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Continue reading →: The Boat
Coming soon in March there’s one of the most popular global user group conferences, The Norwegian Oracle User Group Spring conference, known fondly as “The Boat“, it takes place from 10th to 12th of March sailing on board a cruise ship. The ship sails from Olso on 10th and arrives…
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Continue reading →: UKOUG Tech 15
It’s nearly early December, so it must be time for the UK Oracle User Group Conferences – JDE15, Apps15 and Tech15 There’s some absolutely wonderful presentations, and there’s the 2 I’m giving as well: An Introduction to RAC (12c) at 9am on Monday 6th, and Troubleshooting Goldengate at 12:20 on…
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Continue reading →: Decoding DBA_TAB_COLUMNS high_value and low_value
When performance tuning, it can be important to understand the statistics in the database. It is worth noting that every column records it lowest (low_value) and highest (high_value) values in DBA_TAB_COLUMNS when you gather stats, like a mini-histogram. If the optimizer believes it knows the range of values within a…
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Continue reading →: OEM and monitoring the -MGMTDB GMIR Database
When you create Grid Infrastructure in 12.1.0.2, you are presented with a new (annoyingly named) “-MGMTDB” This database is a standard, 12C CDB/PDB storing transient performance and other information (Grid Infrastructure Management Repository). If it is lost, no biggie. Just re-create it (in your voting disk DG. Aside: create a…
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Continue reading →: Oracle Midlands Presentation
Ever wonder why your SQL execution plan has changed? Wondering why your boss is shouting something about “traders can’t trade” or “shoppers can’t spend” or “well that’s the Airport shut!” ? When you write SQL, Oracle runs it through the Optimiser to determine the fastest way to access the data.…
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Continue reading →: 12C Paging through Data and Restricting Result Sets
Prior to Oracle 12C, if you wanted to page through result sets only returning a bit at a time, or only wanted the first dozen lines of data, it was a right pain. Writing your SQL, then having it as an in-line view with order by, and a rownum on…
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Continue reading →: Oracle 12C Problem with datapatch. Part 2, the “fix”
so after much too-ing and fro-ing with Oracle Support, we finally have a solution to my datapatch problem. Prevent the timeout from happening when running datapatch! We know which part of the code was timing out, and we can do this by setting an undocumented event: 18219841. Here’s a show…
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Continue reading →: Oracle 12C Problem with datapatch
I was minding my business, patching an Oracle 12C RAC Cluster when the darned patch failed ./datapatch -verbose SQL Patching tool version 12.1.0.2.0 on Mon Aug 3 20:47:31 2015 Copyright (c) 2015, Oracle. All rights reserved. Log file for this invocation: /u01/app/oracle/cfgtoollogs/sqlpatch/sqlpatch_9841_2015_08_03_20_47_31/sqlpatch_invocation.log Connecting to database…OK Bootstrapping registry and package to…
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Continue reading →: Oracle Management Database in Grid Infrastructure: -MGMTDB
Oracle, Why? Why is is now mandatory to have the cluster management database as an Oracle CDB, with a PDB having the same name as the cluster? It’s not that I object to having another 1GB of memory lost to this DB, and up to 10GB of disk in the…
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Continue reading →: Oracle on 4096 (4k) sector disks don’t work (ish)
I recently came across 4K (4096 byte) sector drives. They are a fairly new thing and have come about so drives can exceed the 2TB limit imposed by having 512byte sectors. The details behind this can be found here, in much greater detail than I need to understand. What I do…
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Continue reading →: Locking Privileges in Oracle
What permissions do you need to lock rows on an Oracle table? What about to lock the whole table? It’s not quite as much as you may think! Lets have a couple of users; schema_owner and user1 SQL> show user USER is “SYS” SQL> create user schema_owner identified by schema_owner;…
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Continue reading →: Oracle Cluster Health Monitor – changes in 12.1.0.2
From Oracle 12.1.0.2, the Oracle Cluster Health Monitor becomes an Oracle database by default [replacing the old Berkley DB], and it’s called “-MGMTDB” (note the leading “-“) cat /etc/oratab +ASM1:/u01/app/grid:N # line added by Agent -MGMTDB:/u01/app/grid:N # line added by Agent It lives on one of the nodes on your…
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Continue reading →: Oracle 12.1.0.2.0 ACFS on Linux 7 don’t work
I installed OEL 7.1… uname -a Linux rac12c01 3.8.13-55.1.6.el7uek.x86_64 Then I installed Grid Infrastructure and Database 12.1.0.2.0 and looked to configure ACFS for the database files, ready for DB create. And it won’t let me. In asmca, the tabs are greyed-out. Lets just investigate that: acfsdriverstate supported ACFS-9459: ADVM/ACFS is…
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Continue reading →: Linux Annoying Defaults, and changes when moving to RH/OEL7
So why does Linux have an alias for “ls” which turns on colour, by default, making some text impossible to read? eh? alias ls=’ls –color=auto’ To stop this temporarily, you can “unalias ls”, but to stop it permanently for everyone: vi /etc/profile.d/colorls.sh comment out the line: alias ll=’ls -l –color=auto’ 2>/dev/null…
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Continue reading →: PC Pro Oracle DBA Article
I was interviewed recently by UK publication PC Pro magazine for their regular series about IT Careers with regard to database administration (surprise!) The (somewhat abridged!) interview has just appeared in the August 2015 edition of the magazine. I cannot link to the on-line version of the article so here’s my hopefully readable cropped…
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