Known limitation relating to Epoch querying

[rhyslbw]

Currently querying epochs using an order_by argument performs poorly due since the nature of the database design is not optimised for read performance.

{
  epochs(limit: 5, order_by: { number: desc }) {
    ...
  }
}

Instead, the recommended approach is to get the current epoch:

{
  cardano {
    currentEpoch
  }
}

then select the epochs by number (eg latest from the above query is 35):

{
 epochs(where: { number: { in: [35,34,33,32,31]}}) {
    ...
  }
}

[rhyslbw]

input-output-hk/cardano-explorer#188 will resolve this