launchpad-dev team mailing list archive

[Robert Collins <robertc@xxxxxxxxxxxxxxxxx>]

On Wed, Jan 26, 2011 at 4:18 PM, Aaron Bentley <aaron@xxxxxxxxxxxxx> wrote:
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> On 11-01-25 09:46 PM, Robert Collins wrote:
>> given the performance benefits history-db offers I imagine little
>> trouble scheduling it.
>
> Also, history-db is the leading candidate for replacing the
> BranchRevision table:
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> https://dev.launchpad.net/Code/BranchRevisions

Thats a very interesting analysis; I don't see anything there about
using a general purpose graph DB  - did you consider that? (e.g.
flockdb). The general approach in graph heavy domains seems to be:
 - store the original data so that it can be updated easily
 - preprocess graphs such that important questions can be answered rapidly

History db seems like a very specific preprocessing answer to me; its
nice (very nice!) but I'm wondering if we'll get more leverage in
Launchpad by bringing in a slightly heavier tool which can answer all
the things we need for bzr straight away, replace our
TeamParticipation construct (1.3M rows) , let us do the graph logic
needed in derivative distributions, blueprint dependencies (a
transitive data structure when the issue tracker arrives), and
similarly bug dependencies and project relationships.

That said, whoever is working on the problems history-db-in-lp should
solve should solve it as they think best - I'm thinking long term and
will probably schedule a card for consolidating all this stuff
sometime after LEP/Search.

-Rob