One issue I ran into though is their documentation for the Mac is based on a wired ethernet connection.  Who uses patch cables at home anymore?  Luckily I found a link to a site that shows how to get around this on the Mac.  You can read about hit here: http://qmail.jms1.net/djbdns/osx.shtml#dhcp-nameserver

We’ve made a lot of progress on getting things running more effeciently.  We’ve recently upgraded from Postgres 8.1.3 to 8.3.3 which made a huge improvement.  Even though Postgres claims that writes don’t block reads and reads don’t block writes, we were seeing a lot of processes getting hung waiting on a commit to finish.  I think that it was having problems starting a new transaction while a transaction was commiting.  Postgres 8.3 introduced asyncronous commits, so that we no longer have to wait for everything to be flushed to disk before we received the commited status.  Now we immediately get a commited status and transactions are written to disk as they can be.

This has been a HUGE performance gain for out database.  Before we had seem the database hit loads over 300 while getting Drudged.  Now we never see the database get above a load of 10, they ususally over around 3 to 4.

Next we will be working on clustering Postgres.  I have evaluated CyberCluster, PGCluster, Slony, PGPoolII and Sequoia.  The only one that seems to be reliable and meet our needs has been Sequoia, so we will see how that goes.

Oh, and I’ve also got a new MacBook Pro.  More on that latter.

Type about:config in you browser window.  Then type dpi in the filter text box and double click the layout.css.dpi to change the value.  I changed mine to 150.

http://latencytop.org/   - This shows what processes are waiting on and looks very interesting.

The other is Group Scheduling in Linux 2.6.24 and above.  This allows you to put processes in a group so that one set of processes can share the same resources.  For example, you can assign two different users 50% of the processor and one use could be running 50 compiles but should not affect the performance of the second user.

BUT, I was pleasantly surprised to find out how simple this really was. If you want to perform an action the output of a loop in bash then you just pipe done into the fuction you want performed. See the example below.

for VAR in $VARS; do
{someaction}
done | sort -n

Cool, right?

So, back to the all knowing Google. Turns out you have to quote your variable when you use it if you don’t want bash to truncate the spaces. So I quoted my variable when using it and all is good.

BUFFER="$VAR                                                                "
NICE_VAR=`echo "$VAR" | cut -c -15`
echo "$VAR $VAR2"

1. It is a good idea to make a backup of the directory you are moving just in case something goes horribly wrong.
# cp -rp {data_dir} {backup_dir}

2. log in as the oracle user
# su -l oracle

3. move the database files
# mv {data_dir} {new_data_dir}

4. Set SID, log into database.
# export ORACLE_SID={ORACLE_SID}
# sqlplus /nolog
SQL> connect /as sysdba;

5. Create pfile from spfile
SQL> create pfile from spfile;

6. In another terminal, modify the newly created pfile. It is usually called init{SID}.ora and can be in different directories. Look in udump, dbs, and other directories until you find the newly created pfile. Check the date to make sure it is the one you are looking for. Now, fix the directories for the control_files variable.

7. Go back to the original terminal and create spfile from pfile;
SQL> create spfile from pfile;

8. Mount database.
SQL> startup mount;

9. Alter the database to look in the new location for the data files and redo logs. Below is an example. (Do this for all data and redo logs.)
SQL> alter database rename file ‘/home/oracle/oradata/{SID}/sysaux01.dbf’ to ‘/usr/local/app/oracle/oradata/{SID}/sysaux01.dbf’
SQL> alter database rename file ‘/home/oracle/oradata/{SID}/redo01.log’ to ‘/usr/local/app/oracle/oradata/{SID}/redo01.log’

10. Open database.
SQL> alter database open;

Now it should hopefully come up properly. You man want to shut it down and bring it up once more to make sure everything is working properly.