mirror of https://github.com/facebook/rocksdb.git
af2a36d2c7
Summary: This PR does two things: 1. Adds a new table property `newest_key_time` 2. Uses this property to improve TTL and temperature change compaction. ### Context The current `creation_time` table property should really be named `oldest_ancestor_time`. For flush output files, this is the oldest key time in the file. For compaction output files, this is the minimum among all oldest key times in the input files. The problem with using the oldest ancestor time for TTL compaction is that we may end up dropping files earlier than we should. What we really want is the newest (i.e. "youngest") key time. Right now we take a roundabout way to estimate this value -- we take the value of the _oldest_ key time for the _next_ (newer) SST file. This is also why the current code has checks for `index >= 1`. Our new property `newest_key_time` is set to the file creation time during flushes, and the max over all input files for compactions. There were some additional smaller changes that I had to make for testing purposes: - Refactoring the mock table reader to support specifying my own table properties - Refactoring out a test utility method `GetLevelFileMetadatas` that would otherwise be copy/pasted in 3 places Credit to cbi42 for the problem explanation and proposed solution ### Testing - Added a dedicated unit test to my `newest_key_time` logic in isolation (i.e. are we populating the property on flush and compaction) - Updated the existing unit tests (for TTL/temperate change compaction), which were comprehensive enough to break when I first made my code changes. I removed the test setup code which set the file metadata `oldest_ancestor_time`, so we know we are actually only using the new table property instead. Pull Request resolved: https://github.com/facebook/rocksdb/pull/13083 Reviewed By: cbi42 Differential Revision: D65298604 Pulled By: archang19 fbshipit-source-id: 898ef91b692ab33f5129a2a16b64ecadd4c32432 |
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| behavior_changes | ||
| bug_fixes | ||
| new_features | ||
| performance_improvements | ||
| public_api_changes | ||
| README.txt | ||
| add.sh | ||
| release.sh | ||
README.txt
Adding release notes -------------------- When adding release notes for the next release, add a file to one of these directories: unreleased_history/new_features unreleased_history/behavior_changes unreleased_history/public_api_changes unreleased_history/bug_fixes with a unique name that makes sense for your change, preferably using the .md extension for syntax highlighting. There is a script to help, as in $ unreleased_history/add.sh unreleased_history/bug_fixes/crash_in_feature.md or simply $ unreleased_history/add.sh will take you through some prompts. The file should usually contain one line of markdown, and "* " is not required, as it will automatically be inserted later if not included at the start of the first line in the file. Extra newlines or missing trailing newlines will also be corrected. The only times release notes should be added directly to HISTORY are if * A release is being amended or corrected after it is already "cut" but not tagged, which should be rare. * A single commit contains a noteworthy change and a patch release version bump Ordering of entries ------------------- Within each group, entries will be included using ls sort order, so important entries could start their file name with a small three digit number like 100pretty_important.md. The ordering of groups such as new_features vs. public_api_changes is hard-coded in unreleased_history/release.sh Updating HISTORY.md with release notes -------------------------------------- The script unreleased_history/release.sh does this. Run the script before updating version.h to the next development release, so that the script will pick up the version being released. You might want to start with $ DRY_RUN=1 unreleased_history/release.sh | less to check for problems and preview the output. Then run $ unreleased_history/release.sh which will git rm some files and modify HISTORY.md. You still need to commit the changes, or revert with the command reported in the output. Why not update HISTORY.md directly? ----------------------------------- First, it was common to hit unnecessary merge conflicts when adding entries to HISTORY.md, which slowed development. Second, when a PR was opened before a release cut and landed after the release cut, it was easy to add the HISTORY entry to the wrong version's history. This new setup completely fixes both of those issues, with perhaps slightly more initial work to create each entry. There is also now an extra step in using `git blame` to map a release note to its source code implementation, but that is a relatively rare operation.