Open a location as a zarr group, trying format 3 before format 2.
The same v2-first default that openStore works around bites a second
time, independently: zarrita.open consults its version counter keyed on the
STORE OBJECT, and the consolidated wrapper openStore returns is a brand-new
object the counter has never seen. So the very first open on a format-3
store probes .zattrs and then .zgroup — two more 404s, measured at 279 ms
and 269 ms — before falling back to v3.
Only the FIRST open pays it (a successful open increments the counter, so
later array opens already guess v3), which is why this helper is needed only
for the root group and not everywhere.
Falls back to the format-guessing open when the v3 attempt reports a
missing node, so a genuine format-2 store still loads.
Open a location as a zarr group, trying format 3 before format 2.
The same v2-first default that openStore works around bites a second time, independently:
zarrita.openconsults its version counter keyed on the STORE OBJECT, and the consolidated wrapperopenStorereturns is a brand-new object the counter has never seen. So the very firstopenon a format-3 store probes.zattrsand then.zgroup— two more 404s, measured at 279 ms and 269 ms — before falling back to v3.Only the FIRST open pays it (a successful open increments the counter, so later array opens already guess v3), which is why this helper is needed only for the root group and not everywhere.
Falls back to the format-guessing open when the v3 attempt reports a missing node, so a genuine format-2 store still loads.