Laurent Schneider

I wrote a few odbc articles using ODBCCONF in my blog, so I edit them because ODBCCONF will be removed; read https://docs.microsoft.com/en-us/sql/odbc/odbcconf-exe

Using Powershell Add-OdbcDsn is much easier

PS> remove-OdbcDsn -name DB01 -dsntype User
PS> Add-OdbcDsn -name DB01 -DriverName
"Oracle in client12201" -DsnType "User"
-SetPropertyValue @("Server=DB01")
PS> Get-OdbcDsn

Name : DB01
DsnType : User
Platform : 64-bit
DriverName : Oracle in client12201
Attribute : {Password, StatementCache, ...}

PS> remove-OdbcDsn -name DB01 -dsntype User



begin
dbms_output.put_line('Kilroy1');
dbms_lock.sleep(1);
dbms_output.put_line('Kilroy2');
dbms_lock.sleep(1);
dbms_output.put_line('Kilroy3');
dbms_lock.sleep(1);
dbms_output.put_line('Kilroy4');
dbms_lock.sleep(1);
dbms_output.put_line('Kilroy5');
dbms_lock.sleep(1);
end;
/


You wait five seconds, then get the output.

This is the way it works with dbms_output.

Now I try a new trick

The output does not wait the end. There was a trick I wrote in 2007 using utl_file, but it was a bit cheating, because it was only working with local connections.

There are a lot of ways of simulating this, with DBMS_APPLICATION_INFO, UTL_FILE, TABLEs, DBMS_PIPE, but for today, I chosed advanced queuing.
my program has 4 parts. Here it is shell but it could well be perl / java and others

#!/bin/ksh
# 1. create the objects
./init
# 2. create a dequeuing process in the background
./monitor &
# 3. create the connection
./connect
sleep 1
# 4. cleanup the objects
./cleanup


init.sql creates a message type, a queue table and a queue. Then it creates a procedures that enqueue messages.

create type o as object(t timestamp, txt varchar2(40))
/
exec dbms_aqadm.create_queue_table('QT','O')
exec dbms_aqadm.create_queue('Q','QT')
create procedure enqueue(txt varchar2) is
pragma autonomous_transaction;
msgid raw(16);
enqueue_options dbms_aq.enqueue_options_t;
message_properties dbms_aq.message_properties_t;
begin
dbms_aq.enqueue('Q', enqueue_options, message_properties,
o(current_timestamp, txt), msgid);
commit;
end;
/
exec dbms_aqadm.start_queue('Q')


In my “monitor” script, I loop my monitor.sql with a simple while : ; do sqlplus … until failure

declare
msg o;
msgid raw(16);
dequeue_options dbms_aq.dequeue_options_t;
message_properties dbms_aq.message_properties_t;
begin
dbms_aq.dequeue('Q', dequeue_options, message_properties, msg, msgid);
dbms_output.put_line(msg.t||': '||msg.txt);
end;
/
quit


My code now looks like

begin
enqueue('Kilroy1');
dbms_lock.sleep(1);
enqueue('Kilroy2');
dbms_lock.sleep(1);
enqueue('Kilroy3');
dbms_lock.sleep(1);
enqueue('Kilroy4');
dbms_lock.sleep(1);
enqueue('Kilroy5');
dbms_lock.sleep(1);
end;
/


But thanks for my second processes, the monitor, I have now feedback before the end.

It is my first videos on this blog 🙂

Itching to start playing with 18c?

Now you can on @oraclelivesql !

Here's a script to get you started: a dynamic CSV-to-columns converter using polymorphic table functionshttps://t.co/UfddLQ2tn5 pic.twitter.com/BxnXeIKoCx

— Chris Saxon (@ChrisRSaxon) February 17, 2018

The ingenious solution of Anton Scheffer using Data Cartridge is now beaten in 18c using polymorphic table function

Anthologic post of Anton : forums.oracle.com
Chris magic with Oracle 18c :
livesql.oracle.com


SQL> create table t1(x number primary key);
Table created.
SQL> desc t1
Name Null? Type
----------------------- -------- ----------------
X NOT NULL NUMBER


SQL> create table t2 as select * from t1;
Table created.
SQL> desc t2
Name Null? Type
----------------------- -------- ----------------
X NUMBER


The table T2 has the column X, but not the constraint (primary key / not null).

If you want to do a create table as select but want to keep index / constraints etc, then you rather use datapump

SQL> set autop on
SQL> var job_state varchar2(30)
SQL> declare
n number;
begin
n := DBMS_DATAPUMP.open('IMPORT','TABLE','DB01');
DBMS_DATAPUMP.metadata_filter(n,'NAME_LIST','''T1''');
DBMS_DATAPUMP.metadata_remap(n,'REMAP_TABLE','T1','T3');
DBMS_DATAPUMP.start_job(n);
DBMS_DATAPUMP.WAIT_FOR_JOB(n, :job_state);
end;
/
PL/SQL procedure successfully completed.
JOB_STATE
--------------------------------------------------
COMPLETED
SQL> desc t3
Name Null? Type
----------------------- -------- ----------------
X NOT NULL NUMBER


The Table T3 is a copy of T1. DB01 is my implicit loopback database link (database name).

Let me today tell you, I now hate FBI for real.

Let’s start with an easy working example


SQL> CREATE TABLE t(x NUMBER PRIMARY KEY)
Table created.
SQL> insert into t(x) values (1)
1 row created.
SQL> insert into t(x) values (2)
1 row created.
SQL> insert into t(x) values (3)
1 row created.
SQL> commit
Commit complete.
SQL> CREATE FUNCTION f (x NUMBER)
RETURN NUMBER DETERMINISTIC IS
BEGIN
RETURN x * x;
END;
Function created.
SQL> CREATE INDEX i
ON t (f (x))
Index created.
SQL> select * from t where f(x)=4

X
----------
2
Execution Plan
------------------------------------------------
0 SELECT STATEMENT
1 0 TABLE ACCESS BY INDEX ROWID BATCHED T
2 1 INDEX RANGE SCAN I


Okay, this is a nice-working example. I can use where f(x)=4.

A non-fbi code would be something like

SQL> create or replace type tn as table of number;
Type created.
SQL> create or replace function f2(y number)
return tn deterministic is
begin
if (y<0) then return null; end if; return tn (sqrt(y), -sqrt(y)); end; Function created. SQL> select * from t where x member of f2(4)

X
----------
2

Execution Plan
------------------------------------
0 SELECT STATEMENT
1 0 INDEX FULL SCAN SYS_C0026437


The reverse function is somehow more challenging to code, but the benefit is enormous, I have no more fbi.

What’s wrong with fbi?

First example : I recreate my function:

SQL> DROP FUNCTION f
Function dropped.
SQL> CREATE FUNCTION f (x NUMBER)
RETURN NUMBER DETERMINISTIC IS
BEGIN
RETURN power(x,2);
END;
Function created.
SQL> select * from t where f(x)=4
*
Error at line 0
ORA-30554: function-based index I is disabled
SQL> SELECT object_type, object_name, status
FROM user_objects
WHERE object_name IN ('F','I')

OBJECT_TYPE OBJECT_NAME STATUS
----------------------- ------------ -------
INDEX I VALID
FUNCTION F VALID
SQL> SELECT index_name,
table_name,
index_type,
status,
funcidx_status
FROM user_indexes
WHERE index_name = 'I'

INDEX TABLE INDEX_TYPE STATUS FUNCIDX_STATUS
----- ----- -------------- ------ --------------
I T FUNCTION-BASED VALID DISABLED


Remember this error. ORA-30554. And this not-so-well-known column, USER_INDEXES.FUNCIDX_STATUS. The behavior is pretty agressive, every object is valid, but you can no longer select from the table.

A small parenthese. We all know about unusable indexes. Index often get unusable due to partition maintenance and the like.


SQL> create table t2(x number)
Table created.
SQL> insert into t2 values (1)
1 row created.
SQL> create index i2 on t2(x) unusable
Index created.
SQL> SELECT index_name,
table_name,
status
FROM user_indexes
WHERE index_name = 'I2'

INDEX TABLE STATUS
----- ----- ---------
I2 T2 UNUSABLE
SQL> insert into t2 values (2)
1 row created.
SQL> select * from t2 where x=2

X
----------
2

Execution Plan
---------------------------------
0 SELECT STATEMENT
1 0 TABLE ACCESS FULL T2


The index is not unused, but it prevents neither INSERT nor SELECT.

Let’s add a constraint

SQL> alter index i2 rebuild
Index altered.
SQL> alter table t2 add primary key (x)
Table altered.
SQL> alter index i2 unusable
Index altered.
SQL> insert into t2 values (2)
ORA-01502: index 'I2' or partition of such index is in unusable state
SQL> select * from t2 where x=2

X
----------
2

If the index is used by a constraint or is unique, then insert is prevented. But no select is prevented ever.

Okay, frequent readers may wonder why I did DROP FUNCTION and CREATE FUNCTION instead of CREATE OR REPLACE FUNCTION.

Fine, let’s try.

SQL> CREATE or replace FUNCTION f (x NUMBER)
RETURN NUMBER
DETERMINISTIC
IS
BEGIN
RETURN power(x,2);
END;
Function created.
SQL> alter index i rebuild
Index altered.
SQL> alter index i enable
Index altered.
SQL> select x, f(x) from t where f(x)=4

X F(X)
---------- ----------
2 4
SQL> create or replace function f(x number)
return number deterministic is
begin
return 1;
end;
Function created.
SQL> select x, f(x), f(2) from t where f(x)=4

X F(X) F(2)
---------- ---------- ----------
2 4 1


Oh my goodness, select returns completly wrong result, but the index is valid and enabled.

There is more than way to solve this

1. rebuild your index after create function. You could find the candidates by looking at the last ddl time and dependencies


SQL> select name from user_dependencies d
where referenced_type = 'FUNCTION'
and type = 'INDEX' and
(
select last_ddl_time
from user_objects i
where i.object_name=d.name
) < ( select last_ddl_time from user_objects f where f.object_name=d.referenced_name ) NAME ----- I SQL> alter index i rebuild
Index altered.
SQL> select x, f(x), f(2) from t where f(x)=4
no rows selected.
SQL> select x, f(x), f(2) from t where f(x)=1

X F(X) F(2)
---------- ---------- ----------
1 1 1
2 1 1
3 1 1

SQL> select name from user_dependencies d
where referenced_type = 'FUNCTION'
and type = 'INDEX' and
(
select last_ddl_time
from user_objects i
where i.object_name=d.name
) < ( select last_ddl_time from user_objects f where f.object_name=d.referenced_name ) no rows selected.

2. file an SR and encourage Oracle to test features before making them available
3. stop using FBI immediately

The most well-known administrative privilege is sysdba. Back in Oracle 7.2, oracle recommended to no longer use the INTERNAL but to connect as sysdba. A second one, seldom used, is SYSOPER.

When you use sqlplus / as sysdba, or connect / as sysdba in sqlplus / srvmgrl, the you log as SYS.

That’s the most powerfull user in the database.

SYSOPER has less privileges, it can shutdown the database and the like.

While often refered as the SYSDBA role, or SYSDBA system privilege, SYSDBA is an administrative privilege. It is not listed in DBA_ROLES, DBA_ROLE_PRIVS, DBA_SYS_PRIVS, etc…

In non-cdb, you’ll look in V$PWFILE_USERS.
In cdb/pdb, look into cdb_local_admin_privs


grant SYSDBA, SYSOPER, SYSBACKUP, SYSDG, SYSKM to u;


SYSRAC and SYSASM also exists, but I have not tested them yet.

SQL> select CON, USERNAME, SYSDBA, SYSOPER, SYSASM,
SYSBACKUP, SYSDG, SYSKM from V$PWFILE_USERS;

CON USERNAME SYSDBA SYSOPER SYSBACKUP SYSDG SYSKM
--- -------- ------ ------- --------- ----- -----
0 SYS TRUE TRUE FALSE FALSE FALSE
3 U TRUE TRUE TRUE TRUE TRUE

SQL> select * from cdb_local_admin_privs;

CON_NAME GRANTEE SYSDBA SYSOPER SYSBACKUP SYSDG SYSKM
-------- ------- ------ ------- --------- ----- -----
PDB01 U TRUE TRUE TRUE TRUE TRUE


What’s really happening when you log as sysdba?


SQL> conn u/***@DB01 as sysdba
Connected.
SQL> sho user
USER is "SYS"
SQL> select privilege from session_privs
where privilege like 'SYS%';
PRIVILEGE
------------------------------
SYSDBA
SYSOPER
SQL> def _PRIVILEGE
DEFINE _PRIVILEGE = "AS SYSDBA" (CHAR)
SQL> select privilege from dba_sys_privs
where privilege like 'SYS%';
no rows selected


Even if you use your U-credentials, you are SYS and you have SYSDBA privielege. It is not a System privilege but an an administrative privilege. You also get SYSOPER for free.

What happens when you log as SYSOPER?


SQL> conn u/***@DB01 as sysoper
Connected.
SQL> sho user
USER is "PUBLIC"
SQL> select * from session_privs;
PRIVILEGE
------------------------------
CREATE SESSION
RESTRICTED SESSION
SYSOPER

SQL> create public synonym p for x.y;
create public synonym p for x.y
*
ERROR at line 1:
ORA-01031: insufficient privileges
SQL> create synonym p for x.y;
create synonym p for x.y
*
ERROR at line 1:
ORA-01031: insufficient privileges


You are logged as the pseudo-user PUBLIC. It doesn’t give you the right to create “PUBLIC” objects, but you could do a few things, with your SYSOPER privilege, like shutdown;

For the other users, it is no longer matched to SYS or PUBLIC, but they have they own underlying users;


SQL> conn u/***@DB01 as sysbackup;
Connected.
SQL> sho user
USER is "SYSBACKUP"
SQL> select * from session_privs;

PRIVILEGE
------------------------------
ALTER SYSTEM
ALTER SESSION
ALTER TABLESPACE
DROP TABLESPACE
UNLIMITED TABLESPACE
CREATE ANY TABLE
CREATE ANY CLUSTER
AUDIT ANY
ALTER DATABASE
CREATE ANY DIRECTORY
RESUMABLE
SELECT ANY DICTIONARY
SELECT ANY TRANSACTION
SYSBACKUP
SQL> conn u/***@DB01 as sysdg;
Connected.
SQL> sho user
USER is "SYSDG"
SQL> select * from session_privs;

PRIVILEGE
------------------------------
ALTER SYSTEM
ALTER SESSION
ALTER DATABASE
SELECT ANY DICTIONARY
SYSDG
SQL> conn u/***@DB01 as syskm
Connected.
SQL> sho user
USER is "SYSKM"
SQL> select * from session_privs;

PRIVILEGE
------------------------------
SYSKM
ADMINISTER KEY MANAGEMENT


This allows different administrators, that are not in the core dba team, to execute some administrative operation like Dataguard-Switchover / Restore / Shutdown /Startup on their databases, without SYS.

Remember, SYS can now be locked in a PDB 🙂 see lock sys

To get the status of a directory, I wrote my own function, which uses DBMS_LOB.FILEEXISTS.


CREATE FUNCTION
status (DIRECTORY_NAME VARCHAR2)
RETURN VARCHAR2
IS
BEGIN
IF (DBMS_LOB.FILEEXISTS(
BFILENAME (DIRECTORY_NAME, '.')) = 1)
THEN
RETURN 'VALID';
ELSE
RETURN 'INVALID';
END IF;
EXCEPTION
WHEN OTHERS
THEN
RETURN SQLERRM;
END;
/



SELECT
directory_name NAME,
directory_path PATH,
status (directory_name) STATUS
FROM dba_directories;

NAME PATH STATUS
---- ---- ---------
FOO /foo INVALID
TMP /tmp VALID
BAK /u99 VALID


followup of check invalid database link
If you need to check db link in another schema, you need to create code that run with that schema.

base on the example from yesterday, here is an extended version for the dba


CREATE FUNCTION dba_status
(owner VARCHAR2, db_link VARCHAR2)
RETURN VARCHAR2
IS
PRAGMA AUTONOMOUS_TRANSACTION;
status VARCHAR2 (4000);
BEGIN
EXECUTE IMMEDIATE
'create or replace function "'
|| owner
|| '".status(db_link varchar2) return varchar2 is '
|| 'x number;'
|| 'begin execute immediate ''select 1 from dual@"''
||DB_LINK||''"'' into x;'
|| 'return ''OK'';'
|| 'exception when others then return sqlerrm;'
|| 'end;';
EXECUTE IMMEDIATE
'begin :1 := "' || owner
||'".status(''' || db_link || '''); end;'
USING OUT status;
EXECUTE IMMEDIATE 'drop function "' || owner || '".status';
COMMIT;
RETURN status;
END;
/


SELECT
owner, db_link, dba_status (owner, db_link)
FROM dba_db_links;
OWNER DB_LINK DBA_STATUS(OWNER,DB_LINK)
----- ------- --------------------------------
SCOTT L3.EXAM OK
SCOTT L2.EXAM ORA-12154: TNS:could not resolve
SCOTT L1.EXAM ORA-01017: invalid username/pass


If one database link is invalid, you cannot select through it

SQL> select * from dual@z;
select * from dual@z
*
ERROR at line 1:
ORA-02019: connection description for remote database not found


However, there is no STATUS command in your user_db_links table that you could use. For this purpose, write a function.

create function status(db_link varchar2)
return varchar2 is
x number;
begin
execute immediate 'select 1 from dual@"'||
DB_LINK||
'"' into x;
return 'OK';
exception
when others then return sqlerrm;
end;
/


select db_link, status(db_link) from user_db_links;
DB_LINK STATUS(DB_LINK)
------- --------------------------------------------------
L1.EXAM ORA-01017: invalid username/password; logon denied
L2.EXAM ORA-12154: TNS:could not resolve the connect ident
L3.EXAM OK


$p=new XML::Parser;$p->setHandlers(Start=>&b);$p->parsefile("-");sub b{($i,$e,%a)=@_;if($e eq"Target"){print$a{"NAME"}.":".$a{"TYPE"}}}

— laurentsch (@laurentsch) September 19, 2017

As correctly pointed out by dhoogfr , the proper way to list targets on an agent is to use list target

$ emctl config agent listtargets
Oracle Enterprise Manager Cloud Control 13c Release 2
Copyright (c) 1996, 2016 Oracle Corporation. All rights reserved.
[srv01.example.com, host]
[srv01.example.com:3872, oracle_emd]
[agent13c2_2_srv01.example.com_3830, oracle_home]
[DB01.example.com, oracle_database]
[OraDB12Home1_14_srv01.example.com_743, oracle_home]
[DB01_srv01.example.com_CDBROOT, oracle_pdb]
[DB01_srv01.example.com_PDB01, oracle_pdb]
[LISTENER001_srv01.example.com, oracle_listener]


Not really easy to parse, and it does not contain all information. Let’s imagine I want to get the TARGET_NAME out of my SID? hard…

What is actually emctl doing ? It is parsing the targets.xml with perl. Oracle wrote a module, called ias::simpleXPath, that helps parsing the file.


$AGENT_HOME/perl/bin/perl -l -I$AGENT_HOME/sysman/admin/scripts -Mias::simpleXPath -e '
foreach $t(
simpleXPathQueryForNodes(
"targets.xml","Targets/Target")){
print
"[".($t->{"attributes"}->{"NAME"}).
", ".($t->{"attributes"}->{"TYPE"}).
"]"}'


ias::simpleXPath is a wrapper for XML::Parser. XML::Parser is a supported perl that is included in the agent home. So no need to install your own perl modules for this purpose!

back to by example, if I want to get the target name for my SID DB01

$AGENT_HOME/perl/bin/perl -l -MXML::Parser -e '
$xmlfile = "targets.xml";
die "Cannot find file $xmlfile"
unless -f $xmlfile;
$parser = new XML::Parser;
$parser->setHandlers(
Start => \&startElement,
End => \&endElement);
$parser->parsefile($xmlfile);
sub startElement {
( $parseinst, $element, %attrs ) = @_;
if ($element eq "Target") {
$tn=$attrs{"NAME"};
$tt=$attrs{"TYPE"};
}
if ($element eq "Property" &&
$attrs{"NAME"} eq "SID" ) {
$sid=$attrs{"VALUE"};
}
}
sub endElement {
( $parseinst, $element ) = @_;
if ($element eq "Target"){
if (
lc $sid eq lc "DB01"
) {
print $tn . ":" . $tt;
}
$sid="";
}
}
'
DB01.example.com:oracle_database


This could be useful, for instance if you want to start a blackout

emctl start blackout db01_black DB01.example.com:oracle_database


For listener, you could retrieve the LsnrName for your listener LISTENER001

$AGENT_HOME/perl/bin/perl -l -MXML::Parser -e '
$xmlfile = "targets.xml";
die "Cannot find file $xmlfile"
unless -f $xmlfile;
$parser = new XML::Parser;
$parser->setHandlers(
Start => \&startElement,
End => \&endElement);
$parser->parsefile($xmlfile);
sub startElement {
( $parseinst, $element, %attrs ) = @_;
if ($element eq "Target") {
$tn=$attrs{"NAME"};
$tt=$attrs{"TYPE"};
}
if ($element eq "Property" &&
$attrs{"NAME"} eq "LsnrName" ) {
$lsn=$attrs{"VALUE"};
}
}
sub endElement {
( $parseinst, $element ) = @_;
if ($element eq "Target"){
if (
lc $lsn eq lc "LISTENER001"
) {
print $tn . ":" . $tt;
}
$lsn="";
}
}
'
LISTENER001_srv01.example.com:oracle_listener


Which you could also blackout before rebooting.

The parser is not limited to Entreprise Manager targets, you could use it for oraInventory/ContentsXML/inventory.xml or whatever files.

There are plenty of other mean to read xml, from the database, xmllint, powershell.

I wrote about SID there. (CONNECT_DATA=(SID=DB01)) is undocumented since Oracle 11gR1 and breaks things with multi-tenant / single-tenant.

You create a container CDB01 and a pluggable DB01, you can connect with


sqlplus "scott/tiger@
(description=(address=
(host=srv01)(port=1521)(protocol=tcp))
(connect_data=(service_name=DB01.example.com)))"


But one of your application has hardcoded SID=DB01


sqlplus "scott/tiger@
(description=(address=
(host=srv01)(port=1521)(protocol=tcp))
(connect_data=(sid=DB01)))"
ORA-12514: TNS:listener does not currently know of
service requested in connect descriptor


How do you do the trick?

• Remove the domain name in the pluggable


alter session set container=DB01;
alter system set db_domain=''
container=current
scope=spfile;


• You use the listener parameter USE_SID_AS_SERVICE

listener.ora

USE_SID_AS_SERVICE_LISTENER = on


You restart the listener and the database.

sqlplus "scott/tiger@
(description=(address=
(host=srv01)(port=1521)(protocol=tcp))
(connect_data=(sid=DB01)))"
Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0


You just connected with SID to a pluggable database

Long time ago, Maxime Yuen registered 1521 for nCube License Manager.

By googling I found : Ellison cleans house at nCube, and since them 1521 has been used as a default port for Oracle. Still, you’ll see nCube in IANA.ORG service names port numbers and in /etc/services the nCube name. I don’t know which one came first, Oracle using 1521 or Larry investing in nCube, but I am pretty sure it’s related 😉

$ curl https://www.iana.org/assignments/
  service-names-port-numbers/service-names
  -port-numbers.txt | grep 1521
ncube-lm 1521 tcp nCube License Manager 
  [Maxine_Yuen] [Maxine_Yuen]
ncube-lm 1521 udp nCube License Manager 
  [Maxine_Yuen] [Maxine_Yuen]
$ grep -w 1521 /etc/services
ncube-lm 1521/tcp # nCube License Manager
ncube-lm 1521/udp # nCube License Manager
$ netstat -a | grep ncube
tcp 0 0 *.ncube-lm *.* LISTEN

Later, still long time ago, Oracle officially registered 2483 and 2484 (tcps) for the listener communication, as documented on Recommended Port Numbers :
This port number may change to the officially registered port number of 2483 for TCP/IP and 2484 for TCP/IP with SSL.

Still, as of Oracle 12c Release 2, port 1521 is recommended.

Now, another question : do you really want to use port 1521?

On the one hand, it could be good for a hacker to know listener runs on 1521 and ssh on port 22. This is configurable of course.

On the other hand, you better use that is assigned to Oracle. RFC 6335 defines 1024-49151 as User Ports, and 49152-65535 as the Dynamic and/or Private
Ports (aka ephemeral). Remember, if a port is used before you start your listener, your listener won’t start.

Remember every network connection keeps a port busy. So if you start a network client from your database server to another server, ssh, sqlnet, mail, whatever, dns, then your port 1028 or 57313 may be busy for a client connection. Which will prevent your listener from starting. If you use port 9999, you could look on IANA and ask the owner if he plans anything on that port.

Very often, most ports are unused when you start the listener. If you find an unused port in the private range, 49152-65535, you may name it in /etc/services.

Very often I see database servers with more than one listener. Obviously, you cannot run more than one listener on port 1521. There are some case where you want different listener with different sqlnet.ora or different Oracle version. But this render consolidation (e.g. Multitenant) more painful.

The discussion on which port to use is obviously far beyond Oracle. There are gazillions of TCP/UDP servers running in the digital world and less than 65535 ports. For sure you cannot have all them on IANA.ORG, right?

In most cases, stick to Oracle recommendation, use port 1521.

In the old days, locking sys had not much effect.

SQL> alter user sys identified by *** account lock;
User altered.
SQL> select account_status
from dba_users
where username='SYS';
ACCOUNT_STATUS
--------------------------------
LOCKED
SQL> conn / as sysdba
Connected.
SQL> conn sys/** as sysdba
Connected.
SQL> conn sys/***@db01 as sysdba
Connected.


Well, in the very-old days, Oracle7, or with the in 12cR2-deprecated parameter O7_DICTIONARY_ACCESSIBILITY, SYS could be locked. But this is out of the scope of this post.

In 12cR2, it is now possible to lock SYS.

SQL> alter user sys
identified by ***
account lock;
User altered.
SQL> select account_status
from dba_users
where username='SYS';
ACCOUNT_STATUS
--------------------------------
LOCKED
SQL> conn / as sysdba
Connected.
SQL> conn sys/** as sysdba
Connected.
SQL> conn sys/***@db01 as sysdba
ERROR:
ORA-28000: the account is locked


I like it 🙂 Oracle recommends you create other users to perform DBA tasks.

SQL> grant dba, sysdba
to user0001
identified by ***;
Grant succeeded.


Still, probably intentionally left so or simply forgotten, Oracle recommends to lock all Oracle supplied accounts except for SYS and SYSTEM (ref: Changing Passwords for Oracle Supplied Accounts)

Also note, you’ll get an ORA-40365 if you use an old-style password file


SQL> alter user sys identified by *** account lock;
alter user sys identified by *** account lock
*
ERROR at line 1:
ORA-40365: The SYS user cannot be locked
while the password file is in its current format.


If you follow Oracle recommendation to use SingleTenant CDB instead of Non-CDB, then a lot of things will break.

I won’t go into details, but basically, in this new architecture, you have one core container, called CDB$ROOT, which is the default container where you connect to if you connect locally

sqlplus / as sysdba
SQL> select cdb from v$database;
CDB
---
YES
SQL> select sys_context('USERENV','CON_NAME') from dual;
SYS_CONTEXT('USERENV','CON_NAME')
---------------------------------
CDB$ROOT

SQL> select con_id, NAME from V$CONTAINERS

CON_ID NAME
---------- ----------
1 CDB$ROOT
2 PDB$SEED
3 ST01


Then you’ll soon realise, you can no longer do what you used to do

SQL> create user u identified by u;
create user u identified by u
*
ERROR at line 1:
ORA-65096: invalid common user or role name


Some scripts still run in the root container. SHUTDOWN ABORT, ALTER SYSTEM SWITCH LOGFILE. Doing a full backup or clone probably won’t hurt you much. Relatively..

But now let’s imagine I have a very simple and very old script to lock scott

vintage.sh:
echo "alter user scott account lock;"|
sqlplus -s / as sysdba

This won’t work. I need to lock scott in the SingleTenant container ST01.

I could do this in the container

SQL> alter session set container=ST01;
Session altered.
SQL> alter user scott account lock;
User altered.


So fine, so good. NOW : how do I make this work without changing the script ?

Remember, non-cdb database, as they were used in Oracle 11, 10, 9, 8, 7 … are now deprecated. Remember, cdb is recommended. Now face it : it’ll break your dba scripts.

As a production dba, I don’t want to rewrite all the existing scripts. Some are ultra-old and used by people who did not write them.

One method for my script would be to change the container in a login script.

echo "alter session set container=ST01;" > /tmp/login.sql
export ORACLE_PATH=/tmp
vintage.sh
Session altered.
User altered.

(ORACLE_PATH in latest 12.1 and in 12.2, SQL_PATH in older release)

However, if my script must work with both CDB and non-CDB, I need to set the container in only this case.

In my login.sql, I first tried to implement some plsql logic, but alter session set container is not working (aka working with limitation) with execute immediate.

As well, I don’t want my script to break Oracle 11.

So I decide to do some sqlplus magic with defined variable.


set ver off feed off
-- 1) check if the column v$database.cdb exists
col column_name new_v cdb nopri
def cdb=null
select column_name from dba_tab_columns
where owner='SYS' and
table_name='V_$DATABASE' and column_name='CDB';
-- 2) if cdb is YES, then select a dynamic statement using V$PDB
col pdb new_v pdb nopri
def pdb="null stmt from dual where 1=0"
select
'''set container="''||name||''"'' stmt from v$pdbs where name!=''PDB$SEED'''
pdb
from v$database
where &cdb='YES';
-- 3) get a dynamic alter session statement. I use a dummy flagger for non-cdb
col stmt new_val stmt nopri
def stmt="SET FLAGGER=OFF"
select &pdb;
-- 4) alter session
alter session &stmt;
set feed 6
col column_name clear
col stmt clear
col pdb clear
undef cdb
undef stmt
undef pdb
del


Now I run my script

11g: ./vintage.sh
User altered.

12c-non-cdb: ./vintage.sh
User altered.

12cR2-single-tenant: ./vintage.sh
User altered.


DISCLAIMER: you shouldn’t use a global login.sql and you should know that secretly fixing old scripts may have side effects. Test, test and retest your code
DISCLAIMER 2: my frequent readers surely wonder if this statement generating a statement generating a statement is for an obfuscation contest

The default case insensitive string disappeared in 12cR2, let’s call it the 10G string in this post, but it was the same since Oracle 7 at least. It was introduced in V5 or V6 to replace clear-text passwords.

What’s happening then with my ultra-old-accounts?

You could well set a new password (or the same password again) to each account to be migrated in 11g/12cR1 before moving to 12cR2.

If nobody knows the password and nobody can change it because it is hardcoded in the application and neither easy to read (hidden / obfuscated /encrypted) nor to change, then, you are in TROUBLE ! This is documented in Note 2075401.1

First disclaimer : it is a good thing to achieve a better security. SHA1 and SHA2 are a lot better than the oldstyle-longly-hacked-unsalted-case-insensitive-homemade-algorythm. SHA3 has been published in 2015 and it not used in Oracle 12cR2 yet. SHA2 is a bit older (2001) but still recommended. SHA1 is oldish (1995) and no-longer-recommended, collision has been detected. Read more on wikipedia or crypto101

SHA-1 was a really huge improvement when introduced in 11gR1. The old self-made algorythm has been a torture for Oracle Security team. It has been published on Internet. Extremly powerfull password cracker can find your “not-too-long” password in notime. In 11g, Oracle removed the 10g String from the DBA_USERS view. I wrote about this here. It remained on the base table, USER$ until 12cR2. Now Oracle completly removed it by default in 12cR2. 10 years after SHA1 was introduced in 11gR1.

Still. You are the dba. You want to migrate your database not to chase passwords.

You could edit your sqlnet.ora to allow 10g strings.

SQLNET.ALLOWED_LOGON_VERSION_SERVER=11


This works

SQL> sho parameter sec_case_sensitive_logon
NAME VALUE
------------------------- -----
sec_case_sensitive_logon FALSE

SQL> CREATE USER "U" IDENTIFIED BY
VALUES 'DC6F2B33D359A95B';
User created.
SQL> grant create session to u;
Grant succeeded.
SQL> conn u/abcdefg@pdb01
Connected.
SQL> conn u/AbCdEfG@pdb01
Connected.


If you have SQLNET.ALLOWED_LOGON_VERSION_SERVER=11, then you could keep the same setting of sec_case_sensitive_logon as in 11g. I recommmend the default (true).

But, that’s it ? Wellllllll… not sure.

In 12.1

SQL> select dbms_metadata.get_ddl('USER','U') from dual
DBMS_METADATA.GET_DDL('USER','U')
----------------------------------
CREATE USER "U" IDENTIFIED BY
VALUES 'DC6F2B33D359A95B'


Let’s try in 12.2

SQL> select dbms_metadata.get_ddl('USER','U') from dual
DBMS_METADATA.GET_DDL('USER','U')
------------------------------------
CREATE USER "U" IDENTIFIED BY VALUES
'S:0000000000000000000000000000000
00000000000000000000000000000'


While this is a perfectly working syntax, and IDENTIFIED BY VALUES is not supported *. So if create that user, then, obviously, the 10G string is lost.

Well, unsupported feature then? Hmm, yes. You should never have used identified by values.

Ok, so if I refresh my Test database with Production data, how can I save test passwords? You can’t. At least not in a supported way by using identified by values.

You could something like :

SQL> select 'alter user "'||name||
'" identified by values '''||
password||''';' txt
from user$, v$instance
where version > '12.2'
and spare4 is null
and type# = 1
and regexp_like(PASSWORD,'[A-F0-9]{16}');

txt
-----------------------------------
alter user "U" identified by values
'DC6F2B33D359A95B';


This may work. In 12.2.0.1. Maybe not in 13. Maybe not in 12.2.0.1.0PSU July. It’s not supported. If it does not work, it is NOT-A-BUG.

The SHA1 was introduced 10 years ago in Oracle 11gR1. If you have not changed your password in ten years, and you don’t know how many employees and ex-employees know this password, and it is case-insensitive, and its “pseudo-hashing-algorythm” has been hacked for maybe two decades, yet, I can only warmly recommend to change those accounts passwords !

Again: so if I refresh my Test database with Production data, how can I save test passwords ?
If I were you I would design a better system for login. For human users, use global users and an Identity solution, like Oracle Universal directory. For technical account, build yourself a tool that generate a random password, and update the user and credentials, something like


select
substr(
REGEXP_REPLACE(
UTL_RAW.cast_to_varchar2(
SYS.DBMS_CRYPTO.RANDOMBYTES (1024)
) ,'[^!#-~]'
),
1,
20
) PW
from dual;
PW
--------------------
%K0w(^%UN.B82Yjjfu{?


And use it to reset your technical user and to configure your application credentials.

* Note 554605.1: the ‘IDENTIFIED BY VALUES’ clause on a CREATE/ALTER USER statement is not officially documented, and is intended purely for internal

If you access one table via database link and the row is locked, you may get a timeout


SQL> update emp@l set sal=sal+1
where ename='SCOTT';
1 row updated.

SQL> update emp@l set sal=sal+2
where ename='SCOTT';
update emp@l set sal=sal+2
*
ERROR at line 1:
ORA-02049: timeout: distributed
transaction waiting for lock
ORA-02063: preceding line from L

Elapsed: 00:01:00.00

SQL> sho parameter distr
NAME VALUE
--------------------------- -------
distributed_lock_timeout 60


This timeout (default 60 seconds) could be tuned, maybe to 300 seconds, if you are doing huge remote transactions

But what if you don’t want to wait one minute to get an exception? Lock the row before update then !


SQL> select ename, sal from emp@l
where ename='SCOTT'
for update wait 2;
select ename, sal from emp@l
*
ERROR at line 1:
ORA-30006: resource busy;
acquire with WAIT timeout expired
ORA-02063: preceding line from L
Elapsed: 00:00:02.01


If you want to wait only 2 seconds and not one minute, or even NOWAIT (0 second), then lock the row first. Depending on your application, waiting one minute to get an exception may be unacceptable

download it from http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html

sqldeveloper 4.2 is there : http://www.oracle.com/technetwork/developer-tools/sql-developer/overview/index.html

Until 11.2, audit_file_dest used to remain small with default settings and reasonably sized and active database. Suddenly, in 12c, you will sooned or later get ORA-09925: Unable to create audit trail file.

At that point, no more connection is possible to the database, it is a complete loss of service.

Why suddenly in 12c ? This is because the default for audit_sys_operations changed to true. In 11g, you used to get an 1K file each time you connect as sysdba. So a few tousands sysdba connections a weeks, a few mega, no worries.


Mon Mar 27 14:08:01 2017 +02:00
LENGTH : '155'
ACTION :[7] 'CONNECT'
DATABASE USER:[1] '/'
PRIVILEGE :[6] 'SYSDBA'
CLIENT USER:[6] 'oracle'
CLIENT TERMINAL:[0] ''
STATUS:[1] '0'


Suddenly in 12c, you get plenty files that are many Mb. For instance for AUTOTASK jobs, every single select is dumped to the filesystem. A single week-end of an quiet database may generate 1Gb of *.aud files of DBMS_SCHEDULER.

Those DB001_j000_12345_20170327140802123456789.aud files are highly useless and annoying.

LENGTH : '641'
ACTION :[490] 'select /*+ no_parallel(t) no_parallel_index(t) dbms_stats cursor_sharing_exact use_weak_name_resl dynamic_sampling(0) no_monitoring xmlindex_sel_idx_tbl no_substrb_pad */ substrb(dump("PERIOD_END_TIME",16,0
,64),1,240) val,
rowidtochar(rowid) rwid from "SYS"."WRP$_REPORTS_TIME_BANDS" t where rowid in (chartorowid('AABJ58AADAAAMsrAAA'),chartorowid('AABJ58AADAAAMsrAAB'),chartorowid('AABJ58AADAAAMsrAAC'),chartorowid('AABJ58A
ADAAAMssAAA')) order by "PERIOD_END_TIME"'
DATABASE USER:[3] 'SYS'
PRIVILEGE :[4] 'NONE'
CLIENT USER:[0] ''
CLIENT TERMINAL:[7] 'UNKNOWN'
STATUS:[1] '0'


Once your audit_file_dest is getting full, your database stops, so better delete those *_j00*_* and *_m00*_* quickly enough!

Today I had the issue that I could not login as sysoper on one database, despite being in the dba and oper groups.

The problem is that the osoper group was -probably- not selected during installation

e.g. in 12c /AIX
it may be called differently on your system

$ sqlplus -L -s / as sysoper
ERROR:
ORA-01017: invalid username/password; logon denied
$ awk '/H.17.*, 3/,/End/{print}' $ORACLE_HOME/rdbms/lib/config.s
.csect H.17.NO_SYMBOL{RO}, 3
.string ""
# End csect H.17.NO_SYMBOL{RO}


The string is empty. Let’s change this to oper or dba. Stopping any processes using that home is strongly recommended before relink.

$ vi $ORACLE_HOME/rdbms/lib/config.s
.string "dba"
$ relink
$ sqlplus -s -L / as sysoper
sho user
USER is "PUBLIC"
quit
$


I read on note 401934.1 that Oracle 10gR2 jdbc clients are still supported with Oracle 12c.

I have an application using an oracle10gr2 jdbc, and connection to 12c generates ORA-28040.

Connection to 11gR2 works like a charm.

O12.java

import java.util.Properties;
import java.sql.*;

public class O12 {
public static void main(String argv[]) throws
SQLException {
Properties props = new Properties();
props.setProperty("user", "scott");
props.setProperty("password", "tiger");
DriverManager.registerDriver(new
oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection(
argv[0], props);
System.out.println("JDBC Version: "+
conn.getMetaData().getDriverVersion());
conn.close();
}
}


compile

javac -cp ojdbc14.jar O12.java


test with jdbc 10.2.0.2 db 11.2.0.4

java -cp ojdbc14.jar:. O12 jdbc:oracle:thin:@DB11204:1521:DB11204
JDBC Version: 10.2.0.2.0


test with jdbc 10.2.0.2 db 12.1.0.2

java -cp ojdbc14.jar:. O12 jdbc:oracle:thin:@DB12102:1521:DB12102
Exception in thread "main" java.sql.SQLException: ORA-28040: No matching authentication protocol


The easy solution of course is to update the driver. Even without recompile it worked.

test with jdbc 11.2.0.1 db 12.1.0.2

java -cp ojdbc5.jar:. O12 jdbc:oracle:thin:@DB12102:1521:DB12102
JDBC Version: 11.2.0.1.0


Before upgrading the db server to 12c, check 10g jdbc jar’s are upgraded

Yesterday I wrote about execute sql script from plsql. Connor then posted a 12c new feature that I overviewed

Or perhaps just use scheduler to run them, job_type = SQL_SCRIPT

— Connor loves SQL , 🍸and ☕️ (@connor_mc_d) December 21, 2016

If you are still considering the 11g approach with sqlplus, you should read about restricted sqlplus

If you run

sqlplus -L -s -R 3 scott/tiger@db01

lot’s of OS-command are disabled

SQL> get /etc/passwd
SP2-0738: Restricted command "get" not available
SQL> spool /etc/oratab
SP2-0738: Restricted command "spool" not available
SQL> host reboot
SP2-0738: Restricted command "host" not available

There is also a Product User Profile. I never saw any customer using this. I doubt it is very safe.

You could disable some commands

SQL> insert into system.PRODUCT_USER_PROFILE
(PRODUCT,USERID,ATTRIBUTE,CHAR_VALUE)
values
('SQL*Plus','SCOTT','ROLLBACK','DISABLED');


Which prevents SCOTT from doing rollabck


SQL> rollback;
SP2-0544: Command "rollback" disabled in Product User Profile


but it doesn’t resist Rock & Roll


SQL> roll & rock
Rollback complete.


If you have 12c, go have a look at the doc for SQL_SCRIPT jobs

When you want to run a SQL script, you rather use sqlplus. If you want to run it within a PL/SQL stored procedure, you are screwed. You could redo the logic of sqlplus, this is what any decent IDE and code runnner does, and it’s a pile of work and you will get lot’s of bugs…

Another approach is to use sqlplus.

Wait! calling sqlplus from plsql? Well… why not. For instance via external job

1. create a table with sql scripts

create table t(id number primary key, text clob);
insert into t(id, text) values (
  42, 'update emp set sal=sal*2 /* XMas gift */;'
);

2. create a shell script, /tmp/ddl, that spool and executes T.text content

#!/bin/ksh
ORACLE_HOME=/u01/app/oracle/product/12.1.0/db_1
export ORACLE_HOME
$ORACLE_HOME/bin/sqlplus -s -L scott/tiger <
create a UNIX credential
begin 
  dbms_scheduler.create_credential(
    'C','USER01','PW');
end;
/

create and run an external job
begin
  DBMS_SCHEDULER.CREATE_JOB(
    job_name             => 'J',
    job_type             => 'EXECUTABLE',
    number_of_arguments  => 1,
    job_action           => '/tmp/ddl',
    credential_name      => 'C');
  DBMS_SCHEDULER.SET_JOB_ARGUMENT_VALUE(
    'J', 1, '42');
  DBMS_SCHEDULER.run_job('J');
end;
/

CREATE EXTERNAL JOB privilege is powerfull and your DBA won't like it 😉

The doc docs.oracle.com/database/122 is available. Check new features and stay tuned.

Okay, just 12 for today : HIGH compressed index, case insensitive database with bound collation, partitioned external tables, AL32UTF8 default for new database, listagg overflow, VALIDATE_CONVERSION, approx_percentile, json_exists, flashback pluggable database, the SHARING clause, RAC streched clusters site definition and INACTIVE_ACCOUNT_TIME in profile.

Some I like more than others 🙂

Okay, one more : SQLPLUS HISTORY !

If you delete most of the rows in one table, you probably want to regain that space, to minimize IO and fragmentation.

If you delete most of the rows in most of the tables, you probably also want to resize the datafile to reduce storage and backup space.

In this case, you could move your data in a new tablespace

alter table t move tablespace newts;

I wrote about this here : 2006/08/tablespace-maintenance-tasks.html

There is also an option to SHRINK. In oldish (pre-12cR2) releases, this had the advantage of being an online operation. In 12.2, include the online keyword.

SHRINK requires ROW MOVEMENT. I don’t like the idea of having the rowid’s changing. You have also a bunch of restrictions, amoung others on materialized view fast refreshes and index organized tables.

I am impatient to get this 12cR2. According to the doc, during an alter table move, transactions run uninterrupted on the table

#ThanksOTN @oraclebase

No, I am not talking about DBMS_REDEFINITION, where you get a kind of online feeling.

No, I don’t want to rename my table, rename my foreign keys, my primary key, my not-null-constraints, recreate my referential integrity, recompile my triggers.

I just want to partition a non-partitioned table.

ALTER TABLE EMP 
  MODIFY 
  PARTITION BY RANGE(HIREDATE)
  INTERVAL(NUMTOYMINTERVAL(1, 'MONTH'))
  (PARTITION P1 VALUES LESS THAN (DATE '1980-01-01'))
  ONLINE;

This is going to save me a lot of Saturday work 🙂

You need 12.2 to run this.

#EM13R2 is out https://t.co/dIwIn0jxp9

— laurentsch (@laurentsch) October 6, 2016

Download it here : oracle.com/technetwork/oem/grid-control/downloads
Documentation : docs.oracle.com/cd/E73210_01

If your Oracle SID doesn’t match your instance name in init.ora, this is quite confusing.

Check my previous post, what is sid in oracle

In the instance_name column of the view v$instance, as well as in USERENV context, it matches the ORACLE_SID of the underlying operating system.

SQL> var ORACLE_SID varchar2(9)
SQL> set autoprint on
SQL> exec dbms_system.get_env('ORACLE_SID',:ORACLE_SID)
PL/SQL procedure successfully completed.
ORACLE_SID
------------
ORA001
SQL> select sys_context('USERENV','INSTANCE_NAME') from dual;
SYS_CONTEXT('USERENV','INSTANCE_NAME')
---------------------------------------
ORA001
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
ORA001
SQL>

This is not the same as the init.ora parameter

SQL> select name, value, description from v$parameter where name='instance_name';

NAME          VALUE     DESCRIPTION
------------- --------- ----------------------------------------
instance_name INS001    instance name supported by the instance
SQL>

The instance_name doesn’t have to match anything. It’s of relevance if you use ADR. And you probably do. Background dump dest and family are deprecated now. In your ADR docu you’ll read

{ORACLE_BASE}/diag/rdbms/{DB_UNIQUE_NAME}/{SID}/trace

But this SID is actually your init.ora instance name. And not your ORACLE_SID.

In the doc you’ll find, it’s the Oracle system identifier.

Okay, let’s imagine the following

Environment:

ORACLE_SID=ORA001

init.ora:

DB_NAME=DB001
DB_UNIQUE_NAME=UNI001
INSTANCE_NAME=INS001
SERVICE_NAMES=SVC001,SVC002
DB_DOMAIN=EXAMPLE.COM
GLOBAL_NAMES=false

database:

SQL> select * from GLOBAL_NAME;
GLO001.example.com

listener.ora:

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_NAME=GLO001.EXAMPLE.COM)
      (SID_NAME=ORA001)
    )
  )

What is my SID? Actually there is more than one correct answer.

In the environment, Oracle SID is ORA001. This matches SID_NAME in listener.ora. It does not have to match database name, unique name, global name or instance_name.

$ lsnrctl services
Services Summary...
Service "GLO001.EXAMPLE.COM" has 1 instance(s).
  Instance "ORA001", status UNKNOWN, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:7 refused:0
         LOCAL SERVER

As the instance is not running, I have only my listener.ora static connections.

The SERVICE_NAME is GLO001.EXAMPLE.COM and the SID is ORA001.

$ sqlplus "sys/***@
  (DESCRIPTION=
    (ADDRESS=
      (PROTOCOL=TCP)
      (HOST=SRV001)
      (PORT=1521)
    )
    (CONNECT_DATA=
      (SERVICE_NAME=GLO001.EXAMPLE.COM)
    )
  )" as sysdba
Connected to an idle instance.
SQL> 
$ sqlplus "sys/***@
  (DESCRIPTION=
    (ADDRESS=
      (PROTOCOL=TCP)
      (HOST=SRV001)
      (PORT=1521)
    )
    (CONNECT_DATA=
      (SID=ORA001)
    )
  )" as sysdba
Connected to an idle instance.
SQL> 

Let’s start

SQL> startup

and check my services

$ lsnrctl services
Services Summary...
Service "SVC001.EXAMPLE.COM" has 1 instance(s).
  Instance "INS001", status READY, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:0 state:ready
         LOCAL SERVER
Service "SVC002.EXAMPLE.COM" has 1 instance(s).
  Instance "INS001", status READY, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:0 state:ready
         LOCAL SERVER
Service "UNI001.EXAMPLE.COM" has 1 instance(s).
  Instance "INS001", status READY, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:0 state:ready
         LOCAL SERVER
Service "GLO001.EXAMPLE.COM" has 1 instance(s).
  Instance "ORA001", status UNKNOWN, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:13 refused:0
         LOCAL SERVER
The command completed successfully

I know have 4 service names :

1. The global name in listener.ora
2. the unique name in init.ora
3. both service name in init.ora

And 2 sid

1. The SID in listener.ora
2. The instance name in init.ora

While we often have sid = oracle_sid = service_name = service_names = global_name = instance_name = db_name = db_unique_name, if you switch from SID to SERVICE_NAME, this could be help to identify legacy application.

If you read the doc carefully, you may have noticed the SID is no longer documented as a valid clause of CONNECT_DATA in 11g and 12c

In 10gR2 :
http://docs.oracle.com/cd/B19306_01/network.102/b14213/tnsnames.htm#i477921
Use the parameter SID to identify the Oracle8 database instance by its Oracle System Identifier (SID). If the database is Oracle9i or Oracle8, use the SERVICE_NAME parameter rather than the SID parameter.

This is probably a documentation bug, I would rephrase this as If the database is Oracle9i or Oracle8i or later.

In 11g and 12c, the comment disappeared. Oracle 8i was released last century, but SID didn’t completly disappear from tnsnames. Yet.

If you work with large databases, you often wait way to long for the clones. Typically you want to duplicate a 10TB database to production timestamp 9am, and you start at 9am and then you wait for hours.

Is it possible to start the clone, let’s say, at midnight, and set until time 9am?

No! You’ll get

RMAN-06617: UNTIL TIME (2016-05-21 09:00:00) is ahead of last NEXT TIME in archived logs (2016-05-20 23:58:52)

But… you could start to restore the datafiles at midnight.

sqlplus sys/***@db02 as sysdba <
This is exactly when RMAN does when you issue a duplicate. You could use the supported RESTORE command instead of the unsupported RESTORE CLONE command. But then it'll get a bit more complex as you need to find out the location of your backup and so on.
At 9am, you issue your duplicate, and you'll see
skipping datafile 1; already restored to file /db02/system01.dbf
skipping datafile 2; already restored to file /db02/sysaux01.dbf
skipping datafile 3; already restored to file /db02/undotbs1_02.dbf
skipping datafile 4; already restored to file /db02/users01.dbf

You just saved nine hours 🙂
		

In 11g I used to have 30 characters width in my dictionary

SQL> select table_name, column_name from user_tab_columns;

TABLE_NAME                     COLUMN_NAME
------------------------------ ------------------------------
BONUS                          COMM
BONUS                          SAL
BONUS                          JOB
BONUS                          ENAME
DEPT                           LOC
DEPT                           DNAME
DEPT                           DEPTNO
EMP                            DEPTNO
EMP                            COMM
EMP                            SAL
EMP                            HIREDATE

TABLE_NAME                     COLUMN_NAME
------------------------------ ------------------------------
EMP                            MGR
EMP                            JOB
EMP                            ENAME
EMP                            EMPNO
SALGRADE                       HISAL
SALGRADE                       LOSAL
SALGRADE                       GRADE

18 rows selected.

Which was pretty nice to read with no setting.

Now in 12c it is ugly enought to make your eyes tired

SQL> select table_name, column_name from user_tab_columns;

TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
DEPT
DEPTNO

DEPT
DNAME

DEPT
LOC


TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
EMP
EMPNO

EMP
ENAME

EMP
JOB


TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
EMP
MGR

EMP
HIREDATE

EMP
SAL


TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
EMP
COMM

EMP
DEPTNO

BONUS
ENAME


TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
BONUS
JOB

BONUS
SAL

BONUS
COMM


TABLE_NAME
------------------------------------------------------------------------------------------------------------------------
COLUMN_NAME
------------------------------------------------------------------------------------------------------------------------
SALGRADE
GRADE

SALGRADE
LOSAL

SALGRADE
HISAL


18 rows selected.

SQL>

This is due to a change of the width of the underlying column in the dictionary. Probably a good-news for our data modeling colleagues that it may be 128 in future.

But currently it is only 30 characters in 12c. So why not format it correctly ?

Simply add the format in $ORACLE_HOME/sqlplus/admin/glogin.sql

col TABLE_NAME for a30
col COLUMN_NAME for a30 

DISCLAIMER: it’s fine to add UNIQUE_KEY_LEVEL_NAME or REFERENCED_TRIGGER_NAME, but you may have application tables that have columns called OWNER or USER, it is probably safer to not assume they are all smaller than 30 chars, so don’t add common names.

Happy new year 🙂

Today I had to import a subset of a database and the challenge was to restore a parent table without restoring its children. It took me some minutes to write the code, but it would have taken days to restore the whole database.

CREATE TABLE t1(
  c1 NUMBER CONSTRAINT t1_pk PRIMARY KEY);
INSERT INTO t1 (c1) VALUES (1);
CREATE TABLE t2(
  c1 NUMBER CONSTRAINT t2_t1_fk REFERENCES t1,
  c2 NUMBER CONSTRAINT t2_pk PRIMARY KEY);
INSERT INTO t2 (c1, c2) VALUES (1, 2);
CREATE TABLE t3(
  c2 NUMBER CONSTRAINT t3_t2_fk REFERENCES t2,
  c3 NUMBER CONSTRAINT t3_pk PRIMARY KEY);
INSERT INTO t3 (c2, c3) VALUES (2, 3);
CREATE TABLE t4(
  c3 NUMBER CONSTRAINT t4_t3_fk REFERENCES t3,
  c4 NUMBER CONSTRAINT t4_pk PRIMARY KEY);
INSERT INTO t4 (c3, c4) VALUES (3, 4);
COMMIT;

expdp scott/tiger directory=DATA_PUMP_DIR dumpfile=scott.dmp reuse_dumpfiles=y

Now what happen if I want to restore T2 and T3 ?

If possible, I check the dictionary for foreign keys from other tables pointing to T2 and T3.

SELECT constraint_name
FROM user_constraints
WHERE (r_constraint_name) IN (
    SELECT constraint_name
    FROM user_constraints
    WHERE table_name IN ('T2', 'T3'))
  AND table_name NOT IN ('T2', 'T3');

TABLE_NAME                     CONSTRAINT_NAME               
------------------------------ ------------------------------
T4                             T4_T3_FK                      

T4 points to T3 and T4 has data.

Now I can drop my tables with the cascade options

drop table t2 cascade constraints;
drop table t3 cascade constraints;

Now I import, first the tables, then the referential constraints dropped with the cascade clause and not on T2/T3.

impdp scott/tiger tables=T2,T3 directory=DATA_PUMP_DIR dumpfile=scott.dmp

impdp scott/tiger  "include=ref_constraint:\='T4_T3_FK'" directory=DATA_PUMP_DIR dumpfile=scott.dmp

It’s probably possible to do it in one import, but the include syntax is horrible. I tried there