Database Administration Queries

Database administration queries

1. Database version information

Returns the Oracle database version.

SELECT * FROM v$version;

2. Database default information

Some system default information.

SELECT username,        profile,        default_tablespace,        temporary_tablespace   FROM dba_users;

3. Database Character Set information

Display the character set information of database.

SELECT * FROM nls_database_parameters;

4. Get Oracle version

SELECT VALUE   FROM v$system_parameter  WHERE name = 'compatible';

5. Store data case sensitive but to index it case insensitive

Now this ones tricky. Sometime you might querying database on some value independent of case. In your query you might do UPPER(..) = UPPER(..) on both sides to make it case insensitive. Now in such cases, you might want to make your index case insensitive so that they don’t occupy more space. Feel free to experiment with this one.

CREATE TABLE tab (col1 VARCHAR2 (10)); CREATE INDEX idx1    ON tab (UPPER (col1)); ANALYZE TABLE a COMPUTE STATISTICS;

6. Resizing Tablespace without adding datafile

Yet another DDL query to resize table space.

ALTER DATABASE DATAFILE '/work/oradata/STARTST/STAR02D.dbf' resize 2000M;

7. Checking autoextend on/off for Tablespaces

Query to check if autoextend is on or off for a given tablespace.

SELECT SUBSTR (file_name, 1, 50), AUTOEXTENSIBLE FROM dba_data_files; (OR) SELECT tablespace_name, AUTOEXTENSIBLE FROM dba_data_files;

8. Adding datafile to a tablespace

Query to add datafile in a tablespace.

ALTER TABLESPACE data01 ADD DATAFILE '/work/oradata/STARTST/data01.dbf'     SIZE 1000M AUTOEXTEND OFF;

9. Increasing datafile size

Yet another query to increase the datafile size of a given datafile.

ALTER DATABASE DATAFILE '/u01/app/Test_data_01.dbf' RESIZE 2G;

10. Find the Actual size of a Database

Gives the actual database size in GB.

SELECT SUM (bytes) / 1024 / 1024 / 1024 AS GB FROM dba_data_files;

11. Find the size occupied by Data in a Database or Database usage details

Gives the size occupied by data in this database.

SELECT SUM (bytes) / 1024 / 1024 / 1024 AS GB FROM dba_segments;

12. Find the size of the SCHEMA/USER

Give the size of user in MBs.

SELECT SUM (bytes / 1024 / 1024) "size"   FROM dba_segments  WHERE owner = '&owner';

13. Last SQL fired by the User on Database

This query will display last SQL query fired by each user in this database. Notice how this query display last SQL per each session.

SELECT S.USERNAME || '(' || s.sid || ')-' || s.osuser UNAME,          s.program || '-' || s.terminal || '(' || s.machine || ')' PROG,          s.sid || '/' || s.serial# sid,          s.status "Status",          p.spid,          sql_text sqltext     FROM v$sqltext_with_newlines t, V$SESSION s, v$process p    WHERE     t.address = s.sql_address          AND p.addr = s.paddr(+)          AND t.hash_value = s.sql_hash_value ORDER BY s.sid, t.piece;