Updating a Sequential File

[chandra.shekhar@tcs.com]

Hi,

Is there any way/logic to update records in a Sequential File ?

[chulett]

The short answer is no. You read in the file, update whatever needs updating and then write the result out to a new file. Of course, you could rename the new back to the old when you are done.

[chandra.shekhar@tcs.com]

I am too doing the same, but I thought better to ask than regret later.

[chulett]

That's the nature of sequential media.

You may be able to do something magical under the covers with C or something similar but for a "pure" DataStage solution there's no magic that I've ever seen. Of course, our resident Magician may say otherwise.

[ray.wurlod]

I do this a lot when updating values files of Parameter Sets.

One approach is to overwrite the file entirely, using a Sequential File stage. That's the way I normally do it, particularly when the number of parameters in the Parameter Set is small.

The other is to use a Hashed File stage in a server job, opening the file's parent directory as if it were a table, and treating the file name as a record key. This having been done, the individual "fields" (lines) can be updated.

[chulett]

Ah... the second part is where the magic happens.