partitioning/postgresql/procedures/README.md

PostgreSQL Partitioning for Zabbix

This is the declarative (PostgreSQL procedures based) partitioning implementation for Zabbix history, trends, and auditlog tables on PostgreSQL. This solution is intended to replace standard Zabbix housekeeping for the configured tables. Partitioning is very useful for large environments because it completely eliminates the housekeeper from the process. Instead of huge DELETE queries on several million rows, fast DDL queries (ALTER TABLE) are executed, which drop an entire partition.

Warning

High-Load Environments:

1. Data Visibility: After enabling partitioning, old data remains in *_old tables and is NOT visible in Zabbix. You must migrate data manually if needed.
2. Disable Housekeeping: You MUST disable Zabbix Housekeeper for History and Trends in Administration -> Housekeeping. Failure to do so will cause massive DELETE loads.

Architecture

The solution uses PostgreSQL native declarative partitioning (PARTITION BY RANGE). All procedures, information, statistics and configuration are stored in the partitions schema to maintain full separation from Zabbix schema.

Components

1. Configuration Table: partitions.config defines retention policies.
2. Maintenance Procedure: partitions.run_maintenance() manages partition lifecycle.
3. Monitoring View: partitions.monitoring provides system state visibility.
4. Version Table: partitions.version provides information about installed version of the partitioning solution.

Installation

The installation is performed by executing the SQL procedures in the following order:

1. Initialize schema (00_partitions_init.sql).
2. Auditlog PK adjustment (01_auditlog_prep.sql).
3. Install maintenance procedures (02_maintenance.sql).
4. Enable partitioning on tables (03_enable_partitioning.sql).
5. Install monitoring views (04_monitoring_view.sql).

Configuration

Partitioning policies are defined in the partitions.config table.

Column	Type	Description
table_name	text	Name of the Zabbix table (e.g., history, trends).
period	text	Partition interval: day, week, or month.
keep_history	interval	Data retention period (e.g., 30 days, 12 months).
future_partitions	integer	Number of future partitions to pre-create (buffer). Default: 5.
last_updated	timestamp	Timestamp of the last successful maintenance run.

Modifying Retention

To change the retention period for a table, update the configuration:

UPDATE partitions.config 
SET keep_history = '60 days' 
WHERE table_name = 'history';

Maintenance

The maintenance procedure partitions.run_maintenance() is responsible for:

1. Creating future partitions (current period + future_partitions buffer).
2. Creating past partitions (backward coverage based on keep_history).
3. Dropping partitions older than keep_history.

This procedure should be scheduled to run periodically (e.g., daily via pg_cron or system cron).

CALL partitions.run_maintenance();

Automatic Maintenance

To ensure partitions are created in advance and old data is cleaned up, the maintenance procedure should be scheduled to run automatically.

It is recommended to run the maintenance twice a day (e.g., at 05:30 and 23:30).

• Primary Run: Creates new future partitions and drops old ones.
• Secondary Run: Acts as a safety check. Since the procedure is idempotent (safe to run multiple times), a second run ensures everything is consistent if the first run failed or was interrupted.

There are three ways to schedule this, depending on your environment:

Option 1: pg_cron (If you use RDS/Aurora)

If you are running on managed PostgreSQL (like AWS Aurora) or prefer to keep scheduling inside the database, pg_cron is the way to go.

1. Ensure pg_cron is installed and loaded in postgresql.conf (shared_preload_libraries = 'pg_cron').
2. Run the following to schedule the maintenance:

CREATE EXTENSION IF NOT EXISTS pg_cron;
SELECT cron.schedule('zabbix_maintenance', '30 5,23 * * *', 'CALL partitions.run_maintenance();');

Where:

• 'zabbix_maintenance' - The name of the job (must be unique).
• '30 5,23 * * *' - The standard cron schedule (runs at 05:30 and 23:30 daily).
• 'CALL partitions.run_maintenance();' - The SQL command to execute.

Option 2: systemd Timers

For standard Linux VM deployments, systemd timers are modern, prevent overlapping runs, and provide excellent logging.

1. Create a service file (/etc/systemd/system/zabbix-partitioning.service):

[Unit]
Description=Zabbix PostgreSQL Partition Maintenance

[Service]
Type=oneshot
User=zabbix
# Ensure .pgpass is configured for the zabbix user so it doesn't prompt for a password
ExecStart=/usr/bin/psql -U zabbix -d zabbix -c "CALL partitions.run_maintenance();"

2. Create a timer file (/etc/systemd/system/zabbix-partitioning.timer):

[Unit]
Description=Zabbix Partitioning twice a day

[Timer]
OnCalendar=*-*-* 05,23:30:00
Persistent=true

[Install]
WantedBy=timers.target

3. Enable and start the timer:

systemctl daemon-reload
systemctl enable --now zabbix-partitioning.timer

Option 3: Standard Cron

This is the legacy, simple method for standard VMs and containerized environments.

Example Crontab Entry (crontab -e):

# Run Zabbix partition maintenance twice daily (5:30 AM and 11:30 PM)
30 5,23 * * * psql -U zabbix -d zabbix -c "CALL partitions.run_maintenance();" >> /var/log/zabbix_maintenance.log 2>&1

Docker Environment: If running in Docker, you can execute it via the container's host:

30 5,23 * * * docker exec zabbix-db psql -U zabbix -d zabbix -c "CALL partitions.run_maintenance();"

Monitoring & Permissions

System state can be monitored via the partitions.monitoring view. It includes a future_partitions column which counts how many partitions exist after the current period. This is useful for alerting (e.g., trigger if future_partitions < 2).

SELECT * FROM partitions.monitoring;

Versioning

To check the installed version of the partitioning solution:

SELECT * FROM partitions.version ORDER BY installed_at DESC LIMIT 1;

Least Privilege Access (zbx_monitor)

For monitoring purposes, it is recommended to create a dedicated user with read-only access to the monitoring view.

CREATE USER zbx_monitor WITH PASSWORD 'secure_password';
GRANT USAGE ON SCHEMA partitions TO zbx_monitor;
GRANT SELECT ON partitions.monitoring TO zbx_monitor;

Implementation Details

auditlog Table

The standard auditlog table Primary Key is (auditid). Partitioning by clock requires the partition key to be part of the Primary Key. The initialization script modifies the PK to (auditid, clock).

Converting Existing Tables

The enablement script renames the existing table to table_name_old and creates a new partitioned table with the same structure.

• Note: Data from the old table is NOT automatically migrated to minimize downtime.
• New data flows into the new partitioned table immediately.
• Old data remains accessible in table_name_old for manual query or migration if required.

Upgrades

When upgrading Zabbix:

1. Backup: Ensure a full database backup exists.
2. Compatibility: Zabbix upgrade scripts may attempt to ALTER tables. PostgreSQL supports ALTER TABLE on partitioned tables for adding columns, which propagates to partitions.
3. Failure Scenarios: If an upgrade script fails due to partitioning, the table may need to be temporarily reverted or the partition structure manually adjusted.