before this change, we use the default options when creating `test_env`,
and the default options enable `use_uuid`. but the modes of
`perf-sstables` involving reads assumes that the identifiers are
deterministic. so that the previously written sstables using the "write"
mode can be read with the modes like "index_read", which just uses
`test_env::make_sstable()` in `load_sstables()`, and under the hood,
`test_env::make_sstable()` uses `test_env::new_generation()` for
retrieving the next identifier of sstable. when using integer-base
identifier, this works. as the sstable identifiers are generated
from a monotonically increasing integer sequence, where the identifiers
are deterministic. but this does not apply anymore when the UUID-based
identifiers are used, as the identifiers are generated with a
pseudorandom generator of UUID v1.
in this change, to avoid relying on the determinism of the integer-based
sstable identifier generation, we enumerate sstables by listing the
given directory, and parse the path for their identifier.
after this change, we are able to support the UUID-based sstable
identifier.
another option is disable the UUID-based sstable identifier when
loading sstables. the upside is that this approach is minimal and
straightforward. but the downside is that it encodes the assumption
in the algorithm implicitly, and could be confusing -- we create
a new generation for loading an existing sstable with this generation.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#20183
4a405b0af9