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Character versus Memo Fields
Message
De
23/04/2006 02:46:36
 
 
À
22/04/2006 18:04:20
Information générale
Forum:
Visual FoxPro
Catégorie:
Client/serveur
Versions des environnements
Visual FoxPro:
VFP 9 SP1
OS:
Windows XP SP2
Network:
Windows 2000 Server
Divers
Thread ID:
01115658
Message ID:
01115774
Vues:
7
>>>Hi all
>>>
>>>I would appreciate if you could advise the performance difference between using a character C(200) versus a memo fields in both VFP and MSSQL? Thanks
>>
>>I did not notice differences in performance (in VFP). I would concentrate more on the following questions:
>>
  • Is 200 characters enough under all circumstances? If not, memo might be a better choice.
    >>
  • A 200-byte character field will probably waste more space than a memo field. Is this acceptable, for your situatin? Consider the database itself, the space for regular backups, and the fact that VFP files are limited to 2 GB.
    >
    >About the waste of space: If the memo field is filled only once and not updated, then it's less space consuming than a character field that must serve even the largest expected value. However, if the field will be updated more times, then the FPT will grow rapidly. In that case, a PACK MEMO should be done with a regular interval.

    - if SYS(2012)*ceiling(len(memovalue)/SYS(2012))>200 memo consume more space
    - FPT grow only if the update string is too large for the memo's blocks allocated to the current string.
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