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Overview
| Comment: | Improvements to the LEFT JOIN strength reduction optimization. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
548082dfab5d9484279ccc11cd2833ac |
| User & Date: | drh 2019-10-11 16:01:21 |
Context
|
2019-10-11
| ||
| 17:14 | Futher improvements to LEFT JOIN strength reduction. check-in: 8a39167b user: drh tags: trunk | |
| 16:01 | Improvements to the LEFT JOIN strength reduction optimization. check-in: 548082df user: drh tags: trunk | |
| 15:33 | Ensure fts3/4 prefix indexes are flushed to disk before an 'optimize' command. Fix for [745f1abc]. check-in: 4ed905b1 user: dan tags: trunk | |
Changes
Changes to src/expr.c.
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** clause requires that some column of the right table of the LEFT JOIN
** be non-NULL, then the LEFT JOIN can be safely converted into an
** ordinary join.
*/
int sqlite3ExprImpliesNonNullRow(Expr *p, int iTab){
Walker w;
p = sqlite3ExprSkipCollateAndLikely(p);
if( p && p->op==TK_NOTNULL ){
p = p->pLeft;
}
w.xExprCallback = impliesNotNullRow;
w.xSelectCallback = 0;
w.xSelectCallback2 = 0;
w.eCode = 0;
w.u.iCur = iTab;
sqlite3WalkExpr(&w, p);
|
> | > > > |
5227 5228 5229 5230 5231 5232 5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 |
** clause requires that some column of the right table of the LEFT JOIN
** be non-NULL, then the LEFT JOIN can be safely converted into an
** ordinary join.
*/
int sqlite3ExprImpliesNonNullRow(Expr *p, int iTab){
Walker w;
p = sqlite3ExprSkipCollateAndLikely(p);
if( p==0 ) return 0;
if( p->op==TK_NOTNULL ){
p = p->pLeft;
}else if( p->op==TK_AND ){
if( sqlite3ExprImpliesNonNullRow(p->pLeft, iTab) ) return 1;
p = p->pRight;
}
w.xExprCallback = impliesNotNullRow;
w.xSelectCallback = 0;
w.xSelectCallback2 = 0;
w.eCode = 0;
w.u.iCur = iTab;
sqlite3WalkExpr(&w, p);
|