Too many queries cause block importing to crash.

[winder]

Summary

If the indexer is receiving many requests it's possible to hit the Postgres client limit.

I reproduced this with a docker environment which was sending lots of queries to indexer over and over again.

indexer-postgres | 2021-06-01 16:36:04.546 UTC [823] FATAL:  sorry, too many clients already
indexer       | {"error":"error committing block, CommitBlock(): pq: sorry, too many clients already","level":"error","msg":"ImportDecodedBlock 9","time":"2021-06-01T16:36:04Z"}

Scope/Requirements

Make sure we can recover gracefully from Postgres failures during block import.

Urgency/Relative Priority

[winder]

Resolved by #554, I can no longer reproduce this