How to Calculate TCP Socket Buffer Sizes for Data Guard Environments

The MAA best practices contains an example of how to calculate the optimal TCP socket buffer sizes, that is quite important for very busy Data Guard environments, this document Formula to Calculate TCP Socket Buffer Sizes.pdf contains an example of using the instructions provided on the best practices document. In order to execute the calculation you need to know which is the band with or your network interface, usually will be 1Gb, on my example is a 10Gb network; and the...

Wednesday, May 19, 2010 | Read More

Impact of Truncate or Drop Table When Flashback Database is Enabled

Recently I was working on a VLDB on the implementation of a disaster recovery environment configured with data guard physical standby and fast start failover. One of the questions that come up was about the overhead of truncating and dropping tables. There are daily jobs on the database that truncate extremely large partitions, and as note 565535.1 explain, we knew there is an overhead for these operations. But the information on the note was not clear enough, with...

Wednesday, May 19, 2010 | HA | Read More

Oracle Database 11g Underground Advice for Database Administrators, by April C. Sims

Recently I have received a request to review the book "Oracle Database 11g Underground Advice for Database Administrators" by April C. Sims I was happy to have the opportunity to know some details about the author, she is an active contributor to the Oracle DBA community, through her blog "Oracle High Availability" . The book is a serious and interesting work, I think it provides a good study and reference guide for DBA's that want to understand and implement highly available...

Wednesday, May 19, 2010 | HA | Read More

The Next RAC, ASM and Linux Forum. May 4, 2010 Beit HP Raanana

The next RAC, ASM and Linux forum will take place next week, you are still on time to register : Israel Oracle Users Group RAC,ASM and Linux Forum This time we will have a panel formed by Principal Oracle Advanced Customer Services Engineers and RAC experts Galit Elad and Nickita Chernovski and Senior Oracle Advanced Customer Services Engineers and RAC experts Roy Burstein and Dorit Noga. They will address the subject: 5 years of experience with RAC at Israeli Customers,...

Tuesday, April 27, 2010 | ASM | Read More

Cloning A Database On The Same Server Using Rman Duplicate From Active Database

To clone a database using Rman we used to require an existing Rman backup, on 11g we can clone databases using the "from active" database option. In this case we do not require an existing backup, the active datafiles will be used as the source for the clone. In order to clone with the source database open it must be on archivelog mode. Otherwise we can make the clone mounting the source database, as shown in this example. These are the steps required to complete the clone: Confi...

Saturday, March 20, 2010 | RMAN | Read More

Compression for tables with more than 250 columns

Compression for tables with more than 250 columns Tables with more than 250 columns are not supported to be compressed, this restriction remains in place even on 11g R2. On the 11g R2, Sql Language Reference Manual, page 16-36 we can read: Restrictions on Table Compression * COMPRESS FOR OLTP and COMPRESS BASIC are not supported for tables with more than 255 columns. This is a serious limitation specially for Telecoms where CDR tables can have a number of columns way over 255. The...

Monday, March 1, 2010 | Read More

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