is a Materialized View
?
materialized
past participle, past tense of ma·te·ri·al·ize (Verb)
Verb
(of a ghost, spirit,
or similar entity) Appear in bodily form.
Cause to appear in
bodily or physical form.
To cause to become
real or actual:
Materialized view is a
database object that stores the results of a query.
·
A materialized view
(MV) is similar to a view but the data is actually stored on disk (view that
materializes).
·
Materialized views are
often used for summary and pre-joined tables, or just to make a snapshot of a
table available on a remote system.
·
A MV must be refreshed
when the data in the underlying tables is changed.
·
It may be a local copy
of data located remotely, or may be a subset of the rows and/or columns of a
table or join result, or may be a summary based on aggregations of a table's
data.
·
Materialized views,
which store data based on remote tables, are also known as snapshots.
·
A snapshot can be
redefined as a materialized view.
What is the difference
between mv and snapshots ?
·
A materialized view is
the new name for Snapshot since Oracle 8i but 8i also introduced extra query
rewriting functionality.
·
The terms snapshot and
materialized view are synonymous.
·
Snapshot and
materialized view are almost same same but with one difference.
·
You can say that
materialized view =snapshot + query rewrite functionality.
·
Better u say Snapshot
is redefined as Materialized view and Query rewrite feature is added from
Oracle 8i, until oracle 8i it is called as snapshot,after oracle 8i it is
called as materialized view.
·
when we create a
snapshot feedback will come as MATERIALIZED VIEW".
·
Snapshort and
matrilised view both are same.
·
Even we can proof by
executing query.
·
When you create
snapshort we will get conform message saying that materailised view is created
·
The keyword SNAPSHOT
is supported in place of MATERIALIZED VIEW for backward compatibility.
·
Query rewrite
functionality:In materialized view you can enable or disable query rewrite
option. which means databse server will rewrite the query so as to give
high performance.
·
Query rewrite is based
on some prewritten standards(by oracle itself).So the database server will
follow these standards and rewrite the query written in the materilized view..
CREATE SNAPSHOT
TEST_MV
AS SELECT * FROM
ODS_PRODUCT_DIM
We Get Prompt As
Materialized View Created
Prerequisites
1.init.ora parameter
COMPATIBLE=8.1.0
(or above)
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