Overview
brisbane-core is a project towards a bzr-2.0 repository format that is faster for very large histories and trees. We're aiming for a development format in March 2009 and for it to be the default format by June -- see FormatDeliveryProcess. Most of the effort of the Bazaar core developers is going into this project or the related networking projects.
The primary branch adding the core format has landed in bzr.dev. The format is called development-rich-root. You'll sometimes hear this referred to as "split-inventory" or "content-hashed-keys" (CHK) or the "brisbane-core" format.
To give a very brief technical summary, the new format is more efficient at storing and processing inventories, making many operations faster. The overall disk space is dramatically reduced.
Of course, making a lower level change always has knock-on effects in higher layers, e.g. some stuff slows down and needs some tweaking accordingly. brisbane-core is the integration branch pulling together the new format and the associated tweaks.
The technical changes here comprise:
- a key-value data structure called CHKMap that records incremental changes to large structures efficiently
- storing the inventory (dict of present files and directories) in a CHKMap
- for the file texts stored for revisions, inventory parts and files, use better byte-by-byte delta compression than knit compression
There are three types of work to be done:
- core engineering
- integrating them with each other; into brisbane-core; and then into bzr.dev
- top-to-bottom testing of the bzr stack
Work still to do
all launchpad brisbane-core bugs
Before release as a stable format -- goal June/July 2009 |
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bug 373455 - Stacking support |
medium-large |
jam working |
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Performance of commit: currently builds a full inventory then diffs it when nontrivial commit parameters are given - needs changes made to iter_changes to improve. bug 347649 |
medium, in progress |
ian working |
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Overhead of subtree support |
medium to high |
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Check/fix performance of annotate bug 374726 |
medium |
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log DIRECTORY speed bug 374730 |
small |
ian working |
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Plan and UI for upgrading multiple branches bug 374734 |
medium |
ian working |
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Plan and UI for upgrading multiple stacked branches bug 374735 |
medium |
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Settle on, document and test a best method for upgrades of stacked upgrades; check this will work with Launchpad. |
large, risky, in-progress |
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Fetching from old branches slow bug 374738 |
large |
spiv, lifeless working |
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Progress reporting for streaming |
medium, in progress bug 374740 |
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Dogfood by Bazaar and Launchpad? |
medium |
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Convert & test MySQL |
small |
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Convert & test emacs |
small |
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Measure headline performance numbers |
small |
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Benchmarking |
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Traffic light report seems to be broken on orcadas and needs to be fixed |
small |
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Configure pre-canned repositories in this format on orcadas |
small |
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Network benchmarks aren't working on orcadas |
medium, risky |
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Launchpad integration (from shortly before beta up to final release) |
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Test with Launchpad |
large, risky |
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Would be nice to do but not necessary for first release |
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Performance of initial full-tree commit: writing a full inventory (the initial commit case) is more raw work than with xml |
medium, risky |
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Add a format for groupcompression against texts not included in that group: this would help with the case of multi-megabyte user files, which otherwise need to be written once for each group where they're changed |
large, risky |
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Allow stacking across heterogenous formats, which will make upgrades easier |
large, risky |
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Fix format-handling UI, eg bug 330494 |
medium |
probably post-2.0 |
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Strip unneeded data from groups when sending them |
large |
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Alternate format index for CHK records |
medium |
probably post 2.0 |
See also Roadmap/BrisbaneCore/Details and Roadmap/BrisbaneCore/PlusOne