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Overview
Comment:Futher improvements to LEFT JOIN strength reduction.
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SHA3-256: 8a39167bd2d46496f7484cfec371e4bad22da882209b01da9459c4ed5877da25
User & Date: drh 2019-10-11 17:14:40
Context
2019-10-11
18:55
Update the zipfile extension to use deflateBound(), instead of compressBound(), to learn the maximum possible size of a deflate()d buffer. check-in: f5ee30426e user: dan tags: trunk
17:14
Futher improvements to LEFT JOIN strength reduction. check-in: 8a39167bd2 user: drh tags: trunk
16:01
Improvements to the LEFT JOIN strength reduction optimization. check-in: 548082dfab user: drh tags: trunk
Changes
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Changes to src/expr.c.

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*/
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);







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*/
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{
    while( 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);