I checked with the storage team in the company and they saw that I have alot of io on the server. How should I reduce the io that the postgresql uses ?
2017-08-17 9:25 GMT+03:00 Mariel Cherkassky <mariel.cherkas...@gmail.com>: > Hi Daniel, > I already tried to set the destination table to unlogged - it improved the > performance slightly. Is there a way to make sure that I/O is the problem ? > > 2017-08-17 0:46 GMT+03:00 Daniel Blanch Bataller < > daniel.blanch.batal...@gmail.com>: > >> Seems your disks are too slow. On my laptop (nothing special, just one >> disk) using COPY I can dump 3G in ~ 20 secs, loading takes 120 secs, bare >> copying 3G takes 10 secs. >> >> Similar proportion you had, but much faster. >> >> confirm I/O is your bottleneck, and tell us how you solved your problem >> >> Anyway, You can cut import time by half if you set your destination table >> to unlogged (postgres will write half the data, it will save the >> transaction log writing). Remember to set it to logged when finished!! >> >> >> Regards, >> >> Daniel >> >> El 16 ago 2017, a las 16:32, Mariel Cherkassky < >> mariel.cherkas...@gmail.com> escribió: >> >> My server is virtual and it have virtual hd from a vnx storage machine. >> The logs and the data are on the same disk. >> >> 2017-08-16 17:04 GMT+03:00 Daniel Blanch Bataller < >> daniel.blanch.batal...@gmail.com>: >> >>> Considering it has to write logs and data at checkpoints I don’t see it >>> particularly slow compared to the extract phase. What kind of disks you >>> have SSD or regular disks? Different disks for ltransaction logs and data? >>> >>> >>> El 16 ago 2017, a las 15:54, Mariel Cherkassky < >>> mariel.cherkas...@gmail.com> escribió: >>> >>> I run the copy command via psql to create a local dump of a 3G table and >>> it took me 134059.732ms =~2 minutes. After that I imported the data via >>> copy and it took 458648.677ms =~7 minutes. So the copy command works but >>> pretty slow. >>> >>> 2017-08-16 16:08 GMT+03:00 Daniel Blanch Bataller < >>> daniel.blanch.batal...@gmail.com>: >>> >>>> See if the copy command is actually working, copy should be very fast >>>> from your local disk. >>>> >>>> >>>> El 16 ago 2017, a las 14:26, Mariel Cherkassky < >>>> mariel.cherkas...@gmail.com> escribió: >>>> >>>> >>>> After all the changes of the memory parameters the same >>>> operation(without the copy utility) didnt run much faster - it took one >>>> minute less. I made a test with the copy command (without the 'with >>>> binary') and it took 1.5 hours to create the dumpfile in my local >>>> postgresql server. Then I tried to run the copy from the local dump and it >>>> is already running two hours and it didnt even finish. I looked at the >>>> server log and I saw that I run the copy command at 13:18:05, 3 minutes >>>> later checkpoint started and completed and there are no messages in the log >>>> after that. What can I do ? Improving the memory parameters and the memory >>>> on the server didnt help and for now the copy command doesnt help either. >>>> >>>> >>>> >>>> >>>> 2017-08-15 20:14 GMT+03:00 Scott Marlowe <scott.marl...@gmail.com>: >>>> >>>>> On Tue, Aug 15, 2017 at 4:06 AM, Mariel Cherkassky >>>>> <mariel.cherkas...@gmail.com> wrote: >>>>> > Hi, >>>>> > So I I run the cheks that jeff mentioned : >>>>> > \copy (select * from oracle_remote_table) to /tmp/tmp with binary - >>>>> 1 hour >>>>> > and 35 minutes >>>>> >>>>> So 26G takes 95 minutes, or 27 MB/minute or 456k/second? Sound about >>>>> right (it's early, I haven't had enough coffee please check my math). >>>>> That's pretty slow unless you're working across pretty big distances >>>>> with mediocre connections. My home internet downloads about 100MB/s >>>>> by comparison. >>>>> >>>>> > \copy local_postresql_table from /tmp/tmp with binary - Didnt run >>>>> because >>>>> > the remote oracle database is currently under maintenance work. >>>>> >>>>> You shouldn't need the remote oracle server if you've already copied >>>>> it over, you're just copying from local disk into the local pgsql db. >>>>> Unless I'm missing something. >>>>> >>>>> > So I decided to follow MichaelDBA tips and I set the ram on my >>>>> machine to >>>>> > 16G and I configured the effective_cache memory to >>>>> 14G,tshared_buffer to be >>>>> > 2G and maintenance_work_mem to 4G. >>>>> >>>>> Good settings. Maybe set work_mem to 128MB or so while you're at it. >>>>> >>>>> > I started running the copy checks again and for now it coppied 5G in >>>>> 10 >>>>> > minutes. I have some questions : >>>>> > 1)When I run insert into local_postresql_table select * from >>>>> > remote_oracle_table I insert that data as bulk to the local table or >>>>> row by >>>>> > row ? If the answer as bulk than why copy is a better option for >>>>> this case >>>>> > ? >>>>> >>>>> insert into select from oracle remote is one big copy, but it will >>>>> take at least as long as copying from oracle to the local network >>>>> took. Compare that to the same thing but use file_fdw on the file >>>>> locally. >>>>> >>>>> > 2)The copy from dump into the postgresql database should take less >>>>> time than >>>>> > the copy to dump ? >>>>> >>>>> Yes. The copy from Oracle to your local drive is painfully slow for a >>>>> modern network connection. >>>>> >>>>> > 3)What do you think about the new memory parameters that I cofigured >>>>> ? >>>>> >>>>> They should be OK. I'm more worried about the performance of the io >>>>> subsystem tbh. >>>>> >>>> >>>> >>>> >>> >>> >> >> >
