MySQL 5.1 : The Second Major Release of MySQL 5

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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 ...
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34 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 ...
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15 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?
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1answer
31 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 ...
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3answers
30 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 ...
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2answers
61 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 ...
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1answer
20 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 ...
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12 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 ...
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23 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 ...
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3answers
42 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 ...
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2answers
42 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 ...
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25 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 ...
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90 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. ...
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20 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 ...
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26 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 ...
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1answer
37 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 ...
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2answers
67 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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78 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 ...
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38 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 ...
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1answer
34 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 ...
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1answer
77 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, ...
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1answer
55 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 ...
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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 ...
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1answer
310 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 ...
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76 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 ...
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11 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 ...
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19 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 ...
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2answers
133 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 ...
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110 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) ...
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2answers
39 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 ...
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1answer
26 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 ...
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39 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 ...
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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 ...
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1answer
36 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 ...
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91 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 ...
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51 views

MySQL process eating up more than 100% cpu resources

MySQL production server taking more than 100% CPU resources when users searching for data or concurrent users login to the server application (Sugarpro). Scenario: 100 concurrent users login VPS ...
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1answer
62 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 ...
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269 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 ...
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1answer
76 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 ...
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1answer
221 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 ...
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56 views

Understanding how MySQL indexes work

I'm reading this page but I can't get past the following parts: When all tables are processed, MySQL outputs the selected columns and backtracks through the table list until a table is found ...
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368 views

MySQL: High sort_buffer_size setting value

Thing is I was getting plenty of 131104 20:10:36 [ERROR] /usr/sbin/mysqld: Sort aborted with 256M and rather erratic behaviour in my load test. Now at sort_buffer_size = 1024M ...
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587 views

MySQL temporary column in SELECT statement

I'd like to do some calculations in a MySQL query. I've created some temporary columns which I'd like to use for the calculation. SQL fiddle for currently working (but discouraged) SQL query: ...
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1answer
198 views

mysql 5.1 — unknown variable 'basedir=c:/mysql/'

I recently changed the default port(3306) to another for mysql. I did it by changing the my.ini file and did restart of the server. No other changes were made whatsoever. When connecting using a GUI ...
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1answer
46 views

query not taking index into account

EXPLAIN EXTENDED SELECT SQL_CALC_FOUND_ROWS SQL_NO_CACHE g.*, u.user_id FROM geotable g JOIN userstable u ON g.uid = u.uid -- corners selection: WHERE (lat BETWEEN ? and ? AND lon ...
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599 views

Selecting multiple columns from multiple rows in one column (subquery?)

I'm working with MySQL 5.1.68. I have a situation where I'd like to select rows from another table into a column. I'd like to output this: id # name # citizen_name (multiple citizen names) 1 # ...
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985 views

mysql trigger to insert/update date column from datetime column

probably simple question but can't get it to work: I have a table with two datetime columns. In order to set up a date index and have simpler queries, i have added two date columns next to them. ...
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45 views

Accidentally I had deleted a database from production server working with MySQL

I have its backup as a full and an incremental backup took using enterprise backup. Is it possible to restore a specific database or else what should I do as an immediate action?
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191 views

UPDATE SET REPLACE() matches but does not change

I've seen another post about this exact thing but it's 1-1/2 years old so I thought I'd make my own...besides, the other post did not help me. What I am trying to do is pretty straight-forward. To ...
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44 views

mysql's query cache behaviour on LIMIT

Is it accurate to assume that MySQL's query cache gets checked on subsequent execution of queries in the form SELECT ... WHERE ... LIMIT x, y where the the only varying paramaters in the query are x ...