No, I didn't.
As I told this is not a *real* production code. What I actually do in
the real code is add one object per record, so my sample was right.
The problem is why adding to a hashtable kills reader performance...
Steve Faleiro escribió:
>>> while( reader.Read() )
>>> {
>>> for( int j = 0; j < reader.FieldCount; ++j )
>>> val=reader[j];
>>> // table.Add(count, val);
>>> ++count;
>>> }
>>>
>
> while( reader.Read() )
> {
> for( int j = 0; j < reader.FieldCount; ++j )
> {
> val=reader[j];
> table.Add(count, val);
> }
> ++count;
> }
>
>
> Perhaps you meant to do this?
>
>
> --- "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
>
>
>> Hi there,
>>
>> Here I'm trying to save some miliseconds with the Firebird provider
>> (using embedded database!)
>>
>> Well, I've a weird problem and I'd like you to take a look into it.
>>
>> Well, I'm using the following code to read data from a Firebird
>> database:
>>
>> object val;
>>
>> while( reader.Read() )
>> {
>> for( int j = 0; j < reader.FieldCount; ++j )
>> val=reader[j];
>> // table.Add(count, val);
>> ++count;
>> }
>>
>> I'm reading 416310 records.
>>
>> Well, in my poor-slow laptop it takes 50 seconds to read all data.
>>
>> The "funny" thing is: did you see the commented out code? Well, it
>> just
>> adds the last read field from the record to a hash table. It doesn't
>> make any sense, it is just a test case extracted from real code, so
>> don't try to find any logic.
>>
>> Well, the point is: if I uncomment the line -> it takes 158 seconds to
>>
>> read the 416310 records!!!
>>
>> Ok, now you're thinking: yes, that's because adding to the hashtable
>> is
>> slow. Check the following code:
>>
>> Hashtable table = new Hashtable();
>>
>> int ini = Environment.TickCount;
>>
>> for( int i = 0; i < 416310; ++i )
>> table.Add(i, new object());
>>
>> Console.WriteLine(
>> "Time to add {0} objects = {1} ms",
>> table.Count,
>> Environment.TickCount - ini);
>>
>> It takes 250 ms (miliseconds!) to add the same number of dumb objects
>> to
>> the Hashtable!!
>>
>> So, somehow, adding records to the Hashtable breaks reader
>> performance!!! I'm going crazy, and yes, I've repeated the results on
>> a
>> different computer with different OS and I get the same relative
>> results!
>>
>> If you change the Hashtable by an ArrayList... performance hit goes
>> away!!
>>
>> Ideas???
>>
>>
>> Thanks
>>
>>
>> pablo
>>
>>
>>
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