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JDBC Nodes

Crux nodes can use JDBC databases to store their transaction logs and/or document stores.

Local Cluster Mode

Project Dependencies

  • deps.edn

  • pom.xml

juxt/crux-jdbc {:mvn/version "20.09-1.12.1-beta"}
<dependency>
    <groupId>juxt</groupId>
    <artifactId>crux-jdbc</artifactId>
    <version>20.09-1.12.1-beta</version>
</dependency>

Example configuration

JDBC transaction logs and document stores depend on a 'connection pool' component - if you use both, they can share the same connection pool.

Connection pools require a JDBC 'dialect' - out of the box, Crux supports the following:

  • H2: crux.jdbc.h2/->dialect

  • MySQL: crux.jdbc.mysql/->dialect

  • Microsoft SQL Server: crux.jdbc.mssql/->dialect

  • Oracle: crux.jdbc.oracle/->dialect

  • PostgreSQL: crux.jdbc.psql/->dialect

  • SQLite: crux.jdbc.sqlite/->dialect

Each of these also require an additional dependency to pull in the relevant JDBC driver - see the Crux JDBC project.clj for our latest dependencies.

The connection pool also requires a db-spec - a map containing either a full jdbcUrl or its component parts, including dbtype (provided by the dialect by default), host, port, dbname. Any other attributes supplied (user, password, say) are appended to the URL as query parameters - see your individual JDBC driver for full details.

Crux uses HikariCP to provide connection pools. You can pass options directly to HikariConfig via pool-opts - for example, to setMaximumPoolSize, add maximumPoolSize to your configuration.

JDBC as a Transaction Log

  • JSON

  • Clojure/EDN

{
  "crux/tx-log": {
    "crux/module": "crux.jdbc/->tx-log",
    "connection-pool": {
      "dialect": {
        "crux/module": "crux.jdbc.psql/->dialect"
      },
      "pool-opts": { ... },
      "db-spec": { ... }
    },

    "poll-sleep-duration": "PT1S"
  },

  ...
}
{:crux/tx-log {:crux/module 'crux.jdbc/->tx-log
               :connection-pool {:dialect {:crux/module 'crux.jdbc.psql/->dialect}
                                 :pool-opts { ... }
                                 :db-spec { ... }}
               :poll-sleep-duration "PT1S"}
 ...}

If you do not want the local node to index transactions, you can use the crux.jdbc/->ingest-only-tx-log module.

JDBC as a Document Store

  • JSON

  • Clojure/EDN

{
  "crux/document-store": {
    "crux/module": "crux.jdbc/->document-store",
    "connection-pool": {
      "dialect": {
        "crux/module": "crux.jdbc.psql/->dialect"
      },
      "pool-opts": { ... },
      "db-spec": { ... }
    }
  },

  ...
}
{:crux/document-store {:crux/module 'crux.jdbc/->document-store
                       :connection-pool {:dialect {:crux/module 'crux.jdbc.psql/->dialect}
                                         :pool-opts { ... }
                                         :db-spec { ... }}}
 ...}

Sharing connection pools

If you use JDBC for both the transaction log and document store, you can share the same connection pool between the two modules as follows:

  • JSON

  • Clojure/EDN

{
  "crux.jdbc/connection-pool": {
    "dialect": {
      "crux/module": "crux.jdbc.psql/->dialect"
    },
    "pool-opts": { ... },
    "db-spec": { ... }
  },


  "crux/document-store": {
    "crux/module": "crux.jdbc/->document-store",
    "connection-pool": "crux.jdbc/connection-pool"
  },

  "crux/tx-log": {
    "crux/module": "crux.jdbc/->tx-log",
    "connection-pool": "crux.jdbc/connection-pool"
  },

  ...
}
{:crux.jdbc/connection-pool {:dialect {:crux/module 'crux.jdbc.psql/->dialect}
                             :pool-opts { ... }
                             :db-spec { ... }}
 :crux/tx-log {:crux/module 'crux.jdbc/->tx-log
               :connection-pool :crux.jdbc/connection-pool}
 :crux/document-store {:crux/module 'crux.jdbc/->document-store
                       :connection-pool :crux.jdbc/connection-pool}
 ...}

Parameters

Connection pool (crux.jdbc/->connection-pool)

  • dialect (dialect, required): JDBC dialect

  • pool-opts (map): see above

  • db-spec (map, required): see above

Transaction log (crux.jdbc/->tx-log)

  • connection-pool

  • poll-sleep-duration (string/Duration, default 1 second, "PT1S"): time to sleep between each poll, if the previous poll didn’t yield any transactions.

Ingest-only transaction log (crux.jdbc/->ingest-only-tx-log)

  • connection-pool

Document store (crux.jdbc/->document-store)

  • connection-pool

  • doc-cache-size (int): size of in-memory document cache