Public
Edited
Jun 26, 2024
Importers
query_result
Type Table, then Shift-Enter. Ctrl-space for more options.
client
{
client; // just to ensure calculated before
const conn = await db_instance.connect();
// let result = await conn.query(`pragma tpch(1)`);
let result = await conn.query(`
select distinct c_name from customer
`)
return result.toArray()
}
query_answer
Type Table, then Shift-Enter. Ctrl-space for more options.
db_instance.getVersion()
duckdb = import(
"https://cdn.jsdelivr.net/npm/@duckdb/duckdb-wasm@1.28.1-dev232.0/+esm"
)
bundle = {
const bundles = duckdb.getJsDelivrBundles()
if (duckdb_bundle === 'Auto') {
return duckdb.selectBundle(bundles)
} else {
const bun = bundles[duckdb_bundle]
bun['pthreadWorker'] = null;
return bun;
}
// return bundles['mvp']
}
async function makeDB() {
const logger = new duckdb.ConsoleLogger();
const worker = await duckdb.createWorker(bundle.mainWorker);
const db = new duckdb.AsyncDuckDB(logger, worker);
await db.instantiate(bundle.mainModule);
return db
}
db_instance = makeDB()
tpch_table_names = ['customer', 'lineitem', 'nation', 'orders', 'part', 'partsupp', 'region', 'supplier']
client = {
// const c = new DuckDBClient(db_instance);
const client_class = (duckdb_client === 'Compatibility') ? DuckDBClientCompat : DuckDBClient;
const c = new client_class(db_instance);
await c.query(`LOAD tpch;`);
await c.query(`INSTALL tpch;`);
// Need to drop tables because it can append the rows again (instead of raising error)
for (let col of tpch_table_names) {
await c.query(`drop table if exists ${col};`)
}
await c.query(`CALL dbgen(sf = ${scale_factor});`);
return c;
}
tpch_queries = client.query(`from tpch_queries()`)
query_answers = client.query(`from tpch_answers() where scale_factor = ${scale_factor};`)
query = tpch_queries.filter(d => d.query_nr === query_number)[0].query
query_answer_dsv = query_answers.filter(d => d.query_nr === query_number)[0].answer
mosaic_core = await import('https://cdn.jsdelivr.net/npm/@uwdata/mosaic-core@0.9.0/+esm');
observable_stdlib = await import('https://cdn.jsdelivr.net/npm/@observablehq/stdlib@5.8.7/+esm');
getArrowTableSchema = observable_stdlib.getArrowTableSchema
convertArrowValue = mosaic_core.convertArrowValue
class DuckDBClientCompat extends DuckDBClient {
async queryStream(query, params) {
const connection = await this._db.connect();
let reader, batch;
try {
if (params?.length > 0) {
const statement = await connection.prepare(query);
reader = await statement.send(...params);
} else {
reader = await connection.send(query);
}
batch = await reader.next();
if (batch.done) throw new Error("missing first batch");
} catch (error) {
await connection.close();
throw error;
}
// Mosaic utility: convert Arrow value to Javascript value
const converters = {}
batch.value.schema.fields.forEach(d => {
console.log('Type for ', d.name, d.type)
converters[d.name] = convertArrowValue(d.type)
})
return {
schema: getArrowTableSchema(batch.value),
async *readRows() {
try {
while (!batch.done) {
let batch_array = batch.value.toArray();
// Convert all values to Javascript version
let object_array = []
for (let i = 0; i < batch_array.length; i++) {
const d_proxy = batch_array[i];
const d_obj = {}
for (let k of Object.keys(converters)) {
d_obj[k] = converters[k](d_proxy[k])
}
object_array.push(d_obj)
}
yield object_array;
batch = await reader.next();
}
} finally {
await connection.close();
}
}
};
}
}
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
