Over the years I saw some people find themselves in position where they have to start dealing with PostgreSQL with minimal, or none, prior exposure. This leads to problems with seemingly easy tasks – how to change config? How to find stuff in logs?
So I decided to write some blogposts to be able to point such people to pre-made tutorials.
And I start today, with information on how to find PostgreSQL config files.
Every so often, on irc, someone asks if they can remove postgres database, and why is it even there.
Figured I can write one blogpost to answer it once and for all, and use it as ready answer whenever the question resurfaces.
On 1st of February 2021, Peter Eisentraut committed patch:
SEARCH and CYCLE clauses This adds the SQL standard feature that adds the SEARCH and CYCLE clauses to recursive queries to be able to do produce breadth- or depth-first search orders and detect cycles. These clauses can be rewritten into queries using existing syntax, and that is what this patch does in the rewriter. Reviewed-by: Vik Fearing <vik@postgresfriends.org> Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com
Continue reading Waiting for PostgreSQL 14 – SEARCH and CYCLE clauses
Couple of days earlier I wrote about tools to run tasks in db at scheduled times.
In writing this I missed pg_cron. So let's look into it now.
Continue reading How to run some tasks without user intervention, at specific times? – part 2
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
Every now and then someone complains (me included) that PostgreSQL doesn't have job scheduler.
This is true, to some extent. I'll try to show you couple of approaches to solving this particular problem.
Continue reading How to run some tasks without user intervention, at specific times?
On 6th of January 2021, Tom Lane committed patch:
Add idle_session_timeout. This GUC variable works much like idle_in_transaction_session_timeout, in that it kills sessions that have waited too long for a new client query. But it applies when we're not in a transaction, rather than when we are. Li Japin, reviewed by David Johnston and Hayato Kuroda, some fixes by me Discussion: https://postgr.es/m/763A0689-F189-459E-946F-F0EC4458980B@hotmail.com
Continue reading Waiting for PostgreSQL 14 – Add idle_session_timeout.
On 6th of January 2021, Tomas Vondra committed patch:
Report progress of COPY commands This commit introduces a view pg_stat_progress_copy, reporting progress of COPY commands. This allows rough estimates how far a running COPY progressed, with the caveat that the total number of bytes may not be available in some cases (e.g. when the input comes from the client). Author: Josef Šimánek Reviewed-by: Fujii Masao, Bharath Rupireddy, Vignesh C, Matthias van de Meent Discussion: https://postgr.es/m/CAFp7QwqMGEi4OyyaLEK9DR0+E+oK3UtA4bEjDVCa4bNkwUY2PQ@mail.gmail.com Discussion: https://postgr.es/m/CAFp7Qwr6_FmRM6pCO0x_a0mymOfX_Gg+FEKet4XaTGSW=LitKQ@mail.gmail.com
Continue reading Waiting for PostgreSQL 14 – Report progress of COPY commands
A bit ago I wrote a blog post that was supposed to show how to keep number of rows in table to N per some category.
Unfortunately, I overlooked a problem related to concurrency.
Continue reading How to limit rows to at most N per category – fix