Polkadot is a relay chain with a set of system chains beside it, each handling one job of its own. Every one is its own dataset, queried as <chain_id>.<table>, and all of them have the same three core tables. The relay chain has two more.
| Chain | chain_id | Since | What it holds |
|---|
| Relay chain | polkadot | 2020-06 | Consensus and the chains connected to it. |
| Asset Hub | polkadotassethub | 2021-12 | Fungible and non-fungible assets. Its tokens reach the token list. |
| Bridge Hub | polkadotbridgehub | 2023-05 | Bridges from Polkadot to other networks. |
| Collectives | polkadotcollectives | 2022-11 | On-chain bodies, including the Technical Fellowship. |
| Coretime | polkadotcoretime | 2024-09 | Sales of blockspace to the chains that use it. |
| People | polkadotpeople | 2024-07 | Identities, which moved off the relay chain onto their own. |
Every column is documented at Substrate βΈ Overview.
Asset Hub is where Polkadotβs tokens live, and those reach the catalogβs token list. Chains covers the list of chains and the daily tables built on it. Tokens covers the token list.
Every chain above has blocks, extrinsics and events. The relay chain has two more.
| Table | Chains | Description |
|---|
blocks | All | One row per block, with its author and extrinsic count. |
extrinsics | All | One row per extrinsic, the Substrate equivalent of a transaction. |
events | All | One row per event emitted during block execution. |
initialize_finalize_events | polkadot | Events emitted while a block is initialized and finalized. |
chain_ids | polkadot | A mapping of numeric ids to chain identifiers. |
initialize_finalize_events has the same columns as events; it was retired on 2024-07-29 and its history ends there. chain_ids is unpartitioned and has two columns, id and chain_id.
Sample queries
The tables split by day on block_timestamp (blocks on timestamp). Bound that column in every query; without a bound the query reads the whole table.
Event-emitting pallets
One system chain
Chain entry lookup
Rank event-emitting pallets on the relay chain on one day. Count daily extrinsics on Asset Hub over one week. Swap the dataset name for any other chain in the table above; the shape is the same. Look up Polkadotβs chain entry and the project it belongs to.