BlockDataStore

Documentation for eth_defi.event_reader.block_data_store.BlockDataStore Python class.

class BlockDataStore

Persistent storage interface to store aby processed data from blockchains.

Store any block data that is block oriented

• Input is indexed by the block number

• Input and output as py:class:pd.DataFrame

• Append writes with chain reorganisation support

• Partial tail reads

Used for

• Cache downlaoded block headers and timestamps, so you do not need to fetch them again over JSON-RPC when restarting an application.

• Cache downlaoded trades

The input data

• Must be py:class:pd.DataFrame

• Must have key block_number

• Must have key partition if the storage implementation does partitioning. This can be the block number rounded down to the nearest partition chunk.

Methods summary

__init__()
is_virgin()	Has this store any stored data.
load([since_block_number])	Load data from the store.
peak_last_block()	Get the block number of the last data entry stored.
save(data)	Save to the store.
save_incremental(data)	Save the latest data to the store.

abstract is_virgin()

Has this store any stored data.

Returns

There is data to load.

Return type

bool

abstract load(since_block_number=0)

Load data from the store.

Parameters

since_block_number (int) –

Return only blocks after this (inclusive).

The actual read datasets may contain more blocks due to partition boundaries.

Returns

Data read from the store.

Return type

pandas.core.frame.DataFrame

abstract save(data)

Save to the store.

Parameters

data (pandas.core.frame.DataFrame) –

abstract save_incremental(data)

Save the latest data to the store.

Write the minimum amount of data to the disk we think is

• Valid

• Needs to be written to keep partitions intact

Usually this is data worth of two partitions.

Parameters

data (pandas.core.frame.DataFrame) – Must have column ‘block_number’. Must have column partition if partitioning is supported.

Returns

Block range written (inclusive).

Return type

Tuple[int, int]

abstract peak_last_block()

Get the block number of the last data entry stored.

Returns

None if the store is empty.

Return type

Optional[int]