Recently, at a customer site, I faced a performance issue. However, as often the statement is embedded in the application so it’s not possible to rewrite the query. In this blog post, we’ll change the execution plan to solve the problem without changing the code – thanks to SQL Patch. The faulty statement was part of a daily job that…
By Franck Pachot . Recently, I described the Partial Join Evaluation transformation that appeared last year in Oracle 12c. I did it as an introduction for another transformation that appeared long time ago in 10.1.0.3 but was not used by default. And even in the latest Oracle 12c patchset 1 (aka 12.1.0.2.0) it is still not enabled. But it’s there…
I have recently used perfmon (performance monitor) at a customer site. I created a Data Collector Set to monitor CPU, Memory, Disk, and Network during one day. Then, I ran the monitor and I received a “beautiful” error message… What happened? 😉 Ok, to be sure that it was not a rights or a setting problem in my Data Collector…
By Franck Pachot . In a previous blog, I discussed the difference between rownum and row_number(), in particular their behaviour in implicitely adding a first_rows(n) to the optimizer. That reminded me that I forgot to blog about an issue I encountered and which concerns both approaches. It was on an Exadata: a nice full table scan with smartscan was taking…
SQL Server 2014 is definitively designed for performance and I will try to demonstrate it during this blog post. I like to talk about hidden performance features because generally it does not require any changes for applications unlike in-memory tables for instance (aka hekaton tables). Since SQL Server 2005 version some improvements have been made for tempdb. Tempdb caching is…
By Franck Pachot . At dbi services, we really like Lighty for Oracle, a tool which helps exploring performance statistics whether they originate from AWR (available only in Enterprise Edition with Diagnostic Pack option) or from Statspack (available via Standard Edition). As a matter of fact, we like it so much that we have became Orachrome Partner. If you want…
A couple of weeks ago, I had to provide some best practices in term of architecture for a “heavy writes” environment that consists in importing data from different sources into SQL Server tables. At the customer place, I was asked about interesting new SQL Server features that could be used to increase the performance speed of the data import process.…
I have read some blog postings concerning the new perfmon counters, but I have not seen really extensive overviews yet. In this post, I would like to present not only what is new, but also what has changed (or not) and how to find it. The first step is to select all objects in SQL2008R2 and SQL2012 from the view sys.dm_os_performance_counters.…
Today it’s the real beginning of the TechEd with several sessions in parallel.
Data can be corrupted in different ways, for example an I/O issue when reading data from the storage or a memory issue when updating data. The db_block_checking parameter allows to change the behavior of an Oracle database concerning block checking.
This posting will present this parameter and some tests to measure its impact on the database.
Who never had to measure the disk performances on a system?
Speaking about Linux performance monitoring includes a significant part on disk performances. If you are facing applications or databases running slower than expected or than on other environments, you may take a look on the I/O performances.
This blog aims to provide to introduction to a pretty interesting tool,
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Last week, Oracle Ace Director Jonathan Lewis held an Oracle Optimizer Workshop at dbi services BaselArea. I would like to share some of the key learnings of this really interesting exchange I experienced together with my colleagues.
