Tagged Questions

MySQL 5.1 : The Second Major Release of MySQL 5

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0
votes
1answer
69 views

How to avoid/prevent Aborted Connections in mysql

We are using MySQL Version 5.1.73. Database is getting huge number of connections around 600 at one time. I observed Aborted Connections are getting increased from Global Status variables. So I ...
2
votes
1answer
107 views

Do triggers affect DB performance

I have a database with 250 small and medium sized tables. These tables are related with both MyISAM and InnoDB storage engines. There are multiple triggers that have been created on different tables. ...
1
vote
1answer
164 views

InnoDB engine is not loading after tuning parameters

After installing MySQL-5.1.73, I placed default my-huge.cnf into /etc/my.cnf and started the mysql service. It was running without any issue. Now, I tunned some parameters in /etc/my.cnf file. Below ...
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vote
3answers
468 views

Is there any command to optimize all MySQL tables one by one automatically?

I execute below command line statement to optimize a table: optimize table tablename; Is there any command or statement which can optimize all the tables one by one of the selected database?
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0answers
34 views

Switching from Windows to LINUX server with lower configuration

As of now, My application is running on dedicated windows DB server which configuration is below: RAM 8.00 GB Processor Intel(R) Xeon(R) CPU X5460 @3.16GHz, OS Windows Server ...
0
votes
1answer
153 views

Difference between [mysql] and [mysqld] in MySQL configuration file

There are multiple sections in MySQL configuration file: [mysql] [mysqld] [myisamchk] [mysqld_safe] [mysqlhotcopy] [mysqldump] [client] I found that same variables with different values have ...
1
vote
1answer
64 views

What does this mean - ~/.my.cnf

When I run $ mysqld --verbose --help | less I got information like Default options are read from the following files in the given order: /etc/mysql/my.cnf /etc/my.cnf ~/.my.cnf As per my ...
2
votes
1answer
103 views

Is there any difference between these two version of MySQL - 5.1.73-community-log Vs 5.1.73-community

I have installed MySQL 5.1.73 in Oracle LINUX 5 server. Just after RPM installation, I checked system variables and found that version is 5.1.73-community. When I copid ...
1
vote
2answers
571 views

Does MySQL have a version of Change Data Capture?

We're in the process of phasing out an old system and migrating onto a new one. The last time that we phased out an old system, we ran both systems in parallel and integrated data between both until ...
0
votes
0answers
45 views

MySql - multi-column index using only null values from one column

I have a Innodb table with a index that looks at 3 columns. ColA is integer and always has a value. ColB is varchar and always has a value. ColC is datetime and sometimes has a value (NULL). My ...
1
vote
1answer
20 views

Unable to start mysql

I am using Oracle LINUX5. I installed MySQL 5.1.73 community edition through RPM command and it was working. Now, I stop mysql by running below command: $ mysqladmin -u root -ptmpassword shutdown I ...
1
vote
1answer
368 views

MySQL master master replication, safe to delete rows on both masters?

We have a MySQL (v5.1.61) cluster with two masters (and two slaves). We have a table logs with a primary key column logID. This log table grows rather huge, and we'd like to delete data from it. So ...
0
votes
1answer
152 views

How can i import 150GB database after deleting ibdata1,logfile in MYSQL?

I have 150GB database and my ibdata1 file size is 240GB so i want shrink the ibdata1 file so for that i have to export the DB and then drop the tables and then stop mysql, delete the ibdata1 file and ...
0
votes
1answer
290 views

MySQL: Prevent DROP TABLE and TRUNCATE TABLE on Slaves

Can someone tell me how to prevent the following commands DROP TABLE <tbl-name>; TRUNCATE TABLE <tbl-name>; from being replicated to slaves?
0
votes
1answer
435 views

MySQL: Use Sysbench on Windows

Sysbench is a tool to analyze the MySQL performance. I downloaded it and extracted but there is no executable file. Files having extensions like .sh or .c or .h are available. I gone through the ...
0
votes
3answers
199 views

Changing MySQL auto_increment_offset

Sorry for the wall of text, but I don't know what's relevant and what's not. I have MySQL a MySQL database that it is being replicated from our production environment to our development/test ...
0
votes
2answers
596 views

How to trace a MySQL session like in Oracle

I have an application running in MySQL 5.1.58 community edition. My application is working fine, but suddenly any query stuck and then after all queries is getting logged in slow query log. I am ...
0
votes
1answer
286 views

MySQL 5.1.x: Performance improvement in Enterprise edition Vs community edition

My application is running on MySQL 5.1.58 community edition. I tried to search enterprise edition of MySQL 5.1.X but only MySQL 5.6.X version of enterprise edition is available. Is it possible to ...
0
votes
0answers
47 views

MySQL grant select not working properly 5.1.73-log

I have created new users with GRANTS SELECT but this is not applied and still user have full privileges and can still DELETE, DROP, INSERT. SHOW GRANTS for dbreader; GRANT SELECT ON *.* TO ...
0
votes
1answer
41 views

MySQL: How to find MySQL 5.1 (with built-in InnoDB) or MySQL 5.1 (with InnoDB-plugin)?

My DB server has MySQL 5.1.58-community-log and I am planning to upgrade it to MySQL 5.6 with specific purpose of improving my system performance and removing the bottleneck issue. So, I have gone ...
2
votes
3answers
112 views

How to update cust_id from Customer table to order table Cust_id field while inserting customer name using trigger

I have two tables 1. Customer_details and 2. Order_details. 1.Customer_details table -->fields--> Cust_Id(Primary Key) and Customer_Name, 2.Order_details table --> fields-- Ord_Id(Primary ...
0
votes
2answers
71 views

MySQL: Moving Database from Windows to Linux

I have a Windows based dedicated server have below configuration: Windows edition: Windows Server 2008 R2 Standard Service Pack 1 Processor: Intel(R) Xeon(R) CPU X5460 @3.16GHZ 3.16 GHZ (2 ...
0
votes
0answers
49 views

MySQL Server constantly crashes

my apologies for having already posted on this issue, but it has moved on so far I feel a new question is the only way to go. First a little history - I have a MySQL server which runs a few small ...
3
votes
1answer
156 views

Merge difference MySQL DBs into a single new server

I have 4 servers which has it's own MySQL server along with databases and users. Now we have a new server dedicated only for MySQL and we would like to merge those MySQL servers into this new one. ...
0
votes
0answers
35 views

On replicating all tables of a given database except for those starting with some pattern

I'd like a slave to replicate all tables of a given database except for those starting with some pattern, eg. those with names starting with 'nc' (non-critical, redundant denormalized tables). So I ...
0
votes
0answers
169 views

Best way to select rows containing a substring

I've a table named comments where comment is a field where comment will be stored. Now I want to find -1 within that comment. the -1 should be independent. That is, it should not be joined with ...
0
votes
1answer
276 views

MySQL: Different thread states in Query execution

My MySQL 5.1 bases Intranet system is facing very bad performance during high load. When observe through MonYog, I found below thread states: We can simply understand the different thread state by ...
1
vote
2answers
378 views

MySQL views and table locking (5.1 MyISAM)

I have a large (160 million rows, 50GB) table in MySQL 5.1 using MyISAM. If I were to construct a view defined by a fairly complicated query, would a SELECT on the view lock the underlying table?
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vote
2answers
142 views

Mysql select ends with 'killed'

Okay, I'm sure this will turn out to be something dumb, but then I'm a dumb n00b DBA. I've got a largish table, about 163 million rows and something like 44 GiB. After some experiments with ...
1
vote
0answers
69 views

MySQL: Sometimes query failed to use index

I have a complex query including join of 4-5 tables. 1 months back, I have optimized this query and it was using the index. Also, two months back, index of all tables had been rebuilt by just export ...
0
votes
1answer
44 views

MySQL: Algebra in Union operation

I have below query: select entity_id from table1 exc UNION select entity_id from tabl2 inc On execution, I got 24419 rows. When I execute select entity_id from table1 exc I got 16235 rows and on ...
0
votes
0answers
582 views

The total number of locks exceeds the lock table size, even after increasing buffer pool size

I am trying to partition a table with 200 million records in it. This table already exists: CREATE TABLE linkmap_ntoken ( target_nToken varchar(200) NOT NULL, ntoken_hashcode int(15) NOT NULL, ...
0
votes
1answer
159 views

MySQL: What is SQL mode and why we use it

If in an application, if we execute sql_mode=mysql4.0 as a first query in my application but using MySQL 5.1 in my application then what will happen? Will my system use MySQL 4.0 or MySQL 5.1 ...
0
votes
0answers
29 views

MySQL: why provide size of a datatype in table definition? [duplicate]

Below is an example table definition: CREATE TABLE IF NOT EXISTS `mytable` ( `id` MEDIUMINT(5) NOT NULL AUTO_INCREMENT, `title` varchar(255) DEFAULT NULL DEFAULT '', `content` text ...
1
vote
1answer
2k views

statistics State in MySQL Processlist

I have a busy MySQL Server having query SELECT sys_sess_state, index_state, timeout_lvl, last_queued_dt, last_polled_wait_dt, create_id, create_dt, modify_id, modify_dt FROM PQR_AM_SYSTEM_SESSION ...
2
votes
1answer
254 views

MySQL: What is the most optimized way to use datetime type field in query

I am working on optimization of some slow queries in my application. I found a query in which datetime comparison has been used. Below is the subquery: select * from jos_content c where c.visible = 1 ...
0
votes
0answers
17 views

MySQL: How logging is useful in performance improvement

My application is facing performance hit. Its a MySQL-5.1.55 version. I am using Windows 2008 dedicated server with 8 GB for the database. There is only one database in this whole system. Till now, I ...
0
votes
0answers
34 views

MySQL: system variables and status variables related with Disk I/O

How disk I/O is related with MySQL performance improvement. I have a MySQL-5.1.58 based Intranet application equipped with Windows 2008 server and 8 GB RAM. Even, When my application face performance ...
0
votes
2answers
578 views

MySQL: why assign NULL as default value

When we define a table, multiple times we assign default value of a column as NULL. I have How NULL is different than empty value('') as well as 0? Is there any impact of NULL value in query ...
0
votes
0answers
161 views

MySQL: how to determine key_len and its role in performance improvement of a query

I have a query, below is the structure of the table: CREATE TABLE `jos_tag_rules_fields` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL DEFAULT '', `label` varchar(255) ...
0
votes
2answers
61 views

MySQL using swap during conversion to InnoDB

I'm trying to convert some MyISAM tables in my database to InnoDB (MySQL 5.1). The server has quite a bit of memory (96G), and the tables that are giving me problems can be on the order of 50 millions ...
0
votes
1answer
46 views

Tracking changes on a replication slave

I suspect the answer to this is "you're boned", but I'd like to see if there are any good options that I haven't explored. We're building a system that will integrate with a 3rd-party POS system and ...
0
votes
0answers
246 views

MySQL: How to get locked tables list at a time

Is there any way or any query exist in mysql which list down all the locked tables at a time. I have dedicated Windows 2008 DB server with 8GB memory. In my MySQL5.1 based application, suddenly we get ...
12
votes
4answers
7k views

Why use WHERE 1 or WHERE 1=1?

Usually, if conditions are not required in our query statements, we don't use a WHERE clause. But I see a WHERE 1 clause being used in many places, even where other conditions are not present. Why ...
0
votes
1answer
133 views

MySQL: fetch multiple global status and system variable in a single query

When we execute SHOW global status; or SHOW variables; we get list of 291 and 278 records in the resultset. For performance perspective, only few of them are much important. I have to fetch these ...
0
votes
0answers
167 views

MySQl: slow query is not using index in joining

Below is the configuration of my DB server: Apache version : Apache/2.2.22 (Win32) mod_ssl/2.2.22 OpenSSL/0.9.8 PHP version : 5.3.13 MySQL version : mysqlnd 5.1.11 Windows Server 2008 Standard ...
0
votes
1answer
109 views

Help interpreting a MySQL execution plan

I'm trying to understand a slow query. The SELECT has been running (at this moment) for almost 18000 seconds (output from a SELECT on PROCESSLIST): id: 22 time: 17870 ...
1
vote
2answers
1k views

Difference between show status and show global status in mysql

When I execute "show status" and "show global status" in MySQL at interval of 5 seconds , I got set of 291 results each time. But, value of some parameters are different. Below are the list of those ...
1
vote
1answer
107 views

How big is a tmp table?

I've got an RDF table in MySQL 5.1 with the MyISAM engine. Here's the table definition: CREATE TABLE `node` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `graph` varchar(100) CHARACTER SET latin1 ...
0
votes
1answer
400 views

TCP sockets bottleneck with InnoDB/Debian?

We have a big mysql performance issue on a production environment with 18 "front" servers sending mysql queries to a unique mysql server. We are using Redis on each front server for a number of ...