Contents

• pg_statviz
  • Design Philosophy
  • Installation
    • Extension
    • Utility
    • Requirements
  • Usage
  • snapshot
  • delete_snapshots
  • Scheduling
  • Visualization
    • Specific module usage
    • Example:
    • Produces:
  • Export data

pg_statviz

pg_statviz is a minimalist extension and utility pair for time series analysis and visualization of PostgreSQL internal statistics.

Created for snapshotting PostgreSQL's cumulative and dynamic statistics and performing time series analysis on them. The accompanying utility can produce visualizations for selected time ranges on the stored stats snapshots, enabling the user to track PostgreSQL performance over time and potentially perform tuning or troubleshooting.

Design Philosophy

Designed with the K.I.S.S. and UNIX philosophies in mind, pg_statviz aims to be a modular, minimal and unobtrusive tool that does only what it's meant for: create snapshots of PostgreSQL statistics for visualization and analysis. To this end, a utility is provided for retrieving the stored snapshots and creating with them simple visualizations using Matplotlib.

Installation

Extension

The extension can be installed like this, for example inside psql:

CREATE EXTENSION pg_statviz;

This will create the needed tables and functions under schema pgstatviz (note the lack of underscore in the schema name).

Utility

The visualization utility can be installed from PyPi:

pip install pg_statviz

Requirements

Python 3.9+ is required for the visualization utility.

Usage

The extension can be used by superusers, or any user that has pg_monitor role privileges. To take a snapshot, e.g. from psql:

SELECT pgstatviz.snapshot();

``` NOTICE: created pg_statviz snapshot

snapshot

2023-01-27 11:04:58.055453+00

(1 row) ````

Older snapshots and their associated data can be removed using any time expression. For example, to remove data more than 90 days old:

DELETE FROM pgstatviz.snapshots
WHERE snapshot_tstamp < CURRENT_DATE - 90;

Or all snapshots can be removed like this:

SELECT pgstatviz.delete_snapshots();

``` NOTICE: truncating table "snapshots" NOTICE: truncate cascades to table "conf" NOTICE: truncate cascades to table "buf" NOTICE: truncate cascades to table "conn"
NOTICE: truncate cascades to table "lock" NOTICE: truncate cascades to table "wait"
NOTICE: truncate cascades to table "wal" NOTICE: truncate cascades to table "db"

delete_snapshots

(1 row) ```

The pg_monitor role can be assigned to any user:

GRANT pg_monitor TO myuser;

Scheduling

Periodic snapshots can be set up with any job scheduler. For example with cron:

crontab -e -u postgres

Inside the postgres user's crontab, add this line to take a snapshot every 15 minutes:

*/15 * * * * psql -c "SELECT pgstatviz.snapshot()" >/dev/null 2>&1

Visualization

The visualization utility can be called like a PostgreSQL command line tool:

pg_statviz --help

``` usage: pg_statviz [--help] [--version] [-d DBNAME] [-h HOSTNAME] [-p PORT] [-U USERNAME] [-W] [-D FROM TO] [-O OUTPUTDIR] {analyze,buf,cache,checkp,conn,lock,tuple,wait,wal} ...

run all analysis modules

positional arguments: {analyze,buf,cache,checkp,conn,tuple,wait,wal} analyze run all analysis modules buf run buffers written analysis module cache run cache hit ratio analysis module checkp run checkpoint analysis module conn run connection count analysis module lock run locks analysis module tuple run tuple count analysis module wait run wait events analysis module wal run WAL generation analysis module

options: --help --version show program's version number and exit -d DBNAME, --dbname DBNAME database name to analyze (default: 'myuser') -h HOSTNAME, --host HOSTNAME database server host or socket directory (default: '/var/run/postgresql') -p PORT, --port PORT database server port (default: '5432') -U USERNAME, --username USERNAME database user name (default: 'myuser') -W, --password force password prompt (should happen automatically) (default: False) -D FROM TO, --daterange FROM TO date range to be analyzed in ISO 8601 format e.g. 2023-01-01T00:00 2023-01-01T23:59 (default: []) -O OUTPUTDIR, --outputdir OUTPUTDIR output directory (default: -) ```

Specific module usage

pg_statviz conn --help

``` usage: pg_statviz conn [-h] [-d DBNAME] [--host HOSTNAME] [-p PORT] [-U USERNAME] [-W] [-D FROM TO] [-O OUTPUTDIR] [-u [USERS ...]]

run connection count analysis module

options: -h, --help show this help message and exit -d DBNAME, --dbname DBNAME database name to analyze (default: 'myuser') --host HOSTNAME database server host or socket directory (default: '/var/run/postgresql') -p PORT, --port PORT database server port (default: '5432') -U USERNAME, --username USERNAME database user name (default: 'myuser') -W, --password force password prompt (should happen automatically) (default: False) -D FROM TO, --daterange FROM TO date range to be analyzed in ISO 8601 format e.g. 2023-01-01T00:00 2023-01-01T23:59 (default: []) -O OUTPUTDIR, --outputdir OUTPUTDIR output directory (default: -) -u [USERS ...], --users [USERS ...] user name(s) to plot in analysis (default: []) ```

Example:

pg_statviz buf --host localhost -d postgres -U postgres -D 2023-01-24T23:00 2023-01-26

Produces:

Export data

Data from pg_statviz internal tables can be exported to a tab separated values (TSV) file for use by other tools:

psql -c "COPY pgstatviz.conn TO STDOUT CSV HEADER DELIMITER E'\t'" > conn.tsv