Querydsl
HikariCP


Querydsl | HikariCP | |
---|---|---|
7 | 37 | |
4,800 | 20,243 | |
0.5% | 0.6% | |
0.8 | 8.8 | |
10 days ago | 2 months ago | |
Java | Java | |
Apache License 2.0 | Apache License 2.0 |
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Querydsl
- Querydsl – Unified Queries for Java
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PostgreSQL Is Enough
There is a bit of tooling needed but is already around. For Java for example I had very good experience with a combination of flyway [1] for migrations, testcontainers [2] for making integration tests as easy as unit tests and querydsl [3] for a query and mapping layer.
[1] https://github.com/flyway/flyway
[2] https://java.testcontainers.org/modules/databases/postgres/
[3] https://github.com/querydsl/querydsl
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Apache Empire-Db: Full SQL Freedom for Java
http://querydsl.com/ also seems similar
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Useful & Unknown Java Libraries - Piotr's TechBlog
As for JPA: I cannot miss the QueryDSL library for building typesafe queries. Another interesting alternative is Jinq, that provides a java stream api to query entities.
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You might not need an ORM
> all I really want is a nice API for building queries (that actually supports all underlying database features) and automatic mapping of the results to whatever objects/structs and primitives the language supports.
For Java based solutions, check out https://www.jooq.org/ or http://querydsl.com/
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How do access sql through java in the real world?
QueryDsl -- http://querydsl.com
- How to build SQL query strings?
HikariCP
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A Major Postgres Upgrade with Zero Downtime
> are they using a connection pooler
We use Hikari [1] an in-process connection pooler. We didn't opt for pgbouncer at al, because we didn't want to add the extra infra yet.
> since what they did in code can be natively done with PgBouncer, PgCat, et al.
Can you point me to a reference I could look at, about doing a major version upgrade with PgBouncer et al? My understanding that we would still need to write a script to switch masters, similar to what we wrote.
> all the active connections
The active connections we were referring too were websocket connections, we haven't had problems with PG connections.
Right now the algorithm we use to find affected queries and notify websockets starts to falter when the number of active websocket connections get too high. We're working on improving it in the coming weeks. I'll update the essay to clarify.
> I did feel for them here:
Thank you! That part was definitely the most frustrating.
[1] https://github.com/brettwooldridge/HikariCP
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Kapper, a Fresh Look at ORMs for Kotlin and the JVM
// Create a DataSource object, for example using [HikariCP](https://github.com/brettwooldridge/HikariCP) // Kapper is un-opinionated about which pooler, if any you use. val dataSource = HikariDataSource().apply { jdbcUrl = "jdbc:PostgreSQL://localhost:5432/mydatabase" username = "username" password = "password" } // The Kapper API is exposed as an extension of the java.sql.Connection interface: dataSource.connection.use { connection -> // Do database stuff }
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O que é o hikari pool?
No contexto específico estava sendo falado sobre o Hikari Connection Pool. Mas, se o Hikari é um Connection Pool, o que seria um "Pool"?
- Melhorando o desempenho de aplicações Spring Boot - Parte II
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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.
What are some alternatives?
jOOQ - jOOQ is the best way to write SQL in Java
Vibur DBCP - Vibur DBCP - concurrent and dynamic JDBC connection pool
JDBI - The Jdbi library provides convenient, idiomatic access to relational databases in Java and other JVM technologies such as Kotlin, Clojure or Scala.
c3p0 - a mature, highly concurrent JDBC Connection pooling library, with support for caching and reuse of PreparedStatements.
Apache Hive - Apache Hive
Jinq - LINQ-style queries for Java 8
Speedment - Speedment is a Stream ORM Java Toolkit and Runtime
Presto - The official home of the Presto distributed SQL query engine for big data
spring-boot-r2dbc - An example implementation of Spring Boot R2DBC REST API with PostgreSQL database.

