueries ****/ explainComposite(pParse, p->op, iSub1, iSub2, 0); return pParse->nErr!=0; } #endif #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* Forward Declarations */ | > > > > > > > > > > > > > | | | | < < < | | | | > | | | | | | < < | | | < < | | | | | | | | | 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 | **** subqueries ****/ explainComposite(pParse, p->op, iSub1, iSub2, 0); return pParse->nErr!=0; } #endif #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) /* An instance of the SubstContext object describes an substitution edit ** to be performed on a parse tree. ** ** All references to columns in table iTable are to be replaced by corresponding ** expressions in pEList. */ typedef struct SubstContext { Parse *pParse; /* The parsing context */ int iTable; /* Replace references to this table */ ExprList *pEList; /* Replacement expressions */ } SubstContext; /* Forward Declarations */ static void substExprList(SubstContext*, ExprList*); static void substSelect(SubstContext*, Select*, int); /* ** Scan through the expression pExpr. Replace every reference to ** a column in table number iTable with a copy of the iColumn-th ** entry in pEList. (But leave references to the ROWID column ** unchanged.) ** ** This routine is part of the flattening procedure. A subquery ** whose result set is defined by pEList appears as entry in the ** FROM clause of a SELECT such that the VDBE cursor assigned to that ** FORM clause entry is iTable. This routine makes the necessary ** changes to pExpr so that it refers directly to the source table ** of the subquery rather the result set of the subquery. */ static Expr *substExpr( SubstContext *pSubst, /* Description of the substitution */ Expr *pExpr /* Expr in which substitution occurs */ ){ if( pExpr==0 ) return 0; if( pExpr->op==TK_COLUMN && pExpr->iTable==pSubst->iTable ){ if( pExpr->iColumn<0 ){ pExpr->op = TK_NULL; }else{ Expr *pNew; Expr *pCopy = pSubst->pEList->a[pExpr->iColumn].pExpr; assert( pSubst->pEList!=0 && pExpr->iColumn<pSubst->pEList->nExpr ); assert( pExpr->pLeft==0 && pExpr->pRight==0 ); if( sqlite3ExprIsVector(pCopy) ){ sqlite3VectorErrorMsg(pSubst->pParse, pCopy); }else{ sqlite3 *db = pSubst->pParse->db; pNew = sqlite3ExprDup(db, pCopy, 0); if( pNew && (pExpr->flags & EP_FromJoin) ){ pNew->iRightJoinTable = pExpr->iRightJoinTable; pNew->flags |= EP_FromJoin; } sqlite3ExprDelete(db, pExpr); pExpr = pNew; } } }else{ pExpr->pLeft = substExpr(pSubst, pExpr->pLeft); pExpr->pRight = substExpr(pSubst, pExpr->pRight); if( ExprHasProperty(pExpr, EP_xIsSelect) ){ substSelect(pSubst, pExpr->x.pSelect, 1); }else{ substExprList(pSubst, pExpr->x.pList); } } return pExpr; } static void substExprList( SubstContext *pSubst, /* Description of the substitution */ ExprList *pList /* List to scan and in which to make substitutes */ ){ int i; if( pList==0 ) return; for(i=0; i<pList->nExpr; i++){ pList->a[i].pExpr = substExpr(pSubst, pList->a[i].pExpr); } } static void substSelect( SubstContext *pSubst, /* Description of the substitution */ Select *p, /* SELECT statement in which to make substitutions */ int doPrior /* Do substitutes on p->pPrior too */ ){ SrcList *pSrc; struct SrcList_item *pItem; int i; if( !p ) return; do{ substExprList(pSubst, p->pEList); substExprList(pSubst, p->pGroupBy); substExprList(pSubst, p->pOrderBy); p->pHaving = substExpr(pSubst, p->pHaving); p->pWhere = substExpr(pSubst, p->pWhere); pSrc = p->pSrc; assert( pSrc!=0 ); for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ substSelect(pSubst, pItem->pSelect, 1); if( pItem->fg.isTabFunc ){ substExprList(pSubst, pItem->u1.pFuncArg); } } }while( doPrior && (p = p->pPrior)!=0 ); } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) |
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3756 3757 3758 3759 3760 3761 3762 | ); assert( pParent->pGroupBy==0 ); pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0); }else{ pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere); } if( db->mallocFailed==0 ){ | > > > > | | 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 | ); assert( pParent->pGroupBy==0 ); pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0); }else{ pParent->pWhere = sqlite3ExprAnd(db, pWhere, pParent->pWhere); } if( db->mallocFailed==0 ){ SubstContext x; x.pParse = pParse; x.iTable = iParent; x.pEList = pSub->pEList; substSelect(&x, pParent, 0); } /* The flattened query is distinct if either the inner or the ** outer query is distinct. */ pParent->selFlags |= pSub->selFlags & SF_Distinct; |
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3859 3860 3861 3862 3863 3864 3865 3866 | nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, iCursor); pWhere = pWhere->pLeft; } if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */ if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){ nChng++; while( pSubq ){ pNew = sqlite3ExprDup(pParse->db, pWhere, 0); | > > > > | | 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 | nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, iCursor); pWhere = pWhere->pLeft; } if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */ if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){ nChng++; while( pSubq ){ SubstContext x; pNew = sqlite3ExprDup(pParse->db, pWhere, 0); x.pParse = pParse; x.iTable = iCursor; x.pEList = pSubq->pEList; pNew = substExpr(&x, pNew); pSubq->pWhere = sqlite3ExprAnd(pParse->db, pSubq->pWhere, pNew); pSubq = pSubq->pPrior; } } return nChng; } #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ |
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