Posts by Marc Fielding

Sleuthing for Temporary Space Spendthrifts

I was recently looking at an issue where a large database server was running out of temp space. The issue had happened in the past, so the goal was to identify what had been causing the system to run out of temp. Although ORA-1555 messages will appear in the database alert log (with query text) when a query runs out of temporary space, they only talk about the query that was “unlucky” enough to be attempting to get space when the tablespace was full, not who was using the temp space.

Revealing the Hints Behind the Automatic SQL Tuning Advisor

A client recently supplied a list of 50+ SQL IDs that should receive SQL profiles, and I’ve been working with Gwen Shapira to review the list. Further discussion showed that this list had come from the Automatic SQL Tuning feature, installed by default in Oracle 11g. The report includes a list of recommended SQL profiles ordered by “Maximum Benefit”, and in our case it included several hundred statements. The expected workflow, as far as I can gather, is to see the recommendations, look at the before- and after- execution plans, and accept the recommendations. Before blindly accepting recommendations, though, I like to see what exact changes are being proposed. They aren’t listed anywhere in the report, and require some extra work to uncover. The first step is to get the automatic SQL tuning advisor report. (

Temporary Tablespaces: to BIGFILE or Not to BIGFILE

The environment was an Exadata environment undergoing pre-production stress testing. We used Real Application Testing to take a highly-concurrent OLTP workload, and replayed the workload with the synchronization parameter set to FALSE, effectively increasing concurrency beyond the original test system. AWR showed a large volume of buffer busy activity.

Exadata X3H2M2: A Few Thoughts

Tonight at Oracle OpenWorld, Oracle CEO Larry Ellison announced the latest Exadata release: X3. It sports a hardware refresh including a big expansion in RAM and flash storage capacity: 4TB and 22TB respectively on a full rack. Read my thoughts on this here.

Troubleshooting ORA-27090 Async I/O Errors with Systemtap

There’s a known bug, 7306820 “ORA-7445 [krhahw] / ORA-27090 during file header read. Instances may crash, but this bug is fixed in, and this database is running And on top of that, it’s an Exadata system, so I/O to storage servers goes over the InfiniBand network rather than using async I/O (AIO) calls.

A Few Thoughts on OSCon and the Open Source Community

This past week I attended OSCon, the annual conference for open source’s true believers. And there was a religious fervor in the air, particularly from the point of view of someone more accustomed to Oracle conferences. The companies generating buzz were the small companies built around development of their own open source products. There are a surprising number of them out there, especially relating to multiple forks of a popular product like MySQL or Hadoop.

The Exadata Installed Base, Quantified

Update 13-June-2012: It has come to my attention that the numbers from the original source may have been incorrect or improperly released. To avoid confusion and potentially misleading information, the original content of this blog post has been removed.

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