HikariCP
H2
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HikariCP | H2 | |
---|---|---|
33 | 11 | |
19,369 | 4,042 | |
- | 1.1% | |
6.5 | 9.1 | |
24 days ago | 4 days ago | |
Java | Java | |
Apache License 2.0 | GNU General Public License v3.0 or later |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
HikariCP
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Java virtual threads caused a deadlock in TPC-C for PostgreSQL
Looks like HikariCP is also awaiting fixes for this https://github.com/brettwooldridge/HikariCP/pull/2055
- About Pool Sizing
- HikariCP maximumPoolSize based on AWS ECS number of tasks
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Writing to db
I have used hikari and exposed to do this in the past with postgres, although other dialects are supported.
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A Tale of Two Connection Pools
I found one suggestion from the author of HikariCP on how to address this, which I implemented and it worked. However, there are additional classes involved, and it feels a little clunky and hard to follow.
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Spring boot change password runtime
Not really, you can change some things in spring boot but doing so will typically trigger a refresh which is less reliable than restarting but still causes a large performance hit. You could probably do it with hikari if you really needed to but it's inadvisable to build your application around this mechanic.
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Help with bungeecord server
# https://github.com/brettwooldridge/HikariCP/wiki/About-Pool-Sizing
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Currently load testing a Django API I don’t get good results, Help me brainstorm this
Not familiar with Python but this thread about a Java connection pool might be interesting: https://github.com/brettwooldridge/HikariCP/wiki/About-Pool-Sizing
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Should I use diesel ORM if performance is the most important thing?
Whatever you choose, presuming your app is database heavy, I highly recommend spending time on DB schema design to make all queries as short as possible, avoid relying on transactions, and keep your connection pool tiny. For reference: https://github.com/brettwooldridge/HikariCP/wiki/About-Pool-Sizing
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Art of README
You reminded me of the HikariCP library and it’s documentation: Clear and simple with references to other libraries trying to accomplish the same thing. It is not in the closure space though.
H2
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H2 Database – CVE getting flagged by automated scans
The URL should point to a particular comment, but HN removes fragments: https://github.com/h2database/h2database/issues/3686#issueco...
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“Our paying customers need X, when will you fix it?”
This sounds very much like the idiocy of "infosec" lunkheads who know nothing about what they're "fixing" but if an automated system tells them a CVE exists, they've absolutely got to have it "patched". They don't look into what the claims of the CVE are, or whether their specific use case is vulnerable. They don't know, they don't care, they're not even programmers. All they know is a box needs ticking.
A similar thing happened with h2database - a "security researcher" found that if you do something you're told not to do, then bad things happen.. but they demanded and got a CVE allocated anyway. Anyone who looks at it realises it's bullshit, but the mere existence of a CVE is all that matters to these idiots.
What the h2database developer said about it: https://github.com/h2database/h2database/issues/3686#issueco...
> I struggle to understand why I should feel the slightest shred of sympathy for "major corporations" that are using a volunteer-developed open-source project. Feel free to get your corporation to pay someone to deal with this, or pay for a similar commercial library.
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SQLite Internals: How the Most Used Database Works
> ...than it would be to learn the exact syntax and quirks and possibly bugs of someone else's implementation...
Yup. Also, having deep knowledge of the language is required.
SQLite's grammar is neat. Creating a compatible parser would make a fun project. Here's a pretty good example: https://github.com/bkiers/sqlite-parser (Actual ANTLR 4 grammar: https://github.com/bkiers/sqlite-parser/blob/master/src/main... )
Postgres, which tries to be compliant with the latest standards, however...
SQL-2016 is a beast. Not to mention all the dialects.
I'm updating my personal (soon to be FOSS) grammar from ANTLR 3 LL(k) to ANTLR 4 ALL().
I've long had a working knowledge of SQL-92, with some SQL-1999 (eg common table expressions).
But the new structures and extensions are a bit overwhelming.
Fortunately, ANTLR project has ~dozen FOSS grammars to learn from. https://github.com/antlr/grammars-v4/tree/master/sql
They mostly mechanically translate BNFs to LL(k) with some ALL(). Meaning few take advantage of left-recursion. https://github.com/antlr/antlr4/blob/master/doc/left-recursi...
Honestly, I struggled to understand these grammars. Plus, not being conversant with the SQL-2016 was a huge impediment. Just finding a succinct corbis of test cases was a huge hurdle for me.
Fortunately, the H2 Database project is a great resource. https://github.com/h2database/h2database/tree/master/h2/src/...
Now for the exciting conclusion...
My ANTLR grammar which passes all of H2's tests looks nothing like any of the official or product specific BNFs.
Further, I found discrepancy between the product specific BNFs and their implementations.
So a lot of trial & error is required for a "real world" parser. Which would explain why the professional SQL parsing tools charge money.
I still think creating a parser for SQLite is a great project.
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Database of Databases
H2 - Free, Embedded & Open source
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🎀 Spring Boot 2.7.0 Released
H2 2.1
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How is the market for Kotlin developers where you live?
H2 for mocking relational database connections
- Ask HN: Who wants to be hired? (December 2021)
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Best Database option for a Swing application
It's open-source and written in Java, so you can even create custom procedures and register them straight in your application!
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Reliable WebSockets-based pub/sub with Spring Boot
Firstly, let's set up a basic Spring Boot application. We can use the Spring Initializr with Spring Data JPA, H2 Database, Lombok added. H2 Database will provide us with a simple database, and Spring Data JPA will allow us to easily interact with it using Hibernate. Lombok will make it easier to write concise and readable classes.
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Why are tar.xz files 15x smaller when using Python's tar compared to macOS tar?
Sorting chunks by similarity: commonly used tools don't do that. Most archive tools only sort by file type.
I wrote a tool that chunks the data (into variable-sized blocks, to re-sync if there are multiple files that have different length prefixes, but that's another story), and then sorts the chunks by LSH (locality sensitive hash). LSH is used by search engines to detect similar text. It can compress directories that contain multiple version of e.g. source code very well (e.g. trunk, branches). https://github.com/h2database/h2database/blob/master/h2/src/...
I discussed this approach with a researcher in this area in January 2020. AFAIK there is active research in this area, specially to compress DNA sequences. But he also wasn't aware of papers or research in this area for general-purpose data compression.
So, I think this area is largely uncharted. I would be interested (as a hobby side project) to help, if somebody is interested.
What are some alternatives?
c3p0 - a mature, highly concurrent JDBC Connection pooling library, with support for caching and reuse of PreparedStatements.
MapDB - MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.
spring-boot-r2dbc - An example implementation of Spring Boot R2DBC REST API with PostgreSQL database.
MariaDB4j - MariaDB Embedded in Java JAR
Vibur DBCP - Vibur DBCP - concurrent and dynamic JDBC connection pool
Flyway - Flyway by Redgate • Database Migrations Made Easy.
JDBI - The Jdbi library provides convenient, idiomatic access to relational databases in Java and other JVM technologies such as Kotlin, Clojure or Scala.
JetBrains Xodus - Transactional schema-less embedded database used by JetBrains YouTrack and JetBrains Hub.
Chronicle Map - Replicate your Key Value Store across your network, with consistency, persistance and performance.
jOOQ - jOOQ is the best way to write SQL in Java
Speedment - Speedment is a Stream ORM Java Toolkit and Runtime