Exadata Hybrid Columnar Compression (EHCC)

Let's see how EHCC help us to reduce storage space with performance database improvement.

Here we have created three tables with same data as per below.

1. Test  with no compression

2. Test_hcc_archive with archive high compression

3. Test_hcc_query with query high compression

#### List of tables with compression types ####

SQL> select table_name,compression,compress_for

  2    from user_tables

  3   where table_name in ('TEST','TEST_HCC_QUERY','TEST_HCC_ARCHIVE');

TABLE_NAME                 COMPRESS COMPRESS_FOR                            

------------------------------ -------- ------------                            

TEST                           DISABLED                                         

TEST_HCC_ARCHIVE      ENABLED    ARCHIVE HIGH                            

TEST_HCC_QUERY         ENABLED    QUERY HIGH                              

#### Each Tables are with 100000 row data ####

SQL> select count(*) from test;

  COUNT(*)                                                                      

----------                                                                      

    100000                                                                      

Elapsed: 00:00:00.11

SQL> select count(*) from test_hcc_query;

  COUNT(*)                                                                      

----------                                                                      

    100000                                                                      

Elapsed: 00:00:00.10

SQL> select count(*) from test_hcc_archive;

  COUNT(*)                                                                      

----------                                                                      

    100000                                                                      

Elapsed: 00:00:00.10

#### Checking the size of data for each tables ####

Sample Questions for Exadata Certification 1

Exadata Implementation Specialist Examination (1Z0-536)

1. Which types of data are most likely to be cached In the Exadata Smart Flash Cache?

A. Results of random reads.

B. Results of table scans.

C. Write to a mirror

D. Redo data

E. All data is cached In the Flash Cache

2. Your customer wants to use Hybrid Columnar Compression to get maximum compression on their data. Which option represents a best practice for achieving this goal?

A. Load compressed files with Direct Path loading

B. Sort incoming data on a column with a low cardinality

C. Use DBFS and external flies to load the data

D. Use Data Pump to load data

3. Which statement would you make about sharing I/O resources in an Exadata environment?

A. You can manage workloads within a database with Database Resource Manager.

B. You can manage workloads across multiple databases with Database Resource Manager.

C. You can manage workloads within a database with 10 Resource Manager.

D. You cannot manage workloads across multiple databases.

4. How do you back up the software used on an Exadata storage cell?

A. You use RMAN.

B. You back up the software files using an operating system method.

C. You do a complete copy of their system storage area.

D. You do not need to backup this software, as there is an automated recovery mechanism built into each cell.

5. Which statement properly describes potential allocation for a grid disk?

A. A grid disk must use all of a cell disk.

B. A grid disk can only use portions of a cell disk across all cells.

C. A grid disk can use portions of a cell disk on a subset of cells.

D. A grid disk can span multiple Exadata Storage Server ceils.

Exadata Features

Let's make a note of major features of exadata. We will see all the features in depth in next couple of posts.

1. Smart Scan / Offloading
2. Storage Index
3. Hybrid Columnar Compression (HCC)
4. Smart Flash Cache
5. IORM