Summary:
Similarly to how https://github.com/facebook/rocksdb/issues/7345
integrated blob file writing into the flush process,
the patch adds support for writing blob files to the compaction logic.
Namely, if `enable_blob_files` is set, large values encountered during
compaction are extracted to blob files and replaced with blob indexes.
The resulting blob files are then logged to the MANIFEST as part of the
compaction job's `VersionEdit` and added to the `Version` alongside any
table files written by the compaction. Any errors during blob file building fail
the compaction job.
There will be a separate follow-up patch to perform blob garbage collection
during compactions.
In addition, the patch continues to chip away at the mess around computing
various compaction related statistics by eliminating some code duplication
and by making the `num_output_files` and `bytes_written` stats more consistent
for flushes, compactions, and recovery.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7573
Test Plan: `make check`
Reviewed By: riversand963
Differential Revision: D24404696
Pulled By: ltamasi
fbshipit-source-id: 21216af3a172ad3ce8f85d11cd30923784ae426c
a7a04b6898