CreateAndConnect connects and creates the requested DB (dropping if exists) then returns a new connection to the created DB.
ExecPgbench returns a ready-to-run pgbench Cmd, that will run against the db specified by `pgURL`.
RunOne executes one iteration of the query batch that `pgbench` executes.
SetupBenchDB sets up a db with the schema and initial data used by `pgbench`. The `-i` flag to `pgbench` is usually used to do this when testing postgres but the statements it generates use postgres-specific flags that cockroach does not support. The queries this script runs are based on a dump of a db created by `pgbench -i`, but sticking to the compatible subset that both cockroach and postgres support.
SetupExec creates and fills a DB and prepares a `pgbench` command to be run against it.