A while ago someone wrote on irc that PostgreSQL has built in hard limit to number of partitions. This tweet was linked as a source of this information.
Decided to check it.
How to run some tasks without user intervention, at specific times?
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.
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Waiting for PostgreSQL 14 – Add idle_session_timeout.
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
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Waiting for PostgreSQL 14 – Report progress of COPY commands
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
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How to limit rows to at most N per category – fix
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
Fixes on why-upgrade.depesz.com
In case you're not familiar with this site, why-upgrade.depesz.com shows you aggregated changelog between any two releases, with optionally searching for some keywords.
Yesterday azeem on irc pointed me towards a problem on why-upgrade.depesz.com. Specifically, when displaying changes from 9.5.24 to 13.1 site showed 30 security fixes. But in reality there should be only 10.
Reconnecting to SSH servers
In my work I'm often in situation where I want to restart remote server, and then immediately connect to it over ssh.
This can be done by repeating ssh HOST in shell, but it gets tedious.
How to install and configure PostgreSQL Debian/Ubuntu – for developer use – part 2
In previous post I showed how I'd install PostgreSQL for developer.
But that's not all. Now we need to add some configuration. What, how, where?
Continue reading How to install and configure PostgreSQL Debian/Ubuntu – for developer use – part 2
How to install and configure PostgreSQL Debian/Ubuntu – for developer use – part 1
Recently I spent some time thinking about what can be improved when it comes to helping new users start using PostgreSQL.
One thing that almost immediately jumped to my mind is – how to install PostgreSQL? The task is theoretically simple. But there are always some caveats – which packages to use, what to configure in the beginning, where to find config files and logs.
With that in mind I decided to write a howto based on my ideas on what is right. These do not necessarily mean that these are the best for everybody, but I think this is a good start for anyone wanting to start their adventure with PostgreSQL.
Final note of warning – this post is for installing and setting PostgreSQL on developer workstation. As in: server where user can do anything, and we don't really care about security. Please do not configure production servers using this howto.
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Waiting for PostgreSQL 14 – Multirange datatypes
On 20th of December 2020, Alexander Korotkov committed patch:
Multirange datatypes Multiranges are basically sorted arrays of non-overlapping ranges with set-theoretic operations defined over them. Since v14, each range type automatically gets a corresponding multirange datatype. There are both manual and automatic mechanisms for naming multirange types. Once can specify multirange type name using multirange_type_name attribute in CREATE TYPE. Otherwise, a multirange type name is generated automatically. If the range type name contains "range" then we change that to "multirange". Otherwise, we add "_multirange" to the end. Implementation of multiranges comes with a space-efficient internal representation format, which evades extra paddings and duplicated storage of oids. Altogether this format allows fetching a particular range by its index in O(n). Statistic gathering and selectivity estimation are implemented for multiranges. For this purpose, stored multirange is approximated as union range without gaps. This field will likely need improvements in the future. Catversion is bumped. Discussion: https://postgr.es/m/CALNJ-vSUpQ_Y%3DjXvTxt1VYFztaBSsWVXeF1y6gTYQ4bOiWDLgQ%40mail.gmail.com Discussion: https://postgr.es/m/a0b8026459d1e6167933be2104a6174e7d40d0ab.camel%40j-davis.com#fe7218c83b08068bfffb0c5293eceda0 Author: Paul Jungwirth, revised by me Reviewed-by: David Fetter, Corey Huinker, Jeff Davis, Pavel Stehule Reviewed-by: Alvaro Herrera, Tom Lane, Isaac Morland, David G. Johnston Reviewed-by: Zhihong Yu, Alexander Korotkov
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