On 18th of July, Robert Haas committed patch:
Avoid index rebuild for no-rewrite ALTER TABLE .. ALTER TYPE. Noah Misch. Review and minor cosmetic changes by me.
Continue reading Waiting for 9.2 – Avoiding reindexing on alter type of indexed column
Tag: postgresql
Write Ahead Log + Understanding postgresql.conf: checkpoint_segments, checkpoint_timeout, checkpoint_warning
explain.depesz.com update
Just updated explain.depesz.com site with new functionality – when showing parsed plan, there is new tab “stats". In there you can see some basic statistics of the query, used types of nodes, and tables that were used by it.
There are probably some problems with stats (it's new functionality, so bugs are imminent), but
As usual, some stats need to be added 🙂
- Total count of plans in database: 18127
- Count of private (not listed on history page) plans: 6965
- Count of anonymized plans: 166 (this feature proved to be much less used than I thought it will be)
- Since (including) May 2011, there are more private plans added than public ones. In June – 58.9% of all plans were private.
Wish list for psql
Yesterday I talked a bit with David Fetter about improvements in psql. We both would like to get proper stored procedures (with multiple result sets, and transaction control), but since this seems to be too complicated, I thought about what I'd like to have added to psql.
Waiting for 9.2 – relative paths in psql
On 6th of July, Robert Haas committed patch:
Add \ir command to psql. \ir is short for "include relative"; when used from a script, the supplied pathname will be interpreted relative to the input file, rather than to the current working directory. Gurjeet Singh, reviewed by Josh Kupershmidt, with substantial further cleanup by me.
Bloat happens
For various reasons, and in various cases, bloat happens. Theoretically autovacuum protects us all, but sometimes it doesn't. Sometimes someone disables it, or mis-configures, or bad planet alignment happens, and we end up in deep bloat.
What to do then? Vacuum? Vacuum Full? Cluster? No. pg_reorg!
Understanding postgresql.conf : work_mem
For todays post in Understanding postgresql.conf series, I chose work_mem parameter.
Waiting for 9.2 – NOT VALID CHECKS
On 30th of June, Alvaro Herrera committed patch:
Enable CHECK constraints to be declared NOT VALID This means that they can initially be added to a large existing table without checking its initial contents, but new tuples must comply to them; a separate pass invoked by ALTER TABLE / VALIDATE can verify existing data and ensure it complies with the constraint, at which point it is marked validated and becomes a normal part of the table ecosystem. An non-validated CHECK constraint is ignored in the planner for constraint_exclusion purposes; when validated, cached plans are recomputed so that partitioning starts working right away. This patch also enables domains to have unvalidated CHECK constraints attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT VALID, which can later be validated with ALTER DOMAIN / VALIDATE CONSTRAINT. Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various reviews, and Robert Hass for documentation wording improvement suggestions. This patch was sponsored by Enova Financial.
Why is “depesz” between “de luca” and “de vil”?
Every so often someone asks why sorting behaves irrational. Like here:
$ select string from test order by string; string ---------- dean deer de luca depesz de vil dyslexia (6 rows)
Why aren't “de luca" and “de vil" together?
Continue reading Why is “depesz" between “de luca" and “de vil"?
How to let clients to create new users?
Some (quite long) time ago, someone, somewhere (my memory is pretty fragile) asked a question. I don't have it exact, but the gist was: is it possible to give some users rights to create new users, without making them superusers, and forcing new users to have access only to one particular database.
After some discussion it was clear that the scenario was shared hosting with PostgreSQL, so the situation could look like this:
you are administrator of shared hosting service. One of services is PostgreSQL. You have client, named “depesz", and you want him to be able to create new users, but these users shouldn't be able to connect to any other database than depesz's db.
Is it doable?