Re: PLEASE GOD HELP US!

Sounds like all you need to do is to check what keys your app needs on
the tables and then ensure that you have these set up.
There is no way that MySQL will be faster than PG... seems like your
MySQL DB was optimised and your PG wasn't.

Should be very easy and quick to sort out.

Brad

Shane | SkinnyCorp wrote:

>Hey, my name is Shane Witschen and I'm the Systems Administrator (mainly a
>developer) for a small web development company. We recently switched over
>to PostgreSQL after going over some of the powerful features that it holds
>over MySQL.
>
>However, after we launched one site, we slapped ourselves in the head. We
>have run a message board for a few years now, and have always used MySQL for
>the backend, but recently switched to PostgreSQL. It has always been
>lightening fast with MySQL, but has slowed to nearly a halt in terms of
>online access time. I can't seem to do anything about it!! PLEASE HELP
>US!!
>
>Now, I've read as much as I could about optimizing PostgreSQL for
>performance, and nothing I do seems to help anything. Just so I don't get
>20 links to the same sites I've read... I'll post what I've already used for
>reference:
>
>http://postgis.refractions.net/pipermail/postgis-users/2004-January/003757.html
>http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
>http://www.phpbuilder.com/columns/smith20010821.php3?page=2
>http://techdocs.postgresql.org/techdocs/pgsqldbtuning.php
>http://www.lyris.com/lm_help/6.0/tuning_postgresql.html
>
>Nothing makes much of a difference. I even attempted to use persistant
>connections to the database to get around the connection overhead... and
>THAT just seemed to eat up all the system's memory while giving little or no
>gain in performance. All of my optimizations seem to help at first, but
>everything soon gets just as slow as it was before... and I mean SLOW.
>
>
>Sooo.... I'll give you as much info as I can... it may be too much, but I
>suppose that's better than not enough....
>
># HARDWARE #
> Pentium 4 2.5ghz
> 1.5 gb of DDR 400
> Unlimited bandwidth
> # MEMORY USAGE (top output sorted on memory) of persistant PgSQL
>connections:
> 27149 postgres 15 0 74840 73M 71360 S 0.3 4.8 1:46 0
>postmaster
> 27392 postgres 15 0 72976 71M 70084 S 0.0 4.7 0:25 0
>postmaster
> 27448 postgres 16 0 72708 70M 70052 S 2.5 4.6 0:20 0
>postmaster
> 27367 postgres 15 0 72036 70M 70132 S 0.0 4.6 0:36 0
>postmaster
> 27401 postgres 15 0 71908 70M 69920 S 0.0 4.6 0:32 0
>postmaster
> 27320 postgres 15 0 71900 70M 69844 S 0.5 4.6 0:40 0
>postmaster
> 27443 postgres 17 0 71880 70M 69368 S 8.5 4.6 0:24 0
>postmaster
> 27441 postgres 15 0 71832 70M 69336 S 0.0 4.6 0:25 0
>postmaster
> 27437 postgres 16 0 71828 70M 69812 S 0.7 4.6 0:22 0
>postmaster
> 27466 postgres 16 0 71788 70M 69432 S 2.5 4.6 0:18 0
>postmaster
> 27403 postgres 16 0 71780 70M 69816 S 0.1 4.6 0:26 0
>postmaster
> 27467 postgres 15 0 71728 69M 69384 S 0.0 4.6 0:15 0
>postmaster
> 27405 postgres 15 0 71496 69M 69612 S 0.0 4.6 0:26 0
>postmaster
> 27468 postgres 15 0 71392 69M 69108 S 0.0 4.6 0:17 0
>postmaster
> 27439 postgres 15 0 71184 69M 69456 S 0.0 4.5 0:30 0
>postmaster
> 27488 postgres 15 0 71184 69M 68996 S 10.5 4.5 0:03 0
>postmaster
> 27489 postgres 15 0 70176 68M 68752 S 1.1 4.5 0:00 0
>postmaster
> 27526 postgres 20 0 70020 68M 68752 S 17.3 4.5 0:00 0
>postmaster
> 27499 postgres 16 0 61204 59M 59620 S 5.9 3.9 0:00 0
>postmaster
> 27507 postgres 17 0 55040 53M 52888 S 24.1 3.5 0:02 0
>postmaster
> 27491 postgres 15 0 53988 52M 51824 S 0.0 3.4 0:02 0
>postmaster
> 27490 postgres 15 0 53040 51M 50880 S 0.0 3.4 0:02 0
>postmaster
> 27520 postgres 15 0 41960 40M 40428 S 1.3 2.7 0:00 0
>postmaster
> 27494 postgres 15 0 41224 40M 39876 S 0.7 2.6 0:00 0
>postmaster
> 27492 postgres 15 0 38980 38M 37552 S 0.3 2.5 0:00 0
>postmaster
> 27517 postgres 15 0 18444 17M 17308 S 0.5 1.1 0:00 0
>postmaster
> 27522 postgres 18 0 14112 13M 12976 S 0.3 0.9 0:00 0
>postmaster
> 27524 postgres 19 0 14040 13M 12908 S 0.3 0.9 0:00 0
>postmaster
> 27521 postgres 18 0 13364 12M 12228 S 0.0 0.8 0:00 0
>postmaster
> 27523 postgres 18 0 12848 12M 11716 S 0.0 0.8 0:00 0
>postmaster
> 1935 root 15 0 12144 11M 1372 S 0.0 0.7 0:00 0
>mdmpd
> 27516 postgres 18 0 12028 11M 10980 S 0.0 0.7 0:00 0
>postmaster
> 27518 postgres 17 0 11932 11M 10800 S 0.0 0.7 0:00 0
>postmaster
>
>
>
># WEBSITE #
> 30-60 users online at any given time
> 15,000 rows in the 'threads' table
> joined on
> 300,000 rows in the 'posts' table
> Total size of database on disk is 1.1 Gigabytes
>
> # SAMPLE DUMP OF COMMON PAGE-SPECIFIC QUERIES
> (this happened to be not so bad.... which may say a lot since it
>took 10 seconds...)
>
> 8 Queries Totaling 10.7413 Seconds
>
> SQL: SELECT count(*) AS count FROM thread_listing
> Num Rows: 1
> Affected Rows: 0
> Exec Time: 0.75249910354614
>
> SQL: SELECT * FROM thread_listing AS t ORDER BY t.status=5
>DESC,t.lastreply desc LIMIT 25 OFFSET 0
> Num Rows: 25
> Affected Rows: 0
> Exec Time: 9.1602659225464
>
> SQL: SELECT * FROM thread_categories WHERE parentcategoryid=0 AND
>threadcategoryid<>0 ORDER BY orderid ASC
> Num Rows: 4
> Affected Rows: 0
> Exec Time: 0.81906294822693
>
> SQL: SELECT * FROM thread_categories WHERE parentcategoryid=1 AND
>promoted=true ORDER BY orderid ASC
> Num Rows: 9
> Affected Rows: 0
> Exec Time: 0.0021350383758545
>
> SQL: SELECT * FROM thread_categories WHERE parentcategoryid=2 AND
>promoted=true ORDER BY orderid ASC
> Num Rows: 5
> Affected Rows: 0
> Exec Time: 0.0019958019256592
>
> SQL: SELECT * FROM thread_categories WHERE parentcategoryid=3 AND
>promoted=true ORDER BY orderid ASC
> Num Rows: 4
> Affected Rows: 0
> Exec Time: 0.0019819736480713
>
> SQL: SELECT * FROM thread_categories WHERE parentcategoryid=4 AND
>promoted=true ORDER BY orderid ASC
> Num Rows: 5
> Affected Rows: 0
> Exec Time: 0.0021347999572754
>
> SQL: SELECT userid,username FROM users WHERE userid IN (select *
>from buddynetwork(0,2)) ORDER BY username ASC
> Num Rows: 1
> Exec Time: 0.0011849403381348
>
>
>
> # PGSQL Version 7.4.2
> # -----------------------------
> # PostgreSQL configuration file
> # -----------------------------
>
>#---------------------------------------------------------------------------
> # CONNECTIONS AND AUTHENTICATION
>
>#---------------------------------------------------------------------------
> # - Connection Settings -
> tcpip_socket = true
> max_connections = 50
> #superuser_reserved_connections = 2
> port = 5432
> #unix_socket_directory = ''
> #unix_socket_group = ''
> #unix_socket_permissions = 0777
> #virtual_host = ''
> #rendezvous_name = ''
> # - Security & Authentication -
> #authentication_timeout = 60
> ssl = true
> password_encryption = true
> #krb_server_keyfile = ''
> #db_user_namespace = false
>
>
>#---------------------------------------------------------------------------
> # RESOURCE USAGE (except WAL)
>
>#---------------------------------------------------------------------------
> # - Memory -
> shared_buffers = 8192
> sort_mem = 8192
> vacuum_mem = 127072
>
> # - Free Space Map -
> max_fsm_pages = 50000 # min max_fsm_relations*16, 6 bytes each
> max_fsm_relations = 1000 # min 100, ~50 bytes each
> # - Kernel Resource Usage -
> max_files_per_process = 3052 # min 25
> #preload_libraries = ''
>
>
>#---------------------------------------------------------------------------
> # WRITE AHEAD LOG
>
>#---------------------------------------------------------------------------
> # - Settings -
> fsync = true # turns forced synchronization on or off
> #wal_sync_method = fsync
> wal_buffers = 8192 # min 4, 8KB each
>
> # - Checkpoints -
> #checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
> #checkpoint_timeout = 300 # range 30-3600, in seconds
> #checkpoint_warning = 30 # 0 is off, in seconds
> #commit_delay = 0 # range 0-100000, in microseconds
> #commit_siblings = 5 # range 1-1000
>
>
>#---------------------------------------------------------------------------
> # QUERY TUNING
>
>#---------------------------------------------------------------------------
>
> # - Planner Method Enabling -
> #enable_hashagg = true
> #enable_hashjoin = true
> #enable_indexscan = true
> #enable_mergejoin = true
> #enable_nestloop = true
> enable_seqscan = false
> #enable_sort = true
> #enable_tidscan = true
> # - Planner Cost Constants -
> effective_cache_size = 131072 # typically 8KB each
> random_page_cost = 4 # units are one sequential page fetch cost
> cpu_tuple_cost = .01 # (same) default .01
> cpu_index_tuple_cost = .001 # (same) default .001
> cpu_operator_cost = 0.0025 # (same) default .0025
> # - Genetic Query Optimizer -
> geqo = true
> geqo_threshold = 20
> #geqo_effort = 1
> #geqo_generations = 0
> #geqo_pool_size = 0 # default based on tables in statement,
> #geqo_selection_bias = 2.0 # range 1.5-2.0
> # - Other Planner Options -
> #default_statistics_target = 10 # range 1-1000
> #from_collapse_limit = 8
> #join_collapse_limit = 8 # 1 disables collapsing of explicit JOINs
>
>
>#---------------------------------------------------------------------------
> # ERROR REPORTING AND LOGGING
>
>#---------------------------------------------------------------------------
> # - Syslog -
> #syslog = 0 # range 0-2; 0=stdout; 1=both; 2=syslog
> #syslog_facility = 'LOCAL0'
> #syslog_ident = 'postgres'
> # - When to Log -
> client_min_messages = error
> log_min_messages = error
> log_error_verbosity = default
> log_min_error_statement = panic
> log_min_duration_statement = -1
>
> #silent_mode = false # DO NOT USE without Syslog!
>
> # - What to Log -
>
> debug_print_parse = false
> debug_print_rewritten = false
> debug_print_plan = false
> debug_pretty_print = false
> log_connections = false
> log_duration = false
> log_pid = false
> log_statement = false
> log_timestamp = false
> log_hostname = false
> log_source_port = false
>
>
>
>#---------------------------------------------------------------------------
> # RUNTIME STATISTICS
>
>#---------------------------------------------------------------------------
>
> # - Statistics Monitoring -
>
> log_parser_stats = false
> log_planner_stats = false
> log_executor_stats = false
> log_statement_stats = false
>
> # - Query/Index Statistics Collector -
>
> stats_start_collector = false
> stats_command_string = false
> stats_block_level = false
> stats_row_level = false
> stats_reset_on_server_start = false
>
>
>
>#---------------------------------------------------------------------------
> # CLIENT CONNECTION DEFAULTS
>
>#---------------------------------------------------------------------------
>
> # - Statement Behavior -
>
> #search_path = '$user,public' # schema names
> #check_function_bodies = true
> #default_transaction_isolation = 'read committed'
> #default_transaction_read_only = false
> #statement_timeout = 0 # 0 is disabled, in milliseconds
>
> # - Locale and Formatting -
>
> #datestyle = 'iso, mdy'
> #timezone = unknown # actually, defaults to TZ environment
>setting
> #australian_timezones = false
> #extra_float_digits = 0 # min -15, max 2
> #client_encoding = sql_ascii # actually, defaults to database encoding
>
> # These settings are initialized by initdb -- they may be changed
> lc_messages = 'en_US.UTF-8' # locale for system error message
>strings
> lc_monetary = 'en_US.UTF-8' # locale for monetary formatting
> lc_numeric = 'en_US.UTF-8' # locale for number formatting
> lc_time = 'en_US.UTF-8' # locale for time formatting
>
> # - Other Defaults -
>
> explain_pretty_print = true
> #dynamic_library_path = '$libdir'
> #max_expr_depth = 10000 # min 10
>
>
>
>#---------------------------------------------------------------------------
> # LOCK MANAGEMENT
>
>#---------------------------------------------------------------------------
>
> #deadlock_timeout = 1000 # in milliseconds
> #max_locks_per_transaction = 64 # min 10, ~260*max_connections bytes each
>
>
>
>#---------------------------------------------------------------------------
> # VERSION/PLATFORM COMPATIBILITY
>
>#---------------------------------------------------------------------------
>
> # - Previous Postgres Versions -
>
> #add_missing_from = true
> regex_flavor = advanced # advanced, extended, or basic
> #sql_inheritance = true
>
> # - Other Platforms & Clients -
>
> #transform_null_equals = false
>
>
>
>
>
>
>PLEASE HELP ME FIND THE BOTTLE NECK!!
>
>Sometimes just ONE page load (approx. 13 queries) takes up to 30 seconds,
>and that is absolutely unacceptable in terms of online use. If I can't fix
>this I'm going to have to spend the month or two switching back to MySQL...
>and I really don't want to do that, so anything you could do to help us
>would be amazing!!
>
>Thanks in advance!!
>
>- Shane
>
>
>
>
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