Multiple workflows reading/writing from same database

KNIME Analytics Platform
#1

I encountered some strange behavior with the database read/write nodes, and wanted to see if anybody else had observed it as well. Locally on my machine, I am creating a set of workflows that work with different portions of a social service API, and I noticed that when one of my workflows has started writing its result set to our database, than the other workflows reading from that same database (different tables) pause. When it's finished, they go to town like nothing it happened. 

Has anybody else observed this? Or know if the behavior carries over to the KNIME server environment? 

#2

Hi,

KNIME uses a single connection per user and database accross all workflows. By default the database nodes check if the connection is already in use by other node and wait until the node is done. That is why the reader node is waiting for the writer node in your case. The behavior is the same on the server.

If the used database driver supports concurrent operations per transaction you can disable the waiting in KNIME by adding the following flag to the knime.ini file which is located in the KNIME installation directory:

-Dknime.database.enable.concurrency=false

Bye

Tobias