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ISVA HVDB enableSharingForDirectLookups

  • 1.  ISVA HVDB enableSharingForDirectLookups

    IBM Champion
    Posted Sat November 19, 2022 12:11 PM

    In a recent opened (but now closed) case, IBM Support Guru Nick Lloyd has mentioned to us that the HVDB tuning isam_cluster.hvdb.connectionManager.enableSharingForDirectLookups = False would be beneficial because it was found to be better performing in general (default value is true).

    Now that this configuration setting is applied a couple weeks back now, we can see a sharp decrease in the number of connection pool size growth and decrease cycles and/or decrease of the amplitudes, for the same OAuth user workload (we do lots of id_token claims enrichment and persistence in and out of HVDB).

    I would like to understand the underlying technical background of such improvement, because it kind of defeats my understanding of what happens when you opt to share a resource (likely more serialization required around the management of connection in your pool but maybe at a lower number of concurrent connection active) vs when you opt not to (less serialization around the management of connection in your pool but maybe at the cost on higher number of concurrent connection active).

    But here again, I agree to be totally wrong, but I would appreciate some more insight.



    Sylvain Gilbert