id/counter for database_api::get_trade_history

[vanissoft]

For make use of get_trade_history could be easier if the return could have an op id or something unique and ordered.
At this moment is returned date but fall in problems where there are many ops in the same second.

[oxarbitrage]

Yes, we had the same issue with a new call i was trying to make very similar to this, it was get_account_history_by_date that was later discarded(not by this problem exactly but due others + this).
At that time we had a few workarounds for it but we cant apply here so easy as this is a production call, with clients using it as we speak so we can't change results format and can't add arguments to the call(like a start) without breaking some of this apps.

here are a few options to discuss, they all have some pros and cons:

1. create new get_trade_history2, add an id to the results and add a start parameter to call.
2. use current one and add to results all the trades until the time::second is finished bypassing the hard coded limit of 100. this haves the problem that one call can return 100 results, other 120 , etc.
3. check the impact(what is the max number of trades per second the blockchain saw) and extend the limit.

[vanissoft]

For me the limits are ok. Only have to make a loop with the calls. For id i think that it could be done adding some digits in the date when there are orders that fall in the same second.

[abitmore]

create new get_trade_history2, add an id to the results and add a start parameter to call.

I like this approach. Will work on it in #455.

[abitmore]

See #455, get_trade_history API now returns a sequence in each row, which can be used as start in the new get_trade_history_by_sequence API.

[abitmore]

Implemented in #455.