[WIP] Dictionary compressed arrangements #32095
Draft
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
frankmcsherry
force-pushed
the
dictionary_arrangements
branch
7 times, most recently
from
5768a61 to
6b555df
Compare
frankmcsherry
force-pushed
the
dictionary_arrangements
branch
from
6b555df to
35774af
Compare
antiguru
reviewed
Jun 6, 2025
Member
antiguru
left a comment
antiguru
left a comment
There was a problem hiding this comment.
Left some feedback, but otherwise I like the change. We should figure out the runtime overhead, but I suspect it won't be too bad.
Comment on lines
+1169
to
+1313
| fn report(&self) { | ||
| if self.total > 500000 { | ||
| //} && self.columns.iter().all(|c| c.decode.len() > 0) { | ||
| println!( | ||
| "REPORT: {:?} -> {:?} (x{:?})", | ||
| self.total, | ||
| self.bytes, | ||
| self.total / self.bytes | ||
| ); | ||
| println!("COLUMNS: {:?}", self.columns.len()); | ||
| for column in self.columns.iter() { | ||
| column.report() | ||
| } | ||
| } | ||
| } |
Member
There was a problem hiding this comment.
This might need to change before we turn it on in prod :) I think it'd be fine to use trace! instead.
Comment on lines
+1186
to
+1321
| ColumnsIter { | ||
| index: None, | ||
| column: 0, | ||
| data: row.data(), | ||
| } |
Member
There was a problem hiding this comment.
This could call without_codec instead. Would require unsafe and the associated safety argument, but then we'd have a comment as to why this is safe.
Comment on lines
+1472
to
+1620
| // /// Allocates a Misra-Gries summary which intends to hold up to `k` examples. | ||
| // /// | ||
| // /// After `n` insertions it will contain only elements that were inserted at least `n/k` times. | ||
| // /// The actual memory use is proportional to `2 * k`, so that we can amortize the consolidation. | ||
| // pub fn with_capacity(k: usize) -> Self { | ||
| // Self { | ||
| // inner: Vec::with_capacity(2 * k), | ||
| // } | ||
| // } |
Member
There was a problem hiding this comment.
Nit: Remove, or allow dead code.
Comment on lines
+1338
to
+1493
| fn report(&self) { | ||
| let mut tags_used = 0; | ||
| tags_used += self.stats.1[0].count_ones(); | ||
| tags_used += self.stats.1[1].count_ones(); | ||
| tags_used += self.stats.1[2].count_ones(); | ||
| tags_used += self.stats.1[3].count_ones(); | ||
| let mg = self.stats.0.clone().done(); | ||
| let mut bytes = 0; | ||
| for (vec, _count) in mg.iter() { | ||
| bytes += vec.len(); | ||
| } | ||
| // if self.total > 10000 && !mg.is_empty() { | ||
| println!( | ||
| "\t{:?}v{:?}: {:?} -> {:?} + {:?} = (x{:?})", | ||
| tags_used, | ||
| mg.len(), | ||
| self.total, | ||
| self.bytes, | ||
| bytes, | ||
| self.total / (self.bytes + bytes), | ||
| ) | ||
| // } | ||
| } |
Member
There was a problem hiding this comment.
Remove, or use tracing instead.
| /// Enable per-column dictionary compression for row containers in arrangements. | ||
| pub const ENABLE_ARRANGEMENT_DICTIONARY_COMPRESSION: Config<bool> = Config::new( | ||
| "enable_arrangement_dictionary_compression", | ||
| true, |
Member
There was a problem hiding this comment.
Suggested change
| true, | |
| false, |
Please disable by default before you merge.
antiguru
force-pushed
the
dictionary_arrangements
branch
2 times, most recently
from
8df3452 to
1d08926
Compare
frankmcsherry
force-pushed
the
dictionary_arrangements
branch
from
1d08926 to
5ea8e0c
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Evolving PR for enabling dictionary compression in arrangements.
Roughly, as each
row: &[u8]is presented, we'll rip it apart into columns, and look for the option to use otherwise unused byte patterns (tags, otherwise used for row decoding) to reference popular values in each column. Columns are encoded independently, so things can be differently popular in different columns.Fair bit of work still to do, but checking in for the moment.
Motivation
Tips for reviewer
Checklist
$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way), then it is tagged with aT-protolabel.