parallel-actions v0.0.3

parallel-actions

This library simplifies running parallel actions with dependencies, ensuring only the actions with complete dependencies run in parallel.

Example

Run multiple SQL commands that require certain ordering, e.g. REFRESH MATERIALIZED VIEW must be run in the order of their dependencies. In this example we refresh 3 materialized views, two of which are based on real tables, and the 3rd depends on the first two. parallel-actions lib will simplify execution, making sure v3 does not start until v1 and v2 are complete.

const { Pool } = require('pg');
const pexec = require('parallel-actions');

async function run() {
  // Use PostgreSQL pool to run queries and restrict
  // the number of simultaneous connections.
  const pgpool = new Pool({
    max: 5,
    host: '...', port: '...', database: '...',
  });

  // Which views we need to refresh
  const views = {
    v1: {view: 'view1'},
    v2: {view: 'view2'},
    v3: {view: 'view3', dependsOn: ['v1', 'v2']},
  };
 
  await pexec(views,
    v => pgpool.query(`REFRESH MATERIALIZED VIEW ${v.view};`)
  );
}