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Overview
Comment:Performance improvement to sqlite3WhereExprUsage().
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SHA3-256:fd0934139076848f2f2edfd3d74d54608531031a05a60ca6ac1d7016dcd538df
User & Date: drh 2018-06-09 02:49:11
Context
2018-06-09
14:13
Improved comments an presentation for the recent IN operator decision improvement. check-in: 31e480f6 user: drh tags: trunk
02:49
Performance improvement to sqlite3WhereExprUsage(). check-in: fd093413 user: drh tags: trunk
01:12
Compute the bitmask of indexed columns for each index once when the Index objecct is constructed, instead of recomputing it every time it is needed. check-in: d735872e user: drh tags: trunk
Changes
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Changes to src/whereInt.h.

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);

/* whereexpr.c: */
void sqlite3WhereClauseInit(WhereClause*,WhereInfo*);
void sqlite3WhereClauseClear(WhereClause*);
void sqlite3WhereSplit(WhereClause*,Expr*,u8);
Bitmask sqlite3WhereExprUsage(WhereMaskSet*, Expr*);

Bitmask sqlite3WhereExprListUsage(WhereMaskSet*, ExprList*);
void sqlite3WhereExprAnalyze(SrcList*, WhereClause*);
void sqlite3WhereTabFuncArgs(Parse*, struct SrcList_item*, WhereClause*);











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/* whereexpr.c: */
void sqlite3WhereClauseInit(WhereClause*,WhereInfo*);
void sqlite3WhereClauseClear(WhereClause*);
void sqlite3WhereSplit(WhereClause*,Expr*,u8);
Bitmask sqlite3WhereExprUsage(WhereMaskSet*, Expr*);
Bitmask sqlite3WhereExprUsageNN(WhereMaskSet*, Expr*);
Bitmask sqlite3WhereExprListUsage(WhereMaskSet*, ExprList*);
void sqlite3WhereExprAnalyze(SrcList*, WhereClause*);
void sqlite3WhereTabFuncArgs(Parse*, struct SrcList_item*, WhereClause*);




Changes to src/whereexpr.c.

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    }
  }else if( op==TK_ISNULL ){
    pTerm->prereqRight = 0;
  }else{
    pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
  }
  pMaskSet->bVarSelect = 0;
  prereqAll = sqlite3WhereExprUsage(pMaskSet, pExpr);
  if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
  if( ExprHasProperty(pExpr, EP_FromJoin) ){
    Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
    prereqAll |= x;
    extraRight = x-1;  /* ON clause terms may not be used with an index
                       ** on left table of a LEFT JOIN.  Ticket #3015 */
    if( (prereqAll>>1)>=x ){
................................................................................


/*
** These routines walk (recursively) an expression tree and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
  Bitmask mask;
  if( p==0 ) return 0;
  if( p->op==TK_COLUMN ){
    return sqlite3WhereGetMask(pMaskSet, p->iTable);



  }
  mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
  assert( !ExprHasProperty(p, EP_TokenOnly) );
  if( p->pLeft ) mask |= sqlite3WhereExprUsage(pMaskSet, p->pLeft);
  if( p->pRight ){
    mask |= sqlite3WhereExprUsage(pMaskSet, p->pRight);
    assert( p->x.pList==0 );
  }else if( ExprHasProperty(p, EP_xIsSelect) ){
    if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
    mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
  }else if( p->x.pList ){
    mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
  }
  return mask;



}
Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
  int i;
  Bitmask mask = 0;
  if( pList ){
    for(i=0; i<pList->nExpr; i++){
      mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);







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    }
  }else if( op==TK_ISNULL ){
    pTerm->prereqRight = 0;
  }else{
    pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
  }
  pMaskSet->bVarSelect = 0;
  prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
  if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
  if( ExprHasProperty(pExpr, EP_FromJoin) ){
    Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
    prereqAll |= x;
    extraRight = x-1;  /* ON clause terms may not be used with an index
                       ** on left table of a LEFT JOIN.  Ticket #3015 */
    if( (prereqAll>>1)>=x ){
................................................................................


/*
** These routines walk (recursively) an expression tree and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
  Bitmask mask;

  if( p->op==TK_COLUMN ){
    return sqlite3WhereGetMask(pMaskSet, p->iTable);
  }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
    assert( p->op!=TK_IF_NULL_ROW );
    return 0;
  }
  mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;

  if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
  if( p->pRight ){
    mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pRight);
    assert( p->x.pList==0 );
  }else if( ExprHasProperty(p, EP_xIsSelect) ){
    if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
    mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
  }else if( p->x.pList ){
    mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
  }
  return mask;
}
Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
  return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
}
Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
  int i;
  Bitmask mask = 0;
  if( pList ){
    for(i=0; i<pList->nExpr; i++){
      mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);