Hi Cetin
After 100000 inserts
The index size is 2,994,176 bytes
After Reindex is 2,161,152 bytes
I think that is because are random generated.
From what I've read about B-tree indexes, this can be the cause.
>Dorin,
>A GUID is actually a 16 bytes value. Using it as 16 bytes I think timings would get down too.
>Since you have the test code, would you test with this :
>
>
>Local loGUID
>loGUID = Createobject('GUIDLib')
>
>lcPKey = loGUID.GetGUID16()
>
>Define Class GUIDLib As Relation
> Procedure Init
> Declare Integer UuidCreate In 'RPCRT4.dll' String @pguid
> Declare Integer CoCreateGuid In 'Ole32.dll' ;
> string @pguid
> Declare Integer StringFromGUID2 In 'Ole32.dll' ;
> string rguid, String @lpsz, Integer cchMax
> Declare RtlMoveMemory In WIN32API ;
> INTEGER @DestNumeric, ;
> STRING @pVoidSource, ;
> INTEGER nLength
>Endproc
>
> Procedure GUID16ToStr
> lparameters tcGUID16
> Local rguid
> rguid=Replicate(Chr(0),80)
> StringFromGUID2(tcGUID16,@rguid,40)
> Return Strconv(Left(rGUID,76),6)
>endproc
>
> Procedure GetGUID16
> Local pguid
> pguid=Replicate(Chr(0),16)
> UuidCreate(@pguid)
> Return pGUID
>endproc
>
> Procedure GetGUID
> Local pguid,rguid,lcFail
> lcFail = ""
> pguid=Replicate(Chr(0),16)
> rguid=Replicate(Chr(0),80)
>
> If Inlist(UuidCreate(@pguid),0,1824)
> Return Iif(StringFromGUID2(pguid,@rguid,40) # 0, ;
> Strconv(Left(rguid,76),6), lcFail)
> Endif
> Return lcFail
>Endproc
>Enddefine
>>Cetin
>
>>You can think also to sys(2015)+WorkstationId as a character type PK solution. Only WorkstationId must be an unique value, saved in registry or local config files. GUIDs are very random generated values and I think that there is an overhead to mantain indexes (also think about one-to-many relationships).
>>
>>I've done some tests, maybe results can be useful:
>>
>>With 100000 records, only one PK fields, 38 bytes GUID type as in sample...
>>
http://support.microsoft.com/support/kb/articles/Q269/3/87.asp>>and right(SYS(2015),3) + 3 chars workstation id (12 in total)
>>
>>
>>Index size GUID : 6.786.548 bytes
>>Index size SYS(2015)+WsId : 863.744 bytes
>>
>>7.85 times more for GUID index
>>
>>After a REINDEX command
>>Index size GUID : 4.767.744 bytes
>>Index size SYS(2015)+WsId : 850.432 bytes
>>
>>5.60 times more for GUID indexes
>>
>>Average seek times , 100000 iterations, random keys
>>Index on GUID : 1.880 seconds
>>The othe index : 0.954 seconds
>>
>>
>>
>>>>Hi,
>>>>I am designing database for my new application. I think to use AutoNumber as PK, however, it will cause problem while replication. Do you think combination of AutoNumber and BrandID as PK is a good solution? Will it complicated coding? how about GUID?
>>>>
>>>>Thank you
>>>
>>>As Sylvain said already,
>>>Go with GUID.
>>>
>>>For a long discussion and sample on it check :
>>>
>>>
http://oldlook.experts-exchange.com/Databases/FoxPro/Q_20764442.html>>>
>>>Cetin
