...unless the client requests it specifically using a new flag:
X-Backend-Auto-Create: true
Previously, you could get real jittery listings during a rebalance:
* Partition with a shard DB get reassigned, so one primary has no DB.
* Proxy makes a listing, gets a 404, tries another node. Likely, one of
the other shard replicas responds. Things are fine.
* Update comes in. Since we use the auto_create_account_prefix
namespace for shards, container DB gets created and we write the row.
* Proxy makes another listing. There's a one-in-three chance that we
claim there's only one object in that whole range.
Note that unsharded databases would respond to the update with a 404 and
wait for one of the other primaries (or the old primary that's now a
hand-off) to rsync a whole DB over, keeping us in the happy state.
Now, if the account is in the shards namespace, 404 the object update if
we have no DB. Wait for replication like in the unsharded case.
Continue to be willing to create the DB when the sharder is seeding all
the CREATED databases before it starts cleaving, though.
Change-Id: I15052f3f17999e6f432951ba7c0731dcdc9475bb
Closes-Bug: #1881210
ce4c0fb14b