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Database Size Trends

The Database Size tab tracks the storage evolution of all monitored databases over the selected time period, and monitors transaction ID (XID) age as a wraparound risk indicator.

AWR Trends Database Size

KPI Summary Cards​

Three summary cards give an immediate snapshot of the current storage state:

CardDescription
Total SizeCombined size of all monitored databases on this instance
DatabasesNumber of databases currently monitored on this server
Largest DatabaseName of the largest database + its current size

AWR Trends Database Size

Charts​

Chart 1 — Database Size Evolution (GB)​

A line chart showing the size evolution of each monitored database over time, expressed in GB.

  • X axis — Time (based on the selected range)
  • Y axis — Database size in GB
  • Each line — One database on the instance

AWR Trends Database Size

Use for:

  • Tracking storage growth per database over days, weeks or months
  • Projecting future storage needs based on observed growth rate
  • Detecting unexpected size spikes (runaway inserts, missing cleanup jobs)
  • Identifying which database is consuming the most storage

Capacity Planning Formula​

Projected size in N days = Current Size + (Avg Daily Growth × N)

If a database is currently 50 GB and growing at 500 MB/day:

  • In 30 days → ~65 GB
  • In 90 days → ~95 GB

Plan storage provisioning accordingly with a comfortable safety buffer.

Chart 2 — XID Age — Wraparound Risk​

A line chart showing the transaction ID (XID) age of each database over time. XID age measures how far a database is from the transaction ID wraparound limit.

AWR Trends Database Size

Understanding XID Wraparound

PostgreSQL uses 32-bit transaction IDs. After approximately 2 billion transactions, the XID counter wraps around. If a database reaches this limit without having been vacuumed, PostgreSQL enters emergency shutdown mode to prevent data corruption.

XID age = distance (in transactions) from the oldest unvacuumed transaction to the current transaction ID.

XID AgeRisk LevelAction
< 500M🟢 LowNormal — no action needed
500M – 1B🟡 WarningMonitor — ensure autovacuum is running
1B – 1.5B🟠 HighInvestigate — run manual VACUUM on old tables
> 1.5B🔴 CriticalImmediate action — risk of emergency shutdown
XID Wraparound is Critical

If XID age approaches 2 billion, PostgreSQL will refuse all new transactions and enter read-only mode to protect data integrity. Monitor this chart regularly and ensure autovacuum is not disabled or throttled on any database.

To check current XID age:

SELECT datname,
       age(datfrozenxid) AS xid_age,
       pg_size_pretty(pg_database_size(datname)) AS size
FROM pg_database
ORDER BY age(datfrozenxid) DESC;

Use for:

  • Monitoring wraparound risk across all databases continuously
  • Detecting databases where autovacuum is not keeping up with XID consumption
  • Identifying databases that need aggressive VACUUM FREEZE intervention

Detecting Unexpected Growth​

A sudden jump in database size in the Size Evolution chart may indicate:

  • A large batch data load or ETL operation
  • A missing DELETE or TRUNCATE in a scheduled cleanup job
  • A bloat spike caused by high-churn tables not being vacuumed
  • Temporary table accumulation

Cross-reference with the AWR Viewer for the same time period to identify the source — check Top SQL by Executions for bulk INSERT patterns and Bloat Analysis for table bloat growth.

Next Steps​