Oracle Notes

Sharing Oracle technology knowledge and experiences.

Protecting Archive Logs in the Event of a Disaster

Posted by sdefilip on May 6, 2011

 Summary of Methods to Protect Archive Log Tapes

 I have a client who is concerned about losing archive logs and being able to recover their database in the event of a disaster.  We take full RMAN backups, including archive logs and control files every night, but the concern is what would happen if their server is destroyed in between these backups. With the knowledge that a full Disaster Recovery Plan is not a simple undertaking and that they would need more than archive logs to recover their database in case of the destruction of their server, they asked me to provide options which I am sharing on this blog.  I am sharing the results of this undertaking. The environment is AIX 6.5 and Oracle 11.2 Standard Edition.  Please feel free to comment and share your suggestions.

 Options to protect archive log tapes (and the full database) are:

 I.  Have RMAN take more frequent backups, including archive logs.

II. Oracle allows specification of an alternate destination for archive logging that is 

     additional to the primary destination. 

      NFS mount a directory on a remote server. Use an alternate “archive_log_dest”    parameter to specify the NFS mounted remote directory as the alternate log destination.

III.  SFTP or rsynch a copy of the archive logs to a remote server through a shell script. The shell script would have to:

  1. check the V$ARCHIVED_LOG view to determine if each archive log file in the archive log directory has completed its archiving process.
  2. use the AIX rsynch command (or SFTP) to synchronize the remote archive log destination with the primary server archive log destination
  3. run this script every nn time intervals, leaving a window for the RMAN backups

IV. Use the pre-RMAN method of database backup. Copy the database user datafiles, control files, archive logs and parameter file to a directory on an NFS mounted remote server directory. This requires that an Oracle instance is installed on the remote server to recover the database from these files. This method has it’s weaknesses and so RMAN was created and offered as an alternative.

V.  Use RMAN to rig a standby database without DataGuard or GoldenGate;

      this involves another Oracle instance running on the remote server, use of 

    RMAN to clone the primary database, shipping primary database RMAN backup

    files to remote server and, finally, running an RMAN recovery of the database on

   the remote server.

VI.  Create an Oracle RAC 2-node cluster with one cluster being on a remote server.

       I believe that this is possible with 11.2 tandard Edition, possibly with a small

       charge per node.

 I recommend option “III” because it does not require another instance of Oracle on the remote server, it will not slow down the log writer Oracle process (LGWR) which would most likely result in a general database slowdown. In addition, the AIX/network resources used, if the script is not run very excessively, should not be sufficient to slowdown the Oracle database or the application.  My suggestion is to determine the average amount of time that the database takes to fully archive a log, decide how many logs you would like copied at the same time and use that average as a guideline to determine how frequently to schedule the script.

 

Posted in Best Practices, Disaster Recovery, Oracle 11g, Oracle 11g Database Administration, Tips | Tagged: , | Leave a Comment »

Giving Oracle a Checkup

Posted by sdefilip on January 27, 2011

ORACLE 11g HEALTH CHECK MONITOR

The Oracle Health Check Monitor (HM) facility is new with Oracle 11.1 database.  It can run diagnostic checks that detect:

>   file corruptions – reports failures if these files are inaccessible, corrupt or inconsistent. If the database is in mount or open mode, this check examines the log files and data files listed in the control file. If the database is in NOMOUNT mode, only the control file is checked.

>   physical and logical block corruptions – detects disk image block corruptions such as checksum failures, head/tail mismatch, and logical inconsistencies within the block. Most corruptions can be repaired using Block Media Recovery. Corrupted block information is also captured in the V$DATABASE_BLOCK_CORRUPTION view. This check does not detect inter-block or inter-segment corruption.

> undo and redo corruptions -

For redo, HM scans the contents of the redo log for accessibility and corruption, as well as the archive logs, if available. The Redo Integrity Check reports failures such as archive log or redo corruption.

For undo, HM finds logical undo corruptions. After locating an undo corruption, this check uses PMON and SMON to try to recover the corrupted transaction. If this recovery fails, then Health Monitor stores information about the corruption in V$CORRUPT_XID_LIST. Most undo corruptions can be resolved by forcing a commit.

>   transaction integrity check – identical to the Undo Segment Integrity Check except that it checks only one

specific transaction

>  data dictionary corruptions – examines the integrity of core dictionary objects, such as tab$ and col$. It  performs the following operations:

    • Verifies the contents of dictionary entries for each dictionary object.
    • Performs a cross-row level check, which verifies that logical constraints on rows in the dictionary are enforced.
    • Performs an object relationship check, which verifies that parent-child relationships between dictionary objects are enforced.

The Dictionary Integrity Check operates on the following dictionary objects:

tab$, clu$, fet$, uet$, seg$, undo$, ts$, file$, obj$, ind$, icol$, col$, user$, con$, cdef$, ccol$, bootstrap$, objauth$, ugroup$, tsq$, syn$, view$, typed_view$, superobj$, seq$, lob$, coltype$, subcoltype$, ntab$, refcon$, opqtype$, dependency$, access$, viewcon$, icoldep$, dual$, sysauth$, objpriv$, defrole$, and ecol$.

Each of the above checks can be used with parameters that provide specific subcategories of information.

Run HM Checker Manually

The Oracle Health Monitor (HM) can be run using the following syntax manually:

BEGIN

DBMS_HM.RUN_CHECK(‘type of check’, ‘name of HM check run’);

END;

Example:

SQL>
BEGIN

DBMS_HM.RUN_CHECK(‘Data Block Integrity Check’, ‘db_blk_integ_run’);

END;
SQL> /

The types of checks that can be obtained in this manner (in place of ‘type of check’ above) are:

HM Test Check
DB Structure Integrity Check
CF Block Integrity Check
Data Block Integrity Check
Redo Integrity Check
Logical Block Check
Transaction Integrity Check
Undo Segment Integrity Check
No Mount CF Check
Mount CF Check
CF Member Check
All Datafiles Check
Single Datafile Check
Tablespace Check Check
Log Group Check
Log Group Member Check
Archived Log Check
Redo Revalidation Check
IO Revalidation Check
Block IO Revalidation Check
Txn Revalidation Check
Failure Simulation Check
Dictionary Integrity Check
ASM Mount Check
ASM Allocation Check
ASM Disk Visibility Check
ASM File Busy Check

Most health checks accept input parameters. You can view parameter names and descriptions with the V$HM_CHECK_PARAM view. Some parameters are mandatory while others are optional. If optional parameters are omitted, defaults are used. The following query displays parameter information for all health checks:

SELECT c.name check_name, p.name parameter_name, p.type,

p.default_value, p.description

FROM v$hm_check_param p, v$hm_check c

WHERE p.check_id = c.id and c.internal_check = ‘N’

ORDER BY c.name;

Input parameters are passed in the input_params argument as name/value pairs separated by semicolons (;). The following example illustrates how to pass the transaction ID as a parameter to the Transaction Integrity Check:

BEGIN

DBMS_HM.RUN_CHECK (

check_name   => ‘Transaction Integrity Check’,

run_name     => ‘my_run’,

input_params => ‘TXN_ID=7.33.2′);

END;

Running HM Checker using Enterprise Manager:

1.      On the Database Home page, in the Related Links section, click Advisor Central.

2.      Click Checkers to view the Checkers subpage.

3.      In the Checkers section, click the checker you want to run.

4.      Enter values for input parameters or, for optional parameters, leave them blank to accept the defaults.

5.      Click Run, confirm your parameters, and click Run again.

Viewing HM Checker Reports

You can now view a report of a checker execution. The report contains findings, recommendations, and other information. You can view reports using Enterprise Manager, the ADRCI utility, or the DBMS_HM PL/SQL package. The following table indicates the report formats available with each viewing method.

Report Viewing Method Report Formats Available
Enterprise Manager HTML
DBMS_HM PL/SQL package HTML, XML, and text
ADRCI utility XML

To view run findings using Enterprise Manager

  1. Access the Database Home page.
  2. In the Related Links section, click Advisor Central.
  3. Click Checkers to view the Checkers subpage.
  4. Click the run name for the checker run that you want to view.

The Run Detail page appears, showing the findings for that checker run.

  1. Click Runs to display the Runs subpage.

Enterprise Manager displays more information about the checker run.

  1. Click View Report to view the report for the checker run.

The report is displayed in a new browser window.

Viewing Reports Using DBMS_HM

You can view Health Monitor checker reports with the DBMS_HM package function GET_RUN_REPORT. This function enables you to request HTML, XML, or text formatting. The default format is text, as shown in the following SQL*Plus example:

SET LONG 100000

SET LONGCHUNKSIZE 1000

SET PAGESIZE 1000

SET LINESIZE 512

SELECT DBMS_HM.GET_RUN_REPORT(‘HM_RUN_1061′) FROM DUAL;

DBMS_HM.GET_RUN_REPORT(‘HM_RUN_1061′)

———————————————————————–

Run Name                     : HM_RUN_1061

Run Id                       : 1061

Check Name                   : Data Block Integrity Check

Mode                         : REACTIVE

Status                       : COMPLETED

Start Time                   : 2011-01-12 22:11:02.032292 -07:00

End Time                     : 2011-01-12 22:11:20.835135 -07:00

Error Encountered            : 0

Source Incident Id           : 7418

Number of Incidents Created  : 0

Input Paramters for the Run

BLC_DF_NUM=1

BLC_BL_NUM=64349

Run Findings And Recommendations

Finding

Finding Name  : Media Block Corruption

Finding ID    : 1065

Type          : FAILURE

Status        : OPEN

Priority      : HIGH

Message       : Block 64349 in datafile 1:

‘/ade/sfogel_emdb/oracle/dbs/t_db1.f’ is media corrupt

Message       : Object BMRTEST1 owned by SYS might be unavailable

Finding

Finding Name  : Media Block Corruption

Finding ID    : 1071

Type          : FAILURE

Status        : OPEN

Priority      : HIGH

Message       : Block 64351 in datafile 1:

‘/ade/sfogel_emdb/oracle/dbs/t_db1.f’ is media corrupt

Message       : Object BMRTEST2 owned by SYS might be unavailable

Viewing Reports Using the ADRCI Utility

You can create and view Health Monitor checker reports using the ADRCI utility.

To create and view a checker report using ADRCI

  1. Ensure that operating system environment variables (such as ORACLE_HOME) are set properly, and then enter the following command at the operating system command prompt:

2.      ADRCI

The utility starts and displays the following prompt:

adrci>>

Optionally, you can change the current ADR home. Use the SHOW HOMES command to list all ADR homes, and the SET HOMEPATH command to change the current ADR home. See Oracle Database Utilities for more information.

3. Enter the following command:

show hm_run

This command lists all the checker runs (stored in V$HM_RUN) registered in the ADR repository.

4. Locate the checker run for which you want to create a report and note the checker run name. The REPORT_FILE field contains a filename if a report already exists for this checker run. Otherwise, generate the report with the following command:

5.      create report hm_run run_name

6. To view the report, enter the following command:

show report hm_run run_name

**  For more details regarding HM views, parameters and more see

http://download.oracle.com/docs/cd/B28359_01/server.111/b28310/diag007.htm

*** Reference Oracle® Database Administrator’s Guide 11g Release 1 (11.1)

Part Number B28310-04

Posted in Oracle 11g, Oracle 11g Database Administration, Oracle 11g New Features, Oracle Performance, Oracle Troubleshooting, Tips | Leave a Comment »

Oracle 11g GoldenGate and Compressed Tables

Posted by sdefilip on January 6, 2011

Oracle GoldenGate and Compressed Tables

OGG does not support compressed tables or partitions, neither does it handle it well with proper error messages until OGG v10.4. The abends may or may not produce any error message and sometimes produce wrong messages.

From V11.1.1.0.0, Oracle has enhanced the error handling part in BugDB 9425542, which gives meaningful error message on the compressed record before Extract abend. It will list out the table name, rowid, etc

Example :
ERROR OGG-01028 Record on table QATEST1.TAB1 with rowid AAM4EkAAEAACBguAAA from transaction 5.24.270123 (0x0005.018.00041f2b) is compressed. Compression is not supported.

However, due to bug 10063108, sometimes the error message on compressed tables are not entirely correct. This problem has been fixed in 11.1.1.0.3 and above

A table created as compressed will cause all of the DML’s to go into compressed blocks on disk. If the user does an “alter table nocompress”, every DML that goes into the table AFTER that point in time will be uncompressed. The query for compression will return “nocompress” now, but the simple “alter” does not change the already existing compressed blocks on disk that were created before the “alter”. So to capture the records from a table which was compressed we need to do the following

SQL> alter table move nocompress;

This will touch every single block on disk and will uncompress everything thereby causing OGG to work properly and not abend.

If there is even a single partition in a partitioned table that is compressed, it will cause an abend. Partition compression can be verified by getting the full DDL for the table by running the DBMS_METADATA.GET_DDL package. For table partitions that are compressed, run the below query and get the partition names & tablespace names.

SQL> SELECT partition_name, subpartition_name, tablespace_name, high_value FROM user_tab_subpartitions WHERE table_name = ‘table_name';

Alter statement for partition to move to nocompress:

SQL> ALTER TABLE MOVE PARTITION NOCOMPRESS TABLESPACE ;

Eensure that you have enough disk space within your tablespaces before running the ALTER statement.

Support of compressed tables will be in future releases of OGG, however, in current V10.4 and V11.1.1.x, the only option, if a “move nocompress” is not possible, is to comment the compressed table or exclude them from the Extract.

Listing some scenarios in which we have seen similar errors for compression  :
1) The extract abends with the following error

GGS ERROR ZZ-0QY Failed to validate table <SCHEMA>.<TABLE NAME>. The table is compressed and extract will not be able to extract data from Oracle logs.

This bug happens when DDL is enabled, the checking was not done correctly when table resides on Bigfile tablespace.

Issue is fixed in V10.4.0.93 and V11.1.1.0.4

Reference bugdb – 10063075

2) When running with OGG version earlier than V11.1.1.0.10, Extract might abend with below error message, without telling the name of the table or the Objectid of the compressed table

Source Context :

SourceModule : [er.redo.ora.sr]
SourceID : [/mnt/ecloud/workspace/Build_OpenSys_r11.1.1.0.9_004
_[40043]/perforce/src/app/er/redo/oracle/redoorasr.c]
SourceFunction : [get_subrec(int32_t, mempool_t *, unsigned char *, u
nsigned short, subrec_info_t *, redo_thread_t *, BOOL, log_context_t *)]
SourceLine : [5434]

2010-11-10 11:50:26 ERROR OGG-01028 compressed tables are not supported.

This is because there is a temp table created as compressed, then followed directly by a direct load operation.

Try to exclude the table DBMS_TABCOMP_TEMP_UNCMP and DBMS_TABCOMP_TEMP_CMP, which was created by Compression advisory.

From OGG v11.1.1.0.10 onwards when the extract abends because of direct load inserts on tables with compressed partitions, the extract gives the table name in the error.

Reference bugdb – 10279456

However, if the table has been dropped immediately after creation, the Extract will only give out the object ID of the “compressed” table.  To find out exactly what was the compressed table name, you could query GGS_DDL_HIST table if DDL replication is enabled.  A sample query

select OBJECTID, OBJECTNAME, METADATA_TEXT FROM GGS_DDL_HIST WHERE OBJECTID = xxxxx

 

 

Posted in Golden Gate, Oracle 11g, Oracle 11g Database Administration, Oracle 11g New Features, Oracle Fusion Middleware, Oracle GoldenGate, Oracle Troubleshooting, Tips | 5 Comments »

A Useful Oracle 11g New Feature

Posted by sdefilip on September 18, 2010

Server Result Cache

  • Enables query result to be cached in memory which can be used during future execution of a similar query by bypassing the regular processing thereby returning the results faster.
  • Decreases the wait time for both physical and logical IO by directly fetching the results from the cached memory.
  • Cached result set is completely shareable between the sessions and various statements as long as they share a common execution plan.
  • Server result cache is the new component of SGA that caches results of queries and is managed by automatic memory management.
  • New parameter RESULT_CACHE_MAX_SIZE is used to enable result cache by setting the maximum size of the cache.
  • A new optimizer hint allows use of result cache at the query level.

Query execution without result cache hint.

Query execution without result cache hint - Oracle 11gQuery execution without result cache hint – Oracle 11g

Query execution with result cache hint.

Query execution with result cache hint - Oracle 11gQuery execution with result cache hint – Oracle 11g

Parameters  related to Result Cache

RESULT_CACHE_MAX_RESULT  :  specifies the percentage of RESULT_CACHE_MAX_SIZE that any single result can use
RESULT_CACHE_MAX_SIZE    :  specifies the maximum amount of SGA memory (in bytes) that can be used by the Result Cache.
RESULT_CACHE_REMOTE_EXPIRATION   : specifies the number of minutes that a result using a remote object is allowed to remain valid
RESULT_CACHE_MODE    : specifies when a ResultCache operator is spliced into a query’s execution plan.

How to find result cache information:
V$RESULT_CACHE_STATISTICS
V$RESULT_CACHE_MEMORY
V$RESULT_CACHE_OBJECTS
V$RESULT_CACHE_DEPENDENCY

DBMS_RESULT_CACHE – PL/SQL API for result cache management:
Functions : Status – displays the current status of the result cache.

SELECT DBMS_RESULT_CACHE.status FROM dual;
STATUS
—————————————————–
ENABLED

Flush: remove all objects from the result cache and release memory.

I will cover some more features in next post . Keep reading

Posted in Oracle 11g, Oracle 11g Database Administration, Oracle 11g New Features, Oracle Architecture, Oracle Performance, Tips | Tagged: , , , | Leave a Comment »

Log Buffer #198, A Carnival of the Vanities for DBAs

Posted by sdefilip on August 6, 2010

Welcome to Log Buffer, the weekly roundup of database industry news.  I’m guest hosting this week’s edition, Log Buffer #198[S D1] [S2] , normally published by Pythian.  If you want to host your own version of Log Buffer, reach out to the Log Buffer coordinator.

Lots of good “stuff” out there on the technical blogs this week so here are some interesting ones:

In “Kerry Osborne’s Oracle Blog”, Kerry discusses the use of SQL Profiles

which contain sets of hints.

The memory_target parameter, how it behaves and how it relates to other memory structures, is the topic of Steve Karam’s on his “Oracle Alchemist” blog.

On “Mark Rittman’s Oracle Weblog”, Mark Rittman informs us how we can now add incremental patches to an RPD within OBIEE 11GgR1, through the use of XML patch files.

Scalability and the Oracle conflicts of interest that can be brought about by managing it are illustrated by

Jonathan Lewis on Oracle Scratchpad.

Tanel Poder offers his article on Troubleshooting Exadata V2 Smart Scan Performance in his “Core IT for Geeks and Pros” blog.

In a series of posts on the topic of the SQL Server 2008 Optimiser: Constructing a Plan, Part 1 & Part 2, on the “SQL Server Blogspot on the Web”, Paul White provides detail on how to get SQL code and queries to perform at their best.

Simon Sabin discusses Creating a Unique Constraint on a Column That Allows Nulls on “Simon’s SQL Blog”.

Distributed Transactions and Two-Phase Commit in PostgreSQL is the subject of Joshua Tolley’s informative post on “The Endpoint” blog.

Dimitri Fontaine talks about Querying the Catalog to plan an upgrade, on Planet PostgreSQL.  In more news, PostgreSQL 9.0 beta 4 is out and ready for testing.

On the “MySQL Performance Blog”,  Baron Shwartz cautions Why You Can’t Rely on a Replica for Disaster Recovery.


[S D1]http://wp.me/pYWgn-1o

Posted in Tips, Uncategorized | 1 Comment »

Using Oracle GoldenGate’s Logdump Utility

Posted by sdefilip on August 5, 2010

USING ORACLE GOLDENGATE’S LOGDUMP UTILITY

A recent client had a problem which required the use of the OGG Logdump utility to verify whether a particular table row had been extracted and placed in the Replicat trail file for replication to the target.  In this post, I will outline the steps that were used to find the answer.

1.   Begin logdump session:

            $ logdump

          GoldenGate Log File Dump Utility

          Version 10.4.0.12 Build 001

          Copyright (C) GoldenGate Software, Inc. 1995-2009.

          The GoldenGate software may include other code written by third parties;

          details regarding such third party code, including applicable copyright,

          legal and licensing notices are available at http://support.goldengate.com.

                   

2.    Open Replicat Trail File

 

Logdump 1>open ./dirdat/ad000053

Current LogTrail is /shared/oradb/GoldenGate/pnet01d/dirdat/ad000053

Logdump 2 >ghdr on       <–shows record header info about transaction

Logdump 3 >detail data     <– adds  hex and ASCII data values to the

                                                        column information                       

Logdump 4 >next            <–  moves to the first record; advances by one

                                                    record

 

2010/08/04 21:22:18.134.541 FileHeader           Len   928 RBA 0

Name: *FileHeader*

 3000 01ad 3000 0008 4747 0d0a 544c 0a0d 3100 0002 | 0…0…GG..TL..1…

 0002 3200 0004 ffff fffd 3300 0008 02f1 b33c d650        | ..2…….3……<.P

 840d 3400 0031 002f 7572 693a 7473 7332 6130 3137 | ..4..1./uri:tss2a017

 6e33 3a3a 7368 6172 6564 3a6f 7261 6462 3a47 6f6c  |::shared:oradb:Gol

 6465 6e47 6174 653a 706e 6574 3031 6436 0000 1300 |denGate:anondb02

 112e 2f64 6972 6461 742f 6164 3030 3030 3533 3700 |…/dirdat/ad0000537

 0001 0138 0000 0400 0000 3539 0000 0800 0000 001d | …8……59……..

(above is header data in hex and char)

2010/08/04 22:36:23.000.000 Insert               Len   456 RBA 6608  <–this is

                                                                                                                                an insert

                                                                                                                                 at this rba

Name: FIN_AUDIT.FIN_GL_ATTR      <– source object

 

Logdump 5>next      <– shows next record which contains continuing header

                                            info; “next’ or ‘n’ also  scans through records in

                                            sequential order

___________________________________________________________________

Hdr-Ind    :     E  (x45)     Partition  :     .  (x00)

UndoFlag   :     .  (x00)     BeforeAfter:     A  (x41)

RecLength  :     0  (x0000)   IO Time    : 2010/08/04 21:22:17.611.797

IOType     :   151  (x97)     OrigNode   :     0  (x00)

TransInd   :     .  (x03)     FormatType :     R  (x52)

SyskeyLen  :     0  (x00)     Incomplete :     .  (x00)

AuditRBA   :          0       AuditPos   : 0

Continued  :     N  (x00)     RecCount   :     0  (x00)

 

2010/08/04 21:22:17.611.797 RestartOK            Len     0 RBA 936

Name:

After  Image:                                             Partition 0   G  s

 

3.    Search for Timestamp in Trail File

 

Logdump 6 >sfts 2010-08-04       <–searches for the timestamp ‘2010-08-04’

Scan for timestamp >= 2010/08/04 04:00:00.000.000 GMT    <– timestamp

                                                                                                                          found

Column    41 (x0029), Len    31 (x001f)       <–column info with data

 0000 3230 3130 2d30 382d 3034 3a32 323a 3336 3a30 | ..2010-08-04:22:36:0

 372e 3839 3333 3139 3030 30                       | 7.893319000RecLength :9 (x0000)   IO Time    : 2010/08/04 21:22:17.611.797

 Since we were looking for any records that were inserted on 2010/08/04, we have found a valid entry in the Replicat trail file that verifies that the record has been placed in the file on the target side by the OGG Collector component.

 A few other of my favorite, very useful  Logdump commands are:

 >filter include filename FIN_AUDIT.FIN_GL_ATTR   

     Which will filter out all records that do not contain the table name

     specified and narrow down the set of records that subsequent commands

     will operate on until a “>filter clear” is issued

>pos FIRST

      Which will go to the first record in the file

 >pos <rba>

       Which will go to a specific rba in the trail file

 >log to <filename>.txt

        Which will log your Logdump session

There are several other useful commands for examining trail files or redo logs.  See the Oracle GoldenGate Troubleshooting Guide  for a complete list.

 

 

Posted in Data Integration, Data Warehouse, Golden Gate, Oracle GoldenGate, Oracle Troubleshooting, Replication, Tips | Tagged: , , , , | 1 Comment »

Oracle GoldenGate – Positioning a Read of Extract/Replicat Trail File or Oracle Redo Log

Posted by sdefilip on July 26, 2010

Positioning in Extract / Replicat Trail and Log

In the event that there is ever a need to position an extract in the
Transaction Log (aka redo log), extract trail file or replicat trail file,
the following options can be used:

INFO EXTRACT <groupname>,  DETAIL

This will name your current redo log along with the RBA and sequence number and your extract trail name along with the RBA. RBA is the relative byte address of the record in the trail file at which the checkpoint was made

INFO EXTRACT, SHOWCH

Will show you your read checkpoint in the data source and write
checkpoint in the trail files.

Log Read Checkpoint File /orarac/oradata/racq/redo01.log  ß- Oracle redo
2006-06-09 14:16:45 Thread 1, Seqno 47, RBA 68748800          info
Log Read Checkpoint File /orarac/oradata/racq/redo04.log
2006-06-09 14:16:19 Thread 2, Seqno 24, RBA 65657408
Current Checkpoint Detail:
Read Checkpoint #1
Oracle RAC Redo Log
Startup Checkpoint (starting position in data source):
Sequence #: 47
RBA: 68548112     ß– RBA offset of entry in redo log
Timestamp: 2006-06-09 13:37:51.000000
SCN: 0.8439720
Redo File: /orarac/oradata/racq/redo01.log
Recovery Checkpoint (position of oldest unprocessed transaction in
data source):
Sequence #: 47
RBA: 68748304
Timestamp: 2006-06-09 14:16:45.000000
SCN: 0.8440969
Redo File: /orarac/oradata/racq/redo01.log
Current Checkpoint (position of last record read in
the data source)

Write Checkpoint #1
GGS Log Trail       ß– start of GG Trail Information
Current Checkpoint (current write position):
Sequence #: 2
RBA: 2142224       ß–  RBA offset of entry in Trail file
Timestamp: 2006-06-09 14:16:50.567638
Extract Trail: ./dirdat/eh
Header:
Version = 2
Record Source = A
Type = 6
# Input Checkpoints = 2
# Output Checkpoints = 1

Once you have your checkpoint RBAs, you can use a few ggsci
commands to help you debug:

ADD EXTRACT <groupname>

Allows creation of an extract from a specific position in a trail file or
transaction log.
Some useful options are:

EXTTRAILSOURCE <trail name>
Specifies a trail as the data source. For <trail name>, specify the
fully qualified path name  of the trail, for example c:\ggs\dirdat\aa.

BEGIN <begin spec>
Specifies a timestamp in the data source at which to begin
processing.
<begin spec>  value is either:
□  NOW    –  the time at which the ADD EXTRACT command
is issued.
□   A date and time in the format of:
yyyy-mm-dd [hh:mi:[ss[.cccccc]]]

*** if you have a 4-node RAC cluster environment, use the
“THREADS 4”  option to any command to which it applies.

EXTRBA <relative byte address>
Specifies an RBA at which to start extracting.  This can be used to
skip over a bad entry in a trail file.

ALTER EXTRACT <group name>

Allows changing the attributes of an extract file created by the ADD EXTRACT
command and allows the incrementing of an extract to the  next file in the sequence.

***Always  “STOP EXTRACT <group name>”  before using this command.

You can use this command to make any changes using any of the options to the ADD EXTRACT command (above).  So, for example, you can ALTER EXTRACT an extract file to begin at a specific RBA for skipping over an entry in the extract file.
Ex.:   ALTER EXTRACT finance, EXTSEQNO 26, EXTRBA 338

You can change any of the attributes specified with the ADD EXTRACT command, except for the following:
□ Altering an Extract specified with the EXTTRAILSOURCE
option.
□ Altering the number of RAC threads specified with the THREADS
option.

SEND EXTRACT

Allows you to send commands to a running extract process.
Some useful options are:

GETLAG shows lag time between the extract and the data source

LOGEND shows whether or not extract has processed all record in
the data source

ROLLOVER makes extract increment to the next file in the trail upon
startup

SHOWTRANS shows information about current transactions:
□   Process Checkpoint
□   Transaction ID
□    Extract Group Name
□    Redo Thread Number
□    Timestamp of first transaction of extract
□     System Change Number  (SCN)
□     RBA and Redo Log Number
□     STATUS ( commit after it has been forced by FORCETRANS
(Pending Commit) or “running”)

Posted in CDC, Data Integration, Data Warehouse, Golden Gate, Oracle GoldenGate, Replication, Tips, Uncategorized | 2 Comments »

Posted by sdefilip on July 19, 2010

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Useful Oracle GoldenGate Troubleshooting Commands

Posted by sdefilip on July 15, 2010

Troubleshooting Commands

Extract

If there are any errors, the extract would appear as STOPPED. In this case, you have to investigate the errors.

First, check the report file C:\OGG10G\dirrpt\EMP_EXT.rpt.

Next, see if there are any indicative messages in the log files ggserr.log and sqlnet.log, which are in the main C:\OGG10G directory.

The ggserr.log file contains event information such as:

2009-12-02  14:53:26  GGS INFO        301   Oracle GoldenGate

Manager for Oracle, mgr.prm:  Command received from GGSCI on host 10.10.10.10 (START EXTRACT  EMP_EXT ).

2009-12-02  14:53:26  GGS INFO        302   Oracle GoldenGate Manager for Oracle, mgr.prm:

EXTRACT EMP_EXT starting.

These events can also be seen in the following way:

GGSCI (AnonDB) 1> VIEW GGSEVT

….

2009-12-02 15:09:34  GGS INFO        302  Oracle GoldenGate Manager for Oracle,

mgr.prm:  EXTRACT EMP_EXT starting.

2009-12-02 15:13:26  GGS INFO        399  Oracle GoldenGate Command Interpreter

for Oracle:  GGSCI command (AnonDB): EDIT PARAM emp_ext.

The sqlnet.log file may show errors such as

TNS-12557: TNS:protocol adapter not loadable

This particular error indicates a database connection issue, so you need to explore at the listener level. Make sure the Path includes the Oracle Home bin subdirectory right at the start. There may be other TNS errors that may indicate other solutions.

EMP_EXT.rpt may show an error such as the following:

2009-12-08 13:01:27  GGS ERROR       182  OCI Error beginning

session (status = 28009-ORA-28009: connection as SYS should be as SYSDBA or SYSOPER).

2009-12-08 13:01:27  GGS ERROR       190  PROCESS ABENDING.

This indicates that the Extract process is trying to log on as sys without being the SYSDBA. Simply change the login in the parameter file for the Extract to “system”.

I should note here that specifying SYSDBA at the end of the login line in the Extract parameter file doesn’t work, although it does work with the DBLOGIN command in GGSCI that you will see next.

The ggserr.log file may show similar errors:

2009-12-03 00:43:16  GGS INFO        399  Oracle GoldenGate

Command Interpreter for Oracle:  GGSCI command (AnonDB): start manager.

2009-12-03 00:43:25  GGS ERROR       182  Oracle GoldenGate

Manager for Oracle, mgr.prm:  OCI Error during OCIServerAttach

(status = 12154-ORA-12154: TNS:could not resolve the connect identifier specified).

2009-12-03 00:43:25  GGS ERROR       190  Oracle GoldenGate

Manager for Oracle, mgr.prm:  PROCESS ABENDING.

This indicates an issue with the login credentials supplied in the Manager parameter file, mgr.prm. The Manager has not started as a result.

Another possible error can be seen in the Extract report file. For example, EMP_EXT.rpt can have this error:

2009-12-07 16:40:08  GGS ERROR       190  No minimum supplemental

logging is enabled. This may cause extract process to handle key

update incorrectly if key column is not in first row piece.

2009-12-07 16:40:08  GGS ERROR       190  PROCESS ABENDING.

The solution to this is obviously to enable supplemental logging at the database level. C

Replicat

The first step is to use the GGSCI command DBLOGIN to connect to the database, so that other commands can be issued that will work on the database.

Note that DBLOGIN works fine as follows:

GGSCI ( AnonDB) 1>

DBLOGIN USERID system@localhost:1521/FIPRD3 PASSWORD fipassword1

Successfully logged into database.

Now you need to add a checkpoint table for the employees table that you are replicating:

GGSCI ( AnonDB) 2> ADD CHECKPOINTTABLE HR.EMPLOYEES_CHKPT

Successfully created checkpoint table HR.EMPLOYEES_CHKPT.

Checkpoints that are stored in this table refer to the current read and write positions of the Replicat process. This is used to prevent the loss of data in case the process needs to be restarted, or if there is any fault in the server or a hiccup in the network that would otherwise result in data loss. The other advantage is that multiple Extract or Replicat processes can be read from the same set of trails by using checkpoints.

Checkpoints are optional in the sense that they are not required for Extract and Replicat processes that run in batch mode, because such processes can always be restarted. However, checkpoints are necessary in the case of continuously operating Extract and Replicat processes.. They are normally maintained as files in the dirchk subdirectory, but in the case of Replicat they can optionally be stored in the database in the checkpoint table.

If you specify the checkpoint table in the GLOBALS parameter file, the above command can use that specification. In this scenario, the command could simply be

GGSCI (AnonDB) 3> ADD CHECKPOINTTABLE

No checkpoint table specified, using GLOBALS specification (hr.employees_chkpt).

Successfully created checkpoint table HR.EMPLOYEES_CHKPT.

You can now add the Replicat group as follows, specifying the exact same EXTTRAIL that was used by the Extract group set up in the first database. So the Replicat group feeds on or consumes the trail created by the Extract group:

GGSCI (AnonDB) 4> ADD REPLICAT emp_rep, EXTTRAIL C:\OGG10G\dirdat\et, CHECKPOINTTABLE hr.employees_chkpt,

REPLICAT added.

Edit the parameter file for this Replicat group as follows:

GGSCI (AnonDB) 5> EDIT PARAM emp_rep

In the new file, enter the following:

REPLICAT emp_rep

USERID system@localhost:1521/FIPRD3, PASSWORD fipassword1

ASSUMETARGETDEFS

MAP hr.employees, TARGET hr.employees;

Because the tables have exactly the same DDL structure, you use the ASSUMETARGETDEFS parameter.

Now you can start the Replicat group:

GGSCI (AnonDB) 6> start REPLICAT emp_rep

Sending START request to MANAGER (‘GGSMGR’) …

REPLICAT EMP_REP starting

Wait a few seconds to see the status; if you try immediately, the status may say “stopped.” When you see the status asrunning”, check the detailed information, and also issue an info all command to show all running processes:

GGSCI (AnonDB) 7> status REPLICAT emp_rep

REPLICAT EMP_REP: STOPPED

GGSCI (AnonDB) 8> status REPLICAT emp_rep

REPLICAT EMP_REP: RUNNING

GGSCI (AnonDB) 11> info REPLICAT emp_rep detail

REPLICAT   EMP_REP   Last Started 2009-12-08 13:35   Status RUNNING

Checkpoint Lag       00:00:00 (updated 00:00:01 ago)

Log Read Checkpoint  File C:\OGG10G\dirdat\et000001

2009-12-08 13:33:24.000000  RBA 985

Extract Source                          Begin             End

C:\OGG10G\dirdat\et000001               2009-12-08 13:33  2009-12-08 13:33

C:\OGG10G\dirdat\et000000               * Initialized *   2009-12-08 13:33

Current directory    C:\OGG10G

Report file          C:\OGG10G\dirrpt\EMP_REP.rpt

Parameter file       C:\OGG10G\dirprm\EMP_REP.prm

Checkpoint file      C:\OGG10G\dirchk\EMP_REP.cpr

Checkpoint table     HR.EMPLOYEES_CHKPT

Process file         C:\OGG10G\dirpcs\EMP_REP.pcr

Error log            C:\OGG10G\ggserr.log

GGSCI (AnonDB) 12> info all

Program     Status      Group       Lag           Time Since Chkpt

MANAGER     RUNNING

EXTRACT     RUNNING     EMP_EXT     00:00:00      00:00:03

REPLICAT    RUNNING     EMP_REP     00:00:00      00:00:06

Posted in Best Practices, CDC, Data Integration, Data Warehouse, Oracle GoldenGate, Oracle Troubleshooting, Tips | Tagged: , , , , | Leave a Comment »

Oracle GoldenGate Best Practices and Tips

Posted by sdefilip on July 3, 2010

Lately I’ve been working, once again, with GoldenGate (now Oracle GoldenGate) data integration software. GoldenGate offers tremendously useful capabilities which include CDC (Change Data Capture), Data Warehouse ETL, efficient/low impact data replication from diverse database management systems, real time standby database maintenance (for high-availability, upgrades and patches, feeding Oracle Data Integrator (ODI) and data distribution. So, I thought I’d offer some GoldenGate Best Practices and Tips that I’ve learned largely by making mistakes:

I. Best Practices

PARALLEL PROCESSING

Ensure the system has enough shared memory. GoldenGate runs as an Oracle process. Each Extract or Replicat process requires upwards of 25-50 MB of system shared memory. This means less memory for the Oracle DBMS, especially the SGA.

Use parallel Replicat groups on the target system to reduce latency thru parallelism. Consider parallel Extract groups for tables that are fetch intensive (e.g., those that trigger SQL procedures).

Group tables that have R.I. to each other in the same Extract-Replicat pair.

Pair each Replicat with its own trail and corresponding Extract process.

When using parallel Replicats, configure each one to process a different portion of the overall data.

PASSTHRU PARAMETER

Consider using this parameter if there is no filtering, conversion or mapping required and you’re using DATAPUMP.

In pass-through mode, the Extract process does not look up table definitions, either from the database or from a data definitions file. Pass-through mode increases the throughput of the data pump, because all of the functionality that looks up object definitions is bypassed.

This saves database fetches to improve performance.

INSERTAPPEND

A new GoldenGate 10.4 feature.

Use for large transactions .

Puts records at end of table rather than doing a more costly insert into other areas of table.

DATAPUMP (not the Oracle DB utility)

1. Primary Extract group writes to a trail on the source system.

2. Reads this trail and sends the data across the network to a remote

trail on the target.

3. Adds storage flexibility and also serves to isolate the primary

Extract process from TCP/IP activity.

4. Can be configured for online or batch.

5. Can perform data filtering, mapping, and conversion, or it can be

configured in pass-through mode, where data is passively

transferred as-is, without manipulation.

6. Use to perform filtering thereby removing that processing overhead

from the primary extract group.

7. Use one or more pumps for each source and each target for

parallelism.

In most business cases, it is best practice to use a data pump. Some reasons for using a data pump include the following:

● Protection against network and target failures:

In a basic GoldenGate configuration, with only a trail on the target system, there is nowhere on the source system to store data that the Extract process continuously extracts into memory. If the network or the target system becomes unavailable, the primary Extract could run out of memory and abend. However, with a trail and data pump on the source system, captured data can be moved to disk, preventing the abend. When connectivity is restored, the data pump extracts the data from the source trail and sends it to the target system(s).

● You are implementing several phases of data filtering or transformation. When using complex filtering or data transformation configurations, you can configure a data pump to perform the first transformation either on the source system or on the target system,

and then use another data pump or the Replicat group to perform the second transformation.

● Consolidating data from many sources to a central target. When synchronizing multiple source databases with a central target database, you can store extracted data on each source system and use data pumps on each of those systems to send the data to a trail

on the target system. Dividing the storage load between the source and target systems reduces the need for massive amounts of space on the target system to accommodate data arriving from multiple sources.

● Synchronizing one source with multiple targets. When sending data to multiple target systems, you can configure data pumps on the source system for each target. If network connectivity to any of the targets fails, data can still be sent to the other targets

————————————————————————————————-

STEP BY STEP Datapump Configuration

ON THE SOURCE SYSTEM

To configure the Manager process . (Reference: Oracle GoldenGate Administration Guide, Version 10.4):

1. On the source, configure the Manager process according to the instructions in Chapter 2.

2. In the Manager parameter file, use the PURGEOLDEXTRACTS parameter to control the purging of files from the local trail.

To configure the primary Extract group:

3. On the source, use the ADD EXTRACT command to create a primary Extract group. For documentation purposes, this group is called ext.

ADD EXTRACT , TRANLOG, BEGIN [, THREADS ]

❍ Use TRANLOG as the data source option.

4. On the source, use the ADD EXTTRAIL command to create a local trail. The primary Extract writes to this trail, and the data-pump Extract reads it.

ADD EXTTRAIL , EXTRACT

❍ Use the EXTRACT argument to link this trail to the primary Extract group. The primary Extract group writes to this trail, and the data pump group reads it.

5. On the source, use the EDIT PARAMS command to create a parameter file for the primary Extract group. Include the following parameters plus any others that apply to your database environment:

– Identify the Extract group:

EXTRACT

– Specify database login information as needed for the database:

[SOURCEDB ,][USERID [, PASSWORD ]]

– Specify the local trail that this Extract writes to:

EXTTRAIL

– Specify tables to be captured:

TABLE .
;

To configure the data pump Extract group:

6. On the source, use the ADD EXTRACT command to create a data pump group. For documentation purposes, this group is called pump. In reality, I suggest naming this to match the extract name e.g., dpext1.

ADD EXTRACT , EXTTRAILSOURCE , BEGIN

❍ Use EXTTRAILSOURCE as the data source option, and specify the name of the local trail.

7. On the source, use the ADD RMTTRAIL command to specify a remote trail that will be created on the target system.

ADD RMTTRAIL , EXTRACT

❍ Use the EXTRACT argument to link the remote trail to the data pump group. The linked data pump writes to this trail.

8. On the source, use the EDIT PARAMS command to create a parameter file for the data pump. Include the following parameters plus any others that apply to your database environment.

————————————————————————————————

– Identify the data pump group:

EXTRACT

– Specify database login information as needed for the database:

[SOURCEDB ,][USERID [, PASSWORD ]]

– Specify the name or IP address of the target system:

RMTHOST , MGRPORT

– Specify the remote trail on the target system:

RMTTRAIL

– Allow mapping, filtering, conversion or pass data through as-is:

[PASSTHRU | NOPASSTHRU]

– Specify tables to be captured:

TABLE ;

NOTE – To use PASSTHRU mode, the names of the source and target objects must be identical. No column mapping, filtering, SQLEXEC functions, transformation, or other functions that require data manipulation can be specified in the parameter file. You can combine normal processing with pass-through processing by pairing PASSTHRU and NOPASSTHRU with different TABLE statements.

ON THE TARGET SYSTEM

To configure the Manager process:

9. On the target, configure the Manager process according to the instructions in the Administration Guide, Chapter 2.

10. In the Manager parameter file, use the PURGEOLDEXTRACTS parameter to control the purging of files from the local trail.

To configure the Replicat group:

11. On the target, create a Replicat checkpoint table. This is a best practice. For instructions, see “Creating a checkpoint table” on page 121 of Administration Guide.

12. On the target, use the ADD REPLICAT command to create a Replicat group. For documentation purposes, this group is called rep.

ADD REPLICAT , EXTTRAIL , BEGIN

❍ Use the EXTTRAIL argument to link the Replicat group to the remote trail.

13. On the target, use the EDIT PARAMS command to create a parameter file for the Replicat group. Include the following parameters plus any others that apply to your database environment.

– Identify the Replicat group:

REPLICAT

– State whether or not source and target definitions are identical:

SOURCEDEFS | ASSUMETARGETDEFS

– Specify database login information as needed for the database:

[TARGETDB ,] [USERID [, PASSWORD ]]

– Specify error handling rules:

REPERROR (, )

– Specify tables for delivery:

MAP .

, TARGET .

[, DEF <template name>];

(Reference: Oracle GoldenGate Administration Guide, Version 10.4)

REPLICAT CHECKPOINT TABLE

Create on target.

Can be used by all Replicat groups.

Prevents loss of data in case Replicat needs to be restarted.

PRIMARY KEYS

Must have a unique, non-null identifier, even if not the primary key.

Option is to use KEYCOLS option of MAP and TABLE parameters to

create a substitute key. Otherwise, GG uses multiple columns from

the table; will usually degrade performance. For data integrity,

the key used must contain the same values in corresponding rows of

all subject databases and contain the same columns in databases

where key resides

ADD TRACETABLE

Use default name of “GGS_TRACE”.

FAULT TOLERANCE

In a data distribution configuration, include a primary Extract

group and a data-pump Extract group in the source configuration, one

for each target.

If network connectivity fails, data can still be sent to the target.

————————————————————————————————-

II. PERFORMANCE

This section will cover anything that is performance related that was not also in section “I. Best Practices”.

A. MONITORING

Run Status of Particular Process

To find the run status of a particular process:

GGSCI (development) 23> status manager

Manager is running (IP port development.7809).

GGSCI (development) 24> status extract ext1

EXTRACT EXT1: RUNNING

Detailed information of a particular process:

GGSCI (development) 6> info extract ext1, detail

EXTRACT EXT1 Last Started 2010-01-23 11:19 Status RUNNING

Checkpoint Lag 00:00:00 (updated 00:00:02 ago)

Log Read Checkpoint Oracle Redo Logs

2010-01-23 10:45:18 Seqno 786, RBA 44710400

Target Extract Trails:

Remote Trail Name Seqno RBA Max MB

/u01/oracle/software/goldengate/dirdat/lt 55644 2 55644 10

Extract Source Begin End

/u02/oradata/acme/redo03.log 2010-01-23 11:13 2010-01-23 10:45

/u02/oradata/acme/redo02.log 2010-01-23 11:04 2010-01-22 11:13

/u02/oradata/acme/redo02.log 2010-01-23 10:42 2010-01-21 11:04

Not Available * Initialized * 2010-01-20 10:42

Current directory /u01/oracle/software/goldengate

Report file /u01/oracle/software/goldengate/dirrpt/EXT1.rpt

Parameter file /u01/oracle/software/goldengate/dirprm/ext1.prm

Checkpoint file /u01/oracle/software/goldengate/dirchk/EXT1.cpe

Process file /u01/oracle/software/goldengate/dirpcs/EXT1.pce

Stdout file /u01/oracle/software/goldengate/dirout/EXT1.out

Error log /u01/oracle/software/goldengate/ggserr.log

Detailed information of a particular process:

GGSCI (devu007) 6> info extract ext1, detail

EXTRACT EXT1 Last Started 2010-02-19 11:19 Status RUNNING

Checkpoint Lag 00:00:00 (updated 00:00:02 ago)

Log Read Checkpoint Oracle Redo Logs

2010-02-19 10:45:18 Seqno 786, RBA 44710400

Target Extract Trails:

Remote Trail Name Seqno

/u01/oracle/software/goldengate/dirdat/lt 2

RBA Max MB

55644 10

Extract Source Begin End

/u02/oradata/acme/redo03.log 2010-02-19 11:13 2010-02-26 10:45

/u02/oradata/acme/redo02.log 2010-02-19 11:04 2010-02-19 11:13

/u02/oradata/acme/redo02.log 2010-02-18 10:42 2010-02-19 11:04

Not Available * Initialized * 2010-02-18 10:42

Current directory /u01/oracle/software/goldengate

Report file /u01/oracle/software/goldengate/dirrpt/EXT1.rpt

Parameter file /u01/oracle/software/goldengate/dirprm/ext1.prm

Checkpoint file /u01/oracle/software/goldengate/dirchk/EXT1.cpe

Process file /u01/oracle/software/goldengate/dirpcs/EXT1.pce

Stdout file /u01/oracle/software/goldengate/dirout/EXT1.out

Error log /u01/oracle/software/goldengate/ggserr.log

View processing rate – can use ‘hr’,’min’ or ‘sec’ as a parameter:

GGSCI (devu007) 37> stats extract ext2 reportrate hr

Sending STATS request to EXTRACT EXT2 …

Start of Statistics at 2010-02-19 10:04:46.

Output to /u01/oracle/ggs/dirdat/cc:

Extracting from SH.CUSTOMERS to SH.CUSTOMERS:

*** Total statistics since 2010-02-19 09:29:48 ***

Total inserts/hour: 0.00

Total updates/hour: 95258.62

Total deletes/hour: 0.00

Total discards/hour: 0.00

Total operations/hour: 95258.62

*** Daily statistics since 2010-02-19 09:29:48 ***

Total inserts/hour: 0.00

Total updates/hour: 95258.62

Total deletes/hour: 0.00

Total discards/hour: 0.00

Total operations/hour: 95258.62

*** Hourly statistics since 2010-02-19 10:00:00 ***

No database operations have been performed.

*** Latest statistics since 2010-02-19 09:29:48 ***

Total inserts/hour: 0.00

Total updates/hour: 95258.62

Total deletes/hour: 0.00

Total discards/hour: 0.00

Total operations/hour: 95258.62

End of Statistics.

View latency between the records processed by Goldengate and the timestamp in the data source:

GGSCI (development) 13> send extract ext2, getlag

Sending GETLAG request to EXTRACT EXT2 …

Last record lag: 3 seconds.

At EOF, no more records to process.

GGSCI (development) 15> lag extract ext*

Sending GETLAG request to EXTRACT EXT1 …

Last record lag: 1 seconds.

At EOF, no more records to process.

Sending GETLAG request to EXTRACT EXT2 …

Last record lag: 1 seconds.

At EOF, no more records to process.

Viewing the GoldenGate error log as well as history of commands executed and other events:

For UNIX:

vi ggserr.log

Or

GGSCI command: VIEW GGSEVT

View the process report:

GGSCI (development) 2> view report ext1

GGSCI (development) 2> view report rep1

B. PERFORMANCE TIPS

To reduce bandwidth requirements:

Use compression options of the RMTHOST parameter to compress data

before it is sent across the network. Weigh the benefits of

compression against the CPU resources that are required to perform

the compression.

To increase the TCP/IP packet size:

a.  Use the TCPBUFSIZE option of the RMTHOST parameter to increase the

size of the TCP socket buffer that Extract maintains. By increasing

the size of the buffer, you can send larger packets to the target

system. Consult with Network Support before setting TCPBUFSIZE.

b.  Use SQL Arrays

The BATCHSQL parameter will increase the performance of Replicat. BATCHSQL causes Replicat to create arrays for similar SQL statements and apply them at an accelerated rate. Normally, Replicat applies one SQL statement at a time.

• At 100 bytes of data per row change, BATCHSQL can

improve Replicat’s performance by up to 300 percent; actual

performance benefits will vary, depending on the oeverall

demand on system resources.

• At around 5,000 bytes of data per row change, the benefits of

using BATCHSQL diminish.

. Improve I/O within the system configuration

• Place trail files on the fastest disk controller.

• Use RAID 0+1 disk configuration because GoldenGate performs

sequential writes.

* Be careful with the following points. Increasing the values of

these parameters will improve performance but take longer to

reprocess your data in case of process failure.

• Use the CHECKPOINTSECS in Extract or Replicat; if increased,

less frequent checkpoints; increases data to be reprocessed if

process fails; keep transaction logs available in case of

reprocessing

• Use the GROUPTRANSOPS; increases number of SQL operations in a Replicat ;

reduces I/O to checkpoint file and checkpoint table

Data Filtering and Conversion:

Use primary Extract for data capture only.

Use a data pump on the source to perform filtering and thereby send

less data over the network.

Alternatively, use Replicat for conversion and, if the network can

handle large amounts of data, also for filtering.

**(Upcoming Post - “Troubleshooting GoldenGate Extracts”)

Posted in Best Practices, CDC, Data Integration, Data Warehouse, Golden Gate, Oracle GoldenGate, Replication, Tips | Leave a Comment »

 
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