Re: PLEASE GOD HELP US! - Mailing list pgsql-admin

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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