Public
Edited
Jan 2
6 forks
client
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 = {
// Initialize database
const db = await makeDB()
// Insert files directly into tables
await insertFile(db, 'penguins_file', penguins_file);
// Alternatively, register file into the db's filesystem
const iris_buffer = await iris_file.arrayBuffer();
await db.registerFileBuffer(
'iris.csv', // Choose filename to use inside db
new Uint8Array(iris_buffer)
);
return db
}
client = {
const client_class = (duckdb_client === 'Compatibility') ? DuckDBClientCompat : DuckDBClient;
const c = new client_class(db_instance);
// Create tables here
await c.query(`
create or replace table penguins as (
from penguins_file
)
`)
await c.query(`
create or replace table iris as (
from 'iris.csv' -- Filename used as first arg to db.registerFileBuffer
)
`)
return c;
}
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();
}
}
};
}
}
getArrowTableSchema = observable_stdlib.getArrowTableSchema
convertArrowValue = mosaic_core.convertArrowValue
observable_stdlib = await import('https://cdn.jsdelivr.net/npm/@observablehq/stdlib@5.8.7/+esm');
mosaic_core = await import('https://cdn.jsdelivr.net/npm/@uwdata/mosaic-core@0.9.0/+esm');
penguins_file = FileAttachment("penguins.csv")
iris_file = FileAttachment("iris.csv")
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.
