When the planner runs, it needs to determine if any files have tombstones.
The code to determine if a tombstone existed involved stating the .tombstone
file. Since the planner runs very frequently when there are many shards, this
causea a lot of system calls that are unnecessary.
Instead, cache the results of the stats calls and only refresh them when we
haven't checked at least once or we write new tombstone data.
This also caches the results of the TSMReader.Stats call to avoid creating
garbage.
Due to an bug in TSM tombstone files, it was possible to create
empty tombstone files. At startup, the TSM file would error out
and not load the TSM file.
Instead, treat it as an empty v1 file so the TSM file can load
correctly.
Fixes#6641
This adds support for a time range to tombstone files to allow a subset
of points to be deleted instead of the whole series. It changes the
tombstone file format to a binary format and maintains backwards compatibility
with the old text format tombstone files.
This writes a tombstone file containing a line per deleted key. This
file is read when a TSMReader is created and any keys listed in the file
are removed from the index.
Jason Wilder
Ben Johnson