MySQL check query execution time, number of executions - Using general log

-

How to get MySQL Query Time using general log data

Quickly finding the query execution time can be very helpful during scenarios such as load tests. Below are simple set of steps to extract the query time , number of execution based on general log.
  • Set general_log and log_output parameters, this should log all queries to mysql.general_log table
    • SET global general_log = 1;
     SET global log_output = 'table';
  • Create a table with id column included to general log table
    • CREATE TABLE `test.general_log_id` ( id MEDIUMINT NOT NULL AUTO_INCREMENT, `event_time` timestamp(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6) ON UPDATE CURRENT_TIMESTAMP(6), `user_host` mediumtext NOT NULL, `thread_id` bigint(21) unsigned NOT NULL, `server_id` int(10) unsigned NOT NULL, `command_type` varchar(64) NOT NULL, `argument` mediumblob NOT NULL, PRIMARY KEY (id) ) ENGINE=innodb DEFAULT CHARSET=utf8 COMMENT='General log';
  • Filter out the data from mysql.general_log and insert to create table above, e.g. below filters by load test app server
    • insert into general_log_id(id,event_time,user_host,thread_id,server_id,command_type,argument) select null,event_time,user_host,thread_id,server_id, command_type,argument from mysql.general_log where user_host like '%86.36%' order by event_time;
The inclusion of the ID column can be utilized in various scenarios, one of it is to find the query time for each query using below.
Note : This query time is the difference in which mysql started each of query execution, so this include time taken outside of the database as well.
select * from (SELECT A.id, A.event_time, (B.event_time - A.event_time) AS timedifference, A.argument FROM general_log_id A INNER JOIN general_log_id B ON B.id = (A.id + 1) ORDER BY A.id ASC) as C order by 3;

MySQL query time

How to get MySQL number of query execution

Same extracted data set can be used to get the number of query execution from filtered data set.
e.g. select queries with more than 5 execution
select argument as query, count(*) as noexe from general_log_id where command_type='query' and argument like '%SELECT%' group by query having count(*) >5 order by 2;

Other than the two listed above, above general log data with the addition of ID can be used in many scenarios.

Comments

Post a Comment

Popular posts from this blog

ORA-16433: The database or pluggable database must be opened in read/write

-
Image
ORA-16433 is an error returned when a database cannot be opened. This can be a result of multiple conditions including, The inconsistency of the database Physical corruption Loss of dependent files or access issues etc.. More often than not the solution is to recover from available backups, but there can be situations where backups are not available, specially on UAT or Test setups. Although not the ideal scenario, in this type of situation you might want to open the databases even with inconsistency.  In Comes --> _ALLOW_RESETLOGS_CORRUPTION First, if you are in a position to use _ALLOW_RESETLOGS_CORRUPTION=TRUE, that means it has to be a critical moment, and when you come across more ora- errors while you are trying to reopen the databsae, that can be annoying. Note - _ALLOW_RESETLOGS_CORRUPTION=TRUE must only be used after Oracle support confirmation as a last resort. Also make sure to take cold backup before proceeding. Basic steps to be followed to resolve ORA 16433 after
Read more

Oracle Multitenant - Create new service for PDB using DBMS_SERVICE

-
Image
When an Oracle PDB is created it starts up a default service with the PDB name. For direct connections to    PDB this service can be used. But there are situations where new service name is required in PDB level, common example is after a PDB restoration/clone, in order to enable application connections without changes in connection string. Setting service_names parameter in PDB level is not possible hence it is not an option in multitenant setup. How to create a new PDB service on Oracle 12C Check the current services, here only the default service is running, SQL> show pdbs; CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ------------------------------ ---------- ---------- 3 NFACTORPDB READ WRITE NO SQL> select service_id, name, pdb from dba_Services; SERVICE_ID NAME PDB ---------- ---------------------------------------- ---------- 7 nfactorpdb NFACTORPDB SQL> Create
Read more

Wait for unread message on broadcast channel - Blocking Sessions

-
Image
What is Wait for unread message on broadcast channel wait event? Wait for unread message on broadcast channel is a wait event where source destination communication is involved and the database is waiting for a reply from remote party. Mostly this wait is seen related to data pump export (expdp) or import (impdp) operations. Although categorized in idle wait class "Wait for unread message on broadcast channel" can become the blocking session for some other sessions. Common causes for stuck sessions waiting on this wait event includes, Broken databases links, where remote database is not responding. Abnormally killed remote processes causing the sessions to wait. When a session is waiting on "Wait for unread message on broadcast channel" it can become a blocking session for dependent sessions. Most probably these sessions will be waiting on "library cache pin" or related concurrency wait events. The blocking_session column of (g)v$session view
Read more