Blog

Monitoring Exadata Storage Indexes

Storage indexes are unique Exadata structures whose goal is to reduce the amount of IO returned and required from the Exadata cell. When queries run in which storage indexes are eligible, Oracle tracks minimum and maximum predicate values and stores these into 1Mb memory regions in each cell. When a query is passed to the […]

Read More

Automatic Degree of Parallism (Auto DOP)

Parallel Query Parallel query works the same on Exadata as it does on non-Exadata 11gR2.  With Exadata, which you’ve cost-justified based on your database’s performance requirements, business-criticality, or some other reason, you want to get the most performance out of your investment, so exploiting the benefits of parallel query is important. Depending on which size […]

Read More

Using DBFS and External Tables

What is DBFS? DBFS stands for Database File System, and it’s Oracle’s method for housing an operating system-like file-system within an Oracle relational database.  It has its roots with iFS, but its functionality and capabilities have been extended.  Here are some reasons why DBFS is a good thing: When you store files in DBFS, they […]

Read More

Understanding CBO with SQL_COMPILER Tracing

What is SQL Compiler Tracing? SQL compiler tracing is a method to generate trace files that indicate what steps and actions the cost-base optimizer (CBO) used to determine a SQL statement’s execution plan.  It is an extension of the 10053 trace that’s been around for years, enhanced in 11g to provide arguably easier syntax and additional […]

Read More

SQL Test Case Builder in Oracle 11g

What is SQL Test Case Builder? SQL Test Case Builder is a diagnostic tool in 11g, back-ported to 10g, that is designed to be able to obtain a reproducible test case for developers, DBAs, or Oracle Support. Oracle built the SQL Test Case Builder diagnostics utility primarily to assist Oracle Support and customers for performance-related […]

Read More

SQL Monitoring in Oracle 11g

Starting with 11g, Oracle introduced a new tool to add to the performance optimizer’s toolkit called “Real Time SQL Monitoring”.  Real Time SQL Monitoring, or just “SQL Monitoring”, enables you to measure the performance of SQL statements while they are executing.  SQL Monitoring is enabled any time a statement runs in parallel or when it […]

Read More

Monitoring Exadata Smart Scan

Exadata Smart Scan processing is one of the key components of Exadata’s “secret sauce”. It enables certain operations to be offloaded to the storage cell, reducing the amount of work required on the database tier nodes and reducing the impact of shipping blocks over the storage interconnect. Scripts are provided in this that can be […]

Read More

Using IORM with Exadata

IO Resource Management (IORM) provides a means to govern and meter IO from different workloads in the Exadata Storage Server. Consolidation means that multiple databases and applications could share Exadata storage. Different databases in a shared Exadata storage grid could have different IO performance requirements. One of the common challenges with shared storage infrastructure is […]

Read More

Exadata Storage Indexes

What is a Storage Index? Storage Indexes are a feature unique to Oracle Exadata. A storage index is a memory-based structure that reduces the amount of physical IO required by the cell. A storage index keeps track of minimum and maximum values from query predicates and builds storage index regions based on usage.   need […]

Read More

Why Does Exadata Require a 4MB Allocation Unit Size (AU_SIZE)?

Oracle publishes that Exadata IO works best with a 4MB allocation unit size for ASM disk groups, so ASM disk groups should be created with AU_SIZE=4M.  Further, Oracle also recommends that segment extents sizes should be a multiple of 4Mb if they’re to be accessed via Smart Scan. Here, we’ll attempt to demonstrate why this is […]

Read More

Whatever we ask them to do, we know they'll deliver a solution and not leave us hanging.

Tony Deller Manager Data Center Technical Engineering