Inconsistent ledger view in /accounts/{id} when streaming

[bartekn]

I noticed Some extra balances error in /accounts/{id} stream. At first, I thought that it was the inconsistency issue propagated from stellar-core (we build Account object using a few DB queries without REPEATABLE READ transaction). But then I realized that we don't use REPEATABLE READ transaction in Horizon DB while streaming.

We should update the streaming code to start a REPEATABLE READ transaction (if not in a transaction already) before calling an action function and then rollback (only if not in a previously started transaction).

Additionally, we may do the same thing for a function getting data from core inside the action however we should first check if it affects core DB in any way.

[bartekn]

Additionally, we may do the same thing for a function getting data from core inside the action however we should first check if it affects core DB in any way.

We've seen another instance today for non-streaming request and the reason is getting data from core in multiple requests. So we should probably add start a new REPEATABLE READ transaction when getting data from Stellar-Core.