Currently Cockroach isn't performant for concurrent database setup and
tear-down. Instead of a single instance allow setting multiple potential
connection strings and let the tests pick one connection string
randomly.
This improves test duration by ~10 minutes.
While we are at significantly changing how pgtest works, introduce
helper PickPostgres and PickCockroach for selecting the database to
reduce code duplications in multiple places.
Change-Id: I8ad171d5c4c8a4fc081ec2ae9bdd0cc948a80619
This ought to make it so that all single statements (Exec- or Query-) on
a CockroachDB backend will get retried as necessary. As there is no need
for savepoints to be allocated or released in this case, there is no
round-trip overhead except when statements actually do need to be
retried.
Change-Id: Ibd7f1725ff727477c456cb309120d080f3cd7099
