2018-01-14 19:09 GMT-08:00 Justin Pryzby <pryzby@xxxxxxxxxxxxx>: > On Sun, Jan 14, 2018 at 06:25:40PM -0800, Neto pr wrote: >> > The query plan is all garbled by mail , could you resend? Or post a link from >> > https://explain.depesz.com/ > > On Sun, Jan 14, 2018 at 06:36:02PM -0800, Neto pr wrote: >> I was not able to upload to the site, because I'm saving the execution >> plan in the database, and when I retrieve it, it loses the line breaks, > > That's why it's an issue for me, too.. > >> > What OS/kernel are you using? LVM? filesystem? I/O scheduler? partitions? >> >> See below the Disk FileSystem -------------------------------- >> root@hp2ml110deb:/# fdisk -l >> Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors >> >> Disk /dev/sdb: 465.8 GiB, 500107862016 bytes, 976773168 sectors >> Units: sectors of 1 * 512 = 512 bytes >> Sector size (logical/physical): 512 bytes / 512 bytes >> I/O size (minimum/optimal): 512 bytes / 512 bytes >> ---------------------------------------------------------------------------- > What about sdb partitions/FS? I used EXT4 filesystem in Debian SO. > > On Sun, Jan 14, 2018 at 06:25:40PM -0800, Neto pr wrote: >> The DBMS and tablespace of users is installed in /dev/sdb SSD. > > Is that also a temp_tablespace ? Or are your hashes spilling to HDD instead ? > How can I find out where my temp_tablesapce is? With the command \db+ (see below) does not show the location. But the DBMS I asked to install inside the SSD, but how can I find out the exact location of the temp_tablespace ? ---------------------------------------------------------------------------- tpch40gnorssd=# \db+ List of tablespaces Name | Owner | Location | Access privileges | Options | Size | Description ------------+----------+--------------------------------+-------------------+---------+--------+------------- pg_default | postgres | | | | 21 MB | pg_global | postgres | | | | 573 kB | tblpgssd | postgres | /media/ssd500gb/dados/pg101ssd | | | 206 GB | (3 rows) ------------------------------------------------------------------------------ > Group Key: nation.n_name, (date_part(_year_::text, (orders.o_orderdate)::timestamp without time zone)) > Buffers: shared hit=3773802 read=7120852, temp read=3550293 written=3541542 > > Are your SSD being used for anything else ? > > What about these? > >> > readahead? blockdev --getra > About knowing if the SSD is being used by another process, I will still execute the command and send the result. But I can say that the SSD is only used by the DBMS. Explaining better, My server has an HDD and an SSD. The Debian OS is installed on the HDD and I installed the DBMS inside the SSD and the data tablespace also inside the SSD . The server is dedicated to the DBMS and when I execute the queries, nothing else is executed. I still can not understand how an HDD is faster than an SSD. I ran queries again on the SSD and the results were not good see: execution 1- 00:16:13 execution 2- 00:25:30 execution 3- 00:28:09 execution 4- 00:24:33 execution 5- 00:24:38 Regards Neto >> > If you're running under linux, maybe you can just send the output of: >> > for a in /sys/block/sdX/queue/*; do echo "$a `cat $a`"; done >> > or: tail /sys/block/sdX/queue/{minimum_io_size,optimal_io_size,read_ahead_kb,scheduler,rotational,max_sectors_kb,logical_block_size,physical_block_size} > >> > Can you reproduce the speed difference using dd ? >> > time sudo dd if=/dev/sdX of=/dev/null bs=1M count=32K skip=$((128*$RANDOM/32)) # set bs to optimal_io_size >> > >> > Or: bonnie++ -f -n0 > > Justin
