ORA-02495

March 12, 2014, 1:53 pm

≫ Next: Can You Use BETWEEN and a Subquery Together?

≪ Previous: Data Dictionary Cache Hit Ratio

This was tested on Oracle 11.2. If you try to resize a datafile in a read only tablespace, you get an ORA-02495. Changing the tablespace to read write makes the problem go away:

SQL> create tablespace andrew

2 datafile '/tmp/andrew.dbf'

3 size 100m

4 /

Tablespace created.

SQL> alter tablespace andrew read only

2 /

Tablespace altered.

SQL> alter database datafile '/tmp/andrew.dbf'

2 resize 200m

3 /

alter database datafile '/tmp/andrew.dbf'

ERROR at line 1:

ORA-02495: cannot resize file /tmp/andrew.dbf,

tablespace ANDREW is read only

SQL> alter tablespace andrew read write

2 /

Tablespace altered.

SQL> alter database datafile '/tmp/andrew.dbf'

2 resize 200m

3 /

Database altered.

SQL>

↧

Can You Use BETWEEN and a Subquery Together?

March 13, 2014, 1:00 am

≫ Next: ORA-13504

≪ Previous: ORA-02495

I saw a colleague about to throw away his copy of Oracle 7 The Complete Reference so I rescued it from the bin and started to read it (as you do). It said that you could not use BETWEEN and a subquery in the same SQL statement and I wondered if this restriction still applied. The oldest version of Oracle I have access to is Oracle 9 so I decided to try it out there. The examples I came up with are a bit artificial but they show that you can now use BETWEEN and a subquery in the same SQL statement. Furthermore, the subquery can be:

(1) Before the AND.

(2) After the AND.

(3) Before and after the AND.

SQL> select count(*) from dba_users

2 where created between

3 (select created from dba_users

4 where username = 'DATALOAD')

5 and '31-DEC-2013'

6 /

COUNT(*)

----------

SQL> select count(*) from dba_objects

2 where object_id between

3 100 and

4 (select max(object_id) from dba_objects

5 where owner = 'SYSTEM')

6 /

COUNT(*)

----------

8850

SQL> select count(*) from dba_tables

2 where initial_extent between

3 (select min(initial_extent)

4 from dba_tables

5 where owner = 'SYSTEM')

6 and

7 (select max(initial_extent)

8 from dba_tables

9 where owner = 'SYSTEM')

10 /

COUNT(*)

----------

1196

SQL>

↧

ORA-13504

March 13, 2014, 1:08 am

≫ Next: INVALID Materialized View NEEDS_COMPILE

≪ Previous: Can You Use BETWEEN and a Subquery Together?

This was tested on Oracle 11.2.0.4. If you try to create a database like this i.e. without specifying a SYSAUX datafile clause:

create database extent management local

datafile '/database/NBAPERF/nba_system/system1.dbf'

size 100m autoextend on

logfile

group 1 ('/database/NBAPERF/nba_redo1/log1a.rdo',

'/database/NBAPERF/nba_redo2/log1b.rdo') size 50m,

group 2 ('/database/NBAPERF/nba_redo1/log2a.rdo',

'/database/NBAPERF/nba_redo2/log2b.rdo') size 50m

maxlogfiles 3

maxlogmembers 3

user sys identified by secret_password

user system identified by secret_password

default temporary tablespace temp

tempfile '/database/NBAPERF/nba_temp/temp1.dbf'

size 100m autoextend on

undo tablespace undotbs1

datafile '/database/NBAPERF/nba_system/undo1.dbf'

size 100m autoextend on

character set WE8ISO8859P1

Oracle will return an ORA-13504 and your database will not be created:

SQL> 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 create database extent management local

ERROR at line 1:

ORA-13504: No SYSAUX datafile clause specified

SQL>

You can stop this error occurring by specifying a SYSAUX datafile clause, as shown below:

create database extent management local

datafile '/database/NBAPERF/nba_system/system1.dbf'

size 100m autoextend on

sysaux datafile '/database/NBAPERF/nba_system/sysaux1.dbf'

size 100m autoextend on

logfile

group 1 ('/database/NBAPERF/nba_redo1/log1a.rdo',

'/database/NBAPERF/nba_redo2/log1b.rdo') size 50m,

group 2 ('/database/NBAPERF/nba_redo1/log2a.rdo',

'/database/NBAPERF/nba_redo2/log2b.rdo') size 50m

maxlogfiles 3

maxlogmembers 3

user sys identified by secret_password

user system identified by secret_password

default temporary tablespace temp

tempfile '/database/NBAPERF/nba_temp/temp1.dbf'

size 100m autoextend on

undo tablespace undotbs1

datafile '/database/NBAPERF/nba_system/undo1.dbf'

size 100m autoextend on

character set WE8ISO8859P1

… and the database will be created successfully:

SQL> 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Database created.

SQL>

↧

INVALID Materialized View NEEDS_COMPILE

March 14, 2014, 1:06 am

≫ Next: ORA-01921

≪ Previous: ORA-13504

This example was tested on Oracle 11.2. It shows how an on demand materialized view becomes invalid following DML on the underlying table. First I created a table:

SQL> create table tab1 (col1 number)

2 /

Table created.

SQL>

Then I inserted the value 1 into it:

SQL> insert into tab1 values (1)

2 /

1 row created.

SQL>

I created an on demand materialized view on the table:

SQL> create materialized view mv1

2 refresh on demand

3 as select * from tab1

4 /

Materialized view created.

SQL>

I checked that it was VALID:

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW VALID

SQL>

I updated the table, making the materialized view out of date:

SQL> update tab1 set col1 = 2

2 /

1 row updated.

SQL> commit

2 /

Commit complete.

SQL> select * from tab1

2 /

COL1

----------

SQL> select * from mv1

2 /

COL1

----------

SQL>

Although you can still query the materialized view when this happens, it shows as INVALID:

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW INVALID

SQL>

... and in need of compilation:

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 NEEDS_COMPILE

SQL>

This isn't a problem but, if you are not happy with it, you can refresh the materialized view:

SQL> exec dbms_mview.refresh('MV1');

PL/SQL procedure successfully completed.

SQL>

This brings it in line with the underlying table:

SQL> select * from mv1

2 /

COL1

----------

SQL>

It is then shown as VALID again:

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW VALID

SQL>

... and not in need of compilation:

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 VALID

SQL>

I updated the table, making the materialized view out of date again:

SQL> update tab1 set col1 = 3

2 /

1 row updated.

SQL> commit

2 /

Commit complete.

SQL> select * from tab1

2 /

COL1

----------

SQL> select * from mv1

2 /

COL1

----------

2

SQL>

It was also INVALID and in need of compilation as before:

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW INVALID

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 NEEDS_COMPILE

SQL>

Another way to change this, if it bothers you, is to compile it:

SQL> alter materialized view mv1 compile

2 /

Materialized view altered.

SQL>

This way, the materialized view is still out of date:

SQL> select * from mv1

2 /

COL1

----------

SQL>

... but it is no longer INVALID:

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW VALID

SQL>

... and it does not need compiling either:

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 VALID

SQL>

↧

ORA-01921

March 14, 2014, 3:33 pm

≫ Next: Using RMAN to Clone a Database into a Different Database on the Same Server

≪ Previous: INVALID Materialized View NEEDS_COMPILE

This was tested on Oracle 11.2. If you try to create a role which already exists, you get an ORA-01921:

SQL> create role dba

2 /

create role dba

ERROR at line 1:

ORA-01921: role name 'DBA' conflicts with another user

or role name

SQL>

You can check the names of existing roles by looking in DBA_ROLES something like this:

SQL> select count(*) from dba_roles

2 where role = 'DBA'

3 /

COUNT(*)

----------

SQL>

As the error message suggests, roles cannot match existing user names either. In the example below, there is no role called BRIAN. However, there is a user called BRIAN so you cannot create a role called BRIAN:

SQL> select count(*) from dba_roles

2 where role = 'BRIAN'

3 /

COUNT(*)

----------

SQL> select count(*) from dba_users

2 where username = 'BRIAN'

3 /

COUNT(*)

----------

SQL> create role brian

2 /

create role brian

ERROR at line 1:

ORA-01921: role name 'BRIAN' conflicts with another

user or role name

SQL>

↧

Using RMAN to Clone a Database into a Different Database on the Same Server

March 14, 2014, 3:52 pm

≫ Next: ORA-10636

≪ Previous: ORA-01921

This was tested on Oracle 11.2. I had an input or target database as follows:

SQL> select name from v$database

2 /

NAME

---------

ORCL1

SQL> l

1 select tablespace_name, file_name

2* from dba_data_files order by 1

SQL> /

TABLESPACE_NAME FILE_NAME

--------------- --------------------------------------

SYSAUX /database/RMAN_test/ORCL1/sysaux1.dbf

SYSTEM /database/RMAN_test/ORCL1/system1.dbf

UNDOTBS1 /database/RMAN_test/ORCL1/undo1.dbf

SQL>

I wanted to create an output or auxiliary or clone database called ORCL2. First I created the directory structures for it:

Solaris: pwd

/database/RMAN_test

Solaris: mkdir ORCL2

Solaris:

Next I added the auxiliary database to the server’s oratab:

Solaris: cat /var/opt/oracle/oratab|grep ORCL2

ORCL2:/oracle/app/oracle/product/11.2.0:N

Solaris:

Then I copied the target database’s parameter file to create the auxiliary database’s parameter file:

Solaris: pwd

/oracle/app/oracle/product/11.2.0/dbs

Solaris: cp initORCL1.ora initORCL2.ora

Solaris:

I customised the auxiliary database’s parameter file as shown below. Note the db_file_name_convert parameter, which tells Oracle where to put the files for the auxiliary database:

Solaris: cat initORCL2.ora

compatible=11.2.0

control_files=/database/RMAN_test/ORCL2/control1.ctl

db_block_size=2048

db_file_name_convert=('/database/RMAN_test/ORCL1','/database/RMAN_test/ORCL2')

db_name=ORCL2

db_recovery_file_dest=/database/RMAN_test/FRA

db_recovery_file_dest_size=5g

os_authent_prefix=''

processes=100

remote_login_passwordfile='EXCLUSIVE'

sga_target=500m

undo_management=auto

undo_retention=900

undo_tablespace='UNDOTBS1'

Solaris:

I set up a password file for the auxiliary database:

Solaris: . oraenv

ORACLE_SID = [ORCL2] ?

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: cd $ORACLE_HOME/dbs

Solaris: orapwd file=orapwORCL2 password=secret_password

Solaris: ls -l orapwORCL2

-rw-r----- 1 oracle dba 1536 Mar 14 18:17 orapwORCL2

Solaris:

I created a test table in the target database:

Solaris: sqlplus system/secret_password

SQL*Plus: Release 11.2.0.2.0 Production on Fri Mar 14 17:14:31 2014

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> create table tab1 (col1 varchar2(30))

2 /

Table created.

SQL> insert into tab1 values ('Andrew was here')

2 /

1 row created.

SQL> exit

Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Solaris:

I backed up the target database:

Solaris: . oraenv

ORACLE_SID = [ORCL1] ?

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: rman target /

Recovery Manager: Release 11.2.0.2.0 - Production on Fri Mar 14 18:29:32 2014

connected to target database: ORCL1 (DBID=1226554576)

RMAN> backup database;

Starting backup at 14-MAR-14

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=145 device type=DISK

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00001 name=/database/RMAN_test/ORCL1/system1.dbf

input datafile file number=00003 name=/database/RMAN_test/ORCL1/undo1.dbf

input datafile file number=00002 name=/database/RMAN_test/ORCL1/sysaux1.dbf

channel ORA_DISK_1: starting piece 1 at 14-MAR-14

channel ORA_DISK_1: finished piece 1 at 14-MAR-14

piece handle=/database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_nnndf_TAG20140314T182942_9l6lnpnj_.bkp tag=TAG20140314T182942 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

including current control file in backup set

channel ORA_DISK_1: starting piece 1 at 14-MAR-14

channel ORA_DISK_1: finished piece 1 at 14-MAR-14

piece handle=/database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_ncnnf_TAG20140314T182942_9l6lo8pk_.bkp tag=TAG20140314T182942 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

Finished backup at 14-MAR-14

RMAN>

I opened the auxiliary database in NOMOUNT mode:

Solaris: . oraenv

ORACLE_SID = [ORCL1] ? ORCL2

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: sqlplus / as sysdba

SQL*Plus: Release 11.2.0.2.0 Production on Fri Mar 14 17:30:46 2014

Connected to an idle instance.

SQL> startup nomount

ORACLE instance started.

Total System Global Area 521936896 bytes

Fixed Size 2225704 bytes

Variable Size 159386072 bytes

Database Buffers 352321536 bytes

Redo Buffers 8003584 bytes

SQL>

I got the target and auxiliary listening. I think the only one which HAS to be listening is the auxiliary. This involved adding them to /var/opt/oracle/tnsnames.ora:

Solaris: pwd

/var/opt/oracle

Solaris: cat tnsnames.ora

################

# tnsnames.ora #

################

ORCL1 =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS =

(PROTOCOL = TCP)

(HOST = sge-mktred-lab2)

(PORT = 1529)

)

(CONNECT_DATA =

(SID = ORCL1)

)

ORCL2 =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS =

(PROTOCOL = TCP)

(HOST = sge-mktred-lab2)

(PORT = 1529)

)

(CONNECT_DATA =

(SID = ORCL2)

)

Etc

… adding them to $ORACLE_HOME/network/admin/listener.ora:

Solaris: pwd

/oracle/app/oracle/product/11.2.0/network/admin

Solaris: cat listener.ora

SID_LIST_LISTENER_11 =

(SID_LIST =

(SID_DESC =

(SID_NAME = ORCL1)

(ORACLE_HOME = /oracle/app/oracle/product/11.2.0)

)

(SID_DESC =

(SID_NAME = ORCL2)

(ORACLE_HOME = /oracle/app/oracle/product/11.2.0)

)

Etc

… restarting the listener and testing a remote connection:

Solaris: lsnrctl reload listener_11

LSNRCTL for Solaris: Version 11.2.0.2.0 - Production on 14-MAR-2014 17:54:55

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=sge-mktred-lab2)(PORT=1529)))

The command completed successfully

Solaris: sqlplus system/secret_password@orcl1

SQL*Plus: Release 11.2.0.2.0 Production on Fri Mar 14 17:55:24 2014

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>

I archived the redo in the target database:

Solaris: . oraenv

ORACLE_SID = [ORCL1] ?

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: sqlplus / as sysdba

SQL*Plus: Release 11.2.0.2.0 Production on Fri Mar 14 18:39:52 2014

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> alter system archive log current

2 /

System altered.

SQL>

Then I connected to the target and used the duplicate command to clone it into the auxiliary as follows:

Solaris: . oraenv

ORACLE_SID = [ORCL1] ?

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: rman target /

Recovery Manager: Release 11.2.0.2.0 - Production on Fri Mar 14 18:41:18 2014

connected to target database: ORCL1 (DBID=1226554576)

RMAN> connect auxiliary sys/secret_password@orcl2

connected to auxiliary database: ORCL2 (not mounted)

RMAN> duplicate target database to orcl2;

Starting Duplicate Db at 14-MAR-14

using target database control file instead of recovery catalog

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=46 device type=DISK

contents of Memory Script:

{

sql clone "create spfile from memory";

}

executing Memory Script

sql statement: create spfile from memory

contents of Memory Script:

{

shutdown clone immediate;

startup clone nomount;

}

executing Memory Script

Oracle instance shut down

connected to auxiliary database (not started)

Oracle instance started

Total System Global Area 521936896 bytes

Fixed Size 2225704 bytes

Variable Size 163580376 bytes

Database Buffers 348127232 bytes

Redo Buffers 8003584 bytes

contents of Memory Script:

{

sql clone "alter system set db_name =

''ORCL1'' comment=

''Modified by RMAN duplicate'' scope=spfile";

sql clone "alter system set db_unique_name =

''ORCL2'' comment=

''Modified by RMAN duplicate'' scope=spfile";

shutdown clone immediate;

startup clone force nomount

restore clone primary controlfile;

alter clone database mount;

}

executing Memory Script

sql statement: alter system set db_name = ''ORCL1'' comment= ''Modified by RMAN duplicate'' scope=spfile

sql statement: alter system set db_unique_name = ''ORCL2'' comment= ''Modified by RMAN duplicate'' scope=spfile

Oracle instance shut down

Oracle instance started

Total System Global Area 521936896 bytes

Fixed Size 2225704 bytes

Variable Size 163580376 bytes

Database Buffers 348127232 bytes

Redo Buffers 8003584 bytes

Starting restore at 14-MAR-14

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=46 device type=DISK

channel ORA_AUX_DISK_1: starting datafile backup set restore

channel ORA_AUX_DISK_1: restoring control file

channel ORA_AUX_DISK_1: reading from backup piece /database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_ncnnf_TAG20140314T182942_9l6lo8pk_.bkp

channel ORA_AUX_DISK_1: piece handle=/database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_ncnnf_TAG20140314T182942_9l6lo8pk_.bkp tag=TAG20140314T182942

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:01

output file name=/database/RMAN_test/ORCL2/control1.ctl

Finished restore at 14-MAR-14

database mounted

contents of Memory Script:

{

set until scn 400755;

set newname for datafile 1 to

"/database/RMAN_test/ORCL2/system1.dbf";

set newname for datafile 2 to

"/database/RMAN_test/ORCL2/sysaux1.dbf";

set newname for datafile 3 to

"/database/RMAN_test/ORCL2/undo1.dbf";

restore

clone database

;

}

executing Memory Script

executing command: SET until clause

executing command: SET NEWNAME

Starting restore at 14-MAR-14

using channel ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: starting datafile backup set restore

channel ORA_AUX_DISK_1: specifying datafile(s) to restore from backup set

channel ORA_AUX_DISK_1: restoring datafile 00001 to /database/RMAN_test/ORCL2/system1.dbf

channel ORA_AUX_DISK_1: restoring datafile 00002 to /database/RMAN_test/ORCL2/sysaux1.dbf

channel ORA_AUX_DISK_1: restoring datafile 00003 to /database/RMAN_test/ORCL2/undo1.dbf

channel ORA_AUX_DISK_1: reading from backup piece /database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_nnndf_TAG20140314T182942_9l6lnpnj_.bkp

channel ORA_AUX_DISK_1: piece handle=/database/RMAN_test/FRA/ORCL1/backupset/2014_03_14/o1_mf_nnndf_TAG20140314T182942_9l6lnpnj_.bkp tag=TAG20140314T182942

channel ORA_AUX_DISK_1: restored backup piece 1

channel ORA_AUX_DISK_1: restore complete, elapsed time: 00:00:25

Finished restore at 14-MAR-14

contents of Memory Script:

{

switch clone datafile all;

}

executing Memory Script

datafile 1 switched to datafile copy

input datafile copy RECID=4 STAMP=842208178 file name=/database/RMAN_test/ORCL2/system1.dbf

datafile 2 switched to datafile copy

input datafile copy RECID=5 STAMP=842208178 file name=/database/RMAN_test/ORCL2/sysaux1.dbf

datafile 3 switched to datafile copy

input datafile copy RECID=6 STAMP=842208178 file name=/database/RMAN_test/ORCL2/undo1.dbf

contents of Memory Script:

{

set until scn 400755;

recover

clone database

delete archivelog

;

}

executing Memory Script

executing command: SET until clause

Starting recover at 14-MAR-14

using channel ORA_AUX_DISK_1

starting media recovery

archived log for thread 1 with sequence 18 is already on disk as file /database/RMAN_test/FRA/ORCL1/archivelog/2014_03_14/o1_mf_1_18_9l6m849g_.arc

archived log file name=/database/RMAN_test/FRA/ORCL1/archivelog/2014_03_14/o1_mf_1_18_9l6m849g_.arc thread=1 sequence=18

media recovery complete, elapsed time: 00:00:01

Finished recover at 14-MAR-14

Oracle instance started

Total System Global Area 521936896 bytes

Fixed Size 2225704 bytes

Variable Size 167774680 bytes

Database Buffers 343932928 bytes

Redo Buffers 8003584 bytes

contents of Memory Script:

{

sql clone "alter system set db_name =

''ORCL2'' comment=

''Reset to original value by RMAN'' scope=spfile";

sql clone "alter system reset db_unique_name scope=spfile";

shutdown clone immediate;

startup clone nomount;

}

executing Memory Script

sql statement: alter system set db_name = ''ORCL2'' comment= ''Reset to original value by RMAN'' scope=spfile

sql statement: alter system reset db_unique_name scope=spfile

Oracle instance shut down

connected to auxiliary database (not started)

Oracle instance started

Total System Global Area 521936896 bytes

Fixed Size 2225704 bytes

Variable Size 167774680 bytes

Database Buffers 343932928 bytes

Redo Buffers 8003584 bytes

sql statement: CREATE CONTROLFILE REUSE SET DATABASE "ORCL2" RESETLOGS ARCHIVELOG

MAXLOGFILES 3

MAXLOGMEMBERS 3

MAXDATAFILES 30

MAXINSTANCES 1

MAXLOGHISTORY 292

LOGFILE

GROUP 1 SIZE 50 M ,

GROUP 2 SIZE 50 M

DATAFILE

'/database/RMAN_test/ORCL2/system1.dbf'

CHARACTER SET WE8ISO8859P1

contents of Memory Script:

{

set newname for tempfile 1 to

"/database/RMAN_test/ORCL2/temp1.dbf";

switch clone tempfile all;

catalog clone datafilecopy "/database/RMAN_test/ORCL2/sysaux1.dbf",

"/database/RMAN_test/ORCL2/undo1.dbf";

switch clone datafile all;

}

executing Memory Script

executing command: SET NEWNAME

renamed tempfile 1 to /database/RMAN_test/ORCL2/temp1.dbf in control file

cataloged datafile copy

datafile copy file name=/database/RMAN_test/ORCL2/sysaux1.dbf RECID=1 STAMP=842208205

cataloged datafile copy

datafile copy file name=/database/RMAN_test/ORCL2/undo1.dbf RECID=2 STAMP=842208206

datafile 2 switched to datafile copy

input datafile copy RECID=1 STAMP=842208205 file name=/database/RMAN_test/ORCL2/sysaux1.dbf

datafile 3 switched to datafile copy

input datafile copy RECID=2 STAMP=842208206 file name=/database/RMAN_test/ORCL2/undo1.dbf

contents of Memory Script:

{

Alter clone database open resetlogs;

}

executing Memory Script

database opened

Finished Duplicate Db at 14-MAR-14

RMAN>

Finally, I logged into the auxiliary database, made sure that the datafiles were in the correct place and checked the contents of the test table, which I created in the target earlier:

Solaris: . oraenv

ORACLE_SID = [ORCL1] ? ORCL2

The Oracle base remains unchanged with value /oracle/app/oracle/product

Solaris: sqlplus system/secret_password

SQL*Plus: Release 11.2.0.2.0 Production on Fri Mar 14 18:50:30 2014

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select tablespace_name, file_name

2 from dba_data_files

3 order by 1

4 /

TABLESPACE_NAME FILE_NAME

---------------- --------------------------------------

SYSAUX /database/RMAN_test/ORCL2/sysaux1.dbf

SYSTEM /database/RMAN_test/ORCL2/system1.dbf

UNDOTBS1 /database/RMAN_test/ORCL2/undo1.dbf

SQL> select * from tab1

2 /

COL1

------------------------------

Andrew was here

SQL>

↧

ORA-10636

March 15, 2014, 1:03 pm

≫ Next: How to Automatically Trace a User's Sessions

≪ Previous: Using RMAN to Clone a Database into a Different Database on the Same Server

I tested this in an Oracle 11.2.0.1.0 database. I created a table with lots of data:

SQL> create table andrews_table

2 as select * from dba_tables

3 /

Table created.

SQL> begin

2 for a in 1..5 loop

3 insert into andrews_table select * from andrews_table;

4 end loop;

5 end;

6 /

PL/SQL procedure successfully completed.

SQL>

I deleted 30% of the rows. This left the table with some empty space:

SQL> select count(*) from andrews_table

2 /

COUNT(*)

----------

99328

SQL> delete andrews_table where owner = 'SYS'

2 /

30624 rows deleted.

SQL>

I checked the amount of space occupied by the table:

SQL> select bytes from dba_segments

2 where segment_name = 'ANDREWS_TABLE'

3 /

BYTES

----------

29360128

SQL>

I tried to recoup the empty space but this failed as row movement was not enabled:

SQL> alter table andrews_table shrink space

2 /

alter table andrews_table shrink space

ERROR at line 1:

ORA-10636: ROW MOVEMENT is not enabled

SQL>

I enabled row movement…

SQL> alter table andrews_table enable row movement

2 /

Table altered.

SQL>

…then I was able to reclaim the empty space…

SQL> alter table andrews_table shrink space

2 /

Table altered.

SQL>

…and the table had gone down from 29M to 20M:

SQL> select bytes from dba_segments

2 where segment_name = 'ANDREWS_TABLE'

3 /

BYTES

----------

20185088

SQL>

↧

How to Automatically Trace a User's Sessions

March 17, 2014, 1:37 am

≫ Next: ORA-12983

≪ Previous: ORA-10636

This example shows how you can use a logon trigger to automatically trace all sessions for a given user. This can be useful where an application is launched from the desktop and then fails before the DBA has had time to identify the SID and SERIAL# and start tracing it. First create the user:

SQL> conn system/manager@adhoc
Connected.
SQL> create user andrew identified by reid
2 /

User created.

SQL> grant create session,
2 create trigger,
3 alter session to andrew
4 /

Grant succeeded.

SQL>

Create the logon trigger in the new schema:

SQL> conn andrew/reid@adhoc
Connected.
SQL> create or replace trigger immediate_trace
2 after logon on andrew.schema
3 begin
4 execute immediate 'alter session set sql_trace=true';
5 end;
6 /

Trigger created.

SQL>

Logon as the new user again and run some SQL:

SQL> conn andrew/reid@adhoc
Connected.
SQL> select sysdate from dual
2 /

SYSDATE
---------
01-FEB-10

SQL>

This will produce a trace file ready for further analysis e.g. by tkprof. It will contain, among other statements, the following:

=====================
PARSING IN CURSOR #3 len=64 dep=1 uid=86 oct=47 lid=86 tim=3571197485 hv=815087497 ad='2f4d8670' sqlid='ahb55sss9agw9'
begin
execute immediate 'alter session set sql_trace=true';
end;
END OF STMT
EXEC #3:c=0,e=8020,p=0,cr=0,cu=0,mis=0,r=1,dep=1,og=1,tim=3571197471
=====================

and

=====================
PARSING IN CURSOR #3 len=24 dep=0 uid=86 oct=3 lid=86 tim=3573486632 hv=2343063137 ad='2f47564c' sqlid='7h35uxf5uhmm1'
select sysdate from dual
END OF STMT
PARSE #3:c=0,e=341,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=3573486623
EXEC #3:c=0,e=91,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=3573487278
FETCH #3:c=0,e=60,p=0,cr=0,cu=0,mis=0,r=1,dep=0,og=1,tim=3573487570
STAT #3 id=1 cnt=1 pid=0 pos=1 obj=0 op='FAST DUAL (cr=0 pr=0 pw=0 time=0 us cost=2 size=0 card=1)'
FETCH #3:c=0,e=6,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=0,tim=3573490855
*** 2010-12-21 23:12:46.828
XCTEND rlbk=0, rd_only=1
=====================

↧

ORA-12983

March 18, 2014, 2:35 pm

≫ Next: INVALID Materialized View with COMPILATION_ERROR

≪ Previous: How to Automatically Trace a User's Sessions

If you try to drop all columns in a table, you get an ORA-12983 as you cannot have a table with no columns. You can see what I mean in the examples below, which I ran in an Oracle 11.2 database:

SQL> create table tab1

2 (col1 number)

3 /

Table created.

SQL> alter table tab1 drop column col1

2 /

alter table tab1 drop column col1

ERROR at line 1:

ORA-12983: cannot drop all columns in a table

SQL> create table tab2

2 (col1 number,

3 col2 number)

4 /

Table created.

SQL> alter table tab2 drop (col1, col2)

2 /

alter table tab2 drop (col1, col2)

ERROR at line 1:

ORA-12983: cannot drop all columns in a table

SQL>

↧

INVALID Materialized View with COMPILATION_ERROR

March 18, 2014, 2:41 pm

≫ Next: ORA-01442

≪ Previous: ORA-12983

In this example, Andrew grants access on a table to a role then grants this role to John. John creates a materialized view on Andrew’s table. Andrew updates his table, making John’s materialized view INVALID. John then tries to compile his materialized view, which gives it a COMPILE_STATE of COMPILATION_ERROR. Andrew then grants access to his table directly to John and the problem goes away. It was tested on Oracle 11.2:

First, user Andrew creates a table with one row of data:

SQL> conn andrew/reid

Connected.

SQL> create table tab1 (col1 number)

2 /

Table created.

SQL> insert into tab1 values (1)

2 /

1 row created.

SQL>

Then he creates a role and grants access on the table to it:

SQL> create role role1

2 /

Role created.

SQL> grant select on tab1 to role1

2 /

Grant succeeded.

SQL>

A new user called John is set up. He has access to Andrew’s table via ROLE1 and he creates an ON DEMAND materialized view on it:

SQL> conn / as sysdba

Connected.

SQL> create user john identified by smith

2 default tablespace users

3 quota unlimited on users

4 /

User created.

SQL> grant create session,

2 create table,

3 create materialized view,

4 role1

5 to john

6 /

Grant succeeded.

SQL> conn john/smith

Connected.

SQL> create materialized view mv1

2 refresh on demand

3 as select * from andrew.tab1

4 /

Materialized view created.

SQL> select * from mv1

2 /

COL1

----------

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW VALID

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 VALID

SQL>

Andrew updates his table:

SQL> conn andrew/reid

Connected.

SQL> update tab1 set col1 = 2

2 /

1 row updated.

SQL>

This makes John’s materialized view INVALID and gives it a COMPILE_STATE of NEEDS_COMPILE. I showed you this in an earlier example:

SQL> conn john/smith

Connected.

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW INVALID

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 NEEDS_COMPILE

SQL> select * from mv1

2 /

COL1

----------

1

SQL>

Johns spots this and tries to compile his materialized view but this time, it remains INVALID:

SQL> alter materialized view mv1 compile

2 /

Materialized view altered.

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE               VALID

MATERIALIZED VIEW   INVALID

SQL>

… and it now has a COMPILE_STATE of COMPILATION_ERROR:

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 COMPILATION_ERROR

SQL> select * from mv1

2 /

COL1

----------

1

SQL>

Even refreshing the materialized view does not make the problem go away:

SQL> exec dbms_mview.refresh('MV1');

PL/SQL procedure successfully completed.

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW INVALID

SQL> select mview_name, compile_state

2 from user_mviews

  3  /

MVIEW_NAME                     COMPILE_STATE

------------------------------ -------------------

MV1                            COMPILATION_ERROR

SQL>

Although it does bring the data up to date:

SQL> select * from mv1

2 /

COL1

----------

2

SQL>

Andrew grants SELECT access directly to John:

SQL> conn andrew/reid

Connected.

SQL> grant select on tab1 to john

2 /

Grant succeeded.

SQL>

… and when John tries to compile the materialized view again, the problem disappears:

SQL> conn john/smith

Connected.

SQL> alter materialized view mv1 compile

2 /

Materialized view altered.

SQL> select object_type, status

2 from user_objects

3 where object_name = 'MV1'

4 /

OBJECT_TYPE STATUS

------------------- -------

TABLE VALID

MATERIALIZED VIEW VALID

SQL> select mview_name, compile_state

2 from user_mviews

3 /

MVIEW_NAME COMPILE_STATE

------------------------------ -------------------

MV1 VALID

SQL> select * from mv1

2 /

COL1

----------

SQL>

↧

ORA-01442

March 20, 2014, 4:12 pm

≫ Next: Moving a Table Deletes its Statistics

≪ Previous: INVALID Materialized View with COMPILATION_ERROR

This was tested on Oracle 11.2. If you define a column as NOT NULL then try to modify it to NOT NULL again, you get an ORA-01442:

SQL> create table tab1 (col1 number not null)
  2  /
 
Table created.
 
SQL> alter table tab1 modify (col1 number not null)
  2  /
alter table tab1 modify (col1 number not null)
                         *
ERROR at line 1:
ORA-01442: column to be modified to NOT NULL is
already NOT NULL
 
SQL>

↧

Moving a Table Deletes its Statistics

March 23, 2014, 12:27 pm

≫ Next: ORA-00957

≪ Previous: ORA-01442

Statistics are important as they help the optimizer to work out the execution plan for a SQL statement. If you move a table, this deletes its statistics so you need to analyze it again afterwards. You can see this in the example below. First I created a table:

SQL> create table object_list

2 as select * from dba_objects

3 /

Table created.

SQL>

When you create a table it has no statistics so the num_rows column is null:

SQL> select nvl(to_char(num_rows), 'NULL')

2 as row_count

3 from dba_tables

4 where table_name = 'OBJECT_LIST'

5 /

ROW_COUNT
----------------------------------------

NULL

SQL>

When you calculate statistics, the num_rows column is updated:

SQL> analyze table object_list

2 compute statistics

3 /

Table analyzed.

SQL> select nvl(to_char(num_rows), 'NULL')

2 as row_count

3 from dba_tables

4 where table_name = 'OBJECT_LIST'

5 /

ROW_COUNT

----------------------------------------
7932

SQL>

Moving the table deletes the statistics so num_rows is null afterwards:

SQL> alter table object_list move

2 /

Table altered.

SQL> select nvl(to_char(num_rows), 'NULL')

2 as row_count

3 from dba_tables

4 where table_name = 'OBJECT_LIST'

5 /

ROW_COUNT

---------------------------------------- NULL

SQL>

To reinstate the statistics, simply analyze the table again:

SQL> analyze table object_list

2 compute statistics

3 /

Table analyzed.

SQL> select nvl(to_char(num_rows), 'NULL')

2 as row_count

3 from dba_tables

4 where table_name = 'OBJECT_LIST'

5 /

ROW_COUNT
----------------------------------------
7932

SQL>

↧

ORA-00957

March 26, 2014, 2:18 pm

≫ Next: How to Diagnose a Locking Issue

≪ Previous: Moving a Table Deletes its Statistics

I tested this on Oracle 11.2. If you try to use a column name more than once in an Oracle table, you get an ORA-00957:

SQL> create table tab1

  2  (col1 number,

  3   col1 number)

  4  /

 col1 number)

*

ERROR at line 3:

ORA-00957: duplicate column name

SQL>

↧

How to Diagnose a Locking Issue

March 28, 2014, 12:16 am

≫ Next: ORA-29339

≪ Previous: ORA-00957

A user ran an update statement and noticed that it did not seem to be doing anything:

SQL> conn gordon/bennett

Connected.

SQL> update andrew.emp

2 set ename = 'COLIN'

3 where ename = 'BRIAN'

4 /

I looked up his SID in V$SESSION:

SQL> select sid from v$session

2 where username = 'GORDON'

3 /

SID

----------

393

SQL>

I ran the following SQL, waited 10 seconds and ran it again:

SQL> l

1 select event, time_waited/100

2 from v$session_event

3 where sid = 393

4 and wait_class != 'Idle'

5* order by 2 desc

SQL> /

EVENT TIME_WAITED/100

------------------------------ ---------------

enq: TX - row lock contention 249.58

Disk file operations I/O .01

SQL*Net message to client 0

SQL> /

EVENT TIME_WAITED/100

------------------------------ ---------------

enq: TX - row lock contention 258.6

Disk file operations I/O .01

SQL*Net message to client 0

SQL>

This showed me that there was an ongoing locking issue with this user. I looked up the SID of the blocking session like this:

SQL> l

1 select blocking_session from v$session

2* where sid = 393

SQL> /

BLOCKING_SESSION

----------------

101

SQL>

I saw that it belonged to Fred:

SQL> l

1 select username from v$session

2* where sid = 101

SQL> /

USERNAME

------------------------------

FRED

SQL>

I found some SQL on the Internet and hoped that it would tell me what Fred was doing but it did not work:

SQL> l

1 select b.sql_text

2 from v$session a, v$sqlarea b

3 where a.sql_address = b.address

4* and a.sid = 101

SQL> /

no rows selected

SQL>

I wondered if Fred had run his SQL but not commited it and changed my SQL as follows:

SQL> l

1 select b.sql_text

2 from v$session a, v$sqlarea b

3 where a.prev_sql_addr = b.address

4* and a.sid = 101

SQL> /

SQL_TEXT

--------------------------------------------------

update andrew.emp set enum = 2 where enum = 1

SQL>

Then I looked in the EMP table and saw that both Fred and Gordon were trying to update the same row:

SQL> select * from andrew.emp

2 /

ENUM ENAME

----- ----------

1 BRIAN

SQL>

I asked Fred to COMMIT his UPDATE statement:

SQL> update andrew.emp

2 set enum = 2

3 where enum = 1

4 /

1 row updated.

SQL> commit

  2  /

Commit complete.

SQL>

This allowed Gordon’s UPDATE to finish:

SQL> conn gordon/bennett

Connected.

SQL> update andrew.emp

2 set ename = 'COLIN'

3 where ename = 'BRIAN'

4 /

1 row updated.

SQL>

↧

ORA-29339

March 30, 2014, 11:47 am

≫ Next: PLSQL_OPTIMIZE_LEVEL

≪ Previous: How to Diagnose a Locking Issue

I discovered a new error today. I was using Data Pump to copy a database from Sun SPARC to X86 and from Oracle 11.1.0.6.0 to 11.2.0.4.0 for testing purposes. I extracted the tablespace creation SQL from the old database like this. (This is only some of it.):

SQL> set lines 32000

SQL> set pages 50

SQL> exec dbms_metadata.set_transform_param(-

> DBMS_METADATA.SESSION_TRANSFORM,'SQLTERMINATOR',TRUE);

PL/SQL procedure successfully completed.

SQL> select dbms_metadata.get_ddl(-

> 'TABLESPACE','PINDAR_LARGE_32KBLOCKS')

2 from dual

3 /

DBMS_METADATA.GET_DDL('TABLESPACE','PINDAR_LARGE_32KBLOCKS')

--------------------------------------------------------------------------------

CREATE TABLESPACE "PINDAR_LARGE_32KBLOCKS" DATAFILE

'/cisdpt/nbadpt1/nba_data/pindar_large_32kblocks_a.dbf' SIZE 8388608000,

'/cisdpt/nbadpt1/nba_data/pindar_large_32kblocks_b.dbf' SIZE 10485760000,

'/cisdpt/nbadpt1/nba_data/pindar_large_32k_blocks_c.dbf' SIZE 15728640000

LOGGING ONLINE PERMANENT BLOCKSIZE 32768

EXTENT MANAGEMENT LOCAL UNIFORM SIZE 209715200 SEGMENT SPACE MANAGEMENT AUTO;

SQL>

I did a global replace to change part of the file name to bring it in line with the file system naming on the X86 server. Then I ran the SQL to create the tablespace in the new database but it failed:

SQL> CREATE TABLESPACE "PINDAR_LARGE_32KBLOCKS" DATAFILE

2 '/database/GBNBAPF1/nba_data/pindar_large_32kblocks_a.dbf' SIZE 8388608000,

3 '/database/GBNBAPF1/nba_data/pindar_large_32kblocks_b.dbf' SIZE 10485760000,

4 '/database/GBNBAPF1/nba_data/pindar_large_32k_blocks_c.dbf' SIZE 15728640000

5 LOGGING ONLINE PERMANENT BLOCKSIZE 32768

6 EXTENT MANAGEMENT LOCAL UNIFORM SIZE 209715200 SEGMENT SPACE MANAGEMENT AUTO;

CREATE TABLESPACE "PINDAR_LARGE_32KBLOCKS" DATAFILE

ERROR at line 1:

ORA-29339: tablespace block size 32768 does not match configured block sizes

SQL>

The db_block_size was 8192 in both the old and new databases but the old one had the following extra line in its parameter file:

db_32k_cache_size=12m

This is to set up a cache for tablespaces with a 32K block size. I added this line to the parameter file for the new database and bounced it. Then I was able to create the tablespace there successfully:

SQL> CREATE TABLESPACE "PINDAR_LARGE_32KBLOCKS" DATAFILE

2 '/database/GBNBAPF1/nba_data/pindar_large_32kblocks_a.dbf' SIZE 8388608000,

3 '/database/GBNBAPF1/nba_data/pindar_large_32kblocks_b.dbf' SIZE 10485760000,

4 '/database/GBNBAPF1/nba_data/pindar_large_32k_blocks_c.dbf' SIZE 15728640000

5 LOGGING ONLINE PERMANENT BLOCKSIZE 32768

6 EXTENT MANAGEMENT LOCAL UNIFORM SIZE 209715200 SEGMENT SPACE MANAGEMENT AUTO;

Tablespace created.

SQL>

↧

PLSQL_OPTIMIZE_LEVEL

April 3, 2014, 1:24 pm

≫ Next: ORA-12985

≪ Previous: ORA-29339

This parameter controls how much optimization Oracle does to PL/SQL code when it is compiled.

In Oracle 10, valid values were 0, 1 and 2:

Oracle 10: sqlplus / as sysdba

SQL*Plus: Release 10.2.0.3.0 - Production on Thu Apr 3 17:41:02 2014

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production

With the Partitioning, OLAP and Data Mining options

SQL> alter session set plsql_optimize_level = 3

2 /

ERROR:

ORA-00068: invalid value 3 for parameter plsql_optimize_level, must be between

0 and 2

SQL>

In Oracle 11, they were 0, 1, 2 and 3:

Oracle 11: sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Thu Apr 3 17:47:49 2014

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> alter session set plsql_optimize_level = 4

2 /

ERROR:

ORA-00068: invalid value 4 for parameter plsql_optimize_level, must be between

0 and 3

SQL>

You can see the effect of PLSQL_OPTIMIZE_LEVEL in the examples below, which I ran in an Oracle 11 database.

A procedure is compiled with three different values for this parameter. The code contains a loop, which is executed 10 million times. Inside the loop there is a statement, which assigns a value, which is never used. You could achieve the same effect by doing the assignment only once outside the loop. You could even omit the assignment altogether as the only information provided to the outside world by running the procedure is the amount of CPU time it has used.

As far as I understand, Oracle do not say how they will optimize your code, they simply say that they might alter and/or reorder the statements to achieve the same result in a different way.

With the parameter set to 0 i.e. no optimization, the procedure uses 8.1 seconds of CPU. Setting it to 1 reduces the time to 1.04 seconds. Finally, when it is set to 2, no CPU usage is recorded at all:

SQL> alter session set plsql_optimize_level = 0

2 /

Session altered.

SQL> create or replace procedure counter is

2 x number;

3 t1 integer;

4 t2 integer;

5 t3 number;

6 begin

7 t1 := dbms_utility.get_cpu_time();

8 for a in 1..10000000 loop

9 x := 1 + 2 - 3 * 4 / 5;

10 end loop;

11 t2 := dbms_utility.get_cpu_time();

12 t3 := (t2-t1)/100;

13 dbms_output.put_line('CPU used = '||t3||' seconds');

14 end;

15 /

Procedure created.

SQL> exec counter;

CPU used = 8.1 seconds

PL/SQL procedure successfully completed.

SQL> alter session set plsql_optimize_level = 1

2 /

Session altered.

SQL> create or replace procedure counter is

2 x number;

3 t1 integer;

4 t2 integer;

5 t3 number;

6 begin

7 t1 := dbms_utility.get_cpu_time();

8 for a in 1..10000000 loop

9 x := 1 + 2 - 3 * 4 / 5;

10 end loop;

11 t2 := dbms_utility.get_cpu_time();

12 t3 := (t2-t1)/100;

13 dbms_output.put_line('CPU used = '||t3||' seconds');

14 end;

15 /

Procedure created.

SQL> exec counter;

CPU used = 1.04 seconds

PL/SQL procedure successfully completed.

SQL> alter session set plsql_optimize_level = 2

2 /

Session altered.

SQL> create or replace procedure counter is

2 x number;

3 t1 integer;

4 t2 integer;

5 t3 number;

6 begin

7 t1 := dbms_utility.get_cpu_time();

8 for a in 1..10000000 loop

9 x := 1 + 2 - 3 * 4 / 5;

10 end loop;

11 t2 := dbms_utility.get_cpu_time();

12 t3 := (t2-t1)/100;

13 dbms_output.put_line('CPU used = '||t3||' seconds');

14 end;

15 /

Procedure created.

SQL> exec counter;

CPU used = 0 seconds

PL/SQL procedure successfully completed.

SQL>

↧

ORA-12985

April 4, 2014, 12:13 pm

≫ Next: enq: SQ – contention

≪ Previous: PLSQL_OPTIMIZE_LEVEL

If you try to drop a column from a table in a read only tablespace, you get an ORA-12985. If you really need to drop the column, you must put the tablespace back into read write mode first. You can see what I mean in the example below, which I tested in an Oracle 9 database:

SQL> create tablespace andrews_ts

2 datafile '/tmp/andrew.dbf'

3 size 1m

4 /

Tablespace created.

SQL> grant dba to andrew identified by reid

2 /

Grant succeeded.

SQL> alter user andrew default tablespace andrews_ts

2 /

User altered.

SQL> conn andrew/reid

Connected.

SQL> create table tab1

2 (col1 number, col2 number)

3 /

Table created.

SQL> alter tablespace andrews_ts read only

2 /

Tablespace altered.

SQL> alter table tab1 drop column col2

2 /

alter table tab1 drop column col2

ERROR at line 1:

ORA-12985: tablespace 'ANDREWS_TS' is read only,

cannot drop column

SQL> alter tablespace andrews_ts read write

2 /

Tablespace altered.

SQL> alter table tab1 drop column col2

2 /

Table altered.

SQL> drop tablespace andrews_ts

2 including contents and datafiles

3 /

Tablespace dropped.

SQL>

↧

enq: SQ – contention

April 11, 2014, 3:58 pm

≫ Next: ORA-12899

≪ Previous: ORA-12985

This example shows how to deal with the enq: SQ – contention wait event. It was tested on Oracle 11.2. First I created a sequence and queried the amount of time already spent on this wait event:

SQL> create sequence seq1

2 /

Sequence created.

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

no rows selected

SQL>

Then I created the following UNIX shell script to run test.sql 20 times simultaneously:

Oracle 11.2: cat test.ksh

#!/bin/ksh

export ORAENV_ASK=NO

export ORACLE_SID=ORCL

. oraenv

sqlplus / @test 0 &

sqlplus / @test 1 &

sqlplus / @test 2 &

sqlplus / @test 3 &

sqlplus / @test 4 &

sqlplus / @test 5 &

sqlplus / @test 6 &

sqlplus / @test 7 &

sqlplus / @test 8 &

sqlplus / @test 9 &

sqlplus / @test 10 &

sqlplus / @test 11 &

sqlplus / @test 12 &

sqlplus / @test 13 &

sqlplus / @test 14 &

sqlplus / @test 15 &

sqlplus / @test 16 &

sqlplus / @test 17 &

sqlplus / @test 18 &

sqlplus / @test 19 &

Oracle 11.2:

This is test.sql. It accepts a parameter and uses it to generate a SPOOL file name. Then it selects 10,000 values from the sequence created earlier:

Oracle 11.2: cat test.sql

spool test&&1

set echo on

declare

num1 number;

begin

for a in 1..10000 loop

select seq1.nextval into num1 from dual;

end loop;

end;

exit

spool off

Oracle 11.2:

I ran test.ksh and waited until all the SPOOL files had been created:

Oracle 11.2: ls -ltr

total 36

-rwxr--r--   1 oracle   dba          487 Apr 11 13:48 test.ksh

-rw-r--r--   1 oracle   dba          147 Apr 11 13:55 end_test1.sql

-rw-r--r--   1 oracle   dba          147 Apr 11 13:56 end_test2.sql

-rw-r--r--   1 oracle   dba          150 Apr 11 13:56 start_test1.sql

-rw-r--r-- 1 oracle dba 161 Apr 11 13:56 start_test2.sql

-rwxr--r-- 1 oracle dba 154 Apr 11 13:57 test.sql

-rw-r--r-- 1 oracle dba 184 Apr 11 14:43 start_test1.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test16.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test1.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test4.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test6.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test12.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test9.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test13.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test19.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test3.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test2.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test15.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test17.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test11.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test0.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test10.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test14.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test5.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test8.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test7.lst

-rw-r--r-- 1 oracle dba 206 Apr 11 16:12 test18.lst

Oracle 11.2:

Then I looked in one of them to see that it had worked OK:

Oracle 11.2: cat test18.lst

SQL> declare

2 num1 number;

3 begin

4 for a in 1..10000 loop

5 select seq1.nextval into num1 from dual;

6 end loop;

7 end;

8 /

PL/SQL procedure successfully completed.

SQL> exit

Oracle 11.2:

I rechecked the amount of time spent on the wait event. This is the time Oracle spends waiting for the next value to come back from the sequence. It had gone from zero to 436.8 seconds as 20 sessions had been requesting values at the same time:

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

TIME_WAITED/100

---------------

436.8

SQL> drop sequence seq1

2 /

Sequence dropped.

SQL>

I recreated the sequence but this time I told Oracle to cache 10,000 values in memory:

SQL> create sequence seq1 cache 10000

2 /

Sequence created.

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

TIME_WAITED/100

---------------

436.8

SQL>

I reran test.ksh then rechecked the time spent on the wait event. This time it had increased by less than 20 seconds:

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

TIME_WAITED/100

---------------

455.15

SQL> drop sequence seq1

2 /

Sequence dropped.

SQL>

I recreated the sequence but this time I told Oracle to cache 200,000 values in memory:

SQL> create sequence seq1 cache 200000

2 /

Sequence created.

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

TIME_WAITED/100

---------------

455.15

SQL>

I reran test.ksh then rechecked the time spent on the wait event. This time it had not increased at all:

SQL> select time_waited/100

2 from v$system_event

3 where event = 'enq: SQ - contention'

4 /

TIME_WAITED/100

---------------

455.15

SQL> drop sequence seq1

2 /

Sequence dropped.

SQL>

So, when you create a sequence, if you set the cache value appropriately, you can reduce the time spent on this wait event or maybe even eliminate it altogether.

↧

ORA-12899

April 14, 2014, 12:28 pm

≫ Next: How to Rename a Table

≪ Previous: enq: SQ – contention

This was tested on Oracle 11.2. If you try to update a column with a value which is too long, you will get an ORA-12899:

SQL> conn andrew/reid

Connected.

SQL> create table tab1 (first_name varchar2(10))

2 /

Table created.

SQL> insert into tab1 values ('Christopher')

2 /

insert into tab1 values ('Christopher')

ERROR at line 1:

ORA-12899: value too large for column

"ANDREW"."TAB1"."FIRST_NAME" (actual: 11, maximum: 10)

SQL>

If this happens, you can either use a shorter value:

SQL> insert into tab1 values ('Colin')

2 /

1 row created.

SQL>

…or make the column longer:

SQL> alter table tab1 modify first_name varchar2(15)

2 /

Table altered.

SQL> insert into tab1 values ('Christopher')

2 /

1 row created.

SQL>

↧

How to Rename a Table

April 15, 2014, 12:44 pm

≫ Next: ORA-01749

≪ Previous: ORA-12899

I tested this example in Oracle 12.1. First I created a table:

SQL> create table fred

2 as select * from user_synonyms

3 where 1 = 2

4 /

Table created.

SQL>

Then I checked its object_id for later:

SQL> select object_id

2 from user_objects

3 where object_name = 'FRED'

4 /

OBJECT_ID

----------

92212

SQL>

... and described it:

SQL> desc fred

Name Null? Type

-------------------------- -------- ------------------

SYNONYM_NAME NOT NULL VARCHAR2(128)

TABLE_OWNER VARCHAR2(128)

TABLE_NAME NOT NULL VARCHAR2(128)

DB_LINK VARCHAR2(128)

ORIGIN_CON_ID NUMBER

SQL>

Then I changed its name:

SQL> rename fred to joe

2 /

Table renamed.

SQL>

... and finally, to prove I was still looking at the same object, I used the new name to look up the object_id and description and confirmed that they had not changed:

SQL> select object_id

2 from user_objects

3 where object_name = 'JOE'

4 /

OBJECT_ID

----------

92212

SQL> desc joe

Name Null? Type

-------------------------- -------- ------------------

SYNONYM_NAME NOT NULL VARCHAR2(128)

TABLE_OWNER VARCHAR2(128)

TABLE_NAME NOT NULL VARCHAR2(128)

DB_LINK VARCHAR2(128)

ORIGIN_CON_ID NUMBER

SQL>

In Spanish

↧