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MySQL | Maria DB Galera Cluster Concepts | Galera Cluster Components

Galera cluster Components fro MySQL | MariaDB: 

DBMS, Plugins, and Interface.
Transactional Database Management System that runs on the individual node, MySQL or MariaDB.Galera Replication Plugin which enables write-set replication service functionality.Group Communication Plugins, such as gcomm and Spread. The Spread toolkit provides a high performance messaging service that is resilient to faults across local and wide area networks.wsrep API. The interface consists of wsrep hooks and dlopen() 1. wsrep hooks - integration with DB server engine for write-set replication.
2. dlopen() - Function that makes the wsrep provider available to the wsrep hooks

wsrep API uses a Global Transaction ID in order to keep the state identical across the cluster.

Galera Replication Plugin consists of the following components:
Certification Layer which prepares the write-sets and performs certification checks on them, ensuring that they can be applied.Replication Layer which manages the replication protocol a…

MySQL Percona Tool Kit

Kill queries running longer than 60s:
pt-kill --busy-time 60 --kill
Print, do not kill, queries running longer than 60s:
pt-kill --busy-time 60 --print
Print all login processes:
pt-kill --match-state login --print --victims all
Find all tables created more than a day ago, which use the MyISAM engine, and print their names:
 pt-find --ctime +1 --engine MyISAM
Find InnoDB tables and convert them to MyISAM:
pt-find --engine InnoDB --exec "ALTER TABLE %D.%N ENGINE=MyISAM"
Find empty tables in the test and junk databases, and delete them:
pt-find --empty junk test --exec-plus "DROP TABLE %s"
Find tables more than five gigabytes in total size:
pt-find --tablesize +5G
Summarize MySQL information nicely:
pt-mysql-summary --user=root
Diff MySQL configuration files and server variables:
Diff host1 config from SHOW VARIABLES against host2:
pt-config-diff h=host1 h=host2
Diff config from [mysqld] section in my.cnf against host1 config:
pt-config-diff /etc/my.cnf h=host1
Diff the [mysqld] section …

My SQL Daily SQL

Get list of tables with particular column
TABLE_NAME NOT REGEXP "^test_.*(_archive)|(_new)|(_old)$" AND
COLUMN_NAME = '<column_name>' AND
TABLE_SCHEMA ='<schema_name>'

Find number of connections:
SHOW STATUS WHERE `variable_name` = 'Threads_connected';

Find if some table is locked:
`Database` LIKE '[DBNAME]' AND In_use > 0;

Find all foreign keys on a table:
REFERENCED_TABLE_NAME = '<table_name>';

Oracle Gather Schema | Table Statistics | Extended Statistics | method_opt

Select Histograms for tables:-

SELECT column_name, num_distinct, histogram FROM   user_tab_col_statistics WHERE  table_name = '<table_name>';

Gather tables stats using DBMS_STATS for schema
exec dbms_stats.gather_schema_stats
( ownname => '<owner_name>', options => 'GATHER AUTO', estimate_percent => dbms_stats.auto_sample_size, method_opt  => 'FOR ALL COLUMNS SIZE 1', cascade => true, degree => 10, granularity => 'ALL' );
exec dbms_stats.gather_schema_stats
( ownname=> 'SAMAPPL', estimate_percent => dbms_stats.auto_sample_size, method_opt => 'FOR ALL COLUMNS SIZE 1', cascade=> true, granularity=>'ALL', degree => 10 ); Extended statistics Ref.:

method_opt options FOR ALL COLUMNS SIZE 1
FOR COLUMNS SIZE 254 <column_name> FOR ALL IND…

Retrive Exadata Version and Configuration Information

Option 1: Use DBMS_LOB package to get cell configuration information, as column CONFVAL is CLOB
spool confval.txt and search for text make in text file you will see get value in tag <makeModel>  </makeModel>

set pagesize 0
SELECT dbms_lob.substr(CONFVAL,4000,1) from V$CELL_CONFIG;
spool off

This option is good if you don't  have privilege to access storage node and can't execute command Cellcli. You would be able to find out interleaving attribute about Celldisk also as follows.


Explore about interleaving attribute of Celldisk at

Option 2:
From Tanel Podder Blog. I have modified some format to display Make Model properly.
COL cv_cellname       HEAD CELL_NAME        FOR A30
COL cv_cell_path      HEAD CELL_PATH        FOR A30
COL cv_cellversion    HEAD CE…

Oracle ADRCI - Automatic Diagnostic Repository Command Interpreter

adrci - Automatic Diagnostic Repository Command Interpreter

$ adrci
adrci> show homes
Set home for Oracle Database:
adrci> set home
List incidents:
adrci> show incidents
Pack incident for incident number:
adrci> ips pack incident <incident_no> in /tmp
Show incident information in brief:
adrci> show incident -mode brief -p "incident_id=<incident_no>"
Pack incident for problem key (Get problem key by commnad show incidents):
adrci> ips create package problemkey "ORA 600 [qmtGetBaseType]"
Pack incident by time (Get time record by commnd show incidents):
adrci> IPS CREATE PACKAGE TIME '2017-08-23 11:31:44.296000 -07:00' to '2017-08-22 08:32:16.394000 -07:00'