Reading Unix Compressed files without uncompressing them using Zcat, Zless, Zgrep, Zdiff

 

Mostly we have situation that we  need to  see content  of compressed  files without actually  uncompressing it . This  can be achieved using Z commands 

Below are options using z commands 

Viewing the compressed file with zcat.

Paging the compressed file with zless / zmore.

Searching inside the compressed file with zgrep / zegrep.

Comparison of file using zdiff / zcmp

Below are examples : 

$ zcat big-file.txt.gz 

[Note: View the file without uncompressing it]

zcat big-file.txt.gz > big-file.txt

[Note: Uncompress the file]

$ zcat filename.gz | more

$ zcat filename.gz | less

(or)

$ zless filename.gz

$ zmore filename.gz

$ zgrep -i less test-file.txt.gz

$ zdiff file1.txt.gz file2.txt.gz

Oracle Database Health Check with DBMS_HM -- HEALTH CHECK MONITOR

 

Was  trying to explore options  for  Block corruption checks came across this  old gem DBMS_HM  ,  and want to  document  it .  Though it is old utility introduced in 11g 

Health check run in the two mode :

1) Online Mode: Health check run while database is in open or mounted mode.
2) Offline Mode: Health check run while database is in nomount mode.Only the Redo Integrity Check and the DB Structure Integrity Check can be used in DB-offline mode.





Types of health check : 

1) DB Structure Integrity Check: This option  check datafiles if there is corruption or inaccessible situtation.if database is open this check logfile and datafile if nomount mode  only checkhed controlfile.
2) Data Block Integrity Check: This check detects disk image block corruptions such as checksum failures and logical inconsistencies within the block.
3) Redo Integrity Check: This check scans  redo log for accessibility and corruption, as well as the archive logs, if available.
4) Undo Segment Integrity Check: This check finds logical undo corruptions.
5) Transaction Integrity Check: This check is identical to the Undo Segment Integrity Check but it checks only one specific transaction.
6) Dictionary Integrity Check: This check integrity of core dictionary objects, such as tab$ and col$



Sample : 

1) DB Structure Integrity Check: 
SQL> BEGIN
DBMS_HM.RUN_CHECK('Dictionary Integrity Check', 'hk_run');
END;
/


2)  Data Block Integrity Health Check

BEGIN
DBMS_HM.RUN_CHECK (
check_name   => ‘Data Block Integrity Check’,
run_name     => ‘datablockint’,
input_params => ‘BLC_DF_NUM=4;BLC_BL_NUM=111’);
END;
/

3) Transaction Health Check: 
BEGIN
DBMS_HM.RUN_CHECK (
check_name   => ‘Transaction Integrity Check’,
run_name     => ‘transacitoncheck’,
input_params => ‘TXN_ID=7.33.2’);
END;
/

4) Undo Segment Health Check: 
BEGIN
DBMS_HM.RUN_CHECK (
check_name   => ‘Undo Segment Integrity Check’,
run_name     => 'undosegmentcheck',
input_params => ‘USN_NUMBER=1’);
END;
/




 Health Monitor Views:

V$HM_CHECK – lists all Health checks
V$HM_CHECK_PARAM - lists information about Health checks, input parameters and defaults. Join CHECK_ID with V$HM_CHECK.ID.
V$HM_FINDING – Information about findings of Health Monitor runs.
V$HM_INFO – Information about runs, finding and recommendations.
V$HM_RECOMMENDATION – information about any recommendation from Health check runs.
V$HM_RUN – Information about checker runs like name, mode, time of run, etc.


SQL>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;

SQL>select * from V$HM_RECOMMENDATION;
SET LONG 100000
SET LONGCHUNKSIZE 1000
SET PAGESIZE 1000
SET LINESIZE 512
SELECT DBMS_HM.get_run_report('undosegmentcheck') FROM dual;





Viewing Reports Using the ADRCI Utility

adrci>>
adrci> show hm_run

Creating Awr Snapshot in Oracle Active Dataguard Standby Database -- UMF TOPOLOGY

 

The feature uses the Remote Management Framework which comes with a New Oracle built-in user called SYS$UMF. This user is locked by default and should be unlocked before configuring the RMF.

Since Oracle Database 12c Release 2 (12.2), Automatic Workload Repository (AWR) data can be captured for Active Data Guard (ADG) standby databases. This feature enables analyzing any performance-related issues for ADG standby databases

AWR snapshots for ADG standby databases are called remote snapshots. A database node, called destination, is responsible for storing snapshots that are collected from remote ADG standby database nodes, called sources.

Optionally we  can also  use statspack following below documents 

Installing and Using Standby Statspack (Doc ID 454848.1)

Installing and Using Standby Statspack in 12c Multitenant Database (Doc ID 2020285.1)

Step 1: Unlock SYS$UMF user and change its password using SYS user. 

SYS$UMF account is used to administer Remote Management Framework, including the remote Automatic Workload Repository (AWR).

SQL>alter user sys$umf identified by oracle account unlock;

Step 2: Create the database link from primary to the standby database and standby database to a primary.

Primary database DB_UNIQUE_NAME: Primary

Standby database DB_UNIQUE_NAME: Standby

SQL>  create database link primary_to_standby connect to "SYS$UMF" identified by "oracle" using 'Standby';

Database link created.

SQL> create database link standby_to_primary connect to "SYS$UMF" identified by "oracle" using 'Primary';

Database link created.

Step 3: Now we need to configure database to add topology. 

Each database name must be assigned a unique name. Default name is db_unique_name. In my case dbupgrade and std_dbupgarde.

DBMS_UMF.CONFIGURE_NODE procedure configures a node that needs to be registered with the RMF topology. This procedure must be executed on the node that needs to be configured.

DBMS_UMF.CONFIGURE_NODE(

   node_name          IN VARCHAR2 DEFAULT NULL,

   dblink_to_target   IN VARCHAR2 DEFAULT NULL);

On primary :

 alter system set "_umf_remote_enabled"=TRUE scope=BOTH;

SQL> exec dbms_umf.configure_node('Primary');

PL/SQL procedure successfully completed.

On standby :

SQL>exec dbms_umf.configure_node ('Standby','standby_to_primary');

PL/SQL procedure successfully completed.

Step 4: Create RMF topology

DBMS_UMF.CREATE_TOPOLOGY procedure creates the RMF topology and designates the node on which it is executed as the destination node for that topology.

DBMS_UMF.CREATE_TOPOLOGY( topology_name IN VARCHAR2);

SQL> exec DBMS_UMF.create_topology ('Topology_1');

PL/SQL procedure successfully completed.

Step 5: Check DBA_UMF_REGISTRATION and dba_umf_topology view

SQL> select * from dba_umf_topology;

TOPOLOGY_NAME TARGET_ID TOPOLOGY_VERSION TOPOLOGY

--------------- ---------- ---------------- --------

Topology_1 4040060753   8 ACTIVE

SQL> col node_name format a20

SQL> select * from DBA_UMF_REGISTRATION;

TOPOLOGY_NAME      NODE_NAME      NODE_ID  NODE_TYPE AS_SO AS_CA  STATE

-------------------- -------------------- ---------- ---------- ----- -----  -----

Topology_1      Primary 4040060753       0 FALSE FALSE  OK

Step 6: Register the standby database with topology

DBMS_UMF.REGISTER_NODE function and procedure register a node with the RMF topology. This procedure and function must be executed only on the destination node in the RMF topology.

Syntax

DBMS_UMF.REGISTER_NODE(

   topology_name          IN  VARCHAR2,

   node_name              IN  VARCHAR2,

   dblink_to_node         IN  VARCHAR2 DEFAULT NULL,

   dblink_from_node       IN  VARCHAR2 DEFAULT NULL,

   as_source              IN  VARCHAR2 DEFAULT 'TRUE',

   as_candidate_target    IN  VARCHAR2 DEFAULT 'FALSE');

SQL> exec DBMS_UMF.register_node ('Topology_1', 'Standby', 'primary_to_standby', 'standby_to_primary', 'FALSE','FALSE');

PL/SQL procedure successfully completed.

Step 7: Enable AWR service on the remote node

DBMS_WORKLOAD_REPOSITORY.REGISTER_REMOTE_DATABASE

procedure registers a remote database in the Automatic Workload Repository (AWR) using the Remote Management Framework (RMF).

DBMS_WORKLOAD_REPOSITORY.REGISTER_REMOTE_DATABASE(

   node_name      IN VARCHAR2,

   topology_name  IN VARCHAR2 DEFAULT NULL);

SQL> exec DBMS_WORKLOAD_REPOSITORY.register_remote_database(node_name=>'Standby');

PL/SQL procedure successfully completed.

Step 8: Now again verify in dba_umf_registration view

SQL> select * from dba_umf_registration;

TOPOLOGY_NAME NODE_NAME    NODE_ID  NODE_TYPE AS_SO AS_CA STATE

--------------- --------------- ---------- ---------- ----- ----- --------------------

Topology_1 Primary 4040060753     0 FALSE FALSE OK

Topology_1 Standby 1978111757     0 FALSE FALSE OK

Step 9: Create snapshot using RMF in the primary database for the remote database.

function and procedure create a remote snapshot using the Remote Management Framework (RMF). The function returns the snapshot ID.

DBMS_WORKLOAD_REPOSITORY.CREATE_REMOTE_SNAPSHOT(

   node_id     IN NUMBER,

   flush_level IN VARCHAR2 DEFAULT 'BESTFIT');

SQL> exec dbms_workload_repository.create_remote_snapshot('Standby');

PL/SQL procedure successfully completed.

Step 10 : Create AWR report from a standby database

Note: NODE ID generated above consider as DBID for a standby database.

After specifying AWR report type HTML it will ask for DBID, give dbid associated with nodeid in dba_umf_registration.

Step 11 : After Role Switchover 

Everything should be set now, you need to be aware after a switchover this procedure might not work . We can make the role change by executing the following procedure on the candidate destination

SQL> EXEC DBMS_UMF.SWITCH_DESTINATION(topology name, force_switch=>FALSE);

BUG 21046490 - UMF-ADG: FAILED TO TAKE SNAPSHOTS AFTER SWITCHOVERS IN ADG[This section is not visible to customers.]

Per non-published Bug 28930258, if in a hurry and has not constructed a topology, then check the value of _remote_awr_enabled on the current primary database.

SELECT b.ksppstvl "Session Value",

c.ksppstvl "Instance Value"

FROM sys.x$ksppi a,

sys.x$ksppcv b,

sys.x$ksppsv c

WHERE

a.indx = b.indx

AND

a.indx = c.indx

AND a.ksppinm = '_remote_awr_enabled';

If it is equal to TRUE, then simply set it to FALSE.

ALTER SYSTEM SET "_remote_awr_enabled" = FALSE SCOPE = BOTH SID = '*';

This will cause AWR snapshots to be generated automatically again.

-- Run in case want to DROP the topology

SQL>  exec DBMS_UMF.drop_topology('NAME-OF-TOPOLOGY');

Known  Errors : 

We need to run at least two to get the begin_snap and end_snap.

If you encounter "ORA-13516: AWR Operation failed: Remote source not registered for AWR" then manually switch a few (2-3) logfiles on primary:

alter system switch logfile;

If you encounter "ORA-15766: already registered in an RMF topology" unregister the node as below and then rerun "DBMS_UMF.register_node":

exec DBMS_UMF.unregister_node ('Topology_1', 'stby');

PL/SQL procedure successfully completed.

If you encounter "ORA-13519: Database id (1730117407) exists in the workload repository" unregister the remote database as below and then rerun "DBMS_WORKLOAD_REPOSITORY.register_remote_database":

exec DBMS_WORKLOAD_REPOSITORY.unregister_remote_database('stby','Topology_1',TRUE);

Views : 

set line 132

col topology_name format a15

col node_name format a15

select * from dba_umf_topology;

select * from dba_umf_registration;

select * from dba_umf_service;

select * from dba_umf_link;

References : 

https://docs.oracle.com/en/database/oracle/oracle-database/19/tgdba/gathering-database-statistics.html#GUID-E1369092-DA6B-4CF4-B286-69D4A3BDFA1E

How to Generate AWRs in Active Data Guard Standby Databases (Doc ID 2409808.1)