Speed of Blob-writing...

[Thomas Flemming]

Hi Ruslan ,

I even tried without compression, just compare read and write blob, still 
times 15 slower!

Is this really normal? Is there nothing to speed up writing of large blobs?


Tom






Am 10.02.2010 22:35, schrieb Ruslan Zasukhin:
> On 2/8/10 10:47 PM, "Thomas Flemming"<tf at ttqv.com>  wrote:
>
> Hi Thomas,
>
>> its again about speed :-)
>>
>> Im storing map data as Blobs.
>> Works perfect and is very fast in reading.
>>
>> For example reading of 10 mapsegments, each a blob of 2MB is just 200ms in
>> total, including decompression.
>>
>> But why is writing of the same data so slow?
>>
>> The same 10 mapsegments needs 6000ms just for the fldTexture.WriteData(b).
>>
>> I created the table like this:
>>
>>     Dim s As String = "CREATE TABLE ""map_data"" ( "&  _
>>                            """idx_db"" ULLONG  NOT NULL UNIQUE INDEXED,"&  _
>>                            """idx_level"" BYTE  NOT NULL INDEXED,"&  _
>>                            """texture"" BLOB (1024) COMPRESSED ); "
>>     mDatabase.SqlExecute(s)
>>
>>
>> A larger segment-size does not change the time for writing.
>> When I create the field without compression its faster, but still takes
>> 3000ms.
>
> Well, I think it is know that
>
> A) WRITE is slower than READ even for HDD.
>
> B) COMPRESSION is slower of decompression.
>      you can easy see this in any archivator.
>
> May be try to set less compression level. Will be faster but size little
> bigger
>
>

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