In general the move to Leopard has been very smooth for me but there was one notable exception, getting a working PostgreSQL 8 sever up and running on my MacBookPro. A few weeks ago I’d expended a lot of time and effort on this and gotten nowhere so at that stage I’d decided to work around the problem by using a remote PostgreSQL server rather than running one locally. This works fine as long as you have broadband internet access. However, I’m off to Belgium for a week on Saturday where I’ll have no broadband but where I will need to get some development work done that requires access to a PostgerSQL server.

With the end of the week getting closer I had another go at getting PosgreSQL to behave on OS X and I did eventually succeed. I got 90% of the way there by following these instructions but then I ran into a few strange problem that took a little more time and effort to work around. However, the good news is that I got it all figured out in the end!

[tags]PostgreSQL, OS X, OS X 10.5 Leopard[/tags]

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It’s not uncommon that as part of a complex transaction you need to insert a row into a table with an auto-incrementing primary key and then use the key from the row you just generated as a foreign key in another insert within the same transaction. Java provides a mechanism to return the auto-generated keys from an insert query without the need to execute a second query by means of the function java.sql.Statement.getGeneratedKeys(). Unfortunately the PostgreSQL JDBC connector does not appear to support this feature (at least the version I am using does not). Given the fact that we do not have this functionality available to us when using a PostgreSQL database we need to use a separate query to retreive the value of the key we just generated. It goes without saying that we need to do this two-step process as part of a transaction but it may not go without saying that the correct way to extract the value for the key is by querying the sequence that the key is being generated from and not by querying the table directly. It is true that most of the time the highest value of the incrementing variable will be the value just inserted but that is not a guarantee.

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Having recently discussed running MySQL on the Mac I’d now like to tackle PostgreSQL. I’m sorry to say things are not quite as rosy just yet. PostgreSQL don’t provide us with a binary distribution for the Mac nor do they provide a nice Panel for the System Preferences App. There are also less choices when it comes to GUIs for manipulating and designing your database but there are still options and things are still a lot better than they could be. Read more

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