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  • License MIT

PostgreSQL Location Replication client - logical WAL replication streaming

Package Exports

  • pg-logical-replication
  • pg-logical-replication/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (pg-logical-replication) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

pg-logical-replication

Node.js CI NPM Version License

1. Install

$ npm install pg-logical-replication

2. Usage

  • This is an example using wal2json. A replication slot(test_slot_wal2json) must be created on the PostgreSQL server.
    • SELECT * FROM pg_create_logical_replication_slot('test_slot_wal2json', 'wal2json')
const slotName = 'test_slot_wal2json';

const service = new LogicalReplicationService(
  /**
   * node-postgres Client options for connection
   * https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/pg/index.d.ts#L16
   */
  {
    database: 'playground',
    // ...
  },
  /**
   * Logical replication service config
   * https://github.com/kibae/pg-logical-replication/blob/main/src/logical-replication-service.ts#L9
   */
  {
    acknowledge: {
      auto: true,
      timeoutSeconds: 10
    }
  }
)

// `TestDecodingPlugin` for test_decoding and `ProtocolBuffersPlugin` for decoderbufs are also available.
const plugin = new Wal2JsonPlugin({
  /**
   * Plugin options for wal2json
   * https://github.com/kibae/pg-logical-replication/blob/main/src/output-plugins/wal2json/wal2json-plugin-options.type.ts
   */
  //...
});

/**
 * Wal2Json.Output
 * https://github.com/kibae/pg-logical-replication/blob/ts-main/src/output-plugins/wal2json/wal2json-plugin-output.type.ts
 */
service.on('data', (lsn: string, log: Wal2Json.Output) => {
  // Do something what you want.
  // log.change.filter((change) => change.kind === 'insert').length;
});

// Start subscribing to data change events.
(function proc() {
  service.subscribe(plugin, slotName)
    .catch((e) => {
      console.error(e);
    })
    .then(() => {
      setTimeout(proc, 100);
    });
})();

3. LogicalReplicationService

3-1. Constructor(clientConfig: ClientConfig, config?: Partial<LogicalReplicationConfig>)

const service = new LogicalReplicationService(
  /**
   * node-postgres Client options for connection
   * https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/pg/index.d.ts#L16
   */
  clientConfig: {
    user?: string | undefined;
    database?: string | undefined;
    password?: string | (() => string | Promise<string>) | undefined;
    port?: number | undefined;
    host?: string | undefined;
    connectionString?: string | undefined;
    keepAlive?: boolean | undefined;
    stream?: stream.Duplex | undefined;
    statement_timeout?: false | number | undefined;
    parseInputDatesAsUTC?: boolean | undefined;
    ssl?: boolean | ConnectionOptions | undefined;
    query_timeout?: number | undefined;
    keepAliveInitialDelayMillis?: number | undefined;
    idle_in_transaction_session_timeout?: number | undefined;
    application_name?: string | undefined;
    connectionTimeoutMillis?: number | undefined;
    types?: CustomTypesConfig | undefined;
    options?: string | undefined;
  },
  /**
   * Logical replication service config
   * https://github.com/kibae/pg-logical-replication/blob/main/src/logical-replication-service.ts#L9
   */
  config?: Partial<{
    acknowledge?: {
      /**
       * If the value is false, acknowledge must be done manually.
       * Default: true
       */
      auto: boolean;
      /**
       * Acknowledge is performed every set time (sec). If 0, do not do it.
       * Default: 10
       */
      timeoutSeconds: 0 | 10 | number;
    };
  }>
)

3-2. subscribe(plugin: AbstractPlugin, slotName: string, uptoLsn?: string): Promise<this>

3-3. acknowledge(lsn: string): Promise<boolean>

  • After processing the data, it signals the PostgreSQL server that it is OK to clear the WAL log.
  • Usually this is done automatically.
  • Manually use only when new LogicalReplicationService({}, {acknowledge: {auto: false}}).

3-4. Event

  • on(event: 'start', listener: () => Promise<void> | void)
    • Emitted when start replication.
  • on(event: 'data', listener: (lsn: string, log: any) => Promise<void> | void)
    • Emitted when PostgreSQL data changes. The log value type varies depending on the plugin.
  • on(event: 'error', listener: (err: Error) => void)
  • on(event: 'acknowledge', listener: (lsn: string) => Promise<void> | void)
    • Emitted when acknowledging automatically.
  • on(event: 'heartbeat', listener: (lsn: string, timestamp: number, shouldRespond: boolean) => Promise<void> | void)
    • A heartbeat check signal has been received from the server. You may need to run service.acknowledge().

3-5. Misc. method

  • stop(): Promise<this>
    • Terminate the server's connection and stop replication.
  • isStop(): boolean
    • Returns false when replication starts from the server.
  • lastLsn(): string

4. Output Plugins

4-1. PgoutputPlugin for pgoutput (Native to PostgreSQL)

4-2. Wal2JsonPlugin for wal2json

4-3. ProtocolBuffersPlugin for decoderbufs

Contributors