64bit File vs Dynamic File

Hi

If you go for dynamic you do not solve your problem. You change the internal organisation but not the quantity of bytes.

Go to 64BIT to go over 2gb

Or

Take a look to DEFINE.DF (distribution) 

I hope this help

Manu

It depends somewhat on the nature of the file you are considering.  If the file tends to grow and then perhaps shrink to a large degree, the dynamic file might be your best bet.  If it is just undergoing a slow growth pattern over time, I would go with the 64 bit file.  Dynamic files tend to have some performance issues especially at those times when a split or merge needs to happen.  Either way you go, you should continue to try to do the occasional resize to get the best distribution of data possible while still maximizing filling the groups within it.

That said, you should test both file types to see how it is likely to perform over time.  I would lean toward the 64 bit file if you are more familiar / comfortable with normal static hashed files.  Dynamic files definitely have a number of quirks associated with them which take some getting used to administering.

John -

It may depend on how you use the file which is growing.  How long has this file existed?

For Performance I prefer a properly sized 64bit file as a rule.

If this file is just a log that is rarely used and just grows over time then a Dynamic file maybe the better choice.

Either way if you're getting close to 2GB size, you will want to get it resized before you can't write to the file any longer.

Hi John,

Just to clarify on the statements below: 

The real question is do you want a 64 bit static or a 64 bit dynamic file.

A dynamic file spreads the work of resizing over the lifetime of the file. It is therefore slower, though in practice that is rarely noticeable, and there are additional contraints, mostly around operating system level commands. Because it holds the sizing parameters in memory, you need to make sure the detail are sync'ed or the file is closed before doing operations such as backups, and there is a system wide config limit on the number you can have open.

A 64 bit static file is the same as a regular static file, excepting that that record pointers are larger. So it will operate the same as it did before. 

In general, a well sized static file will outperform a dynamic file, and a poorly sized static file will perform worse.

So it depends upon the growth rate of the file and whether you can fit that into a sensible resize policy and window. If not, use dynamic.

Thanks to all.