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Re: RFC: Pausing a query thread


hi marian, you told what i'm think, the main problem is 'pause' query and
'continue' query without disconnect the user, not the priority level

i think that MDEV-4623 is the solution to our problems, plus some others
tunes and automatic scripts that check that a query is blocking the system
and pausing / unpausing it (that what twitter patch do)

the automatic script need information about query since we can't pause a
query 100000 times, or the query will not be executed and process will hang
for a long time (maybe with many memory allocated at client side)

i think that, the main point is MDEV-4623, a interface to control mariadb
the twitter patch MDEV-4427 is interesting since it will kill the query,
but it is a problem sometimes since some applications just stop or give bad
results to a killed query. A pause/unlock is a nice feature
the nice part of twitter patch is the background thread to monitor queries,
instead of doing a external script, they implement it inside server (maybe
a daemon plugin should help us here, instead of a server patch in main line)

any other point that i lost? and we should add to mdev, and after develop?

i don't know if GSoC (google summer of code) will help us, but maybe
someone can help developing this MDEVs
mariadb team is very nice, but we can't force them to do everything we
want, i send some patchs and they accept them with some conditions about
code quality and community use, example display a strange value to priority
column in processlist, like: "HIGH_PRIORITY_CLASS" instead of "HIGH

i'm not from mariadb team, but i can help writing patchs when possible and
writing MDEV feature request to don't lost usefull/interesting ideas