VarChar in Hash Files
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VarChar in Hash Files
Hi All,
We are working with a large data set and have concerns over Hashed File Sizes. I have done my research and understand it is not recommended to change the uvconfig file. So, I'm trying to gather some analysis on which files we will need to explicitely resize to 64bit.
When doing some analysis, I've found that some of our files are 480mb with around 5 million rows. The hashed files have 4 columns: VarChar 999 (stores key columns), varchar 5, varchar 16, timestamp 19. Assuming the Key columns combined were 50 characters, does having the varchar 999 make a difference in the size? In other words, would I see a smaller file if I used Varchar 100 or Char 50.
(By the way, these are delivered hashed files...in case you're wondering why they are set to varchar 999 for the key field.)
Thanks in advance!
We are working with a large data set and have concerns over Hashed File Sizes. I have done my research and understand it is not recommended to change the uvconfig file. So, I'm trying to gather some analysis on which files we will need to explicitely resize to 64bit.
When doing some analysis, I've found that some of our files are 480mb with around 5 million rows. The hashed files have 4 columns: VarChar 999 (stores key columns), varchar 5, varchar 16, timestamp 19. Assuming the Key columns combined were 50 characters, does having the varchar 999 make a difference in the size? In other words, would I see a smaller file if I used Varchar 100 or Char 50.
(By the way, these are delivered hashed files...in case you're wondering why they are set to varchar 999 for the key field.)
Thanks in advance!
Last edited by jpr196 on Thu Aug 21, 2008 3:24 pm, edited 1 time in total.
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480MB is not a problem. VarChar(999) may be, since the default maximum key size in a hashed file is 768.
Hashed files need to be 64-bit only if there is any likelihood they will exceed 2GB in size.
The size of the VarChar does not have any impact on storage in a hashed file; only the required amount of space is used.
Hashed files need to be 64-bit only if there is any likelihood they will exceed 2GB in size.
The size of the VarChar does not have any impact on storage in a hashed file; only the required amount of space is used.
Last edited by ray.wurlod on Thu Aug 21, 2008 4:02 pm, edited 2 times in total.
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Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
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I take it you mean Oracle as the owners of PeopleSoft?mikegohl wrote:I would recommend you open a case with Oracle. I'm sure you are not the first customer that has run into this limitation.
IBM Software Services Group
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
Thanks for the info, I wasn't aware of the Key constraint in hashed files before. I've never seen issues with this in our runs, so I think it's a non-issue. I was just pointing out one example with 5mil/480mb, but we do have many files that will come near or exceed the 2gb mark. I wanted to make sure we've optimized the file structures or atleast not hinder our file capacity before resizing files to 64bit. Thanks for the help guys!