When networking-bgpbpn fetches a bgpvpn object from the database through sqlalchemy, it will use the relations with networks and routers eagerly. This means it will build a query whose skeleton is:
SELECT <columns (240) FROM bgpvpns
LEFT OUTER JOIN bgpvpn_network_associations ON bgpvpns.id = bgpvpn_network_associations.bgpvpn_id LEFT OUTER JOIN networks ON networks.id = bgpvpn_network_associations.network_id
...
LEFT OUTER JOIN bgpvpn_router_associations ON bgpvpns.id = bgpvpn_router_associations.bgpvpn_id
LEFT OUTER JOIN routers ON routers1.id = bgpvpn_router_associations.router_id
...
There are two problems:
- A huge query fetching 240 columns at once and performing 45 outer joins
- An explosion of the number of rows returned: if there are i networks and j routers, there will be i*j rows leading to a potential combinatorial explosion in the size of the result.
The problem is exacerbated by the fact that a single network or routers can be represented by several rows for the same reason (if it has several tags, subnets, rbac rules, prefix in subnetpools, explicit routes etc. )
The solution is to use lazy="select" for the relations between bgpvpn and bgpvpn_network_associations on one hand and bgpvpn_router_assocations on the other hand.
Fix proposed to branch: master
Review: https:/