[Feature]: RPC endpoint for the status of off-chain indexing

[julian-amplica]

Feature Description

Details

It would be helpful to be able to query the current state of off-chain indexing (i.e., the last block number processed) in order to run integration tests involving RPC calls against the standalone node.

Thanks!

Possible Related Issues

• I'm attempting to integrate with msa.get_keys_by_msa_id (RPC to Get the List of Keys Associated with an MSA #418)

Searched for Related Issues

• I have done a search for related issues and either found none, or noted them

[JoeCap08055]

I think this could be solved by an RPC response; either additional info returned by msa.get_keys_by_msa_id, or a separate RPC to query the last finalized block scanned by the node when maintaining the off-chain index.
@aramikm , thoughts?

[aramikm]

There is an RPC for the last finalized block
you can call chain_getFinalizedHead() which will return the hash of the latest finalized block and use that hash to call chain_getBlock(block hash) to get the block details

My understanding is that if you call msa. get_keys_by_msa_id rpc in a non-offchain indexing enabled node you will get the following error OffchainIndexingNotEnabled

[JoeCap08055]

There is an RPC for the last finalized block you can call chain_getFinalizedHead() which will return the hash of the latest finalized block and use that hash to call chain_getBlock(block hash) to get the block details

My understanding is that if you call msa. get_keys_by_msa_id rpc in a non-offchain indexing enabled node you will get the following error OffchainIndexingNotEnabled

I think the intent here is to find out what the last finalized block indexed by the offchain-indexer was. This may not be the same as the actual last finalized block on the chain, as there may be some lag in the node's offchain-indexing. Or is this incorrect?

[aramikm]

We will only have some lag in the pre-populating and indexing the data as a one time operation for new rpc nodes. After that it should be in sync in theory. If they are too paranoid they can always count the (finalized - 1) block as their finalized but that also means you are increasing the latency by additional 6 seconds or more.