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Storage state diffs

State diffs for historical blocks are currently available from SQD Network on the same basis as all other data stored there: for free. If you deploy a squid that indexes traces in real-time to SQD Cloud and use our RPC addon, the necessary trace_ or debug_ RPC calls made will be counted alongside all other calls and the price will be computed for the total count. There are no surcharges for traces or state diffs.

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addStateDiff(options) {#add-state-diff}

Subscribe to changes in the contract storage. This allows for tracking the contract state changes that are difficult to infer from events or transactions, such as the changes that take into account the output of internal calls. options has the following structure: 
{
  // data requests
  address?: string[]
  key?: string[]
  kind?: ('=' | '+' | '*' | '-')[]
  range?: \{from: number, to?: number\}

  // related data retrieval
  transaction?: boolean
}
The data requests here are:
  • address: the set of addresses of contracts to track. Leave undefined to subscribe to state changes of all contracts from the whole network.
  • key: the set of storage keys that should be tracked. Regular hexadecimal contract storage keys and special keys ('balance', 'code', 'nonce') are allowed. Leave undefined to subscribe to all state changes.
  • kind: the set of diff kinds that should be tracked. Refer to the StateDiff section of data items documentation for an explanation of the meaning of the permitted values.
  • range: the range of blocks within which the storage changes should be tracked.
Enabling the transaction flag will cause the processor to retrieve the transaction that gave rise to each state change and add it to the transactions iterable of block data. Note that state diffs can also be requested by the addTransaction() method as related data. Selection of the exact data to be retrieved for each state diff item and its optional parent transaction is done with the setFields() method documented on the Field selection page. Unlike other data items, state diffs do not have any fields that can be enabled, but some can be disabled for improved sync performance.