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darksaints · 3 years ago
Just want to throw out the usefulness of multiranges in my current domain, which is spectrum regulation/licensing. A few of our processes enabled by multirange support have caught serious exclusivity conflicts (where there are more than one licensee with exclusive rights to a specific span of spectrum within a specific geographic area) with licenses that were not caught by the FCC before they were issued. Additionally useful for swaps (where licensees trade licenses to improve their holdings relative to their existing portfolio)...multiranges allow for easy and error free analysis of potential swap targets that maximize benefit to both parties. And we also use it for spot checks to make sure that we are using spectrum legally according to the special conditions constraints (e.g. not using 600MHz A block within a distance that could cause interference with hospital usage of WMTS equipment). I love range types!
durkie · 3 years ago
yeah they've been super useful for me too. i haven't switched to the multirange datatype yet (still use int4range[]), but I'm excited to since you can now do exclusion constraints on multiranges, which will greatly simplify some things for me.

i keep track of roads that a person has biked/walked for Wandrer (wandrer.earth), and storing everything as a geometry would be a storage and analytical nightmare. keeping things as a range lets you easily determine what part of an activity covered new ground, and you can generate the geometry / length on demand while only storing a few integers (plus the raw road geometry, but that's shared among everyone).

thom · 3 years ago
It’s also worth knowing that you can accelerate many sorts of range queries with a GIST index. This often ends up faster than using two separate columns.
phamilton · 3 years ago
However, multirange GiST is implemented by merging all ranges into a single range (ignoring any gaps), which makes it less useful in many cases.

src: https://github.com/postgres/postgres/blob/f14aad5169baa5e2ac...

Tostino · 3 years ago
Right, but it just means the index is not used as the final source of truth and the DB has to run an exact check on the smaller subset of rows returned. You won't get incorrect queries, but depending on the workload it may not be a useful index for improving query speed.
rubyist5eva · 3 years ago
we've been speeding up our time based queries using tsrange and gist indexes and they have been really great
afhammad · 3 years ago
I've used tsrange successfully in 2 projects to optimise storage of temporal data. The same can be achieved with start/end timestamp columns at the cost of more complex and error prone queries.

Multiranges could be used to further optimise for storage of duplicate data (if a data pattern repeats at different intervals) but it's not a big enough margin for me yet.

ainar-g · 3 years ago
I really like PostgreSQL ranges, but I've always been curious, if these are an extension or they are a part of the SQL standard? The “Range Types” page[1] doesn't seem to mention the standard at all, and appendix D.1, “Supported Features”, doesn't mention range types.

The reason I'm curious is because may future SQL database implementations will most likely use the standard at least in some capacity, so it'd be nice to know, how future-proof and DBMS-switch-proof a schema using these could be.

[1]: https://www.postgresql.org/docs/current/rangetypes.html

[2]: https://www.postgresql.org/docs/current/features-sql-standar...

Someone · 3 years ago
Given that https://www.postgresql.org/docs/15/features-sql-standard.htm... doesn’t mention them, I expect them to be non-standard.

(The word ‘range’ appears once there, in “F404. Range variable for common column names”, but reading the English parts of https://github.com/dazuiba008/digoal_blog_fork/blob/master/2..., it’s clear that isn’t about range types)

jansommer · 3 years ago
Range types are not supported in SQL Server. You'd likely need columns for start and end to be compliant.
Nullabillity · 3 years ago
SQL Server/MSSQL is just yet another (relatively poor) implementation of the SQL standard with a very presumptuous name.
pjungwir · 3 years ago
I'm still hoping to use multiranges to add temporal tables to Postgres, but life has been busy the last year. I apologize to you all for the delay.

The coolest application of multiranges I've heard about is for astronomical observations. The authors of this paper were kind enough to share an early draft with me, and they say it greatly speeds up comparisons of sky objects. It's very accessible and a fun read:

https://arxiv.org/abs/2112.06947

timwis · 3 years ago
Wow, I was just trying to solve the problem of merging overlapping periods in ruby. Life would be so much easier if the database did it for me!
awild · 3 years ago
Sort by lowest start, merge left when they overlap. Emit current span if not. Repeat.
badelectron · 3 years ago
If you want to do this with a data structure instead of a database then discrete interval encoding trees solve this problem well. https://xlinux.nist.gov/dads/HTML/discretintrv.html

Dead Comment

kortex · 3 years ago
Is there a name for the ` <@ ` operator? Been calling it the tornado operator but I haven't found anything indicating an "official" name.
panzi · 3 years ago
An older version of the documentation calls them the array containment operators:

> The array containment operators (<@ and @>) [...]

https://www.postgresql.org/docs/9.6/functions-array.html

stuaxo · 3 years ago
This is really useful, I've been doing something like this manually.

What's the performance like to get multiranges from a million row column of unique integers, that has a few gaps in it.

(Also slightly unsorted, but obv can do that in query).