1st March 2014 Interesting articles.

Interesting articles I am reading.

DB2 Battle: Optimization Profile vs. Statement Concentrator

http://blog.4loeser.net/2015/02/db2-battle-optimization-profile-vs.html

Create optimization profile

 <?xml version="1.0" encoding="UTF-8"?>
<OPTPROFILE>
  <STMTMATCH EXACT='FALSE'/>
  <STMTPROFILE ID="REOPT betw">
     <STMTKEY>
        <![CDATA[select id,s from betw where id between :L0 and :L1 ]]>
     </STMTKEY>
     <OPTGUIDELINES>
       <REOPT VALUE="ALWAYS" />
     </OPTGUIDELINES>
  </STMTPROFILE>
</OPTPROFILE>

db2 “import from betw.csv of del modified by lobsinfile insert_update into systools.opt_profile”

db2 flush optimization profile cache

set current optimization profile=”HLOESER”.”PROFILE_BETW”

Statement concentrator convert sql with different constants to same sql with variable hence simple explain plan does not help.

DB2 Battle: Optimization Profile vs. Statement Concentrator (Part 2)

Need explain from actuals!

db2 “create workload betw applname(‘python’) collect activity data with details,section”
db2 “create event monitor betwmon for activities write to table”
db2 “set event monitor betwmon state 1”

select appl_id,uow_id,activity_id,stmt_text from ACTIVITYSTMT_BETWMON

CALL EXPLAIN_FROM_ACTIVITY(‘*LOCAL.hloeser.150227075721’,1,2, ‘BETWMON’,NULL,?,?,?,?,?)

Virtual Packet Loss: The Silent Killer of Network Performance

http://blog.4loeser.net/2015/02/db2-battle-optimization-profile-vs_27.html

Too many VMs – Hypervisor context switching – clock skew – tcp round time times increase – RTO hit – TCP congestion avoidance – send reduces thoughput and retransmits – stall up to a second – throughput hits the floor – Virtual Packet Loss (VPL)!

More visibility is needed for virtualized environments. For VPL need ull-stream reassembly and full-content analysis as well as the ability to conduct sophisticated Layer 2-7 traffic analysis.

How to Install Oracle 12c RAC: A Step-by-Step Guide

http://www.pythian.com/blog/oracle-12c-rac-on-your-laptop-step-by-step-guide/