Recovering from a lost PostgreSQL password.

Let's say you're in situation when you have to connect to PostgreSQL, but you have no idea on what password might be set. But some definitely is, as you get this error message:

=> psql
Password:
psql: FATAL:  password authentication failed for user "depesz"

Continue reading Recovering from a lost PostgreSQL password.

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':

Continue reading Waiting for 8.4 – TABLE

Waiting for 8.4 – array aggregate and array unpacker

Finally, we got very important addons to PostgreSQL, which help with dealing with arrays.

It solves a lot of problems, which were usually solved with standard cookbook code, which was in faqs, blog posts and number of examples on irc.

Continue reading Waiting for 8.4 – array aggregate and array unpacker

Waiting for 8.4 – suppress_redundant_updates_trigger

On 3rd of November Andrew Dunstan committed his patch which adds new function to PostgreSQL – suppress_redundant_updates_trigger().

This function is not for using in selects, but it can help you tremendously if your database access matches certain pattern.

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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 on 31st of October:

Allow SQL-LANGUAGE functions TO RETURN the output OF an INSERT/UPDATE/DELETE
RETURNING clause, NOT just a SELECT AS formerly.
 
A side effect OF this patch IS that WHEN a set-returning SQL FUNCTION IS used
IN a FROM clause, performance IS improved because the output IS collected INTO
a tuplestore WITHIN the FUNCTION, rather than USING the less efficient
value-per-CALL mechanism.

Continue reading Waiting for 8.4 – sql-wrappable RETURNING