I'd like to continue exploring this, just not quite sure of the appropriate way forward.  I gather doing work like this on the toolforge bastion hosts is frowned upon, so I guess what I should be doing is spinning up a VPS instance on https://horizon.wikimedia.org/?  I've been reading through https://wikitech.wikimedia.org/wiki/Help:Cloud_VPS_Instances, from which I gather I need to be a project admin.  Is there some existing project I can join to do this exploratory work, or should I create a new project?

On Mar 31, 2021, at 10:35 PM, Roy Smith <roy@panix.com> wrote:

Thanks for looking into this.  I tried this again a little later, and it ran fine.  Odd that the amount of memory used depends on the number of rows.  I would expect it would stream results to stdout as they came in, but apparently not.

Even weirder that the 100M example runs OOM in 10s, while the 10M example runs to completion in 36s.  Could it be pre-allocating buffer space for the number of rows it expects to ultimately get?  Ugh, that would be a crazy design, but it does seem like that's what's happening.

On Mar 31, 2021, at 9:47 PM, Brooke Storm <bstorm@wikimedia.org> wrote:

On Mar 31, 2021, at 5:18 PM, Roy Smith <roy@panix.com> wrote:

I'm just playing around on tools-sgebastion-08.  I can dump the first 1 million image names about half a minute:

tools.spi-tools-dev:xw-join$ time mysql  --defaults-file=$HOME/replica.my.cnf -h commonswiki.web.db.svc.wikimedia.cloud commonswiki_p -N -e 'select img_name from image limit 10000000 ' > /dev/null

real    0m36.586s

user    0m9.678s

sys     0m1.324s

but if I try 10 million, it fails:

tools.spi-tools-dev:xw-join$ time mysql  --defaults-file=$HOME/replica.my.cnf -h commonswiki.web.db.svc.wikimedia.cloud commonswiki_p -N -e 'select img_name from image limit 100000000 ' > /dev/null

Killed

real    0m9.875s

user    0m1.417s

sys     0m1.561s

Is there some maximum query size configured by default?  The full image table on commons is about 70M rows, so extrapolating from the first example, something like 1 hour to move all that data.

That could be RAM limits on the bastion. 

Actually, scratch that, I’ve confirmed you were killed by the OOM killer on that bastion:

Mar 31 23:29:17 tools-sgebastion-08 kernel: [2860588.199138] mysql invoked oom-killer: gfp_mask=0x6000c0(GFP_KERNEL), nodemask=(null), order=0, oom_score_adj=0

-Brooke_______________________________________________
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