Here's a follow up question. Imagine a situation where you
pass a list of IDs to a query. You know that the query will
only return, at most, the same # of rows as IDs. Taking the
same kind of query, where the amount of bytes returned per
row divided into the buffers size would tell us to
ally it is." - Yoda
-Original Message-
From: Dave Watts [mailto:[EMAIL PROTECTED]]
Sent: Thursday, November 23, 2000 7:14 PM
To: CF-Talk
Cc: '[EMAIL PROTECTED]'
Subject: RE: Dave Watts please read - Re: BLOCKFACTOR and MAXROWS
How large are buffers set to? I often use
BLOCK
How large are buffers set to? I often use
BLOCKFACTOR=100 in a query where I:
SELECT ID FROM foo WHERE bar
Is this setting a large buffer?
The size of the buffer will depend on the maximum size of a returned row.
Given that you're using a field called "ID", which is probably an integer,
CF will not generate an error if the database does not support
block factoring, it's far worse than that.
Actually, I think that there was a problem if you tried to use it with a
Sybase or Informix native datasource - one of these (I forget which) would
cause CF to throw an error.
In any
On 11/21/00, Ben Forta penned:
CF will not generate an error if the database does not support block
factoring, it's far worse than that. CF has no way to poll the database to
see what it supports, so if you specify a number to high it'll try that, if
that fails it'll try a lesser number, and then
According to the article by Mr. Van Horn, any Oracle or ODBC
datasource supports blockfactor. Is that not true?
I don't know for sure.
Also, setting a block factor too high when it is not needed
will hurt performance because allocating and freeing those
larger buffers takes time (and
Hi,
I started this thread, and it's evolution has lead me to believe that in
fact I may not understand the implementation of the BLOCKFACTOR attribute.
The following is from the 4.5 Studio help:
BLOCKFACTOR
Optional. Specifies the maximum number of rows to fetch at a time from the
server. The
On 11/21/00, J.Milks penned:
BLOCKFACTOR
Optional. Specifies the maximum number of rows to fetch at a time from the
server. The range is 1 (default) to 100. This parameter applies to ORACLE
native database drivers and to ODBC drivers. Certain ODBC drivers may
dynamically reduce the block factor
I started this thread, and its evolution has lead me to
believe that in fact I may not understand the implementation
of the BLOCKFACTOR attribute. The following is from the 4.5
Studio help:
BLOCKFACTOR
Optional. Specifies the maximum number of rows to fetch at a
time from the server. The
This is from the April 2000 edition of CFDJ. Article; In Defense of
MS Access, By Bruce Van Horn:
First, add the Blockfactor="100" attribute to all your CFQUERY tags.
This alone will dramatically increase the speed of your queries.
Without this attributes, when you run a query, ODBC hands
: Dave Watts [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, November 21, 2000 2:13 PM
To: CF-Talk
Cc: [EMAIL PROTECTED]
Subject: RE: Dave Watts please read - Re: BLOCKFACTOR and MAXROWS
I started this thread, and its evolution has lead me to
believe that in fact I may not understand the implementation
On 11/21/00, Dave Watts penned:
I don't think you'd always want to simply set BLOCKFACTOR to 100. If you set
the BLOCKFACTOR too large, the database driver will lower it - and I'm not
sure exactly how it figures out what to lower it to. It might simply lower
it back to the default value of 1,
And for the most efficiency, why not just always use BLOCKFACTOR=100 ?
Why is the default the most inefficient choice?
Is there any advantage in uses a lower number?
At 03:12 PM 11/21/00 -0500, Dave Watts wrote:
I started this thread, and its evolution has lead me to
believe that in fact I
Is BLOCKFACTOR=10 the same as a SQL Select top 10 *?
No, it's not. It has absolutely no effect on how many records are returned
from the database to CF. It only affects how they're returned.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
voice: (202) 797-5496
fax: (202) 797-5444
]
www.vividmedia.com
608.270.9770
-Original Message-
From: Dave Watts [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, November 21, 2000 2:13 PM
To: CF-Talk
Cc: [EMAIL PROTECTED]
Subject: RE: Dave Watts please read - Re: BLOCKFACTOR and MAXROWS
I started this thread, and its evolution has
I don't think you'd always want to simply set BLOCKFACTOR to
100. If you set the BLOCKFACTOR too large, the database driver
will lower it - and I'm not sure exactly how it figures out
what to lower it to. It might simply lower it back to the
default value of 1, which won't serve you
And for the most efficiency, why not just always use
BLOCKFACTOR=100 ?
The maximum allowable value for BLOCKFACTOR is 100, according to Allaire.
Why is the default the most inefficient choice?
The default will always work. The ability to specify larger record blocks
isn't universally
wide open
to where its unspecified and CF just dies horribly..
Jeremy Allen
ElliptIQ Inc.
-Original Message-
From: Dave Watts [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, November 21, 2000 4:41 PM
To: CF-Talk
Cc: [EMAIL PROTECTED]
Subject: RE: Dave Watts please read - Re: BLOCKFACTOR and MAX
efficiently used).
--- Ben
-Original Message-
From: Dave Watts [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, November 21, 2000 4:55 PM
To: CF-Talk
Cc: [EMAIL PROTECTED]
Subject: RE: Dave Watts please read - Re: BLOCKFACTOR and MAXROWS
And for the most efficiency, why not just always use
How large are buffers set to? I often use
BLOCKFACTOR=100 in a query where I:
SELECT ID FROM foo WHERE bar
Is this setting a large buffer?
best, paul
At 06:25 PM 11/21/00 -0500, you wrote:
Also, setting a block factor too high when it is not needed will hurt
performance because allocating
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