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Summary: Implement block cache lookup to determine readahead_size during scans. It's enabled if auto_readahead_size, block_cache and iterate_upper_bound - all three are set. Design - 1. Whenever there is a cache miss and FilePrefetchBuffer is called, a callback is made to determine readahead_size for that prefetching. 2. The callback iterates over index and do block cache lookup for each data block handle until existing readahead_size is reached. Then It removes the cache hit data blocks from end to calculate optimized readahead_size. 3. Since index_iter_ is moved, it stores block handles in a queue, and use that queue to get block handle instead of doing index_iter_->Next(). 4. This is for Sync scans. Async scans support is in progress. NOTE: The issue right now is after Seek and Next, if Prev is called, there is no way to do Prev operation. index_iter_ is already pointing to a different block. So it returns "Not supported" in that case with error message - "auto tuning of readahead size is not supported with Prev op" Pull Request resolved: https://github.com/facebook/rocksdb/pull/11860 Test Plan: - Added new unit test - crash_tests - Running scans locally to check for any regression Reviewed By: anand1976 Differential Revision: D49548118 Pulled By: akankshamahajan15 fbshipit-source-id: f1aee409a71b4ad9e5bf3610f43edf30c6630c78 |
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| .. | ||
| behavior_changes | ||
| bug_fixes | ||
| new_features | ||
| performance_improvements | ||
| public_api_changes | ||
| add.sh | ||
| README.txt | ||
| release.sh | ||
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 develpment 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 slighly 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.