feat: introduce configurable future partition buffer and add monitoring for future partitions.

.gitignore

@@ -2,5 +2,9 @@
 docker/
 z_gen_history_data.sql
 
+# Local docs
+QUICKSTART.md
+init_extra_users.sql
+
 # Schemas
 sql-scripts*/

PARTITIONING.md

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+# 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. 
+
+## 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:
+
+```sql
+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).
+
+```sql
+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`).
+
+```sql
+SELECT * FROM partitions.monitoring;
+```
+
+### Versioning
+To check the installed version of the partitioning solution:
+```sql
+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.
+
+```sql
+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.

postgresql/procedures/00_partitions_init.sql

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+-- ============================================================================
+-- SCRIPT: 00_partitions_init.sql
+-- DESCRIPTION: Creates the 'partitions' schema and configuration table.
+--              Defines the structure for managing Zabbix partitioning.
+-- ============================================================================
+
+CREATE SCHEMA IF NOT EXISTS partitions;
+
+-- Configuration table to store partitioning settings per table
+CREATE TABLE IF NOT EXISTS partitions.config (
+    table_name      text NOT NULL,
+    period          text NOT NULL CHECK (period IN ('day', 'week', 'month', 'year')),
+    keep_history    interval NOT NULL,
+    future_partitions integer NOT NULL DEFAULT 5,
+    last_updated    timestamp WITH TIME ZONE DEFAULT now(),
+    PRIMARY KEY (table_name)
+);
+
+-- Table to track installed version of the partitioning solution
+CREATE TABLE IF NOT EXISTS partitions.version (
+    version text PRIMARY KEY,
+    installed_at timestamp with time zone DEFAULT now(),
+    description text
+);
+
+-- Set initial version
+INSERT INTO partitions.version (version, description) VALUES ('1.0', 'Initial release')
+ON CONFLICT (version) DO NOTHING;
+
+-- Default configuration for Zabbix tables (adjust as needed)
+-- History tables: Daily partitions, keep 30 days
+INSERT INTO partitions.config (table_name, period, keep_history) VALUES
+('history', 'day', '30 days'),
+('history_uint', 'day', '30 days'),
+('history_str', 'day', '30 days'),
+('history_log', 'day', '30 days'),
+('history_text', 'day', '30 days')
+ON CONFLICT (table_name) DO NOTHING;
+
+-- Trends tables: Monthly partitions, keep 12 months
+INSERT INTO partitions.config (table_name, period, keep_history) VALUES
+('trends', 'month', '12 months'),
+('trends_uint', 'month', '12 months')
+ON CONFLICT (table_name) DO NOTHING;
+
+-- Auditlog: Monthly partitions, keep 12 months
+INSERT INTO partitions.config (table_name, period, keep_history) VALUES
+('auditlog', 'month', '12 months')
+ON CONFLICT (table_name) DO NOTHING;

postgresql/procedures/01_auditlog_prep.sql

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+-- ============================================================================
+-- SCRIPT: 01_auditlog_prep.sql
+-- DESCRIPTION: Modifies the 'auditlog' table Primary Key to include 'clock'.
+--              This is REQUIRED for range partitioning by 'clock'.
+-- ============================================================================
+
+DO $$
+BEGIN
+    -- Check if PK needs modification
+    -- Original PK is typically on (auditid) named 'auditlog_pkey'
+    IF EXISTS (
+        SELECT 1 FROM pg_constraint 
+        WHERE conname = 'auditlog_pkey' 
+        AND conrelid = 'auditlog'::regclass
+    ) THEN
+        -- Verify if 'clock' is already in PK (basic check)
+        -- Realistically, if 'auditlog_pkey' exists on default Zabbix, it's just (auditid).
+        
+        RAISE NOTICE 'Dropping existing Primary Key on auditlog...';
+        ALTER TABLE auditlog DROP CONSTRAINT auditlog_pkey;
+        
+        RAISE NOTICE 'Creating new Primary Key on auditlog (auditid, clock)...';
+        ALTER TABLE auditlog ADD PRIMARY KEY (auditid, clock);
+    ELSE
+        RAISE NOTICE 'Constraint auditlog_pkey not found. Skipping or already modified.';
+    END IF;
+END $$;

postgresql/procedures/02_maintenance.sql

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+-- ============================================================================
+-- SCRIPT: 02_maintenance.sql
+-- DESCRIPTION: Core functions for Zabbix partitioning (Create, Drop, Maintain).
+-- ============================================================================
+
+-- Function to check if a partition exists
+CREATE OR REPLACE FUNCTION partitions.partition_exists(p_partition_name text) 
+RETURNS boolean AS $$
+BEGIN
+    RETURN EXISTS (
+        SELECT 1 FROM pg_class c
+        JOIN pg_namespace n ON n.oid = c.relnamespace
+        WHERE c.relname = p_partition_name
+        AND n.nspname = 'public'
+    );
+END;
+$$ LANGUAGE plpgsql;
+
+-- Function to create a partition
+CREATE OR REPLACE PROCEDURE partitions.create_partition(
+    p_parent_table text,
+    p_start_time timestamp with time zone,
+    p_end_time timestamp with time zone,
+    p_period text
+) LANGUAGE plpgsql AS $$
+DECLARE
+    v_partition_name text;
+    v_start_ts bigint;
+    v_end_ts bigint;
+    v_suffix text;
+BEGIN
+    v_start_ts := extract(epoch from p_start_time)::bigint;
+    v_end_ts := extract(epoch from p_end_time)::bigint;
+    
+    IF p_period = 'month' THEN
+        v_suffix := to_char(p_start_time, 'YYYYMM');
+    ELSE
+        v_suffix := to_char(p_start_time, 'YYYYMMDD');
+    END IF;
+    
+    v_partition_name := p_parent_table || '_p' || v_suffix;
+
+    IF NOT partitions.partition_exists(v_partition_name) THEN
+        EXECUTE format(
+            'CREATE TABLE public.%I PARTITION OF public.%I FOR VALUES FROM (%s) TO (%s)',
+            v_partition_name, p_parent_table, v_start_ts, v_end_ts
+        );
+    END IF;
+END;
+$$;
+
+-- Function to drop old partitions
+CREATE OR REPLACE PROCEDURE partitions.drop_old_partitions(
+    p_parent_table text,
+    p_retention interval,
+    p_period text
+) LANGUAGE plpgsql AS $$
+DECLARE
+    v_cutoff_ts bigint;
+    v_partition record;
+    v_partition_date timestamp with time zone;
+    v_suffix text;
+BEGIN
+    -- Calculate cutoff timestamp
+    v_cutoff_ts := extract(epoch from (now() - p_retention))::bigint;
+
+    FOR v_partition IN 
+        SELECT 
+            child.relname AS partition_name
+        FROM pg_inherits
+        JOIN pg_class parent ON pg_inherits.inhparent = parent.oid
+        JOIN pg_class child ON pg_inherits.inhrelid = child.oid
+        WHERE parent.relname = p_parent_table
+    LOOP
+        -- Parse partition suffix to determine age
+        -- Format: parent_pYYYYMM or parent_pYYYYMMDD
+        v_suffix := substring(v_partition.partition_name from length(p_parent_table) + 3);
+        
+        BEGIN
+            IF length(v_suffix) = 6 THEN -- YYYYMM
+                v_partition_date := to_timestamp(v_suffix || '01', 'YYYYMMDD');
+                -- For monthly, we check if the END of the month is older than retention? 
+                -- Or just strict retention. 
+                -- To be safe, adding 1 month to check vs cutoff.
+                IF extract(epoch from (v_partition_date + '1 month'::interval)) < v_cutoff_ts THEN
+                    RAISE NOTICE 'Dropping old partition %', v_partition.partition_name;
+                    EXECUTE format('DROP TABLE public.%I', v_partition.partition_name);
+                END IF;
+            ELSIF length(v_suffix) = 8 THEN -- YYYYMMDD
+                v_partition_date := to_timestamp(v_suffix, 'YYYYMMDD');
+                IF extract(epoch from (v_partition_date + '1 day'::interval)) < v_cutoff_ts THEN
+                    RAISE NOTICE 'Dropping old partition %', v_partition.partition_name;
+                    EXECUTE format('DROP TABLE public.%I', v_partition.partition_name);
+                END IF;
+            END IF;
+        EXCEPTION WHEN OTHERS THEN
+            -- Ignore parsing errors for non-standard partitions
+            NULL;
+        END;
+    END LOOP;
+END;
+$$;
+
+-- MAIN Procedure to maintain a single table
+CREATE OR REPLACE PROCEDURE partitions.maintain_table(
+    p_table_name text,
+    p_period text,
+    p_keep_history interval,
+    p_future_partitions integer DEFAULT 5
+) LANGUAGE plpgsql AS $$
+DECLARE
+    v_start_time timestamp with time zone;
+    v_period_interval interval;
+    i integer;
+    v_past_iterations integer;
+BEGIN
+    IF p_period = 'day' THEN
+        v_period_interval := '1 day'::interval;
+        v_start_time := date_trunc('day', now());
+        -- Calculate how many past days cover the retention period
+        v_past_iterations := extract(day from p_keep_history)::integer;
+        -- Safety cap or ensure minimum? default 7 if null?
+        IF v_past_iterations IS NULL THEN v_past_iterations := 7; END IF;
+        
+    ELSIF p_period = 'week' THEN
+        v_period_interval := '1 week'::interval;
+        v_start_time := date_trunc('week', now());
+        v_past_iterations := (extract(day from p_keep_history) / 7)::integer;
+
+    ELSIF p_period = 'month' THEN
+        v_period_interval := '1 month'::interval;
+        v_start_time := date_trunc('month', now());
+        -- Approximate months
+        v_past_iterations := (extract(year from p_keep_history) * 12 + extract(month from p_keep_history))::integer;
+        -- Fallback if interval is just days (e.g. '365 days')
+        IF v_past_iterations = 0 THEN 
+             v_past_iterations := (extract(day from p_keep_history) / 30)::integer; 
+        END IF;
+    ELSE
+        RETURN;
+    END IF;
+
+    -- 1. Create Future Partitions (Current + Buffer)
+    FOR i IN 0..p_future_partitions LOOP
+        CALL partitions.create_partition(
+            p_table_name,
+            v_start_time + (i * v_period_interval),
+            v_start_time + ((i + 1) * v_period_interval),
+            p_period
+        );
+    END LOOP;
+    
+    -- 2. Create Past Partitions (Covering retention period)
+    IF v_past_iterations > 0 THEN
+        FOR i IN 1..v_past_iterations LOOP
+            CALL partitions.create_partition(
+                p_table_name,
+                v_start_time - (i * v_period_interval),
+                v_start_time - ((i - 1) * v_period_interval),
+                p_period
+            );
+        END LOOP;
+    END IF;
+
+    -- 3. Drop Old Partitions
+    CALL partitions.drop_old_partitions(p_table_name, p_keep_history, p_period);
+    
+    -- 4. Update Metadata
+    UPDATE partitions.config SET last_updated = now() WHERE table_name = p_table_name;
+END;
+$$;
+
+-- Global Maintenance Procedure
+CREATE OR REPLACE PROCEDURE partitions.run_maintenance() 
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_row record;
+BEGIN
+    FOR v_row IN SELECT * FROM partitions.config LOOP
+        CALL partitions.maintain_table(v_row.table_name, v_row.period, v_row.keep_history, v_row.future_partitions);
+    END LOOP;
+END;
+$$;

postgresql/procedures/03_enable_partitioning.sql

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+-- ============================================================================
+-- SCRIPT: 03_enable_partitioning.sql
+-- DESCRIPTION: Converts standard Zabbix tables to Partitioned tables.
+--              WARNING: This renames existing tables to *_old.
+-- ============================================================================
+
+DO $$
+DECLARE
+    v_row record;
+    v_table text;
+    v_old_table text;
+    v_pk_sql text;
+BEGIN
+    FOR v_row IN SELECT * FROM partitions.config LOOP
+        v_table := v_row.table_name;
+        v_old_table := v_table || '_old';
+        
+        -- Check if table exists and is NOT already partitioned
+        IF EXISTS (SELECT 1 FROM pg_class WHERE relname = v_table AND relkind = 'r') THEN
+            RAISE NOTICE 'Converting table % to partitioned table...', v_table;
+            
+            -- 1. Rename existing table
+            EXECUTE format('ALTER TABLE public.%I RENAME TO %I', v_table, v_old_table);
+            
+            -- 2. Create new partitioned table (copying structure)
+            EXECUTE format('CREATE TABLE public.%I (LIKE public.%I INCLUDING ALL) PARTITION BY RANGE (clock)', v_table, v_old_table);
+            
+            -- 3. Create initial partitions
+            RAISE NOTICE 'Creating initial partitions for %...', v_table;
+            CALL partitions.maintain_table(v_table, v_row.period, v_row.keep_history, v_row.future_partitions); 
+            
+            -- Optional: Migrate existing data
+            -- EXECUTE format('INSERT INTO public.%I SELECT * FROM public.%I', v_table, v_old_table);
+            
+        ELSIF EXISTS (SELECT 1 FROM pg_class WHERE relname = v_table AND relkind = 'p') THEN
+             RAISE NOTICE 'Table % is already partitioned. Skipping conversion.', v_table;
+             -- Just run maintenance to ensure partitions exist
+             CALL partitions.run_maintenance();
+        ELSE
+             RAISE WARNING 'Table % not found!', v_table;
+        END IF;
+    END LOOP;
+END $$;

postgresql/procedures/04_monitoring_view.sql

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+-- ============================================================================
+-- SCRIPT: 04_monitoring_view.sql
+-- DESCRIPTION: Creates a view to monitor partition status and sizes.
+-- ============================================================================
+
+CREATE OR REPLACE VIEW partitions.monitoring AS
+SELECT
+    parent.relname AS parent_table,
+    c.table_name,
+    c.period,
+    c.keep_history,
+    count(child.relname) AS partition_count,
+    count(child.relname) FILTER (
+        WHERE
+           (c.period = 'day' AND child.relname > (parent.relname || '_p' || to_char(now(), 'YYYYMMDD')))
+           OR
+           (c.period = 'month' AND child.relname > (parent.relname || '_p' || to_char(now(), 'YYYYMM')))
+    ) AS future_partitions,
+    pg_size_pretty(sum(pg_total_relation_size(child.oid))) AS total_size,
+    min(child.relname) AS oldest_partition,
+    max(child.relname) AS newest_partition,
+    c.last_updated
+FROM partitions.config c
+JOIN pg_class parent ON parent.relname = c.table_name
+LEFT JOIN pg_inherits ON pg_inherits.inhparent = parent.oid
+LEFT JOIN pg_class child ON pg_inherits.inhrelid = child.oid
+WHERE parent.relkind = 'p' -- Only partitioned tables
+GROUP BY parent.relname, c.table_name, c.period, c.keep_history, c.last_updated;