rocksdb/unreleased_history
Yu Zhang a571cbed17 Use same logic to assign level for non-overlapping files in universal compaction (#13059)
Summary:
When the input files are not overlapping, a.k.a `files_overlap_=false`, it's best to assign them to non L0 levels so that they are not one sorted run each.  This can be done regardless of compaction style being leveled or universal without any side effects.

Just my guessing, this special handling may be there because universal compaction used to have an invariant that sequence number on higher levels should not be smaller than sequence number in lower levels. File ingestion used to try to keep up to that promise by doing "sequence number stealing" from the to be assigned level. However, that invariant is no longer true after deletion triggered compaction is added for universal compaction, and we also removed the sequence stealing logic from file ingestion.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/13059

Test Plan: Updated existing tests

Reviewed By: cbi42

Differential Revision: D64220100

Pulled By: jowlyzhang

fbshipit-source-id: 70a83afba7f4c52d502c393844e6b3273d5cf628
2024-10-11 11:18:45 -07:00
..
behavior_changes Use same logic to assign level for non-overlapping files in universal compaction (#13059) 2024-10-11 11:18:45 -07:00
bug_fixes Re-implement GetApproximateMemTableStats for skip lists (#13047) 2024-10-02 14:25:50 -07:00
new_features Update HISTORY.md, version.h, and the format compatibility check script for the 9.7 release (#13027) 2024-09-20 19:19:06 -07:00
performance_improvements Update history and version for 9.5.fb release (#12880) 2024-07-22 13:15:09 -07:00
public_api_changes Update main branch for 9.6 release (#12945) 2024-08-19 17:36:23 -07:00
README.txt Trigger compaction to the next level if the data age exceeds periodic_compaction_seconds (#12175) 2023-12-28 12:50:08 -08:00
add.sh Some fixes to unreleased_history/ (#11504) 2023-06-02 15:55:02 -07:00
release.sh Update for 8.5.fb branch cut (#11642) 2023-08-02 12:34:11 -07:00

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.