GreenO

Was looking into backup solutions for a big oracle database and ran across a plugin to RMAN to backup directly to s3! http://www.oracle.com/technology/software/tech/cloud/index.html Seems like a very interesting option.

“As Cloud Backups are done over the public Internet, their performance is highly
dependent on Internet network throughput – typically less than 1 MB/Sec per
connection. Additionally, Cloud vendors may also throttle sessions to prevent
individual users from consuming disproportionate amounts of resources.
According to internal tests conducted at Oracle, Amazon S3 limits an individual
session’s read/write throughput to around 2-3 MB/Sec. However by using the right
Oracle Database Backup in the Cloud Page 9
combination of parallelism and compression, backup speeds of up to 40-50
MB/Sec were attained. ”

Plenty fast for a great offsite backup solution! Can get a little pricy for terabytes of data, but a cheap for 100′s of gigs. May be a good solution for people in need of off site backups.

I have know for a long time that the + operation for Strings in Java is horrible for performance. Because Strings are immutable in Java another String object is created for each +, not so good! I did notice the other day that there is a String.concat() operation. I wondered if it would run faster then + or even as fast as a StringBuilder. The following is the test.

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import java.util.Date;
class st{
	public static void main(String args[]){
		// Test the + operator. We know this one is bad.
		// Its good to know its still bad in Java6
		long t = new Date().getTime();
		String x="";
		for(int i=0;i<100000;i++)
			x = x + " ";
		long e = new Date().getTime();
		System.out.println("Time to use the + operations on a string: " + (e-t));
 
		// Test the String.concat method. 
		// Is it any faster?
		t=new Date().getTime();
		x="";
		for(int i=0;i<100000;i++)
			x = x.concat(" ");
		e=new Date().getTime();
		System.out.println("Time to use the concat method on a string: " + (e-t));
 
		// Finaly out baseline. We know StringBuilder is(was)
		// the fastest way to build Strings.
		t=new Date().getTime();
		StringBuilder sb = new StringBuilder();
		for(int i=0;i<100000;i++)
			sb.append(" ");
		String xx=sb.toString();
		e=new Date().getTime();
		System.out.println("Time to use a StringBuilder object: " + (e-t));
	}
}

And the results are!

abc:~ def$ java -version
java version "1.6.0_15"
Java(TM) SE Runtime Environment (build 1.6.0_15-b03-219)
Java HotSpot(TM) 64-Bit Server VM (build 14.1-b02-90, mixed mode)
abc:~ def$ javac st.java
abc:~ def$ java st
Time to use the + operations on a string: 29464
Time to use the concat method on a string: 7075
Time to use a StringBuilder object: 2
abc:~ def$

So, what did we learn?

After a bunch of trial and error, the following packages are needed to Install cx_Oracle for Python and the required Oracle Instant Client for Red Hat Enterprise Linux 4. Its not that this is too difficult, its that RHEL4 is old. Getting the two to place nice took a sec to figure out. This will install cx_Oracle for python that comes with RHEL4, which as of this writing is Python version 2.3.4 for Red Hat Enterprise Linux AS release 4 (Nahant Update 8). I am sure you can use the newer libraries with the a new install of Python, but I wanted to stay as close as possible to the versions supported by Red Hat. For better for worse!

1. Download the cx_Oracle library.
wget http://prdownloads.sourceforge.net/cx-oracle/cx_Oracle-4.3.1-10g-py23-1.i386.rpm?download

2. Install cx_Oracle
rpm -i cx_Oracle-4.3.1-10g-py23-1.i386.rpm

3. Download Oracle Instant Client from the URL below. Must be logged in so do this from a browser.

http://download.oracle.com/otn/linux/instantclient/10204/oracle-instantclient-basiclite-10.2.0.4-1.i386.rpm

4. Install Oracle Instant Client
rpm -i oracle-instantclient-basic-10.2.0.4-1.i386.rpm

5. Add the path to the instant client libs to LD_LIBRARY_PATH.
echo “export LD_LIBRARY_PATH=/usr/lib/oracle/10.2.0.4/client/lib/:\$LD_LIBRARY_PATH” >> /etc/profile

Thats it! Want to be sure?

[xyz@pdq ~]$ python2
Python 2.3.4 (#1, Jul 16 2009, 07:01:37)
[GCC 3.4.6 20060404 (Red Hat 3.4.6-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
>>> oraConn=cx_Oracle.Connection("username/password@server/SqlNetAlias")
>>> curs = oraConn.cursor()
>>> curs.execute("select 1 from dual")
[]
>>> rows = curs.fetchmany(curs.arraysize)
>>> for row in rows:
... print row[0]
...
1
>>> oraConn.close()
>>>

The more I learn about cx_Oracle and Python I will try to update this space. All I know right now is that it is FAST!

Found a solution for Bluetooth keyboard and mouse issues with my Mac Book Pro using boot camp and Windows 7 beta.

1. Click the Bluetooth icon in the task bar.
2. Go to add device
3. If you device is discoverable you should see it listed, right click and go to properties
4. Put a check in the box next to Mouse, keyboard drivers (Something like that).
5. Continue to add as normal.

Hope that help some other people! It drove me crazy!