IMHO, Internally using varchar to implement char will defeat the entire
purpose of char. Also it seems to a really convoluted design for
implementing char.
Regards
Amrit

2009/7/10 amey samant <ameyas7@...>

>
>
> yes that's the general rule. and even i was under the impression that char
> would be faster so should be used when it comes to fixed size data. what i
> was wondering about certain statements that i came across, which claimed
> that char internally uses varchar. in that case, it would always be
> beneficial to go with varchar. so just wanted to check if some1 has
> first-hand figures on performance :)
> maybe not everything on discussion forums can be relied on ;) or maybe they
> had specific DB in mind.
>
> anyways thanks.
>
> cheers,
> amey
>
> ________________________________
> From: ashutosh <ashutosh9910@... <ashutosh9910%40yahoo.com>>
> To: NCST@yahoogroups.com <NCST%40yahoogroups.com>
> Sent: Thursday, 9 July, 2009 10:39:02 PM
> Subject: [NCST] Re: [query] char vs varchar in DB
>
>
> Here is what I found ....
>
> As a general rule, you would pick CHAR if all rows will have the same
> length and VARCHAR when it is variable length.
>
> CHAR is also a bit faster.
>
> It actually varies by DB implementation, but generally VARCHAR uses one or
> two more bytes of storage (for length or termination) then CHAR.
>
> So (assuming you are using ANSI character set) to store the word "FooBar"
> in a CHAR(6) is 6 bytes. To store the same word in VARCHAR(10) would be 7
> bytes. But to store "FooBar" in a CHAR(10) would be 10 bytes.
>
> Bottom line is CHAR can be faster and more space efficient for fixed with
> data than VARCHAR.
>
> Thanks
> Ashutosh
>
> --- In NCST@yahoogroups. com, amey samant <ameyas7@... > wrote:
> >
> > Hi All,
> >
> > i wanted to know if and how does choosing char over varchar impacts the
> performance.
> > i have some data which will be fixed size (may contain null). i know the
> ground rule that varchar should be used for variable length data (that was
> back in playschool ... :) jus kiddin)
> > what i am looking for is if and how much does char can improve
> performance if we have fixed length data against using varchar for such
> column.
> > one simple reason i got is that for varchar, DB will maintain length so
> there is an overhead of reading length first n then reading tht many chars
> of data. i did browse through lot of discussion forums, some of them claim
> to say that db internally uses varchar even for char. however i really doubt
> if thats the case for all DB. heres one such thread
> > http://sql-server- performance. com/Community/ forums/p/ 4260/28443.
> aspx
> >
> >
> > im sure many of us have already gone through this ... some might have
> even designed their own DB ;)
> > any inputs are welcome. if you have inputs specific to sybase or MS SQL
> sever, that will be gr8.
> > thanks.
> >
> >
> > regards
> > amey
> >
> > Be the change you wish to see in others.
> > - Mahatma Gandhi
> >
> >
> > blogspot me at-: http://ameyas7. blogspot. com
> >
> >
> >
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>
>



--
मंगल भवन, अमंगल हारी !!


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