Waiting for 8.4 – Visibility maps

Yeah. This one patch alone is worth upgrading to 8.4. On 3rd of December Heikki Linnakangas committed his patch. Commit message: Introduce visibility map. The visibility map is a bitmap with one bit per heap page, where a set bit indicates that all tuples on the page are visible to all transactions, and the page … Continue reading “Waiting for 8.4 – Visibility maps”

Waiting for 8.4 – TABLE

On Thursday, 20th of November, Peter Eisentraut committed his own patch, which adds new command to PostgreSQL: TABLE. While this command doesn’t do anything that wasn’t available earlier, it’s worth mentioning, as it’s one of patches that make PostgreSQL compatible with SQL:2008. Basically new command “TABLE” acts like an alias to ‘SELECT * FROM’:

Waiting for 8.4 – sql-wrappable RETURNING

In PostgreSQL 8.2, we got “RETURNING” clause in INSERT/UPDATE/DELETE queries. Unfortunately it could not be used as source of rows for anything in sql. INSERT INTO table_backup DELETE FROM TABLE WHERE … returning *; Well, it’s still not possible, but it is a one step closer, thanks to patch written and committed by Tom Lane … Continue reading “Waiting for 8.4 – sql-wrappable RETURNING”

Waiting for 8.4 – Common Table Expressions (WITH queries)

On 4th of September Tom Lane committed another great patch. This one is very large, and even after applying – it’s has some rough edges. There will be need for additional patches to make the functionality fully robust, but the fact that it got committed means that it will be available in final 8.4. What … Continue reading “Waiting for 8.4 – Common Table Expressions (WITH queries)”

Waiting for 8.4 – new FSM (Free Space Map)

On 30th of September, Heikki Linnakangas committed his patch that changes FSM: Rewrite the FSM. Instead of relying on a fixed-size shared memory segment, the free space information is stored in a dedicated FSM relation fork, with each relation (except for hash indexes; they don’t use FSM).   This eliminates the max_fsm_relations and max_fsm_pages GUC … Continue reading “Waiting for 8.4 – new FSM (Free Space Map)”