Oracle multimaster replication
A Four-phase Approach to Procedural Multi-master Replication by Donald K. Burleson Introduction Do you support customers whose databases are updated by users in multiple locations and across multiple time zones? If so, the challenge for the DBA is how best to manage replicated systems that allow for fast database access over Wide Area Networks. In many shops, popular failover solutions include Rea
Oracle and CPU utilization metrics
If you suspect a CPU utilization problem in your Oracle database, see these important notes on 100% CPU and Oracle. Also see Monitoring CPU with UNIX. CPU utilization and Oracle On most operating systems CPU states include (user, system, wait and idle) components, and it's important to understand that Oracle does not have direct access to CPU utilization statistics. While this note is talking abo
Oracle 100% CPU tips
Question: I checked by server and was dismayed to find my CPU consumption at 100%. How do I reduce Oracle CPU consumption? Answer: Remember, all virtual memory servers are designed to drive CPU to 100% as soon as possible. Hence, 100% CPU utilization may not be sub-optimal because 100% CPU simply means that all the processors are busy (that's how the server SMP architecture is designed). You on
Oracle Database Metric v$ Views
Oracle Database Metric v$ Views For a complete description of the v$ views, get the "free 11g poster" sponsored by UNISYS. In Oracle database releases prior to 11g, Oracle DBAs were often tasked to compute numerous statistics like ratios that give an overview of database performance and workload at a glance. For example, database buffer hit ratio , library cache hit ratio , or physical reads per s
Oracle latch: cache buffers chains
Oracle latch: cache buffers chains Oracle Consulting Tips by Burleson The latch: cache buffers chains Oracle metric are used to protect a buffer list in the buffer cache. These latches are used when searching for, adding, or removing a buffer from the buffer cache. Contention on this latch usually means that there is a block that is greatly contended for (known as a hot block). For more details on
Oracle Index-organized table (IOT) cluster
Oracle Index-organized table (IOT) vs. Cluster table Expert Oracle Tips by Don Burleson I'm often asked "when should I use an Oracle index-organized table (IOT) vs. a single-table cluster?". Both index-organized tables (IOTs) and cluster tables are used to reduce I/O (consistent gets and physical reads) by making the SQL more efficient. The SQL becomes more efficient on an Oracle index-organized
Oracle performance tuning with indexes
Turbocharge SQL with advanced Oracle indexing Oracle Tips by Burleson Consulting March 26, 2002 - Updated April 8, 2015 For complete details on Oracle indexing for high performance, see my book "Oracle Tuning: The Definitive Reference". Oracle includes numerous data structures to improve the speed of Oracle SQL queries. Taking advantage of the low cost of disk storage, Oracle includes many new ind
Oracle index organized tables performance
March 25, 2005 Article Review Indexed Organized Tables By Scott Martin (smartin@tlingua.com) of Teralingua Software IOUG SELECT Journal, First quarter 2005 (www.selectonline.org) Author Scott Martin (with a Masters Degree from M.I.T. and a former member of the Oracle kernel group), has published a comprehensive article on Oracle index-organized table (IOT) technology, complete with clear examples
Reduce I/O with Oracle cluster tables
Reduce I/O with Oracle cluster tables Oracle Tips by Burleson Consulting Experienced Oracle DBAs know that I/O is often the single greatest component of response time and regularly work to reduce I/O. Disk I/O is expensive because when Oracle retrieves a block from a data file on disk, the reading process must wait for the physical I/O operation to complete. Disk operations are about 10,000 times
Oracle interval partitioning tips
Oracle Interval Partitioning Tips Oracle Database Tips by Donald BurlesonApril 31, 2015 Interval partitioning is an enhancement to range partitioning in Oracle 11g and interval partitioning automatically creates time-based partitions as new data is added. Range partitioning allows an object to be partitioned by a specified range on the partitioning key. For example, if a table was used to store
Oracle index blocksize tuning
Update: For the latest consensus on using multiple blocksizes in Oracle, see The latest consensus on multiple blocksizes. The benefits of a large blocksize The benefits of large blocksizes are demonstrated on this OTN thread where we see a demo showing 3x faster performance using a larger block size: SQL> r 1 select count(MYFIELD) from table_8K where ttime >to_date('27/09/2006','dd/mm/y 2* and tti
Optimizing Linux network TCP/IP kernel parameters
Optimizing Linux network TCP/IP kernel parameters Oracle Database Tips by Donald Burleson Many Oracle professionals do not note the required setting for optimizing Oracle*Net on Oracle 10g release 2. Here is a review of the suggested TCP/IP buffer parameters: You can verify the Linux networking kernel parms from the root user with these commands:: $ sysctl –a|grep rmem $ sysctl –a|grep wmem The L
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Optimizing Oracle RAM for SGA & PGA
Oracle Free Buffer Waits
Optimize Oracle Network Tips
Oracle Row Re-sequencing - cluster table
session_cached_cursors sizing
Oracle Secure File (securefile) tips
Chunking Bulk Collections Using the LIMIT Clause
Adjusting Array Size in Oracle SQL*Plus