Subject | Re: Highly variable text data |
---|---|
Author | Adam |
Post date | 2005-01-11T22:32:29Z |
If you can use varchar, it is the better option. It has less overhead
and is generally much easier to work with. There are however times
where you may need to use a BLOB.
You have said you don't need it indexed, but even if you do need it
indexed, it actually is quite easy to do using a smaller field. All
you do is store some hash of the URL and index that. The hash will
not guarantee uniqueness (so you still need an "and url='www.'" in
your where clause somewhere), but it will have a pretty good
selectability, and you can find some hashing algorithms with pretty
low overheads.
We have to use blobs in certain circumstances, but we try to avoid
them where possible.
Adam
--- In firebird-support@yahoogroups.com, "Chad Z. Hower aka Kudzu"
<chad-jm@h...> wrote:
and is generally much easier to work with. There are however times
where you may need to use a BLOB.
You have said you don't need it indexed, but even if you do need it
indexed, it actually is quite easy to do using a smaller field. All
you do is store some hash of the URL and index that. The hash will
not guarantee uniqueness (so you still need an "and url='www.'" in
your where clause somewhere), but it will have a pretty good
selectability, and you can find some hashing algorithms with pretty
low overheads.
We have to use blobs in certain circumstances, but we try to avoid
them where possible.
Adam
--- In firebird-support@yahoogroups.com, "Chad Z. Hower aka Kudzu"
<chad-jm@h...> wrote:
> I have some data like a URL That will vary in size. I don't need toindex it
> or other. Would it be better as a memo insetad of a varchar? Avarchar will
> always use 250 bytes (or whatver) I set it at ,while a memo will bemore
> dynamic in use no? Or doesit not matter in sizes such as 250?
> With a varchar I have to say 250, even though most will be < 80.
>
> --
> Chad Z. Hower aka Kudzu
> "Programming is an art form that fights back"
>
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