Knime -DB Queries are run parallel or sequential

KNIME Analytics Platform
1

Hi,
I have got multiple DB query reader nodes connected to same Teradata-DB. I am just wondering does knime run all these nodes parallely or they are run in sequential order.
In case they running sequentially can i prioritise them without using flow variable.

Thanks,
Raman

2

Hi Raman,

I have no direct solution for you as you don’t to use a flow variable.
Could you give some insights on what you are doing with the tables after the DB query reader nodes? Maybe it’s possible to create a more complex query at once and pass it into one DB query reader node or to use the DB nodes

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Latter I really like and using it regularly.

3

Hello @rds ,
each DB connector node creates a single database session (for details see here). The created session can only be used by one DB node at a time.
If you want to run queries in parallel you have to have to use several DB connectors to open up multiple session.
Bye
Tobias

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4

Hi @rds .

I suppose you don’t need to create variables. You only need to connect the variables out port of one DB table selector node, to the in port of the other, just to force sequence.

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Can you try it?
Br.

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5

Thanks for the reply. I actually wanted to know this thing exactly. That knime actually runs queries parallely or dequentially, so based on your comments it seems knime runs sequentially.
Is there a way we can figure out how DB connection is picking up the node to run first.
So basically if i connect 5 queries to single DB connection node which will it run first or may be which is getting run first at that moment.

Thanks,
Raman

6

if you cannot use flow vars but need sequential order, use the DB connection extractor

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