abt sequential file

4friends · Post by **4friends** » Tue May 15, 2007 8:28 am

why sequential file is not used as a look up???

chulett · Post by **chulett** » Tue May 15, 2007 10:02 am

Because it doesn't really make any sense to do a lookup directly against sequential media. Load it in a hashed file and then do the lookup.

I_Server_Whale · Post by **I_Server_Whale** » Tue May 15, 2007 2:00 pm

Welcome Aboard ! A sequential file cannot have keys to it and hence a look-up cannot be performed against it.

baglasumit21 · Post by **baglasumit21** » Wed May 16, 2007 12:20 am

4friends wrote:why sequential file is not used as a look up???

We use look up as an alternate way to implement joins and use hash file since it uses hash algorithm to look for a match for key columns in the hash file. Sequential file doesnt have key columns. So it wont help you to perform a look-up

ray.wurlod · Post by **ray.wurlod** » Wed May 16, 2007 12:47 am

You can, of course, use a sequential file for lookups, by identifying the lookup key columns in the metadata and employing an ODBC stage via the ODBC driver for text files.

Just don't expect any speed.

chulett · Post by **chulett** » Wed May 16, 2007 7:23 am

Forgot about that option... but perhaps that's for the best.

ray.wurlod · Post by **ray.wurlod** » Wed May 16, 2007 3:34 pm

Maube it's the right approach if you're being paid by the hour!

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abt sequential file

abt sequential file

Re: abt sequential file