DBA Blogs

CQLSH – Unable to connect to any servers Tried connecting to [(‘’, 9042)

VitalSoftTech - Thu, 2016-12-01 09:30
When trying to connect to a node in the Cassandra Cluster using cqlsh, I get the "Unable to connect to any servers. Tried connecting to [('', 9042)" message. Learn how to modify the configuration so that the hostname is not required.
Categories: DBA Blogs

12.2 New Features -- 4 : AWR for Pluggable Database

Hemant K Chitale - Thu, 2016-12-01 03:29
12.2 now allows AWR Snapshots and Reports to be created at the PDB level.

Here I demonstrate a Manual Snapshot.  Although Automatic PDB AWR Snapshots are possible (with the AWR_PDB_AUTOFLUSH_ENABLED parameter) , they are disabled by default and Oracle recommends Manual Snapshots.

SQL> connect / as sysdba
SQL> alter session set container=PDB1;

Session altered.

SQL> exec dbms_workload_repository.create_snapshot();

PL/SQL procedure successfully completed.


I then proceed to create an AWR Report, still in the PDB1 container.

SQL> @?/rdbms/admin/awrrpt

Specify the Report Type
AWR reports can be generated in the following formats. Please enter the
name of the format at the prompt. Default value is 'html'.

'html' HTML format (default)
'text' Text format
'active-html' Includes Performance Hub active report

Enter value for report_type: text

Type Specified: text

Specify the location of AWR Data
AWR_ROOT - Use AWR data from root (default)
AWR_PDB - Use AWR data from PDB
Enter value for awr_location: AWR_PDB

Current Instance
DB Id DB Name Inst Num Instance Container Name
-------------- -------------- -------------- -------------- --------------

Root DB Id Container DB Id AWR DB Id
--------------- --------------- ---------------
947935822 3774315809 3774315809

Instances in this Workload Repository schema
DB Id Inst Num DB Name Instance Host
------------ ---------- --------- ---------- ------

Using 3774315809 for database Id
Using 1 for instance number

Specify the number of days of snapshots to choose from
Entering the number of days (n) will result in the most recent
(n) days of snapshots being listed. Pressing without
specifying a number lists all completed snapshots.

Enter value for num_days: 1

Listing the last day's Completed Snapshots
Instance DB Name Snap Id Snap Started Snap Level
------------ ------------ ---------- ------------------ ----------

HKCORCL HKCORCL 1 01 Dec 2016 08:48 1
2 01 Dec 2016 08:49 1
3 01 Dec 2016 08:52 1

Specify the Begin and End Snapshot Ids
Enter value for begin_snap: 1
Begin Snapshot Id specified: 1

Enter value for end_snap: 3
End Snapshot Id specified: 3

Specify the Report Name
The default report file name is awrrpt_1_1_3.txt. To use this name,
press to continue, otherwise enter an alternative.

Enter value for report_name:

Using the report name awrrpt_1_1_3.txt

Here's a look at the header of the AWR report.


DB Name DB Id Unique Name DB Role Edition Release RAC CDB
------------ ----------- ----------- ---------------- ------- ---------- --- ---

Instance Inst Num Startup Time
------------ -------- ---------------
HKCORCL 1 16-Nov-16 06:13

PDB Name PDB Id PDB DB Id Open Time
------------ ------ ---------- ---------------
PDB1 3 3774315809 25-Nov-16 14:11

Host Name Platform CPUs Cores Sockets Memory(GB)
---------------- -------------------------------- ---- ----- ------- ----------
HKCORCL.compute- Linux x86 64-bit 2 2 1 7.05

Snap Id Snap Time Sessions Curs/Sess
--------- ------------------- -------- ---------
Begin Snap: 1 01-Dec-16 08:48:46 0 4.0
End Snap: 3 01-Dec-16 08:52:08 1 12.0
Elapsed: 3.36 (mins)
DB Time: 0.29 (mins)

Load Profile Per Second Per Transaction Per Exec Per Call
~~~~~~~~~~~~~~~ --------------- --------------- --------- ---------
DB Time(s): 0.1 4.3 0.00 0.06
DB CPU(s): 0.1 2.9 0.00 0.04
Background CPU(s): 0.0 0.0 0.00 0.00
Redo size (bytes): 138,443.8 6,976,599.0
Logical read (blocks): 1,798.4 90,625.0
Block changes: 282.3 14,224.3
Physical read (blocks): 21.0 1,055.8
Physical write (blocks): 0.7 34.5
Read IO requests: 20.9 1,051.8
Write IO requests: 0.3 12.5
Read IO (MB): 0.2 8.3
Write IO (MB): 0.0 0.3
IM scan rows: 0.0 0.0
Session Logical Read IM: 0.0 0.0
User calls: 1.5 77.5
Parses (SQL): 17.9 904.0
Hard parses (SQL): 3.2 161.5
SQL Work Area (MB): 2.5 123.5
Logons: 0.0 1.0
Executes (SQL): 45.7 2,302.3
Rollbacks: 0.0 0.0
Transactions: 0.0

Top 10 Foreground Events by Total Wait Time
Total Wait Avg % DB Wait
Event Waits Time (sec) Wait time Class
------------------------------ ----------- ---------- --------- ------ --------
DB CPU 11.5 66.9
db file sequential read 3,758 2.5 667.74us 14.6 User I/O
direct path write 23 .7 29.08ms 3.9 User I/O
flashback log file sync 36 .6 16.98ms 3.6 User I/O
local write wait 12 .4 37.17ms 2.6 User I/O
acknowledge over PGA limit 9 .1 9.50ms .5 Schedule
control file sequential read 189 .1 293.42us .3 System I
PGA memory operation 3,687 0 11.02us .2 Other
db file scattered read 4 0 8.32ms .2 User I/O
log file sync 3 0 9.35ms .2 Commit

The Header identifies the PDB being reported on.Note that Snapshots 1 to 3 are local to the PDB and are not in the Root.  PDB Snapshots can be maintained (create or drop snapshot) in the same manner as CDB snapshots.  (Note : PDB AWR Snapshots are in the view AWR_PDB_SNAPSHOT,  not DBA_HIST_SNAPSHOT).

In contrast, this below is the Header for a CDB where Automatic Snapshots have meant Snap IDs are already at 379,380.  Thus, the CDB snapshots are different from the PDB snapshots.


DB Name DB Id Unique Name DB Role Edition Release RAC CDB
------------ ----------- ----------- ---------------- ------- ---------- --- ---

Instance Inst Num Startup Time
------------ -------- ---------------
HKCORCL 1 16-Nov-16 06:13

Host Name Platform CPUs Cores Sockets Memory(GB)
---------------- -------------------------------- ---- ----- ------- ----------
HKCORCL.compute- Linux x86 64-bit 2 2 1 7.05

Snap Id Snap Time Sessions Curs/Sess PDBs
--------- ------------------- -------- --------- -----
Begin Snap: 379 01-Dec-16 08:00:47 51 .6 2
End Snap: 380 01-Dec-16 09:00:09 62 .9 2
Elapsed: 59.36 (mins)
DB Time: 1.14 (mins)

Note how it doesn't identify a PDB.

You need to be explicitly connected to a PDB before awrrpt shows you the option to generate PDB-level AWR report.
Categories: DBA Blogs

Y2038 issue

Tom Kyte - Wed, 2016-11-30 20:46
Hello AskTom team, Would this be an issue with Oracle? https://en.wikipedia.org/wiki/Year_2038_problem Thanks!
Categories: DBA Blogs

Archivelog backups taking too long

Tom Kyte - Wed, 2016-11-30 20:46
I am expriencing slowness in archivelog backups. In the last two days we have seen long running archive log backups despite the archive log generation being very low (less than 1gb every day). On Nov 29th it ran for 11 hours (4 am - 3 pm). Even lvl 0...
Categories: DBA Blogs

Compare varchar column with number

Tom Kyte - Wed, 2016-11-30 20:46
Hi Team, I need to update values for a column in my table to null, which are not numeric & greater than 999. Here is sample table - create table checknum ( col1 varchar2(10), col2 varchar2(10) ); Insert into CHECKSUM (COL1,COL2) valu...
Categories: DBA Blogs

PL SQL Functions that work with Read-Only Access

Tom Kyte - Wed, 2016-11-30 20:46
Tom! I've enjoyed your point of view and the clarity of your interactions for a couple of years now. I?ve been using SQL Developer off and on for years but I just recently started running into more complicated needs and I?m hoping you can point...
Categories: DBA Blogs

Global Temporary table use to avoid execution of same SQL's twice

Tom Kyte - Wed, 2016-11-30 20:46
Hi, I have one procedure which has two OUT ref cursors. First REF CURSOR returns below SQL output - SELECT * from tab1 , tab2 , tab3 , tab4 , tab5 WHERE <<certain join conditions>> AND value IN (SELECT VALUE from...
Categories: DBA Blogs

Oracle Subquery Bug?

Tom Kyte - Wed, 2016-11-30 20:46
Hi all, per random I came to this problem. My PL/SQL-Procedure was parsed without any ERROR, whereby the column "tb_id" itself did not exist in "suh_tb_test_1". (If I use an alias in the subquery then the ERROR is thrown!) Here the (strong s...
Categories: DBA Blogs

Delphix Users Panel Webinar

Bobby Durrett's DBA Blog - Wed, 2016-11-30 16:19

Delphix is sponsoring a user webinar on Wednesday from 10 to 11 am California time. I and a couple of other technical Delphix users will take part in a panel discussion. The webinar will give you a good chance to hear about other users’ experience with Delphix and a chance to ask questions. Like any good user meeting it will not be a non-technical sales pitch but it will instead focus on users sharing helpful technical information with other Delphix users.

Noted Oracle expert and Delphix employee Kellyn Pot’Vin-Gorman will also be there facilitating the discussion.

Here is the link to sign up for the free webinar: https://www.delphix.com/resources/webinar/delphix-users-panel

Be there or be square! &#x1f642;


Categories: DBA Blogs

Database Resource Manager, v$active_session_history p1text=location p2text=consumer group id

Tom Kyte - Wed, 2016-11-30 02:46
Hi Tom, Wish you all the best. 1] I have a 12c database 2] Not created as a CDB SQL> select cdb from v$database; CDB --- NO 3] No resource manager is configured SQL> SHOW PARAMETER RESOURCE_MANAGER_PLAN NAME ...
Categories: DBA Blogs

Combining WITH clauses

Tom Kyte - Wed, 2016-11-30 02:46
I've tried to combine an SQL defined in a WITH clause with an inline PL/SQL in 12c. <code>with function is_number(p_str varchar2) return number is l_number number; begin l_number := to_number(p_str); return l_number; exception when v...
Categories: DBA Blogs


Tom Kyte - Wed, 2016-11-30 02:46
I have several different applications using multiple schemas in a single database which used VPD and an after logon trigger to establish initial VPD driving context variables. A second db call, secmgr.my_appl_env spec listed below, is required by al...
Categories: DBA Blogs

Fine-grained Access Control (FGAC) vs. Row Level Security (RLS) vs. Virtual Private Database (VPD) vs. Oracle Label Security (OLS)

Tom Kyte - Wed, 2016-11-30 02:46
Good Evening, Throughout my career, I heard about Fine-grained Access Control (FGAC), Row Level Security (RLS), Virtual Private/Policy Database (VPD) and Oracle Label Security (OLS). These all sound very similar. I've only heard of OLS since it ...
Categories: DBA Blogs

I/O of Database

Tom Kyte - Wed, 2016-11-30 02:46
Hi, I am reading a lot on AWR reports, and also posts about this subject. But everyone say something different. My client asked me for: "I want to know the I/O of the database" Is there a metric, so I can execute a script on a time interva...
Categories: DBA Blogs

Imcomplete CSV File

Tom Kyte - Wed, 2016-11-30 02:46
Hi, Iam exporting a simple select command into a csv file. but the resulting csv file is incomplete ie. amon 44 columns it is displaying only 3 columns. please find my code below, set headsep on set term off set newpage 0 set space 0...
Categories: DBA Blogs

How to check in apex, if there is new data

Tom Kyte - Wed, 2016-11-30 02:46
Hello Tom, I'm a bit new to apex and I wonder if there is a way to check in apex, if new data was inserted in my DATA table. I want to fire a dynamic action that refreshes the region only when new data has arrived. For now, this works for me: ...
Categories: DBA Blogs

Unable to connect to database using sql developer

Tom Kyte - Wed, 2016-11-30 02:46
Hi , I am unable to connect to oracle database using SQL DEVELOPER but I am able to connect through windows cmd command. It gives me error i/o error network adapter could not establish connection. vendor code 17002. Please let me know what are the...
Categories: DBA Blogs

LOB data type comparisons

Tom Kyte - Wed, 2016-11-30 02:46
Hi Team We have migrated data from SQL server to Oracle,As part of data validation we want to compare the data from both databases. We have some tools which compare data but that tool will not compare lob columns. Please note we had migrated dat...
Categories: DBA Blogs

Insert All with sequence - feature or featurette?

Tom Kyte - Tue, 2016-11-29 08:26
I posted this problem elsewhere and we had a bit of a discussion. However I would like to know whether what we see is a feature (i.e. it can be relied upon to be somewhat consistent in future releases) or whether it is a "featurette" - i.e. unintende...
Categories: DBA Blogs

Generating excel report with multiple tabs from Oracle APEX

Tom Kyte - Tue, 2016-11-29 08:26
Hi, I'm new to Oracle Application Express and currently working on an APEX application. We have several reports which can be downloaded as csv files in various modules of the application. What I need is to have a master report(excel file with ...
Categories: DBA Blogs


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