The problem was that the restriction on the JOIN clause does not properly filter the complete set, but actually results in wrongly joining the CFDs.
This resulted in two CFDs returned, where one was wrongly assembled (the id of the first one, but the data of the second one).
In a cases where the wrong one is the first one in the list of returned CFDs we would run into an error when inserting a new state, because we would try to alter the state of a wrong CFD.
Fixed by joining on the id and filtering for the order.uuid in the where clause.
Note:
I also tested to add the `and orders.uuid = ?` restriction to the first join clause (in addition to the id clause) which might theoretically be more optimized.
That would work as well, but I found it harder to reason about it. As part of the overall where clause one can see the restriction to exactly this value more clearly.
"query":"\n select\n cfds.id as cfd_id,\n orders.uuid as order_id,\n orders.initial_price as price,\n orders.min_quantity as min_quantity,\n orders.max_quantity as max_quantity,\n orders.leverage as leverage,\n orders.trading_pair as trading_pair,\n orders.position as position,\n orders.origin as origin,\n orders.liquidation_price as liquidation_price,\n orders.creation_timestamp as creation_timestamp,\n orders.term as term,\n cfds.quantity_usd as quantity_usd,\n cfd_states.state as state\n from cfds as cfds\n inner join orders as orders on cfds.order_uuid = ?\n inner join cfd_states as cfd_states on cfd_states.cfd_id = cfds.id\n where cfd_states.state in (\n select\n state\n from cfd_states\n where cfd_id = cfds.id\n order by id desc\n limit 1\n )\n ",
"query":"\n select\n cfds.id as cfd_id,\n orders.uuid as order_id,\n orders.initial_price as price,\n orders.min_quantity as min_quantity,\n orders.max_quantity as max_quantity,\n orders.leverage as leverage,\n orders.trading_pair as trading_pair,\n orders.position as position,\n orders.origin as origin,\n orders.liquidation_price as liquidation_price,\n orders.creation_timestamp as creation_timestamp,\n orders.term as term,\n cfds.quantity_usd as quantity_usd,\n cfd_states.state as state\n from cfds as cfds\n inner join orders as orders on cfds.order_id = orders.id\n inner join cfd_states as cfd_states on cfd_states.cfd_id = cfds.id\n where cfd_states.state in (\n select\n state\n from cfd_states\n where cfd_id = cfds.id\n order by id desc\n limit 1\n )\n and orders.uuid = ?\n ",
Daniel Karzel
3 years ago