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Technical Case Studies in PostgreSQL
[ Monitoring Methods ]
Rohit Vyas | 11.04.15
Quality Management Group (PostgreSQL Installer and Tools)

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• Technical cases in PostgreSQL
• Database Monitoring Methods
Agenda

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− Bloats
− Updates/Deletes cause bloats in a table in
PostgreSQL.
− Transaction Wraparound
− No new XID’s if 4 billion mark reached.
− Streaming/WAL Replication Lag
− Number of bytes lag from Master database may
be due to bulk load, network etc.,
− Handling WAL Archiving Files
− Piling up .ready files due to failure of archiver
process
− Catalog Corruption
− Database objects repository(pg_catalog schema)
corruption.
Technical Cases on Production Database
ERROR: database is not accepting commands to avoid
wraparound data loss in database "dvnspatial"
Hint: Stop the postmaster and use a standalone
backend to vacuum that database.
You might also need to commit or roll back old prepared
transactions.
Error executing update (updateorg.matter.security.User)
PANIC: could not write to file
“pg_xlog/xlogtemp.556” :No space left on
device
notice: pg_class row has invalid relnamespace "24580":
no matching entry in pg_namespace
row identity: oid="24581" relname="foo" relkind="r"

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• Using pg_catalog Tables/Views/Functions
• Wrapping pg_catalog in Shell or any scripting
language.
• Using open source tools
− check_postgres.pl, pg_catcheck, pg_cluu, munin, Nagios etc
• Proprietary Tools
− EnterpriseDB Postgres Enterprise Manager
Database Monitoring Methods

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• Tables
− pg_class
− pg_database
• Views
− pg_stat_activity
− pg_stat_all_tables
− pg_stat_archiver
− pg_stat_replication
• Functions
− pg_is_in_recovery()
− pg_last_xlog_replay_location()
− pg_last_xact_replay_timestamp()
− pg_xlog_location_diff()
Using pg_catalogs

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Wrapping pg_catalogs in Shell or Other languages
Max
Connections
Long Running
queries
Idle
Connections
Waiting
Connections

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• check_postgres.pl
• pg_catcheck [ catalog corruption ]
• pg_cluu
Using open source tools

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Sample output of critical probes on Production
Environment

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pg_catcheck

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Monitoring with Proprietary Tools
• Postgres Enterprise
Manager [ EnterpriseDB] PostgreSQL
Instances of
different versions
9.0.x
9.1.x
9.4.x
9.3.x
9.2.x
PEM
Server

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PEM Probes And Alerts
Table Bloat Total table bloat in server
Highest Table Bloat in server
Table Frozen XID Table FrozenXID
Database Frozen XID Database FrozenXID
Number of WAL Files Number of WAL Files
WAL Archive status Number of WAL archiving Pending
Streaming Replication Standby server lag behind the master By WAL
segment
Standby server lag behind the master by WAL
pages
Streaming Replication Lag Number of minutes lag in standby server from
master server

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Dashboard's Charts

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PEM Alerts

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• Complete point and click
management of all database
objects
• 225+ pre-configured database
alerts for immediate global at-a-
glance monitoring complete with
SMTP notifications, SNMP traps
and richly configurable notification
rules (New)
• Remote Monitoring (New)
• A Capacity Planning and Forecast
Manager
• PostgreSQL Expert database
configuration recommendations
and deployment
• Log Management and a Log
Analysis Expert (New)
• Team Management
• Custom probes for gathering
metrics (New)
• SQL Profiler
• Index Advisor
• All optimized for working with
multiple databases consistently
across the enterprise.
Primary Product Features

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• On Premise Server
• Public Cloud [AWS]
• Private Cloud [Open stack ]
Deployment

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References
• http://www.enterprisedb.com/products-services-
training/products/postgres-enterprise-manager
Postgres Enterprise Manager

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Questions?

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