Which statement is true about Oracle compression?
A.
A non-partitioned table can use Advanced Compression and Hybrid Columnar Compression
concurrently.
B.
A partitioned table can define the use of Advanced Compression or HybridColumnar
Compression for each partition.
C.
Hybrid Columnar Compression can be defined for a single column.
D.
A partitioned table can use only Advanced Compression or only Hybrid Columnar
Compression.
Explanation:
C: • Tables are organized by column and compressed. This makes it much easier to
get similar
values together, which enhances the compression greatly. D: It is recommended that HCC be
enabled on tables or partitions with no or infrequent DML operations. If frequent DML operations
are planned on a table or partition, then the Oracle Advanced Compression Option is better suited
for such data.
There is only 1 right answer to this question, not 2 and its B. Different partitions of the same table can have different compression attributes.
Hi Matt – could you please share the reference doc for read… Thanks
B
I think B is correct:
http://WWW.ORACLE.COM/TECHNETWORK/TESTCONTENT/O10COMPRESSION-082302.HTML
…
Partitions
If a table to be compressed is partitioned, you may want to apply different degrees of compression to each partition. For instance, you may want to keep the most recent partition uncompressed, the partition for last month compressed for query, and older partitions compressed for archive. You can easily accomplish that, as shown in Listing 5.
Code Listing 5: Separate compression mechanisms for different partitions
CREATE TABLE trans (
acc_no number not null,
txn_id number not null,
txn_dt date not null,
txn_amt number(15,2) not null
)
PARTITION BY RANGE (txn_dt)
(
partition y09m06 VALUES LESS THAN(TO_DATE(‘2009-07-01’, ‘yyyy-mm-dd’)) COMPRESS FOR archive high,
partition y09m07 VALUES LESS THAN(TO_DATE(‘2009-08-01’, ‘yyyy-mm-dd’)) COMPRESS FOR archive low,
partition y09m08 VALUES LESS THAN(TO_DATE(‘2009-09-01’, ‘yyyy-mm-dd’)) COMPRESS FOR query high,
partition y09m09 VALUES LESS THAN(TO_DATE(‘2009-10-01’, ‘yyyy-mm-dd’)) COMPRESS FOR query low,
partition y09m10 VALUES LESS THAN(TO_DATE(‘2009-11-01’, ‘yyyy-mm-dd’)) nocompress
)
B
Answer here:
With the data collected by Heat Map, Oracle Database can automatically compress each partition of a table independently based
on
Heat Map data, implementing compression tiering. This compression tiering can
use all forms of Oracle table compression, including:
Advanced Row Compression and all levels of Hybrid Columnar Compression (HCC) if the underlying storage supports HCC. Oracle
Database can also compress individual database blocks with Advanced Row Compr
ession based on Heat Map data.
Link: http://www.oracle.com/technetwork/database/options/compression/advanced-compression-wp-12c-1896128.pdf
B