Demo Data Schema

The QuestDB demo instance at demo.questdb.io contains two datasets that you can query directly: simulated FX market data and real cryptocurrency trades. This page describes the available tables and their structure.

Overview

The demo instance provides two independent datasets:

1. FX Market Data (Simulated) - Foreign exchange prices and order books
2. Cryptocurrency Trades (Real) - Live cryptocurrency trades from OKX exchange

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FX Market Data (Simulated)

The FX dataset contains simulated foreign exchange market data for 30 currency pairs. We fetch real reference prices from Yahoo Finance every few seconds, but all order book levels and price updates are generated algorithmically based on these reference prices.

core_price Table

The core_price table contains individual FX price updates from various liquidity providers. Each row represents a bid/ask quote update for a specific currency pair from a specific ECN.

Schema

core_price table structure

CREATE TABLE 'core_price' (
    timestamp TIMESTAMP,
    symbol SYMBOL CAPACITY 16384 CACHE,
    ecn SYMBOL CAPACITY 256 CACHE,
    bid_price DOUBLE,
    bid_volume LONG,
    ask_price DOUBLE,
    ask_volume LONG,
    reason SYMBOL CAPACITY 256 CACHE,
    indicator1 DOUBLE,
    indicator2 DOUBLE
) timestamp(timestamp) PARTITION BY HOUR TTL 3 DAYS WAL;

Columns

• timestamp - Time of the price update (designated timestamp)
• symbol - Currency pair from the 30 tracked symbols (see list below)
• ecn - Electronic Communication Network providing the quote: LMAX, EBS, Currenex, or Hotspot
• bid_price - Bid price (price at which market makers are willing to buy)
• bid_volume - Volume available at the bid price
• ask_price - Ask price (price at which market makers are willing to sell)
• ask_volume - Volume available at the ask price
• reason - Reason for the price update: "normal", "liquidity_event", or "news_event"
• indicator1, indicator2 - Additional market indicators

The table tracks 30 currency pairs: EURUSD, GBPUSD, USDJPY, USDCHF, AUDUSD, USDCAD, NZDUSD, EURJPY, GBPJPY, EURGBP, AUDJPY, CADJPY, NZDJPY, EURAUD, EURNZD, AUDNZD, GBPAUD, GBPNZD, AUDCAD, NZDCAD, EURCAD, EURCHF, GBPCHF, USDNOK, USDSEK, USDZAR, USDMXN, USDSGD, USDHKD, USDTRY.

Sample Data

Recent core_price updatesDemo this query

SELECT * FROM core_price
WHERE timestamp IN today()
LIMIT -10;

Results:

timestamp	symbol	ecn	bid_price	bid_volume	ask_price	ask_volume	reason	indicator1	indicator2
2025-12-18T11:46:13.059566Z	USDCHF	LMAX	0.7959	219884	0.7971	223174	liquidity_event	0.641
2025-12-18T11:46:13.060542Z	USDSGD	Currenex	1.291	295757049	1.2982	301215620	normal	0.034
2025-12-18T11:46:13.061853Z	EURAUD	LMAX	1.7651	6207630	1.7691	5631029	liquidity_event	0.027
2025-12-18T11:46:13.064138Z	AUDNZD	LMAX	1.1344	227668	1.1356	212604	liquidity_event	0.881
2025-12-18T11:46:13.065041Z	GBPNZD	LMAX	2.3307	2021166	2.3337	1712096	normal	0.308
2025-12-18T11:46:13.065187Z	USDCAD	EBS	1.3837	2394978	1.3869	2300556	normal	0.084
2025-12-18T11:46:13.065722Z	USDZAR	EBS	16.7211	28107021	16.7263	23536519	liquidity_event	0.151
2025-12-18T11:46:13.066128Z	EURAUD	EBS	1.763	810471822	1.7712	883424752	news_event	0.027
2025-12-18T11:46:13.066700Z	CADJPY	Currenex	113.63	20300827	114.11	19720915	normal	0.55
2025-12-18T11:46:13.071607Z	NZDJPY	Currenex	89.95	35284228	90.46	30552528	liquidity_event	0.69

market_data Table

The market_data table contains order book snapshots for currency pairs. Each row represents a complete view of the order book at a specific timestamp, with bid and ask prices and volumes stored as 2D arrays.

Schema

market_data table structure

CREATE TABLE 'market_data' (
    timestamp TIMESTAMP,
    symbol SYMBOL CAPACITY 16384 CACHE,
    bids DOUBLE[][],
    asks DOUBLE[][]
) timestamp(timestamp) PARTITION BY HOUR TTL 3 DAYS;

Columns

• timestamp - Time of the order book snapshot (designated timestamp)
• symbol - Currency pair (e.g., EURUSD, GBPJPY)
• bids - 2D array containing bid prices and volumes: [[price1, price2, ...], [volume1, volume2, ...]]
• asks - 2D array containing ask prices and volumes: [[price1, price2, ...], [volume1, volume2, ...]]

The arrays are structured so that:

• bids[1] contains bid prices (descending order - highest first)
• bids[2] contains corresponding bid volumes
• asks[1] contains ask prices (ascending order - lowest first)
• asks[2] contains corresponding ask volumes

Sample Query

Recent order book snapshotsDemo this query

SELECT timestamp, symbol,
       array_count(bids[1]) as bid_levels,
       array_count(asks[1]) as ask_levels
FROM market_data
WHERE timestamp IN today()
LIMIT -5;

Results:

timestamp	symbol	bid_levels	ask_levels
2025-12-18T12:04:07.071512Z	EURAUD	40	40
2025-12-18T12:04:07.072060Z	USDJPY	40	40
2025-12-18T12:04:07.072554Z	USDMXN	40	40
2025-12-18T12:04:07.072949Z	USDCAD	40	40
2025-12-18T12:04:07.073002Z	USDSEK	40	40

Each order book snapshot contains 40 bid levels and 40 ask levels.

FX Materialized Views

The FX dataset includes several materialized views providing pre-aggregated data at different time intervals:

Best Bid/Offer (BBO) Views

• bbo_1s - Best bid and offer aggregated every 1 second
• bbo_1m - Best bid and offer aggregated every 1 minute
• bbo_1h - Best bid and offer aggregated every 1 hour
• bbo_1d - Best bid and offer aggregated every 1 day

Core Price Aggregations

• core_price_1s - Core prices aggregated every 1 second
• core_price_1d - Core prices aggregated every 1 day

Market Data OHLC

• market_data_ohlc_1m - Open, High, Low, Close candlesticks at 1-minute intervals
• market_data_ohlc_15m - OHLC candlesticks at 15-minute intervals
• market_data_ohlc_1d - OHLC candlesticks at 1-day intervals

These views are continuously updated and optimized for dashboard and analytics queries on FX data.

FX Data Volume

• market_data: Approximately 160 million rows per day (order book snapshots)
• core_price: Approximately 73 million rows per day (price updates across all ECNs and symbols)

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Cryptocurrency Trades (Real)

The cryptocurrency dataset contains real market data streamed live from the OKX exchange using FeedHandler. These are actual executed trades, not simulated data.

trades Table

The trades table contains real cryptocurrency trade data. Each row represents an actual executed trade for a cryptocurrency pair.

Schema

trades table structure

CREATE TABLE 'trades' (
    symbol SYMBOL CAPACITY 256 CACHE,
    side SYMBOL CAPACITY 256 CACHE,
    price DOUBLE,
    amount DOUBLE,
    timestamp TIMESTAMP
) timestamp(timestamp) PARTITION BY DAY WAL;

Columns

• timestamp - Time when the trade was executed (designated timestamp)
• symbol - Cryptocurrency trading pair from the 12 tracked symbols (see list below)
• side - Trade side: buy or sell
• price - Execution price of the trade
• amount - Trade size (volume in base currency)

The table tracks 12 cryptocurrency pairs: ADA-USDT, AVAX-USD, BTC-USDT, DAI-USD, DOT-USD, ETH-BTC, ETH-USDT, LTC-USD, SOL-BTC, SOL-USD, UNI-USD, XLM-USD.

Sample Data

Recent cryptocurrency tradesDemo this query

SELECT * FROM trades
LIMIT -10;

Results:

symbol	side	price	amount	timestamp
BTC-USDT	buy	85721.6	0.00045714	2025-12-18T19:31:11.203000Z
BTC-USD	buy	85721.6	0.00045714	2025-12-18T19:31:11.203000Z
BTC-USDT	buy	85726.6	0.00001501	2025-12-18T19:31:11.206000Z
BTC-USD	buy	85726.6	0.00001501	2025-12-18T19:31:11.206000Z
BTC-USDT	buy	85726.9	0.000887	2025-12-18T19:31:11.206000Z
BTC-USD	buy	85726.9	0.000887	2025-12-18T19:31:11.206000Z
BTC-USDT	buy	85731.3	0.00004393	2025-12-18T19:31:11.206000Z
BTC-USD	buy	85731.3	0.00004393	2025-12-18T19:31:11.206000Z
ETH-USDT	sell	2827.54	0.006929	2025-12-18T19:31:11.595000Z
ETH-USD	sell	2827.54	0.006929	2025-12-18T19:31:11.595000Z

Cryptocurrency Materialized Views

The cryptocurrency dataset includes materialized views for aggregated trade data:

Trades Aggregations

• trades_latest_1d - Latest trade data aggregated daily
• trades_OHLC_15m - OHLC candlesticks for cryptocurrency trades at 15-minute intervals

These views are continuously updated and provide faster query performance for cryptocurrency trade analysis.

Cryptocurrency Data Volume

• trades: Approximately 3.7 million rows per day (real cryptocurrency trades)

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Data Retention

FX tables (core_price and market_data) use a 3-day TTL (Time To Live), meaning data older than 3 days is automatically removed. This keeps the demo instance responsive while providing sufficient recent data.

Cryptocurrency trades table has no retention policy and contains historical data dating back to March 8, 2022. This provides over 3 years of real cryptocurrency trade history for long-term analysis and backtesting.

Using the Demo Data

You can run queries against both datasets directly on demo.questdb.io. Throughout the Playbook, recipes using demo data will include a direct link to execute the query.

tip

The demo instance is read-only. For testing write operations (INSERT, UPDATE, DELETE), you'll need to run QuestDB locally. See the Quick Start guide for installation instructions.

Related Documentation

• SYMBOL type
• Arrays in QuestDB
• Designated timestamp
• Time-series aggregations