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Achtung!

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TCP/IP TIME-WAITE state and 500 database connections per second

Take a look into TIME-WAIT (sometimes spelled like TIME_WAIT by netstat utility) TCP/IP state: https://tools.ietf.org/html/rfc793 http://www.serverframework.com/asynchronousevents/2011/01/time-wait-and-its-design-implications-for-protocols-and-scalable-servers.html Net effect of how TCP/IP protocol works is that one client can generate about 500 database connections per second and then it [client] will … Continue reading

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SQL directives beat SPM (or not?)

Last edited 1-Sept-2016 For quite a time I have been a happy user of SPM(SQL Plan Management) to resolve SQL performance issues by using a lazy man’s approach and Oracle capabilities: in the latest versions Oracle will¬†generate many SQL plans … Continue reading

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Oracle database on Amazon RDS

Adding more on 8-Sept-2016: Adding more on 2-Sept-2016: Time to throw a few notes about Oracle database on Amazon RDS. It works Issues getting access to data files: file system access is generally forbidden on RDS for reasons understandable. However, … Continue reading

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Recreate/migrate user with password: CREATE USER “USER1” IDENTIFIED BY VALUES ‘S:…’

Just execute select sys.dbms_metadata.get_ddl(‘USER’, ‘USER1′) from dual; to get the new fancier “identified by values” syntax – remember, Oracle has changed and made stronger database user passwords. The old “identified by values” won’t work anymore.      

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log writer latency

if lgwr latency is more important than throughput then as of 11.2.0.4(and 3) consider the following: – apparently log_buffer size governs group commit batch size. A bigger log buffer means bigger write batch size which means longer session waits on … Continue reading

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Oracle Solaris Sun pwrite performance investigation

1. Collect explorer ********************** Run explorer in the following manner : /opt/SUNWexplo/bin/explorer -w default The explorer data collector may be obtained from : http://www.oracle.com/us/support/systems/premier/services-tools-bundle-sun-systems-163717.html Download from : https://support.us.oracle.com/oip/faces/secure/km/DocumentDisplay.jspx?id=1153444.1 Useful documents on explorer : Oracle Explorer Data Collector – Product Information … Continue reading

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