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Overview
Comment:Reduce the performance cost of the constant propagation optimization to less than 200,000 cycles.
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Timelines: family | ancestors | descendants | both | propagate-const-opt
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SHA3-256: 865249de683e6971984a645a30d96f9fcc6f6d9d7af7e269ff68cc3e42e5fe71
User & Date: drh 2018-07-27 20:01:00
Context
2018-07-27
20:37
The WHERE-clause constant propagation optimization attempts to use transitive laws to replace column values with constants in the WHERE clause in order to help to query planner make more aggressive optimizations. check-in: f4229707 user: drh tags: trunk
20:01
Reduce the performance cost of the constant propagation optimization to less than 200,000 cycles. Closed-Leaf check-in: 865249de user: drh tags: propagate-const-opt
18:19
Performance improvement to sqlite3ExprCollSeq(). With this change, the performance of speed-check.sh is within 400,000 cycles of trunk. check-in: a5f86f49 user: drh tags: propagate-const-opt
Changes
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Changes to src/select.c.

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** Add a new entry to the pConst object
*/
static void constInsert(
  WhereConst *pConst,
  Expr *pColumn,
  Expr *pValue
){

  pConst->nConst++;
  pConst->apExpr = sqlite3DbReallocOrFree(pConst->pParse->db, pConst->apExpr,
                         pConst->nConst*2*sizeof(Expr*));
  if( pConst->apExpr==0 ){
    pConst->nConst = 0;
  }else{
    if( ExprHasProperty(pValue, EP_FixedCol) ) pValue = pValue->pLeft;
................................................................................
** Find all terms of COLUMN=VALUE or VALUE=COLUMN in pExpr where VALUE
** is a constant expression and where the term must be true because it
** is part of the AND-connected terms of the expression.  For each term
** found, add it to the pConst structure.
*/
static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
  Expr *pRight, *pLeft;
  CollSeq *pColl;
  if( pExpr==0 ) return;
  if( ExprHasProperty(pExpr, EP_FromJoin) ) return;
  if( pExpr->op==TK_AND ){
    findConstInWhere(pConst, pExpr->pRight);
    findConstInWhere(pConst, pExpr->pLeft);
    return;
  }
  if( pExpr->op!=TK_EQ ) return;
  pRight = pExpr->pRight;
  pLeft = pExpr->pLeft;
  assert( pRight!=0 );
  assert( pLeft!=0 );
  pColl = sqlite3BinaryCompareCollSeq(pConst->pParse, pLeft, pRight);
  if( !sqlite3IsBinary(pColl) ) return;
  if( pRight->op==TK_COLUMN
   && !ExprHasProperty(pRight, EP_FixedCol)
   && sqlite3ExprIsConstant(pLeft)

  ){
    constInsert(pConst, pRight, pLeft);
  }else
  if( pLeft->op==TK_COLUMN
   && !ExprHasProperty(pLeft, EP_FixedCol)
   && sqlite3ExprIsConstant(pRight) ){


    constInsert(pConst, pLeft, pRight);
  }
}

/*
** This is a Walker expression callback.  pExpr is a candidate expression
** to be replaced by a value.  If pExpr is equivalent to one of the







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** Add a new entry to the pConst object
*/
static void constInsert(
  WhereConst *pConst,
  Expr *pColumn,
  Expr *pValue
){

  pConst->nConst++;
  pConst->apExpr = sqlite3DbReallocOrFree(pConst->pParse->db, pConst->apExpr,
                         pConst->nConst*2*sizeof(Expr*));
  if( pConst->apExpr==0 ){
    pConst->nConst = 0;
  }else{
    if( ExprHasProperty(pValue, EP_FixedCol) ) pValue = pValue->pLeft;
................................................................................
** Find all terms of COLUMN=VALUE or VALUE=COLUMN in pExpr where VALUE
** is a constant expression and where the term must be true because it
** is part of the AND-connected terms of the expression.  For each term
** found, add it to the pConst structure.
*/
static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
  Expr *pRight, *pLeft;

  if( pExpr==0 ) return;
  if( ExprHasProperty(pExpr, EP_FromJoin) ) return;
  if( pExpr->op==TK_AND ){
    findConstInWhere(pConst, pExpr->pRight);
    findConstInWhere(pConst, pExpr->pLeft);
    return;
  }
  if( pExpr->op!=TK_EQ ) return;
  pRight = pExpr->pRight;
  pLeft = pExpr->pLeft;
  assert( pRight!=0 );
  assert( pLeft!=0 );


  if( pRight->op==TK_COLUMN
   && !ExprHasProperty(pRight, EP_FixedCol)
   && sqlite3ExprIsConstant(pLeft)
   && sqlite3IsBinary(sqlite3BinaryCompareCollSeq(pConst->pParse,pLeft,pRight))
  ){
    constInsert(pConst, pRight, pLeft);
  }else
  if( pLeft->op==TK_COLUMN
   && !ExprHasProperty(pLeft, EP_FixedCol)
   && sqlite3ExprIsConstant(pRight)
   && sqlite3IsBinary(sqlite3BinaryCompareCollSeq(pConst->pParse,pLeft,pRight))
  ){
    constInsert(pConst, pLeft, pRight);
  }
}

/*
** This is a Walker expression callback.  pExpr is a candidate expression
** to be replaced by a value.  If pExpr is equivalent to one of the