Live pushdown to DuckDB, query by query

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.28.0/lattice-grid.min.css">

<script type="module">
  import { defineLatticeGrid } from 'https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.28.0/modules/webcomponent.esm.js';
  defineLatticeGrid();
</script>

<lattice-grid row-key="reading_id" style="display: block; height: 560px"></lattice-grid>
<pre id="sql" style="margin-top: 12px"></pre>

<script type="module">
  import { duckdbAdapter, createPushdownSource } from 'https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.28.0/modules/webcomponent.esm.js';

  // The web component module carries the grid; DuckDB is your own engine. The
  // page starts DuckDB-Wasm itself from a CDN and hands the adapter a live
  // connection, and the module imports none of it.
  const duckdb = await import('https://cdn.jsdelivr.net/npm/@duckdb/duckdb-wasm@1.29.0/+esm');
  const bundle = await duckdb.selectBundle(duckdb.getJsDelivrBundles());
  const worker = await duckdb.createWorker(bundle.mainWorker);
  const db = new duckdb.AsyncDuckDB(new duckdb.ConsoleLogger(duckdb.LogLevel.ERROR), worker);
  await db.instantiate(bundle.mainModule, bundle.pthreadWorker);
  const connection = await db.connect();

  // from is any SQL table expression. read_parquet streams the file, so a host
  // that honours range requests lets DuckDB read only the bytes a query touches.
  const adapter = duckdbAdapter({
    connection,
    from: "read_parquet('/demo-data/readings.parquet')",
  });

  // The adapter answers every filter and sort on this grid in SQL, so nothing is
  // left to finish in the browser. Only the visible window comes back, per
  // interaction.
  const source = createPushdownSource({ adapter, pageSize: 200 });

  // Wrap execute to show the statement DuckDB ran and how long it took.
  const sqlOut = document.getElementById('sql');
  const inner = adapter.execute.bind(adapter);
  adapter.execute = async (query, request) => {
    const started = performance.now();
    const result = await inner(query, request);
    const ms = Math.round(performance.now() - started);
    const f = adapter.sqlFor(query);
    sqlOut.textContent = f.sql + '\n-- ' + ms + ' ms, ' + result.rows.length + ' of ' + (result.total ?? '?') + ' rows';
    return result;
  };

  const el = document.querySelector('lattice-grid');
  el.config = {
    toolPanel: { side: 'left', panels: ['filters', 'columns'] },
    columns: [
      { field: 'reading_id', title: '#', type: 'number', layout: { width: 110 } },
      { field: 'plant', title: 'Plant', filter: { type: 'set' } },
      { field: 'line', title: 'Line', filter: { type: 'set' } },
      { field: 'product', title: 'Product' },
      { field: 'bore_mm', title: 'Bore', type: 'millimetres',
        spec: { lower: 9.95, upper: 10.05, target: 10 } },
      { field: 'cycle_seconds', title: 'Cycle', type: 'seconds' },
      { field: 'in_spec', title: 'In spec', type: 'boolean' },
      { field: 'taken_at', title: 'Taken', type: 'dateString' },
    ],
    source,   // a hundred thousand rows; DuckDB answers each filter and sort in SQL
  };
</script>