Monthly Archives: April 2011

PostgreSQL 9.1, first beta around the corner

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Joshua Berkus recently gave a heads up on the Advocacy list of the forthcoming release of the first beta for PostgreSQL 9.1, tentatively scheduled for May 3.  I have been following the development fairly closely, though given the number of changes, not in depth.  Good time to point out the Waiting for.. blog series from Hubert ‘depesz’ Lubaczewski found here. It covers many of the changes and uses examples to illustrate, a very handy resource. So what is 9.1 offering?

First some of the headliners.

Synchronous Replication:
Extends the built in replication to eliminate any lag between the master and standby   databases. For those who absolutely need a 1:1 correspondence with their standbys.

Per column collation:
A different language for each column, the Tower of Babel realized:)

Unlogged tables:
Permission is granted to run with scissors. You can now create tables that do not log to the Write Ahead Log(WAL).  This makes data operations on the table faster, at the cost of data security. Data will not be recovered in the event of a crash, nor are unlogged tables replicated.

SE-Postgres.
Speaking of security Postgres will now have access to the SE-Linux framework.

The above are great and I will be exploring them at some point, but what follows are the new features I am really excited about.

PL/Python changes:
Thanks to Jan Urbanski and others there have been a host of changes to the procedural language support for Python.  To mention a few; table function support, better error handling, explicit subtransactions.

pg_basebackup:
Thanks Magnus. A way of doing a basebackup for replication using a Postgres connection. Very handy.  Along with this,  the replication permission for non-superusers.

SQL/MED:
Basically pulling external data sources into Postgres. The implementation for  9.1 is basic, but the potential is too great to ignore.

Extensions:
A easier way to work with database plugins. Combined with the PGXN site a definite plus.

I have just scratched the surface on what is new and improved in PostgreSQL 9.1, for a more in depth look I suggest the latest alpha Release Notes. I mentioned specific people above because I have associated their names with particular features.  Lest I forget, a big thank you to all those who have participated.  There is much to be proud of in this release as in the previous ones.

Troubleshooting

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Some thoughts on the art and science of troubleshooting, or how not to resort to the bigger hammer. What I offer up is based on my experience trying to solve problems across an array of disciplines, from truck repair to software debugging. There are common elements to all that are listed below.

1) Work from the known to the unknown not the other way.
This is best illustrated by working with electrical circuits. There are any number of      reasons why electricity is not reaching the end of circuit and working backwards through the circuit often leads down false branches. It is a lot easier to start at the closest panel box and follow the circuit out until voltage is lost.

2) Keep notes.
I am not talking an encyclopedic compendium, something more along the likes of a bread crumb trail to keep from going in circles or trodding down old paths. To extend the electrical example, was that the green wire with white trace or white wire with green trace?

3) All information is important.
I will not recount the number of times I ignored an error message because I ‘knew’ it was not important, much to my later chagrin.

4) KISS(Keep It Simple Stupid).
The poor mans version of Occam’s Razor. If the choice is between an alien gamma ray device flipping bits in the computer or poor quality memory chips, go with the latter.

5) First guess.
This is the you know more than you think principle. Also known as listening to the little voice. In the absence of definite plan, go with the first thought that strikes you. I use to spend a lot of time fighting the little voice, until I realized it was the part of me that was actually paying attention.

6) Walk away.
My dog has helped me solve many problems. I don’t know how many times I took a break to walk the dog and had the answer present itself while the dog was leaving a message. Disconnecting from the problem is often good way to make the connection.