Press Summary
Testing Exadata with Different ASM AU Sizes
July 18th, 2011
Written by John Clarke
Oracle recommends a 4MB ASM allocation unit (AU) size for its ASM disk groups. In this post, we'll explore test cases with different ASM disk group AU sizes. Let's create some tablespaces to match our testing requirements: Using a 1MB AU SizeIn this section we'll perform tests for full-scanning a table when it's stored in an ASM disk group with a 1MB ASM allocation unit size and compare with the same table stored in a tablespace residing on an ASM disk group with a 4MB AU size. The...
Testing Exadata with cell.smart_scan_capable=FALSE ASM Disk Groups
July 18th, 2011
Written by John Clarke
In this post we'll perform tests for full-scanning a table when it's stored in an ASM disk group with CELL.SMART_SCAN_CAPABLE=FALSE and compare with the same table stored in a tablespace residing on an ASM disk group with CELL.SMART_SCAN_CAPABLE=TRUE. Let's create an ASM disk group to match this requirement: The control-case was done with SYSTEM.MYOBJ, which has the following characteristics:Table: SYSTEM.MYOBJSize (Gb): 14.8Blocks: 1,940,352Tablespace Name: USERSASM Disk Group:...
Building a New Storage Environment on Exadata
July 18th, 2011
Written by John Clarke
What We're Trying to ProveWhen customers deploy a new Exadata Database Machine, it will come pre-seeded with RAC-enabled database on ASM storage spanning the Exadata storage cells. This is one by Oracle's ACS group during the installation, and we at Centroid worked alongside Oracle to build our configuration to meet the specs in our configuration template. In this post, I'll demonstrate the steps required to "wipe it all out", build a new set of Grid Disks, ASM disk groups, and finally, a RAC...
Exadata Smart Scan: What's Eligible Anyway?
July 18th, 2011
Written by John Clarke
With Oracle Exadata, what SQL statements actually are eligible for offload processing? If you've found yourself puzzled by the documentation, test results or not quite putting two and two together, this post attempts to define and prove what types of SQL statements truly are eligible for offload processing, and measure results. A good place to look is V$SQLFN_METADATA. The "OFFLOADABLE" column is relatively self-explanatory. Here are some general rules off cell offload...
Exadata Smart Scan and Parallel Query
July 18th, 2011
Written by John Clarke
As documented, parallel query operations are offload eligible with Exadata Database Machine. Let's put this to the test. We can see that cell offload and Smart Scan worked well and produced a 68% savings in IO. Now let's do a partition-wise join between SOE.ORDERS and SOE.CUSTOMERS. To demonstrate Smart Scan processing, I'll make all indices on both tables invisible. Notice how even though we joined SOE.ORDERS to SOE.CUSTOMERS, partition-wise joining...
