partitioning/postgresql/procedures/README.md

PostgreSQL Partitioning for Zabbix

This is the declarative 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

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.

Table of Contents

• Architecture
  • Components
• Installation
• Configuration
  • Modifying Retention
• Maintenance
  • Scheduling Maintenance
• Monitoring & Permissions
  • Versioning
  • Least Privilege Access (zbxpart_monitor)
• Implementation Details
  • auditlog Table
  • Converting Existing Tables
• PostgreSQL Tuning
• Uninstall / Reverting
• Upgrades

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_schema_create.sql).
2. Install maintenance procedures (01_maintenance.sql).
3. Enable partitioning on tables (02_enable_partitioning.sql).
4. Install monitoring views (03_monitoring_view.sql).

Command Example: You can deploy these scripts manually against your Zabbix database using psql. Navigate to the procedures/ directory and run:

# Connect as the zabbix database user
export PGPASSWORD="your_zabbix_password"
DB_HOST="localhost" # Or your DB endpoint
DB_NAME="zabbix"
DB_USER="zbxpart_admin"

for script in 00_schema_create.sql 01_maintenance.sql 02_enable_partitioning.sql 03_monitoring_view.sql; do
    echo "Applying $script..."
    # -v ON_ERROR_STOP=1 forces psql to exit immediately with an error code if any statement fails
    if ! psql -v ON_ERROR_STOP=1 -h $DB_HOST -U $DB_USER -d $DB_NAME -f "$script"; then
        echo -e "\nERROR: Failed to apply $script."
        read -p "Press [Enter] to forcefully continue anyway, or Ctrl+C to abort... "
    else
        echo -e "Successfully applied $script.\n----------------------------------------"
    fi
done

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();

Scheduling 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 and not in round hours because of the way housekeeper works (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.

You can schedule this using one of the following methods:

Option 1: pg_cron (Recommended)

pg_cron is a cron-based job scheduler that runs directly inside the database as an extension. It is very useful for cloud based databases like AWS RDS, Aurora, Azure, GCP, because it handles the authentication/connections securely for you automatically and its available as a managed extension. You do not need to install OS packages or configure anything. Simply modify the RDS Parameter Group to include shared_preload_libraries = 'pg_cron' and cron.database_name = 'zabbix', reboot the instance, and execute CREATE EXTENSION pg_cron;.

Setup pg_cron (Self-Hosted):

1. Install the package via your OS package manager (e.g., postgresql-15-cron on Debian/Ubuntu, or pg_cron_15 on RHEL/CentOS).
2. Configure it modifying postgresql.conf:

   shared_preload_libraries = 'pg_cron'
   cron.database_name = 'zabbix'
   

3. Restart PostgreSQL:

   systemctl restart postgresql
   

4. Connect to your zabbix database as a superuser and create the extension:

   CREATE EXTENSION pg_cron;
   

5. Schedule the job to run:

   SELECT cron.schedule('zabbix_partition_maintenance', '30 5,23 * * *', 'CALL partitions.run_maintenance();');
   

⚠️ Troubleshooting pg_cron Connection Errors: If your cron jobs fail to execute and you see FATAL: password authentication failed in your PostgreSQL logs, it is because pg_cron attempts to connect via TCP (localhost) by default, which usually requires a password.

Solution A: Use Local Unix Sockets (Easier) Edit your postgresql.conf to force pg_cron to use the local Unix socket (which uses passwordless peer authentication):

cron.host = '/var/run/postgresql'  # Or '/tmp', depending on your OS

(Restart PostgreSQL after making this change).

Solution B: Provide a Password (.pgpass) If you must connect via TCP with a specific database user and password, the pg_cron background worker needs a way to authenticate. You provide this by creating a .pgpass file for the OS postgres user.

1. Switch to the OS database user:

   sudo su - postgres
   

2. Create or append your database credentials to ~/.pgpass using the format hostname:port:database:username:password:

   echo "localhost:5432:zabbix:zabbix:my_secure_password" >> ~/.pgpass
   

3. Set strict permissions (PostgreSQL will ignore the file if permissions are too loose):

   chmod 0600 ~/.pgpass
   

Managing pg_cron Jobs: If you need to verify or manage your scheduled jobs (run as superuser):

• To list all active schedules: SELECT * FROM cron.job;
• To view execution logs/history: SELECT * FROM cron.job_run_details;
• To remove/unschedule the job: SELECT cron.unschedule('zabbix_partition_maintenance');

Option 2: Systemd Timers

Systemd timers provide better logging and error handling properties than standard cron.

1. Create a service file /etc/systemd/system/zabbix-partitions.service:

   [Unit]
   Description=Zabbix PostgreSQL Partition Maintenance
   After=network.target postgresql.service
   
   [Service]
   Type=oneshot
   User=postgres
   ExecStart=/usr/bin/psql -d zabbix -c "CALL partitions.run_maintenance();"
   

2. Create a timer file /etc/systemd/system/zabbix-partitions.timer:

   [Unit]
   Description=Run Zabbix Partition Maintenance Twice Daily
   
   [Timer]
   OnCalendar=*-*-* 05:30:00
   OnCalendar=*-*-* 23:30:00
   Persistent=true
   
   [Install]
   WantedBy=timers.target
   

3. Enable and start the timer:

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

Option 3: System Cron (crontab)

Standard system cron is a simple fallback.

Example Crontab Entry (crontab -e):

# Run Zabbix partition maintenance twice daily (5:30 AM and 5:30 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 host's cron by targeting the container:

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

Monitoring & Permissions

System state can be monitored via the partitions.monitoring view. It includes the information about number of future partitions and the time since the last maintenance run. Plus it includes the total size of the partitioned table in bytes.

SELECT * FROM partitions.monitoring;

Zabbix Agent Integration

To monitor the state of the partitions directly from Zabbix, you need to provide the Zabbix Agent with the SQL query used to fetch this data. You can automatically generate the required partitions.get_all.sql file on your agent using this one-liner:

cat << 'EOF' | sudo tee /etc/zabbix/zabbix_agent2.d/partitions.get_all.sql > /dev/null
SELECT 
    table_name,
    period,
    keep_history::text AS keep_history,
    configured_future_partitions,
    actual_future_partitions,
    total_size_bytes,
    EXTRACT(EPOCH FROM (now() - last_updated)) AS age_seconds
FROM partitions.monitoring;
EOF

(Make sure to adjust the destination path according to your Zabbix Agent template directory)

Versioning

To check the installed version of the partitioning solution:

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

Least Privilege Access (zbxpart_monitor)

For monitoring purposes, it is highly recommended to create a dedicated user with read-only access to the monitoring view instead of using the zbxpart_admin owner account.

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

Warning

Because 03_monitoring_view.sql uses a DROP VIEW command to apply updates, re-running the script will destroy all previously assigned GRANT permissions. If you ever update the view script, you must manually re-run the GRANT SELECT command above to restore access for the zbxpart_monitor user!

Implementation Details

auditlog Table

The standard Zabbix auditlog table has a primary key on (auditid). Partitioning by clock requires the partition key to be part of the primary key. To prevent placing a heavy, blocking lock on an auditlog table to alter its primary key, the enablement script (02_enable_partitioning.sql) detects it and handles it exactly like the history tables: it automatically renames the live, existing table to auditlog_old, and instantly creates a brand new, empty partitioned auditlog table pre-configured with the required (auditid, clock) composite primary key.

Converting Existing Tables

The enablement script guarantees practically zero downtime by automatically renaming the existing tables to table_name_old and creating new partitioned tables matching the exact schema.

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

Housekeeper Interceptor

Even when Zabbix Housekeeping is disabled in the UI for History and Trends, the Zabbix Server daemon may still generate and insert tasks into the housekeeper table (e.g., when an item or trigger is deleted, it schedules the deletion of its historical data). Without intervention, this results in the housekeeper table bloating massively over time, leading to slow sequential scans and autovacuum overhead.

To prevent this, this extension installs a BEFORE INSERT trigger on the housekeeper table.

• When Zabbix attempts to insert a housekeeper task, the trigger intercepts it and checks if the target table is managed in partitions.config.
• If the table is partitioned (like history), the trigger silently discards the insert (RETURNS NULL), preventing disk I/O and table bloat entirely.
• If the table is not partitioned (like events or sessions), the task is allowed to be recorded and is cleaned up naturally by Zabbix.

PostgreSQL Tuning

Before or immediately after enabling partitioning, you should tune your postgresql.conf. The standard configuration is not optimized for partitioned tables and might cause performance degradation or out-of-memory errors.

Parameter	Recommended	Description
max_locks_per_transaction	512 (or higher)	Requires DB Restart. Default is 64, which is far too low. PostgreSQL lock tables per partition. With many partitioned tables (e.g., history x 30 days), operations like pg_dump, VACUUM, or queries crossing multiple boundaries will fail with “out of shared memory”.
jit	off	Highly Recommended. JIT adds overhead to query planning. With many partitions, JIT can drastically increase CPU usage as PostgreSQL attempts to optimize simple queries across dozens of partitions.

Default parameters to verify: The following are usually set correctly by default, but you should verify them just in case:

• enable_partition_pruning = on : Critical. Ensures PostgreSQL only queries the necessary partitions instead of scanning everything.
• enable_partitionwise_join = off : Zabbix does not do massive joins on history tables; enabling this only wastes planner CPU time.
• enable_partitionwise_aggregate = off : Zabbix doesn't perform complex DB-side GROUP BY aggregations on history. Leave it disabled.

Uninstall / Reverting

If you wish to stop using partitioning and revert back to standard, unpartitioned tables without data loss, carefully follow these steps.

Caution

Reverting partitioning replaces your partitioned tables with standard empty tables. If you need to retain data from the partitioned period, you must manually migrate it before dropping the partition sets. Always stop Zabbix Server before proceeding.

1. Stop Zabbix Server to prevent new data from being inserted during the transition.
2. Execute Undo Script: Run the 04_undo_partitioning.sql script to recreate non-partitioned tables matching your original Zabbix schema. This script will rename your current partitioned tables to *_part (history_part, trends_part, etc.) and automatically create native, clean tables (history, trends) in their place.

   psql -h $DB_HOST -U zbxpart_admin -d zabbix -f 04_undo_partitioning.sql
   

3. Data Migration (Optional): If you want to keep the metrics collected during the partitioned period, you must manually insert them into the newly created regular tables. This step can take hours depending on table sizes.

   INSERT INTO history SELECT * FROM history_part;
   INSERT INTO trends SELECT * FROM trends_part;
   -- Repeat for all tables you wish to restore
   

4. Cleanup: Once you have migrated the data you need (or if you don't need it at all), you can drop the heavy partitioned tables and remove the partitioning extensions completely.

   DROP TABLE history_part CASCADE;
   DROP TABLE history_uint_part CASCADE;
   -- Repeat for all *_part tables ...
   
   -- To drop the automatic maintenance infrastructure:
   DROP SCHEMA partitions CASCADE;
   

5. Start Zabbix Server & Re-enable Housekeeper: Once the tables are replaced, you can start the server. Don't forget to re-enable Housekeeping for History and Trends in the Zabbix UI!

Upgrades

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.