Hello > -----Original Message----- > From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of ajmcello > Sent: Freitag, 30. Dezember 2016 05:54 > To: POSTGRES <pgsql-general@xxxxxxxxxxxxxx> > Subject: performance tuning postgresql 9.5.5.10 [enterprisedb] > > > I am trying to optimize and tune my server for fastest simple queries with highest connection to server possible. > Basically, a SELECT item from table takes 30 minutes on a machine with SSD drives. The table has 900K entries and 12 > columns. Using that SELECT query, I then have the ability to make about 500 simultaneous connections to the server > before errors start to occur. So, I can live with 500, but the slow query gives me grief. >From previous posts of other users, I assume that in order to get help you will need to provide some more information. Here the questions that come to my mind. What errors do you get from the server when you reach the 500 connections? How long does it take to run the query without heavy load, e.g. just one user connected? \timing on query How does the execution plan look like? There you may see if the index is used at all. EXPLAIN ANALYZE query; > I have a GIST index for the table. I tried btree, but according to performance tests, GIST was faster. So I went > with GIST. > > The system drive and pgsql drive are separate. I can separate them further if need to be. Total ram is 56GB. I added > 32GB of swap. > > Is there anything I can do to speed up the SELECT statement? Could you provide the statement and the table definition? > Here is what I have: > > [sysctl.conf] > net.ipv4.conf.default.rp_filter=1 > net.ipv4.conf.all.rp_filter=1 > net.ipv4.tcp_syncookies=1 > net.ipv4.ip_forward=1 > net.ipv6.conf.all.forwarding=1 > net.ipv4.conf.all.accept_redirects=0 > net.ipv6.conf.all.accept_redirects=0 > net.ipv4.conf.all.accept_source_route=0 > net.ipv6.conf.all.accept_source_route=0 > net.ipv4.conf.all.log_martians=1 > kernel.sysrq=0 > kernel.shmmax=2147483999999 > kernel.shmall=2097159999999 > #32GBkernel.shmmax=17179869184 > #32GBkernel.shmall=4194304 > kernel.shmmni=999999999 > kernel.shmmin=1 > kernel.shmseg=10 > semmsl, semmns, semopm, semmni kernel.sem=250 32000 100 128 > fs.file-max=65536 > kern.maxfiles=50000 > kern.maxfilesperproc=50000 > net.ipv4.ip_local_port_range=1024 65535 > net.ipv4.tcp_tw_recycle=1 > net.ipv4.tcp_fin_timeout=10 > net.ipv4.tcp_tw_reuse=1 > net.core.rmem_max=16777216 > net.core.wmem_max=16777216 > net.ipv4.tcp_max_syn_backlog=4096 > net.ipv4.tcp_syncookies=1 > kernel.sched_migration_cost_ns=5000000 > kernel.sched_migration_cost_ns=5000000 > kernel.sched_autogroup_enabled=0 > vm.swappiness=10 > > Here are some helpful informations on the settings below: https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server I am not really the big expert, but 100'000 max_connections and work_mem of 100MB seems to me to be a problem: >From the link mentioned right above: "This size (work_mem) is applied to each and every sort done by each user, and complex queries can use multiple working memory sort buffers. Set it to 50MB, and have 30 users submitting queries, and you are soon using 1.5GB of real memory." This is: SELECT * FROM pg_size_pretty((50.0*(2^20)*30.0)::BIGINT); -[ RECORD 1 ]--+-------- pg_size_pretty | 1500 MB Applied to your settings: SELECT * FROM pg_size_pretty((100.0*(2^20)*100000.0)::BIGINT); -[ RECORD 1 ]--+-------- pg_size_pretty | 9766 GB This could explain the errors you get from the server. You may be trying to use much more memory than you have. Regards Charles > [postgresql.conf] > max_connections = 100000 > max_files_per_process = 1000000 > shared_buffers = 24GB > max_locks_per_transaction = 1000 > effective_cache_size = 50GB > work_mem = 100MB > maintenance_work_mem = 2GB > log_min_duration_statement = 10000 > checkpoint_completion_target = 0.9 > wal_buffers = 32MB > default_statistics_target = 100 > listen_addresses = '*' > port = 5432 > ssl = off > wal_sync_method = fdatasync > synchronous_commit = on > fsync = off > wal_level = minimal > #client_min_messages = fatal > #log_min_messages = fatal > #log_min_error_statement = fatal > datestyle = 'iso, mdy' > debug_pretty_print = off > debug_print_parse = off > debug_print_plan = off > debug_print_rewritten = off > default_text_search_config = 'pg_catalog.english' > enable_bitmapscan = on > enable_hashagg = on > enable_hashjoin = on > enable_indexonlyscan = on > enable_indexscan = on > enable_material = on > enable_mergejoin = on > enable_nestloop = on > enable_seqscan = on > enable_sort = on > enable_tidscan = on > from_collapse_limit = 8 > geqo = on > geqo_threshold = 12 > log_checkpoints = off > > log_connections = off > log_disconnections = off > log_duration = off > log_executor_stats = off > log_hostname = off > log_parser_stats = off > log_planner_stats = off > log_replication_commands = off > log_statement_stats = off > log_timezone = 'UTC' > max_wal_size = 1GB > min_wal_size = 80MB > shared_preload_libraries = '$libdir/dbms_pipe,$libdir/edb_gen' > stats_temp_directory = 'pg_stat_tmp' > timezone = 'US/Pacific' > track_activities = on > track_counts = on > track_io_timing = off > > > Thanks in advance. > > > > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
