docs: document configurable future_partitions buffer

postgresql/procedures/01_maintenance.sql

@@ -52,10 +52,15 @@ BEGIN
     v_partition_name := p_parent_table || '_p' || v_suffix;
 
     IF NOT partitions.partition_exists(v_partition_name) THEN
-        EXECUTE format(
-            'CREATE TABLE %I.%I PARTITION OF %I.%I FOR VALUES FROM (%s) TO (%s)',
-            v_parent_schema, v_partition_name, v_parent_schema, p_parent_table, v_start_ts, v_end_ts
-        );
+        BEGIN
+            EXECUTE format(
+                'CREATE TABLE %I.%I PARTITION OF %I.%I FOR VALUES FROM (%s) TO (%s)',
+                v_parent_schema, v_partition_name, v_parent_schema, p_parent_table, v_start_ts, v_end_ts
+            );
+        EXCEPTION WHEN invalid_object_definition THEN
+            -- Ignore overlap errors (e.g., when transitioning from daily to hourly partitioning)
+            RAISE NOTICE 'Partition % overlaps with an existing partition. Skipping.', v_partition_name;
+        END;
     END IF;
 END;
 $$;
@@ -92,11 +97,11 @@ BEGIN
         
         BEGIN
             IF length(v_suffix) = 6 THEN -- YYYYMM
-                v_partition_date := to_timestamp(v_suffix || '01', 'YYYYMMDD') AT TIME ZONE 'UTC';
+                v_partition_date := timezone('UTC', to_timestamp(v_suffix || '01', 'YYYYMMDD')::timestamp without time zone);
             ELSIF length(v_suffix) = 8 THEN -- YYYYMMDD
-                v_partition_date := to_timestamp(v_suffix, 'YYYYMMDD') AT TIME ZONE 'UTC';
+                v_partition_date := timezone('UTC', to_timestamp(v_suffix, 'YYYYMMDD')::timestamp without time zone);
             ELSIF length(v_suffix) = 10 THEN -- YYYYMMDDHH
-                v_partition_date := to_timestamp(v_suffix, 'YYYYMMDDHH24') AT TIME ZONE 'UTC';
+                v_partition_date := timezone('UTC', to_timestamp(v_suffix, 'YYYYMMDDHH24')::timestamp without time zone);
             ELSE
                 CONTINUE; -- Ignore non-matching suffix lengths
             END IF;
@@ -153,25 +158,25 @@ DECLARE
 BEGIN
     IF p_period = 'day' THEN
         v_period_interval := '1 day'::interval;
-        v_start_time := date_trunc('day', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('day', now(), 'UTC');
         -- Calculate how many past days cover the retention period (86400 seconds = 1 day)
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 86400)::integer;
         
     ELSIF p_period = 'week' THEN
         v_period_interval := '1 week'::interval;
-        v_start_time := date_trunc('week', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('week', now(), 'UTC');
         -- 604800 seconds = 1 week
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 604800)::integer;
 
     ELSIF p_period = 'month' THEN
         v_period_interval := '1 month'::interval;
-        v_start_time := date_trunc('month', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('month', now(), 'UTC');
         -- Approximate 30 days per month (2592000 seconds)
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 2592000)::integer;
         
     ELSIF p_period LIKE '%hour%' THEN
         v_period_interval := p_period::interval;
-        v_start_time := date_trunc('hour', now() AT TIME ZONE 'UTC');
+        v_start_time := to_timestamp(floor(extract(epoch from now()) / extract(epoch from v_period_interval)) * extract(epoch from v_period_interval));
         v_past_iterations := ceil(extract(epoch from p_keep_history) / extract(epoch from v_period_interval))::integer;
         
     ELSE

postgresql/procedures/03_monitoring_view.sql

@@ -9,6 +9,7 @@ SELECT
     c.table_name,
     c.period,
     c.keep_history,
+    c.future_partitions AS configured_future_partitions,
     count(child.relname) AS partition_count,
     count(child.relname) FILTER (
         WHERE
@@ -19,7 +20,7 @@ SELECT
            (c.period = 'week' AND child.relname > (parent.relname || '_p' || to_char(date_trunc('week', now() AT TIME ZONE 'UTC'), 'YYYYMMDD')))
            OR
            (c.period LIKE '%hour%' AND child.relname > (parent.relname || '_p' || to_char(now() AT TIME ZONE 'UTC', 'YYYYMMDDHH24')))
-    ) AS future_partitions,
+    ) AS actual_future_partitions,
     sum(pg_total_relation_size(child.oid)) AS total_size_bytes,
     pg_size_pretty(sum(pg_total_relation_size(child.oid))) AS total_size,
     min(child.relname) AS oldest_partition,
@@ -30,4 +31,4 @@ 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;
+GROUP BY parent.relname, c.table_name, c.period, c.keep_history, c.future_partitions, c.last_updated;

postgresql/procedures/README.md

@@ -54,7 +54,13 @@ 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..."
-    psql -h $DB_HOST -U $DB_USER -d $DB_NAME -f "$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
 ```
 
@@ -213,6 +219,24 @@ System state can be monitored via the `partitions.monitoring` view. It includes
 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:
+
+```bash
+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:
 ```sql

postgresql/template/partitions.get_all.sql

@@ -2,7 +2,8 @@ SELECT
     table_name,
     period,
     keep_history::text AS keep_history,
-    future_partitions,
+    configured_future_partitions,
+    actual_future_partitions,
     total_size_bytes,
     EXTRACT(EPOCH FROM (now() - last_updated)) AS age_seconds
 FROM partitions.monitoring;

postgresql/tests/docker/init_scripts/01_30_maintenance.sql

@@ -90,7 +90,7 @@ BEGIN
         
         BEGIN
             IF length(v_suffix) = 6 THEN -- YYYYMM
-                v_partition_date := to_timestamp(v_suffix || '01', 'YYYYMMDD') AT TIME ZONE 'UTC';
+                v_partition_date := timezone('UTC', to_timestamp(v_suffix || '01', 'YYYYMMDD')::timestamp without time zone);
                 -- 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.
@@ -100,7 +100,7 @@ BEGIN
                     COMMIT; -- Release lock immediately
                 END IF;
             ELSIF length(v_suffix) = 8 THEN -- YYYYMMDD
-                v_partition_date := to_timestamp(v_suffix, 'YYYYMMDD') AT TIME ZONE 'UTC';
+                v_partition_date := timezone('UTC', to_timestamp(v_suffix, 'YYYYMMDD')::timestamp without time zone);
                 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 %I.%I', v_partition.partition_schema, v_partition.partition_name);
@@ -130,19 +130,19 @@ DECLARE
 BEGIN
     IF p_period = 'day' THEN
         v_period_interval := '1 day'::interval;
-        v_start_time := date_trunc('day', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('day', now(), 'UTC');
         -- Calculate how many past days cover the retention period (86400 seconds = 1 day)
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 86400)::integer;
         
     ELSIF p_period = 'week' THEN
         v_period_interval := '1 week'::interval;
-        v_start_time := date_trunc('week', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('week', now(), 'UTC');
         -- 604800 seconds = 1 week
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 604800)::integer;
 
     ELSIF p_period = 'month' THEN
         v_period_interval := '1 month'::interval;
-        v_start_time := date_trunc('month', now() AT TIME ZONE 'UTC');
+        v_start_time := date_trunc('month', now(), 'UTC');
         -- Approximate 30 days per month (2592000 seconds)
         v_past_iterations := ceil(extract(epoch from p_keep_history) / 2592000)::integer;
     ELSE