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Overview
Comment:Modify the sqlite3SelectDup() routine to avoid recursing on Select.pPrior.
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SHA1: a7674ead5be986c66f7d61d598adc7e5728bcd30
User & Date: dan 2017-02-03 14:44:52
Context
2017-02-03
19:16
Avoid a performance problem when very large "VALUES(..), (..), (..)" terms are used in queries. Closed-Leaf check-in: f5306ad6 user: dan tags: recursive-selectdup
14:44
Modify the sqlite3SelectDup() routine to avoid recursing on Select.pPrior. check-in: a7674ead user: dan tags: recursive-selectdup
2017-02-02
20:32
Ensure that all cursors have their positions saved prior to rolling back a savepoint. check-in: 8e03a8e9 user: drh tags: trunk
Changes
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Changes to src/expr.c.

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    struct IdList_item *pNewItem = &pNew->a[i];
    struct IdList_item *pOldItem = &p->a[i];
    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
    pNewItem->idx = pOldItem->idx;
  }
  return pNew;
}
Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){



  Select *pNew, *pPrior;

  assert( db!=0 );
  if( p==0 ) return 0;

  pNew = sqlite3DbMallocRawNN(db, sizeof(*p) );
  if( pNew==0 ) return 0;
  pNew->pEList = sqlite3ExprListDup(db, p->pEList, flags);
  pNew->pSrc = sqlite3SrcListDup(db, p->pSrc, flags);
  pNew->pWhere = sqlite3ExprDup(db, p->pWhere, flags);
  pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy, flags);
  pNew->pHaving = sqlite3ExprDup(db, p->pHaving, flags);
  pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, flags);
  pNew->op = p->op;
  pNew->pPrior = pPrior = sqlite3SelectDup(db, p->pPrior, flags);
  if( pPrior ) pPrior->pNext = pNew;
  pNew->pNext = 0;
  pNew->pLimit = sqlite3ExprDup(db, p->pLimit, flags);
  pNew->pOffset = sqlite3ExprDup(db, p->pOffset, flags);
  pNew->iLimit = 0;
  pNew->iOffset = 0;
  pNew->selFlags = p->selFlags & ~SF_UsesEphemeral;
  pNew->addrOpenEphm[0] = -1;
  pNew->addrOpenEphm[1] = -1;
  pNew->nSelectRow = p->nSelectRow;
  pNew->pWith = withDup(db, p->pWith);
  sqlite3SelectSetName(pNew, p->zSelName);





  return pNew;
}
#else
Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
  assert( p==0 );
  return 0;
}
#endif







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    struct IdList_item *pNewItem = &pNew->a[i];
    struct IdList_item *pOldItem = &p->a[i];
    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
    pNewItem->idx = pOldItem->idx;
  }
  return pNew;
}
Select *sqlite3SelectDup(sqlite3 *db, Select *pDup, int flags){
  Select *pRet = 0;
  Select *pNext = 0;
  Select **pp = &pRet;
  Select *p;

  assert( db!=0 );

  for(p=pDup; p; p=p->pPrior){
    Select *pNew = sqlite3DbMallocRawNN(db, sizeof(*p) );
    if( pNew==0 ) break;
    pNew->pEList = sqlite3ExprListDup(db, p->pEList, flags);
    pNew->pSrc = sqlite3SrcListDup(db, p->pSrc, flags);
    pNew->pWhere = sqlite3ExprDup(db, p->pWhere, flags);
    pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy, flags);
    pNew->pHaving = sqlite3ExprDup(db, p->pHaving, flags);
    pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, flags);
    pNew->op = p->op;

    pNew->pNext = pNext;
    pNew->pPrior = 0;
    pNew->pLimit = sqlite3ExprDup(db, p->pLimit, flags);
    pNew->pOffset = sqlite3ExprDup(db, p->pOffset, flags);
    pNew->iLimit = 0;
    pNew->iOffset = 0;
    pNew->selFlags = p->selFlags & ~SF_UsesEphemeral;
    pNew->addrOpenEphm[0] = -1;
    pNew->addrOpenEphm[1] = -1;
    pNew->nSelectRow = p->nSelectRow;
    pNew->pWith = withDup(db, p->pWith);
    sqlite3SelectSetName(pNew, p->zSelName);
    *pp = pNew;
    pp = &pNew->pPrior;
    pNext = pNew;
  }

  return pRet;
}
#else
Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
  assert( p==0 );
  return 0;
}
#endif