pgCenter - top-like statistics viewer for PostgreSQL

1. pgCenter Overview
Alexey Lesovsky
8/2015
PostgreSQL-Consulting.com

2. Agenda
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PostgreSQL statistics.
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PostgreSQL ad-hoc management.
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pgCenter statistics interface.
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pgCenter actions.
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PgCenter usage examples.

3. PostgreSQL Statistics
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http://www.postgresql.org/docs/9.4/static/monitoring-stats.html
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Predefined views show the results of statistics collection.
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Build your own custom views using statistics functions.

4. PostgreSQL Statistics
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pg_stat_activity,
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pg_stat_database,
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pg_stat_all_tables (pg_stat_user_tables, pg_stat_sys_tables),
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pg_stat_all_indexes (pg_stat_user_indexes, pg_stat_sys_indexes),
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pg_statio_all_tables (pg_statio_user_tables, pg_statio_sys_tables),
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pg_statio_all_indexes (pg_statio_user_indexes, pg_statio_sys_indexes),
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pg_stat_user_functions,
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pg_stat_replication,
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pg_stat_bgwriter, pg_stat_archiver, pg_stat_database_conflicts, etc...
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contrib modules (pg_stat_statements, pgstattuple, etc...)

5. PostgreSQL Ad-Hoc Management
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Show configuration.
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Edit configuration (postgresql.conf, pg_hba.conf, etc...).
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Reload PostgreSQL.
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Logs: view, tailing, search.
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Watch long running queries.
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Cancel queries.
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Terminate backends.
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Custom tasks with psql.

6. pgCenter: Goals
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Viewing PostgreSQL statistics.
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Fast access to management tasks:
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Show/Change Configuration;
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Log viewing;
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Cancel queries, Terminate backends.

7. pgCenter Statistics
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Display statistics in top-like manner.
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Overall system and PostgreSQL state.
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Databases, tables, indexes, functions statistics.
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Long queries based on pg_stat_activity.
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Statatements statistics based on pg_stat_statements.
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Tables and indexes sizes.
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Replication statistics based on pg_stat_replication.

8. pgCenter Statistics
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Overview screen
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Time, Load Average, CPU Usage, Current connection state.
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Postgres activity grouped by backends states.
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Autovacuum activity: workers, current longest autovacuum.
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Statements: per second, average duration, current longest
transaction

9. pgCenter Statistics
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Statistics screen
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Hotkeys for switching between various stats.
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Change sort column and order (desc, asc).
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Additional actions for stats.
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Change age threshold for long queries.
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Cancel queries, Terminate backends.

10. pgCenter Actions: Configuration
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Show config with $PAGER or less by default.
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Edit configuration file with $EDITOR or use vi by default
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Available when pgCenter and PostgreSQL runs on the same host
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Edit postgresql.conf, pg_hba.conf, pg_ident.conf, recovery.conf.
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Reload PostgreSQL with pg_reload_conf().

11. pgCenter Actions: Logs
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Log tail in sub-window.
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Open log file in $PAGER or using less by default.
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Available when pgCenter and PostgreSQL runs on the same host.

12. pgCenter Actions: Long queries
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Cancel queries, Terminate backends.
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Use pg_cancel_query(), pg_terminate_backends() functions.
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Cancel or Terminate using backend pid.
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Cancel or Terminate group of backends using state mask.
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active | idle | idle_in_xact | waiting | others

13. pgCenter Actions: Connections
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If I have 2, 4, 8, 16... PostgreSQL hosts?
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Create connections to other hosts (limited by 8).
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Switch between connections.
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Close current connection.
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Write connection options into ~/.pgcenterrc (or another file).
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Open connections with --file=FILENAME option.

14. pgCenter Actions: Others
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Show system tables and indexes statistics (default: off).
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Reset PostgreSQL statistics counters.
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Change long queries age threshold (default: 10 seconds).
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Start psql session to current PostgreSQL.

15. pgCenter Usage: Examples
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Permanent non-zero rollbacks or deadlocks — poor application code
quality.
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Reads > Hits — Insufficient memory or shared buffers prewarm.
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Tmp files and bytes > 0 — Insufficient work_mem value.

16. pgCenter Usage: Examples
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Seq scan > 0 and very high Seq read — index required.
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hot_updates = 0 and very high updates — set fillfactor on table.
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dead > 0 (with high updates or deletes) — bad autovacuum setup
and possible bloat.

17. pgCenter Usage: Examples
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Determine biggest tables in your database
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Table with indexes size
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Table only size.
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Indexes size.
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Size changes — check tables which grows now.

18. pgCenter Usage: Examples
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Queries with high query or transaction age (> hours) — source of
tables/indexes bloat.
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Idle in transaction state — application code not close transaction,
that also cause table/index bloat and may block other transactions.
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Waiting state — one query block others, growing response time.
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If you see here anything — probably it's bad and cause problems.

19. pgCenter Usage: Examples
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pg_stat_statements contrib module
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http://www.postgresql.org/docs/9.4/static/pgstatstatements.html
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Should be installed into your database (see CREATE EXTENSION).
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Statements statistics
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General stats: calls, calls/s, returned rows, rows/s.
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Resource usage stats: CPU time, Read/Write time.
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Periodically reset statistics for accurate results, eg. every day.

20. Thanks.
Alexey Lesovsky
PgCenter
https://github.com/lesovsky/pgcenter
PostgreSQL-Consulting.com
alexey.lesovsky@postgresql-consulting.com