We recently hit an interesting case where planner picked wrong plan. Kinda. And figured it could be used to show how to deal with such cases.
Continue reading Case study: optimization of weirdly picked bad plan
Tag: stats
Waiting for PostgreSQL 16 – Add pg_stat_io view, providing more detailed IO statistics
On 11st of February 2023, Andres Freund committed patch:
Add pg_stat_io view, providing more detailed IO statistics Builds on 28e626bde00 and f30d62c2fc6. See the former for motivation. Rows of the view show IO operations for a particular backend type, IO target object, IO context combination (e.g. a client backend's operations on permanent relations in shared buffers) and each column in the view is the total number of IO Operations done (e.g. writes). So a cell in the view would be, for example, the number of blocks of relation data written from shared buffers by client backends since the last stats reset. In anticipation of tracking WAL IO and non-block-oriented IO (such as temporary file IO), the "op_bytes" column specifies the unit of the "reads", "writes", and "extends" columns for a given row. Rows for combinations of IO operation, backend type, target object and context that never occur, are ommitted entirely. For example, checkpointer will never operate on temporary relations. Similarly, if an IO operation never occurs for such a combination, the IO operation's cell will be null, to distinguish from 0 observed IO operations. For example, bgwriter should not perform reads. Note that some of the cells in the view are redundant with fields in pg_stat_bgwriter (e.g. buffers_backend). For now, these have been kept for backwards compatibility. Bumps catversion. Author: Melanie Plageman <melanieplageman@gmail.com> Author: Samay Sharma <smilingsamay@gmail.com> Reviewed-by: Maciek Sakrejda <m.sakrejda@gmail.com> Reviewed-by: Lukas Fittl <lukas@fittl.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200124195226.lth52iydq2n2uilq@alap3.anarazel.de
Waiting for PostgreSQL 14 – Add pg_stat_database counters for sessions and session time
On 17th of January 2021, Magnus Hagander committed patch:
Add pg_stat_database counters for sessions and session time This add counters for number of sessions, the different kind of session termination types, and timers for how much time is spent in active vs idle in a database to pg_stat_database. Internally this also renames the parameter "force" to disconnect. This was the only use-case for the parameter before, so repurposing it to this mroe narrow usecase makes things cleaner than inventing something new. Author: Laurenz Albe Reviewed-By: Magnus Hagander, Soumyadeep Chakraborty, Masahiro Ikeda Discussion: https://postgr.es/m/b07e1f9953701b90c66ed368656f2aef40cac4fb.camel@cybertec.at
What’s happening in my database?
Lately at least two people on irc asked questions similar to “how do I know how many queries there are in database, per second?“.
So, let's see what we can find out.
Waiting for 9.6 – Add simple VACUUM progress reporting.
On 15th of March, Robert Haas committed patch:
Add simple VACUUM progress reporting. There's a lot more that could be done here yet - in particular, this reports only very coarse-grained information about the index vacuuming phase - but even as it stands, the new pg_stat_progress_vacuum can tell you quite a bit about what a long-running vacuum is actually doing. Amit Langote and Robert Haas, based on earlier work by Vinayak Pokale and Rahila Syed.
Continue reading Waiting for 9.6 – Add simple VACUUM progress reporting.
Waiting for 9.2 – deadlock counter
On 26th of January, Magnus Hagander committed patch:
Adds a counter that tracks number of deadlocks that occurred in each database to pg_stat_database. Magnus Hagander, reviewed by Jaime Casanova
Waiting for 9.2 – temporary file stats per database
On 26th of January, Magnus Hagander committed patch:
Add counters for number and size of temporary files used for spill-to-disk queries for each database to the pg_stat_database view. Tomas Vondra, review by Magnus Hagander
Continue reading Waiting for 9.2 – temporary file stats per database
Change in anonymization of plans on explain.depesz.com
As you perhaps know, explain.depesz.com has anonymization feature.
Couple of days ago Filip contacted me and sent a patch that stopped anonymization of typecasts.
I thought about the patch, and what it achieves, changed it's internals, but kept the effect. And today, it got released.
Continue reading Change in anonymization of plans on explain.depesz.com
explain.depesz.com – new feature and some new stats
First of all, as of today, I added new feature, called anonymization.
It is for all of the people who are afraid that their plans contain information that they don't want to (or can't) share on the internet.
It works like this:
Continue reading explain.depesz.com – new feature and some new stats
Waiting for 9.1 – stats reset tracking
On 10th of February, Magnus Hagander committed patch:
Track last time for statistics reset on databases and bgwriter Tracks one counter for each database, which is reset whenever the statistics for any individual object inside the database is reset, and one counter for the background writer. Tomas Vondra, reviewed by Greg Smith