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Monday, October 2, 2017

Creating Popup windows on your Apex Page

I have been playing with Apex for an internal application  Application Express is a great tool, and Oracle has an internal Apex environment that groups can use for their own internal applications.

In creating the application I learned how to do a Javascript window that pops up within a page to help enter data. This can be very useful to add a function to your application without adding more pages.


This is how its down..

First I created a table to contain breweries..  Since this is running on 12.1, I was able to use the new feature to automagically use a sequence as a default value (it's about time right) ?

Here is my table creation script..


CREATE SEQUENCE brewery_seq
 START WITH     1000
 INCREMENT BY   1
 NOCACHE
 NOCYCLE;

Create table breweries
(brewery_id number default brewery_seq.nextval primary key,
         brewery_name varchar2(255),
         Brewery_rating number);

So first I did was create a new region on the a new page.



ZDLRA and the FRA


ZDLRA and the FRA


I often get questions around the FRA (Flash Recovery Area), and how it should be used when moving backups to the ZDLRA.

First though, the recommendation is to ALWAYS set your db_recovery_file_dest_size to be 10% less than the amount of space available, and don't put other files in this same location (that are not managed as part of the FRA).  
Having a 10% buffer ensures that you can increase the available storage if necessary.  For those experienced on-call DBA's I'm sure there have been times where increasing the db_recovery_file_dest_size by that last 10% was used to keep the database running while space was cleaned up.. And of course this is often at 3:00 AM when the dreaded "archive log destination full" alert comes across.



First let's go through what's in the FRA and how it's being used.   


There is a lot of information in MOS and I will include pertinent MOS notes at the end of this post.

What's in the FRA  (V$FLASH_RECOVERY_AREA_USAGE shows us )?

Here is a sample output 


SQL> Select file_type, percent_space_used as used,
percent_space_reclaimable as reclaimable, 
    number_of_files as "number" from v$flash_recovery_area_usage; 
     
    FILE_TYPE          USED RECLAIMABLE     number 
    ------------ ---------- ----------- ---------- 
    CONTROLFILE           0           0          0 
    ONLINELOG             0           0          0 
    ARCHIVELOG         4.77           0          2 
    BACKUPPIECE       56.80           0         10 
    IMAGECOPY             0           0          0 
    FLASHBACKLOG      11.68       11.49         63 



From this you can see the following items are in the FRA.


CONTROLFILE  -- This comes from setting the location of the CONTROLFILE backup.


configure controlfile autobackup on;

If you configure controlfile backups using the 'FORMAT" option, it will not be managed by the FRA.


ONLINELOG


A copy of the online redo logs go to the FRA  when the DB_RECOVERY_FILE_DEST is set and the DB_CREATE_ONLINE_LOG_DEST_n is not set.





ARCHIVELOG -- 

Archive logs are managed by the FRA when the archive LOG_ARCHIVE_DEST_n parameter contains the clause 'LOCATION=USE_DB_RECOVERY_FILE_DEST'

alter system set LOG_ARCHIVE_DEST_1='LOCATION=USE_DB_RECOVERY_FILE_DEST'';

BACKUPPIECE or IMAGECOPY

RMAN backups are managed by the FRA when you configure RMAN to (or explicitly) send backups to disk AND the FORMAT option is not specified.

FLASHBACKLOG 

If flashback database is turned on for the database, flashback logs will be kept in the FRA automatically.  The database parameter db_flashback_retention_target is set to determine the amount of flashback logs that are kept for the database.

Now lets take a look at how space is managed for each piece 


ONLINELOG  -- Since online redo logs are necessary for the database, this is not affected with space pressure.

FLASHBACKLOG   -- Flashback logs are automatically removed to keep the window specificed in the DB_FLASHBACK_RETENTION_TARGET setting.  If there is space pressure the flashback management will automatically release space until it hits a window of 1 hour.  This is the default and comes from the _MINIMUM_DB_FLASHBACK_RETENTION parameter.

BACKUPPIECE or IMAGECOPY and/or CONTROLFILE and ARCHIVELOG --  these are managed by the setting in RMAN for the retention policy. 

The recommendation for the ZDLRA is to set this parameter to

CONFIGURE RETENTION POLICY SHIPPED to all STANDBY;


Now lets take a look at how space is managed (315098.1)

There is a MOS note on this, but it there are still some misconceptions on what you see happening.



Looking at the output of view V$RECOVERY_FILE_DEST you will see 3 pertinent columns.

SPACE_LIMIT                              ==> this is the amount of space is allocated to the FRA.
SPACE_USED                               ==> This is the amount of space currently used
SPACE_RECLAIMABLE             ==> This is the amount space that the FRA considers reclaimable.
                                                                This NOT the total amount space reclaimable, just the amount
                                                                that the FRA knows about (I'll get to what this means soon).


The note says that 

If the free space becomes less then 15% in the Flash Recovery Area then all  the archivelogs in the Flash Recovery Area which are not needed for recovery by the current backups in the FRA will become obsolete and the space occupied will be shown in the SPACE RECLAIMABLE column of V$RECOVERY_FILE_DEST.

From this I made some assumptions that were incorrect.

I assumed 

1) Since I was immediately sending all backups and archive logs to the ZDLRA (Real Time Apply), the space for the ARCHIVELOG would all show up in the SPACE_RECLAIMABLE column.
2) When the FRA reaches 85%, it would automatically clean up ARCHIVELOGS to bring it down to 85%.

Both of these assumptions where wrong.  By testing I found that this is what actually happens, and this still falls within the verbiage in that note.


This is what happens as the space fills up.  I have a 1 TB FRA.


849 GB used in the FRA.  The reclaimable space is NOT calculated yet because we have not hit the 85% full mark. 

Space_limit             1000GB
Space_used              849GB
Space_reclaimable       0GB


At 850GB  I reached 85% full. This is the point where the database  calculates SPACE_RECLAIMABLE.  Note that it does not fully calculate what's reclaimable, it only finds a portion of the reclaimable space.
 

Space_limit             1000GB
Space_used              850GB
Space_reclaimable       300GB
 

At 999GB it's not quite full.  The reclaimable space shows there is space available, 
but it still only finds a portion of the available space.
 
Space_limit             1000GB
Space_used              999GB
Space_reclaimable       160GB
 

At 1000GB it is completely full. The reclaimable space shows space available to be reclaimed.
At this point I can see in the alert log that archive logs are being removed. 
Only enough logs are removed to make space for new logs.  it remains at 99% used.

Space_limit             1000GB
Space_used              999GB
Space_reclaimable       160GB
 

As I added more logs, it remained at 99% used.

This makes it very difficult to know how much space you have available in your FRA. 
The warnings start occurring at the 85% full mark.
Since the FRA recalculates the SPACE_RECLAIMABLE at 85% full, but only adjusts it to keep  from warning,
it is impossible to tell how much TOTAL space is reclaimable.

Using the formula 

SPACE_LIMIT - SPACE_RECLAIMABLE 

Does not give you amount of space that is actually reclaimable.  
It is only useful to tell you when the amount of unreclaimable space > 85%.



Here are the useful MOS notes.



NOTE:305817.1 - FAQ - Flash Recovery Area feature


How is the space pressure managed in the Flash Recovery Area - An Example. (Doc ID 315098.1)

Correctly configuring the Flash Recovery Area to allow the release of reclaimable space (Doc ID 316074.1)


Monday, January 18, 2016

ZDLRA

I wanted to write a post on one of Oracle's newest products (Well not that new).. The ZDLRA.
The ZDLRA is often referred to as "Zelda".  I know the name ZDLRA does not roll off the tongue well.  Zelda is a much better (and easier to say name).
The other name you will hear the ZDLRA referred to as is RA or Recover Appliance.

Recover Appliance is probably the best description of the product.  One of the things that makes this product unique is the emphasis on RECOVERY.. Notice there is not a mention of backup in the name.


Here is a great starting point for information


It does a lot of it's magic by using incremental forevers   --

    I know what you are thinking... The incremental forever strategy has been around for a long time (since 10.2 I think).  The idea is simple.  You take a full backup (database copy NOT backup set), and then take incrementals from then on.  You use RMAN to apply the incremental to the full, and create a new full (destroying the old full in the process).  I've seen many customers (and me also) use the rolling incrementals in the online recovery area to keep a full backup online from the previous day.
This is used with a second backup strategy for longer term storage to a backup device.

  The way the RA handles this differently, is that it creates "virtual fulls" for each incremental backup you take.  You also tell it how far back to store virtual fulls.  Using this methodology, if you do an incremental backup nightly, you can keep "virtual fulls" from each night as far back as you want.
There is no need to keep an online backup, and one in backup appliance.

Why is the RA different from most backup strategies ?

1) The use of only needing to do incremental forevers uses less I/O to read database blocks, and less backup network I/O -  Using this method, the RA ONLY needs the incremental backups to keep a restore point.  This saves the I/O of doing a full, and it saves the bytes going across the network.

2) RMAN keeps track of all the backups.  RMAN is the backbone of the RA, and the RA contains a recovery catalog.  RMAN verifies that backups are good, and you will always know if you have a good backup to restore.

3) Real time apply.  You can think of the RA receiving redo log information in the same vein as a Dataguard database.  Without the RA, you would backup archive logs as they are written from the redo logs.  This leaves you open to data loss from your backup.. The RA reads from the current Redo log stream in the database (like dataguard) to ensure there there is almost no data loss. Nothing else does this.

4) Performance.  The performance the RA is phenomenal.  You can find a whitepaper here on the performance with multiple databases backing up to a single RA appliance.

This is a fantastic product to backup multiple databases and most importantly be able to recover your databases with next-to-no data loss.

Monday, November 2, 2015

M7 is Here

Yes, I know I am more of a sofware geek, than a hardware geek, but I spent the day listening to all the goodness of the new Sparc M7 chip.. and Wow..

This was announced at OOW '15, and you can find a lot of the information here.

I think what excited me wasn't just the benchmarks that you can find here, ir was the idea of Software-on-Silicon.

That's the big story for software geeks.. The idea of the DAX...

I know DAX sounds like something out of Dr. Seuss.

The DAX (Database Analytics Accelerator) is a special section of the new processor dedicated to In-Memory processes.

If you have read through Maria Colgans blog (which you should) you learn about how In-memory takes advantage of the SIMD instruction set available on the intel Chip.. The SIMD instructions are able to scan multiple rows of data in one CPU cycle.  That's part of what makes the In-Memory option process data so fast.

What does this have to do the M7 ?  The DAX replaces the SIMD instructions when you are running in-memory queries on the M7.  The DAX is specifically built to run this instruction set and the results are then fed to the CPU.  




What does this mean for you ? It means that the DAX is able to not only process the data faster than the SIMD processing on Intel, but it also does not use any of the CPU power to execute the In-Memory scanning.  You get faster performance, and you use less CPU.
That's the point of the DAX, and the Software-on-Silicon.  Faster performance with silicon that is built specially for an oracle workload (In-Memory in this case).












Thursday, August 7, 2014

12.1.0.2 New Features PDB CONTAINERS Clause

When 12.1.0.2 came out, one of the features I wanted to play was the Cross-container functionality, and I finally had time to play with it.

First here is the description of the feature.

The CONTAINERS clause is a new way of looking at multitenant container databases (CDBs). With this clause, data can be aggregated from a single identical table or view across many pluggable databases (PDBs) from the root container. The CONTAINERS clause accepts a table or view name as an input parameter that is expected to exist in all PDBs in that container. Data from a single PDB or a set of PDBs can be included with the use of CON_ID in the WHERE clause. 

I decided to play with this and see what it really means.... And mostly to see the explain plan to see what happens under the covers.

Step 1 --   The first thing you need to do is create a "common user".  A common user is a new term that comes with Pluggable databases.  A common user is a user which is created in the CDB (the Root container), and is then available as a user in all the PDB's that are part of the CDB.  There are some rules around this.

  • In Oracle Database 12c Release 1 (12.1.0.1), the name of a common user must begin with C## or c## and the name of a local user must not begin with C## or c##.
  • Starting with Oracle Database 12c Release 1 (12.1.0.2):
    • The name of a common user must begin with characters that are a case-insensitive match to the prefix specified by the COMMON_USER_PREFIX initialization parameter. By default, the prefix is C##.
    • The name of a local user must not begin with characters that are a case-insensitive match to the prefix specified by the COMMON_USER_PREFIX initialization parameter. Regardless of the value of COMMON_USER_PREFIX, the name of a local user can never begin with C## or c##.

 So here goes for step 1 ..
$ sqlplus "/ as sysdba"

SQL*Plus: Release 12.1.0.2.0 Production on Thu Aug 7 22:23:26 2014

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL create user c##bgrenn identified by bgrenn;
grant dba to c##bgrenn;

User created.

SQL 
Grant succeeded.


One thing to mention at this point is that I granted DBA role to my new common user c##bgrenn.  You also need to set individual privileges at each PDB level

Step 2 --   Now that I have a common user (c##bgrenn), I now need to go into my pdb's and create the objects that I want to have shared across PDB's. 

For simplicity, I chose DBA_TABLES, and DBA_OBJECTS.

The 3  PDBS I want to create this in are "orclpdb", "orclpdba" and "orcldbb"

SQL> COLUMN NAME FORMAT A15
COLUMN RESTRICTED FORMAT A10
COLUMN OPEN_TIME FORMAT A30
 
SELECT NAME, OPEN_MODE, con_id  FROM V$PDBS
SQL /

NAME   OPEN_MODE      CON_ID
--------------- ---------- ----------
PDB$SEED  READ ONLY     2
ORCLPDB  READ WRITE     3
ORCLPDBA  READ WRITE     4
ORCLPDBB READ WRITE     5





I then went into all 3 PDB's and created a local copy of DBA_OBJECTS and DBA_TABLES.

connect sys/oracle@localhost:1521/orclpdb as sysdba

grant dba to c##bgrenn;

create table c##bgrenn.local_objects as select * from dba_objects;

create table c##bgrenn.local_tables as select * from dba_tables; 
Connected.
SQL
Grant succeeded.

SQL 

Table created.

SQL 
 Table created.

SQL


Step 3 - Now that the same objects are created with data in all 3 PDB's, I can now do a combined query from the root PDB.  The next step is create a table in the CDB (root PDB) that is empty.

create table c##bgrenn.local_objects as select * from dba_objects where 1=0;

create table c##bgrenn.local_tables as select * from dba_tables where 1=0;

Table created.

Table created.


Then finally query and see the rows in the local_objects tables across all the PDB's

select count(*) from containers(c##bgrenn.local_objects) where con_id in (3) ;
  COUNT(*)
----------
     90925
select count(*) from containers(c##bgrenn.local_objects) where con_id in (4) ;
  COUNT(*)
----------
     90923
select count(*) from containers(c##bgrenn.local_objects) where con_id in (5) ;
  COUNT(*)
----------
     90925
select count(*) from containers(c##bgrenn.local_objects)  ;
 
  COUNT(*)
----------
    272773


Step 4 - Now to  look at the explain plan for one of the tables across containers

SET LINESIZE 130
SET PAGESIZE 0
SELECT * FROM table(DBMS_XPLAN.DISPLAY);
SQL> SQL> Plan hash value: 1439328272

----------------------------------------------------------------------------------------------------------------------
| Id  | Operation                   | Name       | Rows  | Bytes | Cost (%CPU)| Pstart| Pstop |    TQ  |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |            |     1 |   381 |     0   (0)|       |       |        |      |         |
|   1 |  PX COORDINATOR     |       |            |       |       |            |       |       |        |      |
|   2 |   PX SEND QC (RANDOM)       | :TQ10000   |     1 |   381 |            |       |       |  Q1,00 | P->S | QC (RAND)  |
|   3 |    PX PARTITION LIST ALL    |            |     1 |   381 |            |     1 |   254 |  Q1,00 | PCWC |         |
|   4 |     FIXED TABLE FULL        | X$CDBVW$   |     1 |   381 |            |       |       |  Q1,00 | PCWP |         |
----------------------------------------------------------------------------------------------------------------------



Finally, this is the explain plan for a join query to get all the tables


explain plan for
select *
  from containers(c##bgrenn.local_objects) a,
       containers(c##bgrenn.local_tables) b
where
  a.object_name = b.table_name and
  a.object_type = 'TABLE';

SET LINESIZE 150
SET PAGESIZE 0
SELECT * FROM table(DBMS_XPLAN.DISPLAY);

  2    3    4    5    6    7  
Explained.

SQL> SQL> SQL> SQL> Plan hash value: 198107036

-------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name      | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |    TQ    |IN-OUT| PQ Distrib |
-------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |           |     1 |  1226 |     0     (0)| 00:00:01|       |       |        |      |        |
|   1 |  PX COORDINATOR              |           |       |       |            |           |       |       |        |      |        |
|   2 |   PX SEND QC (RANDOM)        | :TQ10002  |     1 |  1226 |     0     (0)| 00:00:01|       |       |  Q1,02 | P-S  | QC (RAND)  |
|*  3 |    HASH JOIN BUFFERED        |           |     1 |  1226 |     0     (0)| 00:00:01|       |       |  Q1,02 | PCWP |        |
|   4 |     PX RECEIVE               |           |     1 |   381 |            |           |       |       |  Q1,02 | PCWP |        |
|   5 |      PX SEND HYBRID HASH     | :TQ10000  |     1 |   381 |            |           |       |       |  Q1,00 | P-P  | HYBRID HASH|
|   6 |       STATISTICS COLLECTOR   |           |       |       |            |           |       |       |  Q1,00 | PCWC |        |
|   7 |        PX PARTITION LIST ALL |           |     1 |   381 |            |           |     1 |   254 |  Q1,00 | PCWC |        |
|*  8 |     FIXED TABLE FULL         | X$CDBVW$  |     1 |   381 |            |           |       |       |  Q1,00 | PCWP |        |
|   9 |     PX RECEIVE               |           |     1 |   845 |            |           |       |       |  Q1,02 | PCWP |        |
|  10 |      PX SEND HYBRID HASH     | :TQ10001  |     1 |   845 |            |           |       |       |  Q1,01 | P-P  | HYBRID HASH|
|  11 |       PX PARTITION LIST ALL  |           |     1 |   845 |            |           |     1 |   254 |  Q1,01 | PCWC |        |
|  12 |        FIXED TABLE FULL      | X$CDBVW$  |     1 |   845 |            |           |       |       |  Q1,01 | PCWP |        |
-------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("A"."OBJECT_NAME"="B"."TABLE_NAME")
   8 - filter("A"."OBJECT_TYPE"='TABLE')

25 rows selected.






This looks like a very useful feature to get a high level view of all PDB's.  The things to note are.

1) You need to use a common user and this user needs to be the schema owner in all PDB's
2) By looking at the plan, I'm sure there is some high level view that does this using partitions.



Monday, May 5, 2014

Performance tuning using Oracle Internal Packages

I had an interesting problem last week with a customer who was performance testing on a new system compared to their current system.

The script was pretty simple. It was a PL/SQL package that inserted into a table 10M rows, and committed every 1,000 rows.  To make the data more "normal" the customer used DBMS_RANDOM .

The basic insert looked like this.

INSERT INTO TEST_TABLE1
     (ID,DTVAL,
      DTSTAMP,
      COL1,
      NUM)
VALUES
    (:B1 ,
      SYSDATE,
      SYSTIMESTAMP,
      DBMS_RANDOM.STRING('A', 100),
      DBMS_RANDOM.RANDOM);

To me it seemed like a simple test.  Unfortunately the performance results were not as expected.    To step back for a minute the current system was running on 11.1.0.7 and the new system they were benchmarking against was 11.2.0.4.

I even had them check the output of the  Table to ensure no changes in the output.. Everything looked the same.

You wouldn't think that would matter, but the differences in DBMS_RANDOM between versions seemed to be issue.  You see DBMS_RANDOM periodically has logic changes, and the performance of DBMS_RANDOM cannot be compared between versions in a performance benchmark.

I had the customer re-run the tests with constants instead of calling DBMS_RANDOM and the results were much better.

To reproduce what they saw  I finally tested against 11.2.0.2 and  12.1.0.1 (on the same machine).  I could not get a copy of 11.1.0.7 and 11.2.0.4 to test.  These 2 versions were enough to see the difference that affected the Customers Benchmark.

Below I've included the TKPROF formatted output from the trace file on 11.2.0.2

SQL ID: fg7gf0m6a2ca4 Plan Hash: 0

INSERT INTO TEST_TABLE1 (ID,DTVAL,DTSTAMP,COL1,NUM)
VALUES
(:B1 , SYSDATE, SYSTIMESTAMP, DBMS_RANDOM.STRING('A', 100),
  DBMS_RANDOM.RANDOM)


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute 100000     25.81      39.51          0       2464     119161      100000
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total   100001     25.81      39.51          0       2464     119161      100000


Notice the CPU time.. 25.81 seconds of CPU time on 11.2.0.2

Below is the TKPROF formatted output from the trace file on 12..1.0.1

INSERT INTO TEST_TABLE1 (ID,DTVAL,DTSTAMP,COL1,NUM)
VALUES
(:B1 , SYSDATE, SYSTIMESTAMP, DBMS_RANDOM.STRING('A', 100),
  DBMS_RANDOM.RANDOM)


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute 100000     74.01      90.31          1       3722     111116      100000
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total   100001     74.01      90.31          1       3722     111116      100000


This time notice that it 74.01 seconds of CPU.. Same statement executed the same number of times..

The difference between the 2 versions is almost 3X longer in 12.1.0.1

No I re-ran it with constants

11.2.0.2 Test

INSERT INTO TEST_TABLE1 (ID,DTVAL,DTSTAMP,COL1,NUM)
VALUES
(:B1 , SYSDATE, SYSTIMESTAMP, 'a', 1)


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute 100000      4.62       6.02          0        536     108087      100000
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total   100001      4.62       6.02          0        536     108087      100000


12.1.0.1 test

INSERT INTO TEST_TABLE1 (ID,DTVAL,DTSTAMP,COL1,NUM)
VALUES
(:B1 , SYSDATE, SYSTIMESTAMP, 'a', 1)


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute 100000      4.78       7.09          1        586     105731      100000
Fetch        0      0.00       0.00          0          0          0           0
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total   100001      4.78       7.09          1        586     105731      100000



Wow.. Now that I use constants, the CPU time was almost identical.

There are absolutely some major performance differences with DBMS_RANDOM between versions.

Moral of the story is don't use internal packages for benchmarking (unless they are critical to your application).



Finally, this is the package code I used for testing..

OWNER        SET TIME ON
SET TIMING ON
SET ECHO ON
SET SERVEROUTPUT ON
SET TERMOUT ON
SET VERIFY ON
SET FEEDBACK ON

WHENEVER SQLERROR CONTINUE

select to_char(sysdate,'mm/dd/yyyy hh:mi:ss AM') from dual;


prompt create the test_table1

drop table test_table1;

create table test_table1
(
id NUMBER,
dtval DATE,
dtstamp TIMESTAMP,
col1 varchar2(100),
num NUMBER
);   

prompt Insert 1M with commit every 1000 records

alter session set tracefile_identifier = 'test_sess_1';
exec dbms_monitor.session_trace_enable( waits => true );


DECLARE
 x  PLS_INTEGER;
 rn NUMBER(20); 
BEGIN

  SELECT hsecs
  INTO rn
  FROM v$timer;
  
  dbms_random.initialize(rn);
  FOR i IN 1..100000
  LOOP
    x := dbms_random.random;
    rn := x; 
    
    insert into test_table1 (id,dtval,dtstamp,col1,num)
    values(x, sysdate, systimestamp, DBMS_RANDOM.string('A', 100), dbms_random.random);
    
    If ( MOD(i,100) = 0) then
        commit;
    end if;
    
  END LOOP;
  dbms_random.terminate;
END;
/

EXEC DBMS_MONITOR.session_trace_disable;

prompt Count of all records

select count(*) from test_table1;
select count(distinct col1) from test_table1 ;
select count(distinct num) from test_table1 ;





Thursday, December 12, 2013

Monitoring your Exadata health

One of the biggest topics I talk to customers about is the monitoring of your exadata health. 

The best tool for this is the Exachk (see MOS Doc ID 1070954.1)

This document contains the current Exachk release, and any new beta release that is available.

The recommendation for Exachk is to

1) Run the exachk (at a minimum) quarterly, and after any changes are made to the configuration
2) ALWAYS run the current exachk.  This script is periodically updated/improved upon so it is very important to be current
3) Keep track of any failures to ensure that you can identify any new items that appear in the report
4) A score of 80 or above is a good score for production. It is very rare to have a score that is 99+.

There are also a great whitepaper  released in Sept. 2013 (just a few months ago).

This white paper can be  here.

http://www.oracle.com/technetwork/database/availability/exadata-health-resource-usage-2021227.pdf