Time is More Valuable than Money - Be a Proactive DBA! [Part II]

    By: Malathy Mani on Nov 01, 2014

    This article focuses on the importance of tempdb considerations as the performance impact of not getting them right can cause significant pain points which could have been avoided or set right in the first place

    In this second part of the series, "Time is More Valuable than Money - Be a Productive DBA", we'll continue to explore how to achieve better performance. To help accomplish this goal, we need to understand the changes with the new versions for tempdb. Let us focus on the following:

    • Tempdb and User Log cache
    • Tempdb allocations on Master Device
    • Tempdb and device choices
    • Best practice for tempdb
    • What to avoid with tempdb

    Why is TempDB Important?
    Many optimizations that were available in the past versions (SAP ASE 12.5 and earlier) are no longer valid. A lot of users sometimes implement incorrectly thus creating issues with performance. During an upgrade is one of the times that we need to address the common tempdb issues. Prior SAP ASE versions flushed the ULC as user transactions switched databases causing logical and physical IOs in transaction logs and log semaphore contention. The newer versions have a separate ULC for the session’s temporary database as multi-database transactions that include a single user database and the session’s temporary database do not require ULC flushes when the users switch between the databases. So setting ‘session tempdb log cache size’ is required. This is a static parameter and requires a reboot. Setting this parameter to size of 32768 is a good start.


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