How Dataset differ from Sequential File stage

suri · Post by **suri** » Sat Jun 11, 2005 6:58 pm

Hi All,

Can any one explain me the difference between Sequential File stage and Dataset stage in parallel extender.

Thanks in Advance
Suri

elavenil · Post by **elavenil** » Sun Jun 12, 2005 12:38 am

When you sequential file stage in PX, the parallel concept is gone. Though there are many differences, this could be one of the main. Pls read the provided document to understand the differences between the two stages.

Regards
Saravanan

ray.wurlod · Post by **ray.wurlod** » Sun Jun 12, 2005 3:44 am

A (persistent) Data Set has rows on every processing node. It can therefore be processed in parallel. Data in a Data Set are in internal format (for example, an int32 occupies four bytes).

A File Set is like a Data Set, except that the data are stored in external (human-readable) format, so require conversion when being brought into or out of the PX environment.

A sequential file is a single operating system file; it can only be accessed on one node. In general it can only be accessed sequentially by a single process (there is one exception, which requires fixed-length structure). Any sequential file must also be converted when being brought into or out of the PX environment.

bgs · Post by **bgs** » Tue Jun 14, 2005 1:12 pm

dataset preserves partition.It stores data on the nodes,so when you read from a dataset you dont have to re partition your data.

hondaccord94 · Post by **hondaccord94** » Fri Jun 17, 2005 10:31 am

babu suresh

Dataset Stage : Cryptic broken, understandable to Datastage alone

Sequential Stage : ASCII code , understandable to human eye.

ray.wurlod · Post by **ray.wurlod** » Fri Jun 17, 2005 5:13 pm

We trust that by "broken" you mean split over the available processing nodes, not "damaged"!