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Transformation equivalent to 'Blocking Step' in Pentaho

SAPDataMigrate
Participant
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Hi Experts,

I just wanted to confirm if there's any function/transform in BODS which performs the same/equivalent functionality to 'Blocking Step' in Pentaho tool.

Here's what 'Blocking step' does :

The Blocking step blocks all output until the very last row is received from the previous step.

At that point, the last row is sent to the next step or the complete input is sent off to the next step. Use the Blocking Step for triggering plugins, stored procedures, Java scripts, ... or for synchronization purposes.

: How can we achieve this functionality?

Thanks in advance.

Accepted Solutions (1)

Accepted Solutions (1)

former_member187605
Active Contributor
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All depends on your definition of "step". If step is equivalent to a data flow, you have that automatically in DS. When you put 2 data flows in series, the 2nd one will only be started after the first one finishes.

If you steps are more granular, there are also several options:

1/. Use a Data_Transfer transform. Following operations will only start after 100% completion of the initial ones.

2/. Use a Merge or a Query transform with an in-memory sort. DS can only merge or sort when all data is ready.

3/. Use a post-load command (in target table options)

SAPDataMigrate
Participant
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Hi Dirk,

The word 'step' here denotes the transformations in BODS. So the requirement is how to control flow of data, so that the next transformation block gets processed only when previous one has been completely processed till the very last record.

Out of 3 suggestions you gave, can you please elaborate the 2nd and 3rd one?

What is in-memory sort in Query transform? Merge cannot be a solution in this regard because it is scenario dependent when we have atleast two datasets.

Can you please elaborate how can we use post-load command in order to implement this?

Your suggestions are full of learning though!

Thanks

former_member187605
Active Contributor
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OK, option 3 won't apply to you then.

Why would Merge not be a solution? You can have a Merge in any data a flow, it works fine with a single input and results into an in-memory sort that needs all data before it can be done. Just try it, And you'll see.

SAPDataMigrate
Participant
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Before trying this out just now, I thought Merge needs atleast two incoming datasets - which should be the case as per it's name!

former_member187605
Active Contributor
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1 or more. There's no theoretical limit.

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