Sorry, I had meant to reply to all. On Fri, Jan 29, 2010 at 9:53 AM, Jonathan Lange <[email protected]> wrote: > On Thu, Jan 28, 2010 at 7:30 PM, Abel Deuring > <[email protected]> wrote: >> Hi Stuart, hi Jono, >> > > Hello Abel, > >> Tom and myself started to work on sorting bugs/bugtasks by the age of >> the youngest patch attachment (see >> https://bugs.edge.launchpad.net/malone/+bug/506018 , >> https://bugs.edge.launchpad.net/malone/+bug/512500 ). Basically, this >> means to add an option "sort by creation time of youngest patch >> attachment" to IHasBugs.searchTasks(). >> >> We are a bit concerned that a regulary query, where we sort by the >> youngest patch via something like >> >> ORDER BY (SELECT max(message.datecreated) >> FROM message, bugattachment >> WHERE bugattachment.message=message.id AND >> bugattachment.bug=<bug.id from main query> AND >> bugattachment.type=1) >> >> in a query like "SELECT BugTask.whatever FROM BugTask,... WHERE...", >> might easily lead to timeouts when this sorting is used for Ubuntu >> bugs... (Tom wanted to write such a query for a test on staging, so we >> might soon have some data.) >> > > Have you got data yet? > >> So we also considered to add a column date_created_youngest_patch to the >> table Bug, where this column would be updated only by triggers for >> changes of the table BugAttachment, like so: >> > ... >> In other words, a deliberate denormalisation. What do you think, should >> we start with a plain query without such a denormalsation, or do you >> think that it is better to add the "cache column" >> date_created_youngest_patch to the Bug table? >> > > This is really Stuart's province. I don't have a strong opinion on this. > > However, it seems to me that we're getting increasingly frequent > requests to denormalize data in order to make querying faster. Perhaps > we need a general answer, or some other technology. > > jml >
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