12.1.0.2 Introduction to Zone Maps Part II (Changes)

In Part I, I discussed how Zone Maps are new index like structures, similar to Exadata Storage Indexes, that enables the “pruning” of disk blocks during accesses of the table by storing the min and max values of selected columns for each “zone” of a table. A Zone being a range of contiguous (8M) blocks. I […]

Exadata Shellshock: IB Switches Vulnerable

Andy Colvin has the lowdown on the Oracle response and fixes for the bash shellshock vulnerability.

However, when I last looked it seemed Oracle had not discussed anything regarding the IB switches being vulnerable.

The IB switches have bash running on them and Oracle have verified the IB switches are indeed vulnerable.


[root@dm01dbadm01 ~]# ssh 10.200.131.22

root@10.200.131.22's password:

Last login: Tue Sep 30 22:46:41 2014 from dm01dbadm01.e-dba.com

 (more...)

Exadata and Bash Shellshock

There has recently been a lot of news about the exploit revealed in the bash shell.  While the fix is very quick to implement, there are a couple of tricks that are required to install this update on an Exadata environment.  According to Oracle support note #1405320.1, Exadata storage server versions 11.2.3.x.x and 12.1.1.x.x are susceptible to the exploit.  On a typical Oracle Enterprise Linux, a simple (more...)

Exadata: What’s Coming

This is based on the presentation Juan Loaiza gave regarding What’s new with Exadata. While a large part of the presentation focussed on what was already available, there are quite a few interesting new features that are coming down the road.

First of was a brief mention of the hardware. I’m less excited about this. The X4 has plenty of the hardware that you could want: CPU, memory and flash. You’d expect some or all (more...)

eSP

eSPEnkitec’s Sizing and Provisioning (eSP) is a new internal tool designed and developed with Oracle Engineered Systems in mind. Thanks to the experience and insights from Randy Johnson, Karl Arao and Frits Hoogland, what began as a pet project for some of us, over time became an actual robust APEX/PLSQL application, developed by Christoph Ruepprich and myself, and ready to debut at Oracle Open World 2014.

This posting is about eSP, what it does, and (more...)

ASM Diskgroup shows USABLE_FILE_MB value in Negative

Today while working on ASM diskgroup i noticed Negative value for USABLE_FILE_MB. I was little surprised as it has been pretty long that i worked on ASM. So i started looking around for blogs and mos docs and found few really nice one around. A negative value for USABLE_FILE_MB means that you do not have [&hellip

About index range scans, disk re-reads and how your new car can go 600 miles per hour!

Despite the title, this is actually a technical post about Oracle, disk I/O and Exadata & Oracle In-Memory Database Option performance. Read on :)

If a car dealer tells you that this fancy new car on display goes 10 times (or 100 or 1000) faster than any of your previous ones, then either the salesman is lying or this new car is doing something radically different from all the old ones. You don’t just get orders of magnitude (more...)

12c HCC Row-Level Locking

In Oracle Database 12c we can find many new and shiny things… So many that we can miss the little good things really easy. I think that this one, is one of them. Previously I made a post “All About HCC“, describing how HCC is working and some of the issues that we can hit […]

Oracle IO wait events: db file sequential read

(the details are investigated and specific to Oracle’s database implementation on Linux x86_64)

Exadata IO: This event is not used with Exadata storage, ‘cell single block physical read’ is used instead.
Parameters:
p1: file#
p2: block#
p3: blocks

Despite p3 listing the number of blocks, I haven’t seen a db file sequential read event that read more than one block ever. Of course this could change in a newer release.

Implementation:
One of the important things (more...)

Exadata Zone Maps

Just a quick post on a new Exadata feature called Zone Maps. They’re similar to storage indexes on Exadata, but with more control (you can define the columns and how the data is refreshed for example). People have complained for years that storage indexes provided no control mechanisms, but now we have a way to exert our God given rights as DBA’s to control yet another aspect of the database. Here’s a link to the (more...)

The point of predicate pushdown

Oracle is announcing today what it’s calling “Oracle Big Data SQL”. As usual, I haven’t been briefed, but highlights seem to include:

  • Oracle Big Data SQL is basically data federation using the External Tables capability of the Oracle DBMS.
  • Unlike independent products — e.g. Cirro — Oracle Big Data SQL federates SQL queries only across Oracle offerings, such as the Oracle DBMS, the Oracle NoSQL offering, or Oracle’s Cloudera-based Hadoop appliance.
  • Also unlike independent (more...)

21st Century DBMS success and failure

As part of my series on the keys to and likelihood of success, I outlined some examples from the DBMS industry. The list turned out too long for a single post, so I split it up by millennia. The part on 20th Century DBMS success and failure went up Friday; in this one I’ll cover more recent events, organized in line with the original overview post. Categories addressed will include analytic RDBMS (including data (more...)

Combining Bloom Filter Offloading and Storage Indexes on Exadata

Here’s a little known feature of Exadata – you can use a Bloom filter computed from a join column of a table to skip disk I/Os against another table it is joined to. This not the same as the Bloom filtering of the datablock contents in Exadata storage cells, but rather avoiding reading in some storage regions from the disks completely.

So, you can use storage indexes to skip I/Os against your large fact table, based on a (more...)

Enkitec + Accenture = Even More Awesomeness!

Enkitec is the best consulting firm for hands on implementation, running and troubleshooting your Oracle based systems, especially the engineered systems like Exadata. We have a truly awesome group of people here; many are the best in their field (just look at the list!!!).

This is why I am here.

This is also why Accenture approached us some time ago – and you may already have seen today’s announcement that Enkitec got bought!

(more...)

Inserts on HCC tables

There are already a lot of blogposts and presentations done about Hybrid Columnar Compression and i am adding one more blogpost to that list. Recently i was doing some small tests one HCC and noticed that that inserts on a HCC row didn’t got compressed and yes i was using direct path loads:

DBA@TEST1> create table hcc_me (text1 varchar2(4000)) compress for archive high;

Table created.

KJJ@TEST1> insert /*+ append */ into hcc_me select dbms_random.string('x',100)  (more...)

Database Shutdown With crsctl

I noticed something for the first time tonight when I was playing around in the Enkitec lab – something that I have been doing wrong for a while.  When working in the lab, I often rely on the crsctl command to shut down the entire cluster stack for me.  It’s really easy to use “crsctl stop cluster -all” followed by “dcli -l root -g ~/dbs_group /u01/app/11.2.0.4/grid/bin/crsctl stop crs” to get everything down (more...)

Cellcli can lie to you…

Yes that is true, i said it, cellcli can lie to you there are some special cases were the output of cellcli is not the reality and you should double check it’s output with your standard OS tools. So this the output if dcli calling cellcli on an Exadata rack from an client:

[root@dm01db01 ~]# dcli -g cell_group -l root cellcli -e list cell attributes cellsrvStatus,msStatus,rsStatus
dm01cel01: running       running         running
dm01cel02: running       running         running
dm01cel03:  (more...)

SCAN VIP Troubleshooting

We had a client that was running into a strange issue on their Exadata where new connections coming in through the SCAN were failing.  After doing some troubleshooting, it was discovered that it was related to one of the SCAN listeners not properly accepting requests from new sessions.  The VIP and listener were running, and everything looked normal.

We had the following SCAN setup:

SCAN VIP # VIP IP
1 172.25.2.70
2 (more...)

Troubleshooting Oracle DBFS mount issues

On Exadata the local drives on the compute nodes are not big enough to allow larger exports and often dbfs is configured. In my case I had a 1.2 TB dbfs file system mounted under /dbfs_direct/.

While I was doing some exports yesterday I found that my dbfs wasn’t mounted, running quick crsctl command to bring it online failed:

[oracle@exadb01 ~]$ crsctl start resource dbfs_mount -n exadb01
 CRS-2672: Attempting to start 'dbfs_mount' on 'exadb01'
  (more...)

Direct Path Reads and Cell Offloading

Most people are relating direct path reads with an algorithm which is just controlling the way our read is performed. But actually in Exadata environment this is the algorithm which is balancing the load between the Compute and the Storage nodes. Something really important. As usual, the algorithm is not perfect and for some situations […]