There are some cases where you might want to get your own copy of explain.depesz.com. You might not trust me with your explains. You might want to use it without internet access. Or you just want to play with it, and have total control over the site.
Installing, while obvious to me, and recently described by John Poole, is not always 100% clear. So, I decided to write about how to set it up, from scratch.
Continue reading How to install your own copy of explain.depesz.com
Uploaded new version to the server – straight from GitHub. There are two changes – one visible, and one not really.
The invisible change, first, is one for people hosting explain.depesz.com on their own. As you perhaps know you can get sources of explain.depesz.com and install it on any box you want (as log as you can get there PostgreSQL, Perl, and some perl modules). While working on it on my own, I figured I could use a way to tell which version of module-xxx the site is running right now. So I build /info page (which is inaccessible to everyone, but manually-marked admins), which lists versions and interesting paths.
The second change – the one visible to users, is that I made explain.depesz.com commify numbers. Sometimes it can be hard to read value like 12325563, but now it will be displayed as 12,325,563 making is simpler to grasp.
This second change was suggested by Jacek Wielemborek, so if you hate it – blame him. Of course if you love the change – it's all on me 🙂
Hope you'll find it helpful.
Yesterday I had an interesting discussion on irc.
A guy wanted to know why Perl script is causing problems when dealing with Pg
and unicode characters.
The discussion went sideways, I got (a bit) upset, and had to leave anyway, so
I didn't finish it. But it did bother me, as for me the reasons of the problem
seem obvious, yet the person I talked with was very adamant that I have the
whole thing wrong.
So, I figured I'll use my blog to elaborate a bit…
Continue reading PostgreSQL + Perl + Unicode == confusion. Why?
When working with PostgreSQL you generally want to get information about slow queries. The usual approach is to set log_min_duration_statement to some low(ish) value, run your app, and then analyze logs.
But you can log to many places – flat file, flat file on another disk, local syslog, remote syslog. And – perhaps, instead of log_min_duration_statement – just use pg_stat_statements?
Well, I wondered about it, and decided to test.
On 7th of October, Alvaro Herrera committed patch:
Implement SKIP LOCKED for row-level locks This clause changes the behavior of SELECT locking clauses in the presence of locked rows: instead of causing a process to block waiting for the locks held by other processes (or raise an error, with NOWAIT), SKIP LOCKED makes the new reader skip over such rows. While this is not appropriate behavior for general purposes, there are some cases in which it is useful, such as queue-like tables. Catalog version bumped because this patch changes the representation of stored rules. Reviewed by Craig Ringer (based on a previous attempt at an implementation by Simon Riggs, who also provided input on the syntax used in the current patch), David Rowley, and Álvaro Herrera. Author: Thomas Munro
Continue reading Waiting for 9.5 – Implement SKIP LOCKED for row-level locks
On 19th of September, Stephen Frost committed patch:
Row-Level Security Policies (RLS) Building on the updatable security-barrier views work, add the ability to define policies on tables to limit the set of rows which are returned from a query and which are allowed to be added to a table. Expressions defined by the policy for filtering are added to the security barrier quals of the query, while expressions defined to check records being added to a table are added to the with-check options of the query. New top-level commands are CREATE/ALTER/DROP POLICY and are controlled by the table owner. Row Security is able to be enabled and disabled by the owner on a per-table basis using ALTER TABLE .. ENABLE/DISABLE ROW SECURITY. Per discussion, ROW SECURITY is disabled on tables by default and must be enabled for policies on the table to be used. If no policies exist on a table with ROW SECURITY enabled, a default-deny policy is used and no records will be visible. By default, row security is applied at all times except for the table owner and the superuser. A new GUC, row_security, is added which can be set to ON, OFF, or FORCE. When set to FORCE, row security will be applied even for the table owner and superusers. When set to OFF, row security will be disabled when allowed and an error will be thrown if the user does not have rights to bypass row security. Per discussion, pg_dump sets row_security = OFF by default to ensure that exports and backups will have all data in the table or will error if there are insufficient privileges to bypass row security. A new option has been added to pg_dump, --enable-row-security, to ask pg_dump to export with row security enabled. A new role capability, BYPASSRLS, which can only be set by the superuser, is added to allow other users to be able to bypass row security using row_security = OFF. Many thanks to the various individuals who have helped with the design, particularly Robert Haas for his feedback. Authors include Craig Ringer, KaiGai Kohei, Adam Brightwell, Dean Rasheed, with additional changes and rework by me. Reviewers have included all of the above, Greg Smith, Jeff McCormick, and Robert Haas.
Continue reading Waiting for 9.5 – Row-Level Security Policies (RLS)
On 9th of September, Tom Lane committed patch:
Add width_bucket(anyelement, anyarray). This provides a convenient method of classifying input values into buckets that are not necessarily equal-width. It works on any sortable data type. The choice of function name is a bit debatable, perhaps, but showing that there's a relationship to the SQL standard's width_bucket() function seems more attractive than the other proposals. Petr Jelinek, reviewed by Pavel Stehule
Continue reading Waiting for 9.5 – Add width_bucket(anyelement, anyarray).
On 2nd of September, Andres Freund committed patch:
Add psql PROMPT variable showing which line of a statement is being edited. The new %l substitution shows the line number inside a (potentially multi-line) statement starting from one. Author: Sawada Masahiko, heavily editorialized by me. Reviewed-By: Jeevan Chalke, Alvaro Herrera
On 2nd of September, Fujii Masao committed patch:
Support ALTER SYSTEM RESET command. This patch allows us to execute ALTER SYSTEM RESET command to remove the configuration entry from postgresql.auto.conf. Vik Fearing, reviewed by Amit Kapila and me.
Continue reading Waiting for 9.5 – Support ALTER SYSTEM RESET command.
On 29th of August, Tom Lane committed patch:
Add min and max aggregates for inet/cidr data types. Haribabu Kommi, reviewed by Muhammad Asif Naeem
Continue reading Waiting for 9.5 – Add min and max aggregates for inet/cidr data types.