Mastering Concurrent Materialized View Refreshes in Oracle Database 23ai: A Deep-Dive for Experienced DBAs
Materialized views serve as a keystone for performance tuning in Oracle databases, offering a persistent, precomputed store for results of resource-intensive queries. By using materialized views, organizations can deliver instant results for complex analytics and reporting applications, even as their transactional workloads grow. Yet until now, one pressing challenge remained: the process of refreshing materialized views often incurred table locks and interfered with application DML, particularly during full or synchronous refresh operations. This could degrade responsiveness and force DBAs to schedule refreshes for off-peak hours—sometimes sacrificing data freshness for performance.
With Oracle Database 23ai, a transformative feature arrives: the ability to perform concurrent materialized view refreshes. This enhancement redefines best practices for high-availability enterprise systems by letting refreshes occur in parallel with ongoing data modifications. Instead of locking out DML operations during lengthy refreshes, Oracle 23ai leverages advanced transactional logic and sophisticated staging, so most of the refresh occurs without heavy locking the only pause being a momentary metadata switch at completion. This approach offers significant advantages for real-time analytics, enabling organizations to refresh summary tables or dashboards far more frequently without impacting core transactional workloads.
To illustrate how this works in a real-world scenario, imagine a global retail company running an Oracle-powered e-commerce platform. Each hour, business leaders rely on dashboards for insights into regional sales trends, but until recently, refreshing these analytics risked colliding with spikes in customer activity or inventory updates. Now, with concurrent refresh enabled, the DBA can confidently refresh a sales_summary_mv materialized view every hour even at peak times—knowing that order processing and inventory updates will not be blocked. This marks a step change in both operational agility and business intelligence capabilities: transaction processing and analytical reporting can finally run seamlessly, side by side.
Enabling concurrent refresh in Oracle 23ai requires the database to be upgraded and the materialized view to be compatible (for instance, supporting fast or on-demand refresh). Not all materialized views are eligible, particularly those defined with certain complex joins or unsupported aggregate types, so DBAs should validate their view definitions and consult Oracle documentation for specifics. The implementation is elegantly simple: refreshes are invoked using the DBMS_MVIEW.REFRESH procedure with method 'C' and atomic_refresh => FALSE. An example illustrates this clearly:
Suppose we have a sales summary view defined as follows:
CREATE MATERIALIZED VIEW sales_summary_mv
BUILD IMMEDIATE
REFRESH FAST ON DEMAND
ENABLE QUERY REWRITE
AS
SELECT
region_id,
SUM(sales_amount) AS total_sales,
COUNT(*) AS sale_count
FROM sales
GROUP BY region_id;
To perform a concurrent refresh, the DBA executes:
BEGIN
DBMS_MVIEW.REFRESH(
list => 'SALES_SUMMARY_MV',
method => 'C',
atomic_refresh => FALSE
);
END;
/
While this refresh proceeds, users continue to place orders or update records in the sales table we see none of the blocking or contention that characterized earlier Oracle releases. In the event of a failure, Oracle preserves the prior view state, ensuring consistency and eliminating the risk of partial refreshes.
From a practical standpoint, DBAs should be mindful of system resources, as concurrent refreshes use temporary staging and may increase I/O or temp tablespace usage. Monitoring tools such as AWR and ASH become vital for profiling impacts and identifying bottlenecks during refresh cycles. Automated job scheduling, along with robust alerting and documentation, will ensure the new strategy is consistently applied and provides maximum value.
In conclusion, the concurrent materialized view refresh feature in Oracle Database 23ai empowers organizations to achieve near real-time analytics without compromising transactional throughput or application availability. For experienced DBAs, this represents a compelling upgrade, modernizing operational practices and unlocking new use cases for timely, actionable business insights. The seamless coexistence of high-performance OLTP and always-fresh analytical reporting is now within reach, making this feature one of the most strategic advances in Oracle performance optimization.
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