crux
temporal_tables
crux | temporal_tables | |
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16 | 16 | |
1,475 | 897 | |
- | - | |
9.7 | 4.2 | |
over 2 years ago | 2 months ago | |
Clojure | C | |
MIT License | BSD 2-clause "Simplified" License |
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crux
- Speeding Up `Atan2f` by 50x
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Bridging the Blockchain / Database Divide (Temporal Graph Queries for Corda)
Hi, a couple of my colleagues spent some time working on this integration with our open source database product (https://opencrux.com), and I'm curious to know - has anyone done similar things to connect Corda with a secondary off-the-shelf query engine?
- Crux 1.18.0 Is Out
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Crux 1.18.0 is out!
For more details, see the release notes.
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Looking for Intermediate & Advanced SQL Users for Research
The context is that I work on on https://opencrux.com, which offers a bi-temporal Datalog query layer (as well as SQL) that more or less addresses the intersection of the two, since Datalog is great for expressing recursive queries.
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How to query Datomic, Datascript, Asami, or other graph databases
I suppose another somewhat important distinction, once again performance related, is that graph databases will typically track index statistics to aid with query planning. For example, Crux uses stored knowledge of attribute-value cardinalities (recently via HyperLogLog) to optimise the join order of a query - this can make a big difference when attempting to traverse large graphs efficiently.
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Free project to practice sql ?
Agreed, recursive querying & bitemporal modelling in SQL are non-trivial problems, and the combination of the two is harder still. For an alternative perspective on tackling such problems I'd suggest looking at Datalog, which makes recursion a breeze, and a database with first-class bitemporality - both of which feature in https://opencrux.com (which I happen to work on :))
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Ask HN: What under-the-radar technology are you super excited about?
I work on Crux so can share a few details about our implementation of Datalog. The query is compiled into a kind of Worst-Case Optimal Join algorithm [0] which means that certain types of queries (e.g. cyclic graph-analytical queries, like counting triangles) are generally more efficient than what is possible with a non-WCOJ query execution strategy. However, the potency of this approach relies on the query planner calculating a good ordering of variables for the join order, and this is a hard problem in itself.
Crux is usually very competent at selecting a sensible variable ordering but when it makes a bad choice your query will take an unnecessary performance hit. The workaround for these situations is to break your query into smaller queries (since we don't wish to support any kind of hinting). Over the longer term we will be continuing to build more intelligent heuristics that make use of advanced population statistics. For instance we are about to merge a PR that uses HyperLogLog to inform attribute selectivity: https://github.com/juxt/crux/pull/1472
[0] https://cs.stanford.edu/people/chrismre/papers/paper49.Ngo.p...
- Bitemporal History
- Git as a NoSql Database
temporal_tables
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All the ways to capture changes in Postgres
There is also the temporal_tables extension.
[0] https://github.com/arkhipov/temporal_tables
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Show HN: I made a CMS that uses Git to store your data
- https://github.com/arkhipov/temporal_tables
I haven't used any of these but I work on https://xtdb.com which is also implementing SQL:2011's temporal features :)
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Data point versioning infrastructure for time traveling to a precise point in time?
It seems like PG has this extension here anyone ever use it?
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Questions about history table pattern
You could look at that or ask me questions about it (disclaimer, I am the author). Also there is https://github.com/arkhipov/temporal_tables/
- Modern solutions for database auditing?
- How Postgres Audit Tables Saved Us from Taking Down Production
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spring-data-jpa-temporal: a lightweight temporal auditing library
All good. Note there is also https://github.com/arkhipov/temporal_tables/ (which is also type 4 as a postgres extension - pretty similar to what ebean orm is doing)
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Time-travel options for databases
The Temporal Tables Postgres extension works well. https://github.com/arkhipov/temporal_tables
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easy master<->master postgresql 11 cluster solution?
If you're doing this across regions, you really really should reconsider. If you're doing it in the same data center you might be able to get away with it (but then I'm not sure why you're doing it in the first place, if the system fits in one DC then you probably can just scale up). It might be worth considering a sharded & passively combined approach -- i.e. every country has it's own data, and there's some huge public schema which consists of all the data that is drip fed in to materialized views or tables at regular intervals. You could also combine this with temporal_tables to get a very delayed but theoretically time-consistent (well, aside from clock skew across regions of course...) view of your DB to query... Really depends on the use case.
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SQLite the only database you will ever need in most cases
One of postgres's most underrated features. RLS is amazing, can be unseen/basically work silently if your programming language-side tools are good enough, and is documented well (like everything else):
https://www.postgresql.org/docs/current/ddl-rowsecurity.html
But the power of PG is that it doesn't stop there, if you combine this with a plugin like temporal_tables and you can segment by user and time:
https://github.com/arkhipov/temporal_tables
All of this mostly unknown to the thing that's accessing the DB. If that's not enough for you, why not add some auditing with pgaudit:
https://www.pgaudit.org/#section_three
I think it might not actually be hyperbole to say that Postgres is the greatest RDBMS database that has ever existed.
What are some alternatives?
xtdb - An immutable database for application development and time-travel data compliance, with SQL and XTQL. Developed by @juxt
TimescaleDB - An open-source time-series SQL database optimized for fast ingest and complex queries. Packaged as a PostgreSQL extension.
asami - A graph store for Clojure and ClojureScript
pg_bitemporal - Bitemporal tables in Postgres
specter - Clojure(Script)'s missing piece
pgaudit - PostgreSQL Audit Extension
materialize - The data warehouse for operational workloads.
dolt - Dolt – Git for Data
mergestat-lite - Query git repositories with SQL. Generate reports, perform status checks, analyze codebases. 🔍 📊
datasette - An open source multi-tool for exploring and publishing data
mnm - mnm implements TMTP protocol. Let Internet sites message members directly, instead of unreliable, insecure email. Contributors welcome! (Server)
beekeeper-studio - Modern and easy to use SQL client for MySQL, Postgres, SQLite, SQL Server, and more. Linux, MacOS, and Windows.