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 mailto: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
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