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Overview
Comment:Performance enhancement in sqlite3VdbeMemNulTerminate().
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SHA1: f94cacc393e895522b92c9717c53357afc918d60
User & Date: drh 2014-08-27 00:50:11.231
Context
2014-08-27
03:28
Factor out the exception paths from sqlite3ValueToText() into a separate function so that the main routine is much faster for the common case of no required type or encoding conversions. (check-in: 1624916c6e user: drh tags: trunk)
00:50
Performance enhancement in sqlite3VdbeMemNulTerminate(). (check-in: f94cacc393 user: drh tags: trunk)
2014-08-26
15:06
Change the page cache so that a new sqlite3_pcache object is allocated as soon as the page cache is opened, not delayed until the first fetch request. This give a noticable performance boost. The interface between pager and the page cache has changed slightly, which might break ZIPVFS. (check-in: f1f94a971e user: drh tags: trunk)
Changes
Side-by-Side Diff Ignore Whitespace Patch
Changes to src/vdbemem.c.
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    pMem->n += pMem->u.nZero;
    pMem->flags &= ~(MEM_Zero|MEM_Term);
  }
  return SQLITE_OK;
}
#endif


/*
** It is already known that pMem contains an unterminated string.
** Make sure the given Mem is \u0000 terminated.
** Add the zero terminator.
*/
int sqlite3VdbeMemNulTerminate(Mem *pMem){
static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  if( (pMem->flags & MEM_Term)!=0 || (pMem->flags & MEM_Str)==0 ){
    return SQLITE_OK;   /* Nothing to do */
  }
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Make sure the given Mem is \u0000 terminated.
*/
int sqlite3VdbeMemNulTerminate(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
  if( (pMem->flags & (MEM_Term|MEM_Str))!=MEM_Str ){
    return SQLITE_OK;   /* Nothing to do */
  }else{
    return vdbeMemAddTerminator(pMem);
  }
}

/*
** Add MEM_Str to the set of representations for the given Mem.  Numbers
** are converted using sqlite3_snprintf().  Converting a BLOB to a string
** is a no-op.
**
** Existing representations MEM_Int and MEM_Real are invalidated if
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