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Overview
Comment:Do not allow the constant-propagation optimization to apple to ON/USING clause terms as it does not help and it might cause downstream problems.
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SHA3-256: 1bc783da63d58b05c690468b569cb2787846357b63c1100d11777666c5787bf4
User & Date: drh 2020-01-16 16:12:07
Context
2020-01-16
16:32
Add the SQLITE_FCNTL_CKPT_DONE file-control for the use of custom VFSs. (check-in: 3cc39e50 user: dan tags: trunk)
16:12
Do not allow the constant-propagation optimization to apple to ON/USING clause terms as it does not help and it might cause downstream problems. (check-in: 1bc783da user: drh tags: trunk)
12:25
Fix an SQL syntax error in the comment on the omit-left-join optimization. No changes to code. (check-in: 86b5e5a2 user: drh tags: trunk)
Changes
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Changes to src/select.c.

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** columns named in pWalker->u.pConst, then overwrite it with its
** corresponding value.
*/
static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
  int i;
  WhereConst *pConst;
  if( pExpr->op!=TK_COLUMN ) return WRC_Continue;
  if( ExprHasProperty(pExpr, EP_FixedCol) ) return WRC_Continue;
  pConst = pWalker->u.pConst;
  for(i=0; i<pConst->nConst; i++){
    Expr *pColumn = pConst->apExpr[i*2];
    if( pColumn==pExpr ) continue;
    if( pColumn->iTable!=pExpr->iTable ) continue;
    if( pColumn->iColumn!=pExpr->iColumn ) continue;
    /* A match is found.  Add the EP_FixedCol property */








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4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243

** columns named in pWalker->u.pConst, then overwrite it with its
** corresponding value.
*/
static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
  int i;
  WhereConst *pConst;
  if( pExpr->op!=TK_COLUMN ) return WRC_Continue;
  if( ExprHasProperty(pExpr, EP_FixedCol|EP_FromJoin) ) return WRC_Continue;
  pConst = pWalker->u.pConst;
  for(i=0; i<pConst->nConst; i++){
    Expr *pColumn = pConst->apExpr[i*2];
    if( pColumn==pExpr ) continue;
    if( pColumn->iTable!=pExpr->iTable ) continue;
    if( pColumn->iColumn!=pExpr->iColumn ) continue;
    /* A match is found.  Add the EP_FixedCol property */
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