Which two DML operations will add rows compressed by Hybrid Columnar Compression (HCC) to
a table that is created to use HCC?
A.
INSERT
B.
insert with an append hint
C.
UPDATE
D.
CREATE TABLE AS SELECT
Explanation:
To maximize storage savings with Hybrid Columnar Compression, data must be
loaded using data warehouse bulk loading techniques. Examples of bulk load operations
commonly used in data warehouse environments are:
* Insert statements with the APPEND hint
* Parallel DML
* Direct Path SQL*LDR
* Create Table as Select (CTAS)
Incorrect:
Not A, Not C: DML operations (INSERT/UPDATE) against a Hybrid Columnar Compressed
table/partition can reduce the overall compression savings over time since data
INSERTED/UPDATED via DML operations will not be compressed to the same ratio as data that
is bulk loaded.
B, D
B,D
A,C it is asking for DML operations!!
Correct options are B & D
B D
http://www.oracle.com/technetwork/middleware/bi-foundation/ehcc-twp-131254.pdf
To maximize storage savings with Hybrid Columnar Compression, data must be loaded using
data warehouse bulk loading techniques. Examples of bulk load operations commonly used in
data warehouse environments are:
Insert statements with the APPEND hint
Parallel DML
Direct Path SQL*LDR
Create Table as Select (CTAS)
A & B
DML that add rows are only insert and insert append.
Note that while data in Hybrid Columnar compressed tables can be modified using conventional
Data Manipulation Language (DML) operations – INSERT, UPDATE, DELETE – performing
such operations could result in a reduction of the HCC compression ratio. 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.