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Overview
Comment:Avoid unnecessary memory zeroing during expression list allocation.
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SHA3-256:de28e6514a42438411e2c9d833ba660108128ca86d0b90f32925fb73195f4862
User & Date: drh 2017-05-31 02:58:30
Context
2017-05-31
03:20
Reorder fields in the PgHdr object for a performance increase. check-in: 326e63d7 user: drh tags: trunk
02:58
Avoid unnecessary memory zeroing during expression list allocation. check-in: de28e651 user: drh tags: trunk
00:49
Size and performance optimizations to sqlite3ResolveExprNames(). check-in: af8c0fed user: drh tags: trunk
Changes
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Changes to src/expr.c.

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    if( pNew==0 ){
      goto no_mem;
    }
    pList = pNew;
    pList->nAlloc *= 2;
  }
  pItem = &pList->a[pList->nExpr++];
  memset(pItem, 0, sizeof(*pItem));


  pItem->pExpr = pExpr;
  return pList;

no_mem:     
  /* Avoid leaking memory if malloc has failed. */
  sqlite3ExprDelete(db, pExpr);
  sqlite3ExprListDelete(db, pList);







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    if( pNew==0 ){
      goto no_mem;
    }
    pList = pNew;
    pList->nAlloc *= 2;
  }
  pItem = &pList->a[pList->nExpr++];
  assert( offsetof(struct ExprList_item,zName)==sizeof(pItem->pExpr) );
  assert( offsetof(struct ExprList_item,pExpr)==0 );
  memset(&pItem->zName,0,sizeof(*pItem)-offsetof(struct ExprList_item,zName));
  pItem->pExpr = pExpr;
  return pList;

no_mem:     
  /* Avoid leaking memory if malloc has failed. */
  sqlite3ExprDelete(db, pExpr);
  sqlite3ExprListDelete(db, pList);

Changes to src/sqliteInt.h.

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/*
** An instance of this object describes where to put of the results of
** a SELECT statement.
*/
struct SelectDest {
  u8 eDest;            /* How to dispose of the results.  On of SRT_* above. */
  char *zAffSdst;      /* Affinity used when eDest==SRT_Set */
  int iSDParm;         /* A parameter used by the eDest disposal method */
  int iSdst;           /* Base register where results are written */
  int nSdst;           /* Number of registers allocated */

  ExprList *pOrderBy;  /* Key columns for SRT_Queue and SRT_DistQueue */
};

/*
** During code generation of statements that do inserts into AUTOINCREMENT
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that







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/*
** An instance of this object describes where to put of the results of
** a SELECT statement.
*/
struct SelectDest {
  u8 eDest;            /* How to dispose of the results.  On of SRT_* above. */

  int iSDParm;         /* A parameter used by the eDest disposal method */
  int iSdst;           /* Base register where results are written */
  int nSdst;           /* Number of registers allocated */
  char *zAffSdst;      /* Affinity used when eDest==SRT_Set */
  ExprList *pOrderBy;  /* Key columns for SRT_Queue and SRT_DistQueue */
};

/*
** During code generation of statements that do inserts into AUTOINCREMENT
** tables, the following information is attached to the Table.u.autoInc.p
** pointer of each autoincrement table to record some side information that