> CF Docs on the Subject are as follows:
>
> "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 at runtime."
>
> A recent article in SQL Server Magazine (October 2000, p 75)
> discusses "BLOCKING FACTOR"
>
> "BLOCKING FACTOR" bears some resemblance to "BLOCKFACTOR,"
> but I'm not sure how close it is.
>
> BLOCKING FACTOR appears to be determined by the width of a
> RECORD, as it exists in the DB (that is, it includes all columns).
>
> I've assumed BLOCKFACTOR to be determined by the width of the
> RETURNED DATA in each record, which does not have to include
> all columns.
>
> I further assumed a CFQUERY that returned a single column of
> integers could have BLOCKFACTOR set at the maximum of 100,
> without fear of loss of efficiency as in those cases where
> 100 happened to be too large and CF would then have to try
> 99, then 98, etc.
>
> So the question is: Is 100 ALWAYS OK when CFQUERY returns a
> single column of integers?
Your assumptions about how BLOCKFACTOR works are correct. There's a formula
for determining the appropriate BLOCKFACTOR value for a given query:
1. The size of the buffer used by BLOCKFACTOR is 32k.
2. You can store the number of rows that will fit within the buffer.
So, the formula is:
32768 bytes / row size in bytes
Of course, in many cases, you might only have a rough number (when using
varchar columns, for example).
> PS> Keeping in mind that CF4.01 Administrator (but not 4.51
> Administrator) is now known to have incorrectly stated there
> to be limit of 100 cached queries, whereas there really is no
> fixed limit, is BLOCKFACTOR _really_ limited to 100?
I don't know. I haven't tested this. However, in real-life use, it's
unlikely that you'd even get to 100 using most queries.
Dave Watts, CTO, Fig Leaf Software
http://www.figleaf.com/
voice: (202) 797-5496
fax: (202) 797-5444
------------------------------------------------------------------------------
Archives: http://www.mail-archive.com/[email protected]/
To Unsubscribe visit
http://www.houseoffusion.com/index.cfm?sidebar=lists&body=lists/cf_talk or send a
message to [EMAIL PROTECTED] with 'unsubscribe' in the body.
