In this, hopefully 2nd to last, post in the series, I will cover the rest of usually happening operations that you can see in your explain outputs.

On 3rd of November, Heikki Linnakangas committed patch: Support range data types. Selectivity estimation functions are missing for some range type operators, which is a TODO. Jeff Davis

Let's assume you have some simple database with "articles" - each article can be in many "categories". And now you want to get list of all articles in given set of categories. Standard approach: select a.* from ...

On 1st of August Tom Lane committed patch from Itagaki Takahiro: Improve unique-constraint-violation error messages to include the exact values being complained of.   In passing, also remove the arbitrary length limitation in the similar error detail message for foreign key violations.   Itagaki Takahiro and later added ...

On 29th of July ( I know, there is a long backlog in waiting for 8.5 series. I'm working on it :), Tom Lane committed patch by Dean Rasheed: Support deferrable uniqueness constraints.   The current implementation fires an AFTER ROW trigger for ...

Every so often you need to get list of unique elements in some column. The standard way to do it is: select distinct column from table; or select column from table group by column; The only problem is that it's slow - as it ...