Updating a table in oracle

Compression ratios as high as 3.5 : 1 can be achieved.

Table compression can also speed up query execution during reads. AS SELECT * from all_objects WHERE SUBSTR(object_name,1,1) BETWEEN 'A' AND 'WZZZZZ'; SELECT table_name, tablespace_name, compression FROM user_tables WHERE table_name IN ('REGTAB', 'COMPTAB'); exec dbms_stats.gather_table_stats(USER, 'REGTAB'); exec dbms_stats.gather_table_stats(USER, 'COMPTAB'); SELECT table_name, blocks FROM user_tables WHERE table_name IN ('REGTAB', 'COMPTAB'); conn / as sysdba DROP TABLESPACE compressed INCLUDING CONTENTS AND DATAFILES; AS SELECT * FROM all_objects WHERE SUBSTR(object_name,1,1) BETWEEN 'A' AND 'WZZZZZ'; SELECT table_name, tablespace_name, compression FROM user_tables WHERE table_name IN ('REGTAB', 'COMPTAB'); exec dbms_stats.gather_table_stats(USER, 'REGTAB'); exec dbms_stats.gather_table_stats(USER, 'COMPTAB'); SELECT table_name, blocks FROM user_tables WHERE table_name IN ('REGTAB', 'COMPTAB'); CREATE TABLE t1 ( testcol VARCHAR2(50)) TABLESPACE uwdata; CREATE TABLE t2 ( testcol VARCHAR2(50)) TABLESPACE uwdata COMPRESS; DECLARE x t1.testcol%TYPE; BEGIN FOR i IN 1 ..

When you install Oracle, you install it for a region.

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Updating a table in oracle

CASCADE performs the same operations on all dependent objects.

A relational database system contains one or more objects called tables.

If the column name is "LAST_NAME" and the column is defined as CHAR(20) it is be stored as Oracle starts adding rows from the end of the block towards the block header.

In this way, the block header can grow if required.

To see the actual block and row as stored by Oracle use the DBMS_ROWID built-in package.

Table compression saves disk space and reduces memory use in the buffer cache, and is completely transparent to applications.

Doing so may improve response time during subsequent operations on the clustered data. Virtual columns can be used in queries, DML, and DDL statements.

They can be indexed, and you can collect statistics on them. Exceptions and restrictions are listed below in "Notes on Virtual Columns" and "Restrictions on Virtual Columns".

These privileges must be granted explicitly and not acquired through a role.

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