For a long time I was looking for SQL pretty printer.
Some queries that I had to deal with, over the years, were just insane to read, like this:
Continue reading New SQL pretty printer – based on parsing, and not regexps
Better scrolling of long explain plans on explain.depesz.com
Thanks to some discussion on Slack, and work by Alexandre Felipe viewing of large explains will be now a bit easier.
You can see it, for example, in this explain.
First of all, when you scroll down, the column headers stay in place. Plus – you can always see the horizontal scrollbar to see the rest for really long node descriptions.
Thanks a lot, I appreciate the work.
Understanding pg_stat_activity
pg_stat_activity is system view that shows what is currently happening in the DB.
With newer pgs it's rather wide (22 columns as I write this). And, it's not always obvious what all this means. So let's try to figure it out.
How to log selects from specific table?
Stop the war in Ukraine
Since yesterday my sites (explain.depesz.com, paste.depesz.com, and this blog) are no longer available from IPs that are in Russia or Belarus.
I know this is not huge loss for them, but, I think, every single bit counts.
If you'd like to do the same thing for their site/service:
Waiting for PostgreSQL 15 – Documentation for SQL/JSON features
On 8th of April 2022, Andrew Dunstan committed patch:
Documentation for SQL/JSON features This documents the features added in commits f79b803dcc, f4fb45d15c, 33a377608f, 1a36bc9dba, 606948b058, 49082c2cc3, 4e34747c88, and fadb48b00e. I have cleaned up the aggregate section of the submitted docs, but there is still a deal of copy editing required. However, I thought it best to have some documentation sooner rather than later so testers can have a better idea what they are playing with. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
Continue reading Waiting for PostgreSQL 15 – Documentation for SQL/JSON features
Waiting for PostgreSQL 15 – JSON_TABLE
On 4th of April 2022, Andrew Dunstan committed patch:
JSON_TABLE This feature allows jsonb data to be treated as a table and thus used in a FROM clause like other tabular data. Data can be selected from the jsonb using jsonpath expressions, and hoisted out of nested structures in the jsonb to form multiple rows, more or less like an outer join. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu (whose name I previously misspelled), Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
DBA tips ‘n tricks – search in every field in a table
Sometimes you just want to find some value, regardless of which column it's in. If the table has few columns you can easily:
=$ SELECT * FROM TABLE WHERE a ~ '...' OR b ~ '...' OR c ~ '...'
But if there are many columns writing such query quickly becomes tedious. Luckily there is simple solution.
Continue reading DBA tips ‘n tricks – search in every field in a table
Waiting for PostgreSQL 15 – SQL/JSON query functions
On 29th of March 2022, Andrew Dunstan committed patch:
SQL/JSON query functions This introduces the SQL/JSON functions for querying JSON data using jsonpath expressions. The functions are: JSON_EXISTS() JSON_QUERY() JSON_VALUE() All of these functions only operate on jsonb. The workaround for now is to cast the argument to jsonb. JSON_EXISTS() tests if the jsonpath expression applied to the jsonb value yields any values. JSON_VALUE() must return a single value, and an error occurs if it tries to return multiple values. JSON_QUERY() must return a json object or array, and there are various WRAPPER options for handling scalar or multi-value results. Both these functions have options for handling EMPTY and ERROR conditions. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
Continue reading Waiting for PostgreSQL 15 – SQL/JSON query functions
Waiting for PostgreSQL 15 – IS JSON predicate
On 28th of March 2022, Andrew Dunstan
Title: Waiting for PostgreSQL 15 – IS JSON predicate
On 28th of March 2022, Andrew Dunstan committed patch:
IS JSON predicate This patch intrdocuces the SQL standard IS JSON predicate. It operates on text and bytea values representing JSON as well as on the json and jsonb types. Each test has an IS and IS NOT variant. The tests are: IS JSON [VALUE] IS JSON ARRAY IS JSON OBJECT IS JSON SCALAR IS JSON WITH | WITHOUT UNIQUE KEYS These are mostly self-explanatory, but note that IS JSON WITHOUT UNIQUE KEYS is true whenever IS JSON is true, and IS JSON WITH UNIQUE KEYS is true whenever IS JSON is true except it IS JSON OBJECT is true and there are duplicate keys (which is never the case when applied to jsonb values). Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
Continue reading Waiting for PostgreSQL 15 – IS JSON predicate