launchpad-dev team mailing list archive

[Raphaël Badin <raphael.badin@xxxxxxxxxxxxx>]

> Hi Raphaël
> 
> Speaking off the top of my head, not looking at the query or code etc:
> 
> I'm wondering if "owned branches" for example is really that difficult
> to compute? select count(*) from branch where owner = ?

For ~ubuntu-branches, this query takes ~1 sec.

Unfortunately, the expensive part is not the joins or anything complex
but simply the Seq Scan generated by requesting all the public branches
for ~ubuntu-branches.  This fetches ~300K rows (i.e. a significant
proportion of the whole table) and thus the Seq Scan is the right thing
to do; but it's heavy.

Please have a look at this MP if you want details:
https://code.launchpad.net/~rvb/launchpad/branches-timeout-bug-827935/+merge/80875

(if you want more details:
https://code.launchpad.net/~rvb/launchpad/branches-timeout-bug-827935-always-display/+merge/81022
https://code.launchpad.net/~rvb/launchpad/branches-timeout-bug-827935-3/+merge/81262
https://code.launchpad.net/~rvb/launchpad/branches-timeout-bug-827935-4/+merge/81290)