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понедельник, 31 октября 2016 г.

Excluding DDL in IE (Integrated Extract) using DBMS_STREAMS_ADM.SET_TAG

A couple of months ago I had to configure OGG IE (Oracle GoldenGate Integrated Extract) to exclude specific DDL from replication.
Having worked a lot with Oracle Streams, I decided to utilize DBMS_STREAMS_ADM.SET_TAG for that task.
I found a relevant MOS document How to exclude ddl in IE (integrated extract) issued from a specific user? (Doc ID 2107293.1) pretty fast.
The document suggested putting TRANLOGOPTIONS EXCLUDETAG into an extract parameter file and than all DDL statements preceeding with DBMS_STREAMS_SET.TAG should not be replicated.
Unfortunately the provided solution did not work for me.
I used OGG Server 12.2.0.1.160823 on Linux x86-64 (which means that I applied the latest bundle patch available at the moment).
The issue can be easily reproduced.
The database version used in this test was 12.1.0.2.160719.
Here are my extract and replicat parameter files:
GGSCI (misha2 as tc_ogg_replicat@db2) 112> view params etag

EXTRACT ETAG

USERIDALIAS db1_tc_ogg_extract
TRANLOGOPTIONS EXCLUDETAG 34
LOGALLSUPCOLS
EXTTRAIL ./dirdat/tc
DDL INCLUDE ALL

TABLE TC.*;

GGSCI (misha2 as tc_ogg_replicat@db2) 113> view params rtag

REPLICAT RTAG

USERIDALIAS db2_tc_ogg_replicat

MAP TC.*, TARGET TC.*;
Test schema TC will be used for demonstration and I setup the extract to exclude any LCRs with tag 34.
Then I am going to create and start the OGG processes with the following script:
GGSCI (misha2 as tc_ogg_replicat@db2) 138> alter credentialstore add user tc_ogg_extract@db1 password tc_ogg_extract alias db1_tc_ogg_extract


Credential store in ./dircrd/ altered.

GGSCI (misha2 as tc_ogg_replicat@db2) 139> alter credentialstore add user tc_ogg_replicat@db2 password tc_ogg_replicat alias db2_tc_ogg_replicat


Credential store in ./dircrd/ altered.

GGSCI (misha2 as tc_ogg_replicat@db2) 140> 

GGSCI (misha2 as tc_ogg_replicat@db2) 140> dblogin useridalias db1_tc_ogg_extract

Successfully logged into database.

GGSCI (misha2 as tc_ogg_extract@db1) 141> add extract etag integrated tranlog begin now

EXTRACT (Integrated) added.


GGSCI (misha2 as tc_ogg_extract@db1) 142> add exttrail ./dirdat/tc extract etag

EXTTRAIL added.

GGSCI (misha2 as tc_ogg_extract@db1) 143> register extract etag database


2016-10-31 12:46:49  INFO    OGG-02003  Extract ETAG successfully registered with database at SCN 39029510.

GGSCI (misha2 as tc_ogg_extract@db1) 144> 

GGSCI (misha2 as tc_ogg_extract@db1) 146> dblogin useridalias db2_tc_ogg_replicat

Successfully logged into database.

GGSCI (misha2 as tc_ogg_replicat@db2) 147> add replicat rtag , integrated, exttrail ./dirdat/tc

REPLICAT (Integrated) added.


GGSCI (misha2 as tc_ogg_replicat@db2) 148> start extract etag

Sending START request to MANAGER ...
EXTRACT ETAG starting


GGSCI (misha2 as tc_ogg_replicat@db2) 149> start replicat rtag

Sending START request to MANAGER ...
REPLICAT RTAG starting
I used two databases in my setup - db1 and db2 that I named SOURCE and TARGET in the rest of this blog post for the sake of clarity.
The extract configured to capture the changes from db1 database and write data to trail files.
The replicat reads the trail files and applies the changes into db2 database.
Next I am about to run the following code in the source database from which the extract captures changes:
TC@SOURCE> create sequence t_seq;

Sequence created.

TC@SOURCE> 
TC@SOURCE> create table t(
  2    id  int default t_seq.nextval,
  3    msg varchar2(10))
  4  /

Table created.

TC@SOURCE> 
TC@SOURCE> insert into t(msg) values ('NO TAG');

1 row created.

TC@SOURCE> commit;

Commit complete.

TC@SOURCE> 
TC@SOURCE> exec dbms_streams_adm.set_tag( hextoraw('12'))

PL/SQL procedure successfully completed.

TC@SOURCE> 
TC@SOURCE> insert into t(msg) values ('TAG '||rawtohex(dbms_streams_adm.get_tag));

1 row created.

TC@SOURCE> commit;

Commit complete.

TC@SOURCE> 
TC@SOURCE> exec dbms_streams_adm.set_tag( hextoraw('34'))

PL/SQL procedure successfully completed.

TC@SOURCE> 
TC@SOURCE> insert into t(msg) values ('TAG '||rawtohex(dbms_streams_adm.get_tag));

1 row created.

TC@SOURCE> commit;

Commit complete.

TC@SOURCE> 
TC@SOURCE> exec dbms_streams_adm.set_tag( hextoraw('56'))

PL/SQL procedure successfully completed.

TC@SOURCE> 
TC@SOURCE> insert into t(msg) values ('TAG '||rawtohex(dbms_streams_adm.get_tag));

1 row created.

TC@SOURCE> commit;

Commit complete.
Havind done that, I got next results in SOURCE database:
TC@SOURCE> select * from t;

        ID MSG
---------- ----------
         1 NO TAG
         2 TAG 12
         3 TAG 34
         4 TAG 56
And that in TARGET:
TC@TARGET> select * from t order by id;

        ID MSG
---------- ----------
         1 NO TAG
         2 TAG 12
         4 TAG 56
Notice that an insert of a record with ID=3, MSG="TAG 34" was not replicated because we have filtered out that record on the extract.
That works flawlessly being executed for DML, but it does not work for DDL:
TC@SOURCE> exec dbms_streams_adm.set_tag( hextoraw('12'))

PL/SQL procedure successfully completed.

TC@SOURCE> 
TC@SOURCE> alter table t add tag12 int;

Table altered.

TC@SOURCE> 
TC@SOURCE> exec dbms_streams_adm.set_tag( hextoraw('34'))

PL/SQL procedure successfully completed.

TC@SOURCE> 
TC@SOURCE> alter table t add tag34 int;

Table altered.

TC@SOURCE> describe t
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 MSG                                                VARCHAR2(10)
 TAG12                                              NUMBER(38)
 TAG34                                              NUMBER(38)
I have added two columns to the table and the second one, TAG34, should not have been replicated.
But in fact, both of the commands were replicated:
TC@TARGET> describe t
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 MSG                                                VARCHAR2(10)
 TAG12                                              NUMBER(38)
 TAG34                                              NUMBER(38)
It means that aforementioned MOS document How to exclude ddl in IE (integrated extract) issued from a specific user? (Doc ID 2107293.1) does not work in that configuration which, by the way, I think is quite typical.
Luckily, Oracle Support published another note after we concluded our work on the SR: EXCLUDETAG Issue With Integrated Extract While Excluding DDL For Specific User (Doc ID 2185538.1).
We need to put the following line into an extract parameter file to get it working: tranlogoptions _dbfilterddl
GGSCI (misha2 as tc_ogg_replicat@db2) 168> view params etag

EXTRACT ETAG

USERIDALIAS db1_tc_ogg_extract
TRANLOGOPTIONS EXCLUDETAG 34
TRANLOGOPTIONS _dbfilterddl
LOGALLSUPCOLS
EXTTRAIL ./dirdat/tc
DDL INCLUDE ALL

TABLE TC.*;
Having added that, the same code adding two columns worked as it should:
TC@SOURCE> describe t
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 MSG                                                VARCHAR2(10)
 TAG12                                              NUMBER(38)
 TAG34                                              NUMBER(38)

TC@TARGET> describe t
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER(38)
 MSG                                                VARCHAR2(10)
 TAG12                                              NUMBER(38)
It means that TAG34 column, being added with tag 34, was not replicated.
There is also a new line in a ggserr.log file that was not present when I started the extract without _dbfilterddl:
Logmining server DDL filtering enabled.
2016-10-31 13:54:33  INFO    OGG-00963  Oracle GoldenGate Manager for Oracle, mgr.prm:  Command received from GGSCI on host [172.16.113.245]:57437 (START EXTRACT ETAG ).
2016-10-31 13:54:33  INFO    OGG-00960  Oracle GoldenGate Manager for Oracle, mgr.prm:  Access granted (rule #6).
2016-10-31 13:54:34  INFO    OGG-00992  Oracle GoldenGate Capture for Oracle, etag.prm:  EXTRACT ETAG starting.
2016-10-31 13:54:34  INFO    OGG-03059  Oracle GoldenGate Capture for Oracle, etag.prm:  Operating system character set identified as UTF-8.
2016-10-31 13:54:34  INFO    OGG-02695  Oracle GoldenGate Capture for Oracle, etag.prm:  ANSI SQL parameter syntax is used for parameter parsing.
2016-10-31 13:54:38  INFO    OGG-03522  Oracle GoldenGate Capture for Oracle, etag.prm:  Setting session time zone to source database time zone 'GMT'.
2016-10-31 13:54:38  WARNING OGG-04033  Oracle GoldenGate Capture for Oracle, etag.prm:   LOGALLSUPCOLS has set the NOCOMPRESSDELETES and GETUPDATEBEFORES parameters on.
2016-10-31 13:54:38  INFO    OGG-01815  Oracle GoldenGate Capture for Oracle, etag.prm:  Virtual Memory Facilities for: BR
    anon alloc: mmap(MAP_ANON)  anon free: munmap
    file alloc: mmap(MAP_SHARED)  file free: munmap
    target directories:
    /u01/app/oracle/12.2.0.1/ggs/BR/ETAG.
2016-10-31 13:54:38  INFO    OGG-01851  Oracle GoldenGate Capture for Oracle, etag.prm:  filecaching started: thread ID: 140594853938944.
2016-10-31 13:54:38  INFO    OGG-00975  Oracle GoldenGate Manager for Oracle, mgr.prm:  EXTRACT ETAG starting.
2016-10-31 13:54:38  INFO    OGG-01815  Oracle GoldenGate Capture for Oracle, etag.prm:  Virtual Memory Facilities for: COM
    anon alloc: mmap(MAP_ANON)  anon free: munmap
    file alloc: mmap(MAP_SHARED)  file free: munmap
    target directories:
    /u01/app/oracle/12.2.0.1/ggs/dirtmp.
2016-10-31 13:54:58  WARNING OGG-02045  Oracle GoldenGate Capture for Oracle, etag.prm:  Database does not have streams_pool_size initialization parameter configured.
2016-10-31 13:54:59  INFO    OGG-02248  Oracle GoldenGate Capture for Oracle, etag.prm:  Logmining server DDL filtering enabled.
2016-10-31 13:55:08  INFO    OGG-02068  Oracle GoldenGate Capture for Oracle, etag.prm:  Integrated capture successfully attached to logmining server OGG$CAP_ETAG using OGGCapture API.
2016-10-31 13:55:08  INFO    OGG-02089  Oracle GoldenGate Capture for Oracle, etag.prm:  Source redo compatibility version is: 12.1.0.2.0.
2016-10-31 13:55:08  INFO    OGG-02086  Oracle GoldenGate Capture for Oracle, etag.prm:  Integrated Dictionary will be used.
2016-10-31 13:55:09  WARNING OGG-02905  Oracle GoldenGate Capture for Oracle, etag.prm:  Replication of OID column in object tables may diverge.
2016-10-31 13:55:09  INFO    OGG-00993  Oracle GoldenGate Capture for Oracle, etag.prm:  EXTRACT ETAG started.

tl;dr

EXCLUDETAG parameter does not work when a tag is set using DBMS_STREAMS_ADM.SET_TAG in OGG 12.2.0.1.160823
. It prevents replicating only DML commands and does not restrict DDL commands from being replicated.
We could use underscope parameter _dbfilterddl in the extract parameter file like in the following line:
TRANLOGOPTIONS _dbfilterddl
This way we may restrict both DDL and DML commands from being replicated when the appropriate tag is set (or any in case we use "EXCLUDETAG +" in the extract parameter file).

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