https://github.com/metabase/connection-pool

Connection pools for JDBC databases. Simple wrapper around C3P0.
https://github.com/metabase/connection-pool

c3p0 clojure clojure-jdbc connection-pool connection-pooler connection-pooling database jdbc metabase

Last synced: 2 days ago
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Connection pools for JDBC databases. Simple wrapper around C3P0.

• Host: GitHub
• URL: https://github.com/metabase/connection-pool
• Owner: metabase
• License: epl-2.0
• Created: 2019-06-15T00:46:34.000Z (about 6 years ago)
• Default Branch: master
• Last Pushed: 2024-12-11T21:53:49.000Z (7 months ago)
• Last Synced: 2025-06-25T09:58:20.067Z (18 days ago)
• Topics: c3p0, clojure, clojure-jdbc, connection-pool, connection-pooler, connection-pooling, database, jdbc, metabase
• Language: Clojure
• Size: 35.2 KB
• Stars: 14
• Watchers: 41
• Forks: 9
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE
  • Codeowners: .github/CODEOWNERS

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### Creating a Connection Pool

#### From a `clojure.java.jdbc` spec

You can create a C3P0 connection pool with any `clojure.java.jdbc` connection spec map with `:subname` and

`:subprotocol` keys. `connection-pool-spec` will return a `clojure.java.jdbc` connection spec you can use directly:

```clj

(require '[clojure.java.jdbc :as jdbc]

         '[metabase.connection-pool :as connection-pool])

;;; Create a C3P0 connection pool

(let [pool-spec (connection-pool/connection-pool-spec my-jdbc-spec)]

  (jdbc/query pool-spec ["SELECT *"]))

  ```

(You will almost certainly want to store your pool somewhere, such as in an atom).

#### From a JDBC URL String:

You can create a pooled `DataSource` (e.g., for use with [`next-jdbc`](https://github.com/seancorfield/next-jdbc)) by calling `pooled-data-source-from-url`:

```clj

(require '[next.jdbc :as jdbc]

         '[metabase.connection-pool :as connection-pool])

(with-open [connection (jdbc/get-connection (connection-pool/pooled-data-source-from-url "jdbc:postgresql:localhost:3000/my_db"))]

  (reduce my-fn init-value (jdbc/plan connection ["SELECT *"])))

```

### Configuring the connection pool

You can set connection pool options such as size in a `c3p0.properties` file, or by passing them as a map to `connection-pool-spec`:

```clj

(def ^:private connection-pool-properties

  {"maxIdleTime"     (* 3 60 60)

   "minPoolSize"     1

   "initialPoolSize" 1

   "maxPoolSize"     15})

(def my-pool-spec

  (connection-pool/connection-pool-spec my-jdbc-spec connection-pool-properties))

```

See [https://www.mchange.com/projects/c3p0/#configuration_properties](https://www.mchange.com/projects/c3p0/#configuration_properties) for a list of all options.

### Destroying connection pools

`destroy-connection-pool!` will destroy the connection pool you created:

```clj

(connection-pool/destroy-connection-pool! pool-spec)

```

### Legal Stuff

Copyright © 2019 [Metabase, Inc](https://metabase.com/). This project is licensed under the Eclipse Public License, same as Clojure.