Started a new job!

Posted by David Yahalom under General IT

Pop up the champagne bottles people!

I have started a new job as a Senior Project Manager at the Veracity Group , the leading Oracle Consulting group in Israel. Veracity is the only Oracle certified Value Added Distributor (VAD) in Israel and part of a very small and exclusive list of Oracle VADs around the world. Our customers benefit from the unique advantage we offer of both directly licensing and selling Oracle products as well as having an outstanding expert Professional Services team. We’re Simply the best in our field, trust me. As part of my new job at Veracity, I’m also holding the CTO title of a very special group in the Oracle Database development business, but more on this later.

I’ve been able to accomplish a great deal in the last six years as a database consultant, especially during my time at Xpert-One1 which was a very rewarding experience. For some time now I’ve been looking into getting a more managerial position and when the opportunity presented itself, I simply couldn’t resist. My new position puts me directly in the middle decision making process about all things technological - so I think this would make a great learning experience for me. I’m still (and always will be) a bits and bytes kind of guy so I’m looking forward combining my deep passion for technology with having a managerial position. Any tips on how to exactly accomplish this from all you veterans out there are welcome!

Simulate load on your linux server using a one-liner

Posted by David Yahalom under Unix, Linux, General IT

Yesterday I needed a quick way to simulate load on a Linux sever. I wanted to find out that my monitoring system is working and sending alerts.

While there are many many tools that can do this, all I needed was a simple bash one-liner shell script that can make the CPUs beg for mercy.

What I ended up using is this:

dd if=/dev/zero bs=100M | gzip | gzip -d | gzip | gzip -d | gzip | gzip -d > /dev/null &

Send a few of these babies to the background and you’ll start seeing smoke coming from your server soon enough.

Oracle Virtual Directory

Posted by David Yahalom under ETL, General IT, Oracle

Another presentation I’ve made not too long ago at an Israel Oracle User Group meeting (sponsored in part by Xpert-One1, the consulting and solution provider company I work for) was about a relatively little known product (at least by Oracle terms) called Oracle Virtual Directory.

OVD allows for Enterprise Level LDAP without synchronization.

Oracle Virtual Directory provides LDAP and XML views of existing enterprise identity information without synchronizing or moving data from its native locations.

OVD can connect to pretty much anything JAVA can connect to and expose several different LDAP directories and RDMBS data repositories as a single LDAP tree.

Think about it. You can virtually “unify” all the different directories in your organizations (be it RDBMS servers or LDAP directories) as a single directory service - which is so much easier to work with. And without any sort of synchronization.

Very very cool.

You can get my presentation here.

OVD is availiable for download, free, from OTN. 

Misc tip: search for all unread mail in Gmail

Posted by David Yahalom under General IT

For ages I’ve looked for a way to quick search for all unread mail in Gmail.

I need this because most of the time I let a few unimportant (read: advertisements) emails slip by me without reading them or marking them as read. After time, this list grows and I find it annoying to always receive notifications as if I have unread mail in my inbox (I have unread mail, it is just unimportant mail I forgot to mark as read).

Well, there doesn’t seem to be a way to search for only unread mail using Gmail’s interface but there is quick way around this.

Just type:

is:unread

Into the search box!

Oracle extent allocation: AUTOALLOCATE vs. UNIFORM

Posted by David Yahalom under General IT

Starting with Oracle 9i, DBAs can now create locally managed tablespaces.

A Locally Managed TBS manages its own list of free extents in a bitmap block placed inside the header of the first data file of the tablespace. Inside the bitmap block, each bit maps to a free block in the tablespace.

When creating a locally managed tablespace, you can specify the extent allocation method to be used.

AUTOALLOCATE - means that the extent sizes are managed by Oracle.
Oracle will choose the optimal next size for the extents starting with 64KB. As the segments grow and more extents are needed, Oracle will start allocating larger and larger sizes ranging from 1Mb to eventually 64Mb extents. This might help conserve space but will lead to fragmentation. This is usually recommended for small tables or in low managed systems.

UNIFORM - specifies that the extent allocation in the tablespace is in a fixed uniform size. The extent size can be specified in M or K. The default size for UNIFORM extent allocation is 1M. Using uniform extents usually minimizes fragmentation and leads to better overall performance.

SQL>CREATE TABLESPACE test_tablespcae DATAFILE '/emc/oradata/test_tablespace1.dbf' SIZE 50M
EXTENT MANAGEMENT LOCAL AUTOALLOCATE;

SQL>CREATE TABLESPACE test_tablespcae DATAFILE '/emc/oradata/test_tablespace1.dbf' SIZE 50M
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 512K;

I usually prefer to keep large production-grade tables in UNIFORM sized tablespaces and smaller tables or tables in unmanaged environments in AUTOALLOCATE tablespaces.