Interface SessionOptions

A Session bundles the three pieces of state that are otherwise process-wide — the execution runtime (engine, strictness, memory policy), the persist() cache and the IO policy — into one object a server can create per tenant, per request or per test. Nothing a session does is visible to another session or to the process defaults: its frames run on its own Runtime, persist() fills its own PersistCache, and every read it performs must pass its IO policy in addition to the process floor from setIoPolicy().

const tenant = createSession({
  io: { allowedHosts: ['data.acme.example'], denyPrivateHosts: true, maxBytes: 200e6, timeoutMs: 30_000 },
  runtime: { engine: 'cpu', strict: true, memory: { maxBytes: 512 * 1024 * 1024 } },
  persist: { maxBytes: 128 * 1024 * 1024 },
})
const orders = await tenant.readCsv({ url: 'https://data.acme.example/orders.csv' })
const top = await orders.lazy().groupBy('country').agg({ r: col('revenue').sum() }).persist().collect()
tenant.close() // drops the session's cache
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