OraNA :: Oracle News Aggregator

SQL performance can degrade for many reasons, some of most common are:
- plan changes
- data skewness
- low caching efficiency
- data growth
- contention.

All these factors are relatively well known. A somewhat less common, although not exceptionally rare scenario, is read consistency overhead due to concurrent (more...)

SQL> select dbms_java.get_jdk_version() from dual;
select dbms_java.get_jdk_version() from dual
                                        (more...)

Here are two interesting enhancements in Oracle database 12c PL/SQL. PL/SQL subprogram defined using WITH clause of a subquery – Oracle database 12c allows PL/SQL declaration section in the WITH clause. One can define PL/SQL function or procedure into a WITH clause. Functions declared in the PL/SQL declaration section can (more...)

I heard a strange report from a client late last week - they weren't getting any smart scans on their Exadata - a data warehouse, no less (and we checked to see if cell_offload_processing was set to true).  Queries would run normally, but for some reason, the "cell physical IO (more...)

So Oracle database 12c is out now.  The cloud (and hence the “c”) is hanging over us.  At least we don’t have to hear about “the grid” anymore.  New versions of Oracle are funny things – as DBAs, we’re kinda excited about the possibilities, but then reality (more...)

Original Post can be viewed at 12c: Sqlplus Displays Last Login Time For Non – Sys Users

12c database has introduces a pretty nifty Security feature which allows you to check last login time for non-sys user. e.g If I connect to scott user as below, it displays that (more...)

I really didn't think we would be seeing 12c until OpenWorld. I got a nice surprise a couple of weeks ago when people started tweeting that the docs were out. That followed quickly with the actual software being available for download.

 

I realize that people won't really be producing (more...)

Original Post can be viewed at 12c:Limiting PGA with pga_aggregate_limit

This is a interesting feature for Oracle DBA’s. Till now there has been no way of limiting total PGA being used by oracle instance. _pga_max_size (hidden parameter) could be used to limit per process memory. SGA_TARGET used to be hard (more...)

In this example, I’ve already installed the Oracle Database 12c software on one of my Linux 6.4 machines.  Using the DBCA tool (in advanced mode), I’m going to create a new container database named “cdb” and at the same time create a pluggable database named “pdb”. The idea behind (more...)

So there is a new toy in the market for database geeks : Oracle has released database 12c. Every social platform is abuzz with the 12c activity. So thought that I should also complete the ritual

In this post Aman has already summed up many important links.

Maria Colgan has (more...)

It's not often that I run across articles that really resonate with me. Last night was one of those rare occasions. What follows is a sampling of what I consider to be required reading for any IT professional with a slant towards database development.

Bad CaRMa

how NOT to design (more...)

Installation

Install the Oracle Database Gateways 11g R2 (11.2). See the screen snapshots of the installation here.

Configuration

• During the installation, the following default initialization parameter file is created:

[ORACLE_DG_HOME]\dg4msql\admin\initdg4msql.ora

dg4msql = Database gateway for Microsoft SQL Server. 
If you choose a different database option,  (more...)

When to consider sharding a MySQL database

 

Why should you not just design your applications from the start to account for data sharding? Sharding a database, that is horizontally partitioning tables among multiple databases, creates an added level of complexity that is not desirable in an application. However, there are times when sharding is required to maintain acceptable performance. So when is the right time to shard your database?

 

When to consider sharding a MySQL database   Why should you not just design your applications from the start to account for data sharding? Sharding a database, that is horizontally partitioning tables among multiple databases, creates an added level of complexity that is not desirable in an application. However, there are times when sharding is […]

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Schemas and users are frequently used interchangeably as if they were the same thing. For the most part, that's ok. In Oracle the concepts are so tightly coupled that thinking of them as the same thing is not really that far wrong. 

In reality, a user is a database account that is given a password and permissions. A schema is a container, or namespace, for containing schema objects. Schema objects are things like tables, views and indexes.

In Oracle, when a us

The LAST_REFRESH_DATE column of the DBA_MVIEWS or the LAST_REFRESH column of the DBA_MVIEW_REFRESH_TIMES indicates the start refresh time. But what if we’d like to find out how long the refresh of the materialized view really takes. Well, we can query the DBA_MVIEW_ANALYSIS.

For Complete Refresh, the refresh duration will be in the FULLREFRESHTIM column of the DBA_MVIEW_ANALYSIS. For Fast Refresh duration, it will be in the INCREFRESHTIM column.

Both values are in seconds.

SELECT mview_name, last_refresh_date, fullrefreshtim, increfreshtim
FROM dba_mview_analysis
WHERE owner='JOHN';

MVIEW_NAME               LAST_REFRESH_DATE      FULLREFRESHTIM INCREFRESHTIM
------------------------ ---------------------- -------------- -------------
MV_CHANGE_HISTORY        07-JAN-13 04.36.58 PM               0             (more...)