Thursday, February 12, 2015

Oracle Querayable Patch Interface

Starting from Oracle 12c, from within the SQL patching information can be obtained. A new package DBMS_QOPATCH offers some really nifty procedures to get the patch information. Some of that information is shared below:


Wednesday, February 4, 2015

Steps to Blackout Agent of Cloud Control 12c

1) Set the environment to the cloud control agent. You can agent name from /etc/oratab file.

myserver: $ . oraenv
ORACLE_SID = [ORCL] ? agent12c

2) Check which targets are being monitored by the cloud control agent on this server:

myserver: $ emctl config agent listtargets
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
[MYSERVER, host]
[MYSERVER:3872, oracle_emd]
[ORCL, oracle_database]

3) Check if there is any existing blackout of agent on this server:

myserver: $ emctl status blackout
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
No Blackout registered.

4) Start the blackout:

myserver: $ emctl start blackout orcl_down_20150204 ORCL:oracle_database
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
Blackout orcl_down_20150204 added successfully
EMD reload completed successfully

5) Again check the status of the blackout:

myserver: $ emctl status blackout
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
Blackoutname = orcl_down_20150204
Targets = (ORCL:oracle_database,)
Time = ({2015-02-04|16:51:37,|} )
Expired = False

6) Stop the blackout:

myserver: $ emctl stop blackout orcl_down_20150204
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
Blackout orcl_down_20150204 stopped successfully
EMD reload completed successfully

7) Again check the status of blackout:

myserver: $ emctl status blackout
Oracle Enterprise Manager Cloud Control 12c Release 4 
Copyright (c) 1996, 2014 Oracle Corporation.  All rights reserved.
No Blackout registered.

Monday, February 2, 2015

Exadata Vulnerability

This Exadata vulnerability is related to glibc vulnerability. A heap-based buffer overflow was found in glibc's __nss_hostname_digits_dots() function, which is used by the gethostbyname() and gethostbyname2() glibc function calls.

A remote attacker able to make an application call either of these functions could use this flaw to execute arbitrary code with the permissions of the user running the application.

In order to check if your Exadata system suffers from this vulnerability, use:

[root@server ~]# ./ghostest-rhn-cf.sh
vulnerable

The solution and action plan for this vulnerability is available by My Oracle Support in the following document:

glibc vulnerability (CVE-2015-0235) patch availability for Oracle Exadata Database Machine (Doc ID 1965525.1)

Monday, January 26, 2015

Indexing Points to Remember

Indexing depends upon the queries in the application.

There is no one-size-fits-all break-even point for indexed versus table scan access. If only a few rows are being accessed, the index will be preferred.

If almost all the rows are being accessed, the full table scan will be preferred. In between these two extremes, your “mileage” will vary.

A concatenated index is more useful if it also supports queries where not all columns are specified. For instance SURNAME, FIRSTNAME is more useful than FIRSTNAME, SURNAME because queries against SURNAME only are more likely to occur than queries against FIRSTNAME only.

Global indexes provide better performance for queries that must span all partitions.

Sunday, January 18, 2015

Log Buffer #406, A Carnival of the Vanities for DBAs

This Log Buffer Edition covers blog posts from various bloggers of Oracle, SQL Server and MySQL.

Oracle:

Sync tables: generate MERGE using Unique constraint.
What Hardware and Software Do YOU Want Oracle to Build?
There were a number of new features introduced in Ops Center 12.2.2. One of the shiny ones is an expansion of the backup and recovery capabilities to include Proxy Controllers.
Want to Be a Better Leader? Answer One Question.
Managing a remote Oracle Database instance with “Geographic Edition”.

SQL Server:

Learn how you can use SQLCop to prevent your developers from writing stored procedures that are named sp_ something.
Data Cleaning in SQL 2012 with Data Quality Services.
Stairway to PowerPivot and DAX - Level 9: Function / Iterator Function Pairs: The DAX MAX() and MAXX() Functions.
Options to Improve SQL Server Bulk Load Performance.
Dynamically Create Tables Based on an Access Table

MySQL:

Stored Procedures: critiques and defences.
JSON UDF functions 0.3.3 have been released.
Business Scalability, Operational Efficiency and Competitive Edge with MariaDB MaxScale 1.0 GA.
MySQL 5.7 labs and the HTTP Plugin – inserting, updating and deleting records in MySQL via HTTP.
Hyper-threading – how does it double CPU throughput?

Published on Pythian Blog

Friday, January 9, 2015

Histograms Tidbits

Make sure histograms exist on columns with uneven data distributions to ensure that the optimizer makes the best choice between indexes and table scans.


Tuesday, January 6, 2015

Who is a DBA Leader?

Sitting behind a big mahogany table, smoking Cuban Cigar, glaring at the person sitting across, one hand taking the receive of black phone to right ear, and the other hand getting the mobile phone off the left ear can be the image of a DBA boss in any white elephant government outfit, but it certainly cannot work in organization made up of professionals like database administrators. And if such image or similar image is working in any such company then that company is not great. It's as simple as that.





Sunday, January 4, 2015

Script for Exadata I/O Report

select function_name,sum(SMALL_READ_MEGABYTES)/1024 SM_Read_GB,
sum(SMALL_WRITE_MEGABYTES)/1024 SM_Write_GB,
sum(LARGE_READ_MEGABYTES)/1024 LG_Read_GB, sum(LARGE_WRITE_MEGABYTES)/1024 LG_Write_GB,
sum(LARGE_READ_REQS) LG_Read_Requests,
sum(LARGE_Write_REQS) LG_Write_Requests
from v$iostat_function_detail
group by function_name;

Log Buffer #404, A Carnival of the Vanities for DBAs


With new year already in fast gear, bloggers are sparing no stone unturned to come up with innovative ideas. This Log Buffer edition is keeping pace with them as always.

Saturday, December 20, 2014

Log Buffer #402, A Carnival of the Vanities for DBAs

This Log Buffer edition hits the ball out of park by smashing yet another record of surfacing with a unique collection of blog posts from various database technologies. Enjoy!!!

Oracle:

EM12c and the Optimizer Statistics Console.
SUCCESS and FAILURE Columns in DBA_STMT_AUDIT_OPTS.
OBIEE and ODI on Hadoop : Next-Generation Initiatives To Improve Hive Performance.
Oracle 12.1.0.2 Bundle Patching.
Performance Issues with the Sequence NEXTVAL Call.

SQL Server:

GUIDs GUIDs everywhere, but how is my data unique?
Questions About T-SQL Transaction Isolation Levels You Were Too Shy to Ask.
Introduction to Advanced Transact SQL Stairway and Using the CROSS JOIN Operator.
Introduction to Azure SQL Database Scalability.
What To Do When the Import and Export Wizard Fails.

MySQL:

Orchestrator 1.2.9 GA released.
Making HAProxy 1.5 replication lag aware in MySQL.
Monitor MySQL Performance Interactively With VividCortex.
InnoDB’s multi-versioning handling can be Achilles’ heel.
Memory summary tables in Performance Schema in MySQL 5.7.

Also published here.