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Database
Oracle
November 20, 2016

How to make partition elimination/pruning to work

If you have situation when partition elimination/pruning does not work, here are couple effective tricks to fix it. 1. If query derives partition key from sub-query, for example (query where sale_date is a partition key): Replace sub-query with DETERMINISTIC function: In most cases it should not be differences between sub-query and function. But there are […]

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Datastax
October 28, 2016

Cassandra Monitoring

Choice of Tool New Relic http://newrelic.com/plugins/3legs/113Monitor Cassandra statistics using the 3legs plugin. Metrics include Read and Write latency (global and per host), Cache statistics, Pending compactions, flushes and more. Datastax – OpsCenter http://www.datastax.com/documentation/opscenter/4.1/pdf/opscuserguide41.pdfDataStax OpsCenter is a visual management and monitoring solution for Apache Cassandra and DataStax Enterprise.The DataStax agents are installed on the Real-time (Cassandra), […]

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Tips & Tricks
October 24, 2016

Junos Pulse VPN client on Linux. Two phase auth. 64bit. How to make it all work.

There are several problem common problems with Juniper SSL VPN on support of Linux clients: 1.Most 64-bit platforms are not supported.2.Junos Pulse SSL VPN does not support Linux at all. Best way to cover problem “1” is:http://ubuntuforums.org/showthread.php?p=11189826#post11189826There is also well known mad-scientist way but its more complex. Problem “2” is a bit more involved. In […]

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Database
Oracle
October 25, 2014

ORA-01555 on standby

If you see “ORA-01555: snapshot too old” from Select what is been run on Physical standby, but same select runs on primary just fine, and all relevant init.ora parameters and undo tablespace are exactly identical between primary and standby,- its odd. But its easy to explain. First check if DB is below 11.2.0.3 DB it […]

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Performance Tuning
June 4, 2013

High CPU usage on DB host?

Its Unix 101 statement, but I have heard it wrong so many time, so decided to put a blog for it. If in OLTP environment, per ‘top’ %wa (IOWAIT) is major contributor for CPU busy, adding CPU would not help. There is no need for more CPU. Period. ************** %wa IS PERCENTAGE WHAT COUNT TO […]

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Oracle
Performance Tuning
June 3, 2012

Index Clustering factor. One way how to avoid negative performance impact on joins which involves bad clustered indexes.

High Index Clustering factor is popular problem in SQL world.The most known solution for it – rebuild table ordering by columns what are in the index.But in real world, with table size growing exponentially its not always practical or possible to do it. Here is one way to avoid index clustering problem by SQL optimization.. […]

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