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Data Bases > Pgsql Novice > Re: Disadvantag...
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Re: Disadvantages to using "text"

by tgl@[EMAIL PROTECTED] (Tom Lane) May 7, 2008 at 12:54 PM

Bruce Hyatt <brucejhyatt@[EMAIL PROTECTED]
> writes:
> VARCHAR is slower too? There's no check on VARCHAR, is there?

Well, all the textual operators/functions are actually declared to take
and return type TEXT, so when you are working with VARCHAR columns the
expressions have no-op cast nodes in them ("RelabelType" nodes), even
if it's an unconstrained-length VARCHAR.  I'm not sure whether the
execution cost of these would be measurable in real applications, but
it's not zero.  A bigger problem is that sometimes the planner gets
confused by the RelabelTypes and fails to find as good a plan as it
finds for a pure-TEXT query.  Now if you run into that kind of problem
it's a bug and should be re****ted, but nonetheless you'll get stuck with
bad plans until it's fixed ...

			regards, tom lane

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 15 Posts in Topic:
Disadvantages to using "text"
dmies@[EMAIL PROTECTED]   2008-05-07 08:52:27 
Re: Disadvantages to using "text"
rdeleonp@[EMAIL PROTECTED  2008-05-07 11:01:09 
Re: Disadvantages to using "text"
richard.broersma@[EMAIL P  2008-05-07 09:03:57 
Re: Disadvantages to using "text"
tgl@[EMAIL PROTECTED] (T  2008-05-07 12:09:27 
Re: Disadvantages to using "text"
ashaw@[EMAIL PROTECTED]   2008-05-07 10:02:10 
Re: Disadvantages to using "text"
brucejhyatt@[EMAIL PROTEC  2008-05-07 09:44:10 
Re: Disadvantages to using "text"
tgl@[EMAIL PROTECTED] (T  2008-05-07 12:54:51 
Re: Disadvantages to using "text"
brucejhyatt@[EMAIL PROTEC  2008-05-07 18:40:52 
Re: Disadvantages to using "text"
fbax@[EMAIL PROTECTED] (  2008-05-07 12:55:14 
Re: Disadvantages to using "text"
gcocks@[EMAIL PROTECTED]   2008-05-07 11:48:02 
Re: Disadvantages to using "text"
robe.dnd@[EMAIL PROTECTED  2008-05-07 15:15:08 
Re: Disadvantages to using "text"
gcocks@[EMAIL PROTECTED]   2008-05-13 10:58:26 
Re: Disadvantages to using "text"
ktuszynska@[EMAIL PROTECT  2008-05-13 10:04:08 
Re: Disadvantages to using "text" [ArcGIS]
gcocks@[EMAIL PROTECTED]   2008-05-13 11:26:43 
Re: Disadvantages to using "text"
ashaw@[EMAIL PROTECTED]   2008-05-07 13:19:47 

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tan12V112 Sun Oct 12 9:27:24 CDT 2008.