MySQL : Open-Source, Relational Database Management System

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Should I increase max_connections in AWS RDS t1-micro for MySQL?

I have an AWS RDS t1-micro running MySQL 5.5. It gives me too many connections error. I checked and it allows 34 maximum connections concurrently. What I have read is that i can increase this max ...
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2answers
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What does 'ibfk' stand for in MySQL?

If I create a foreign key constraint for table 'photos' in phpmyadmin, I later see that the constraint is named 'photos_ibfk_1', and the next constraint is called 'photos_ibfk_2', etc. From this I ...
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3answers
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Any better way out of MySQL InnoDB log “in the future”?

I've got this InnoDB error in MySQL 5.0. Mysqld was stopped cleanly, but I managed to lose ib_logfile0 & ib_logfile1 afterward. Now after a clean startup, InnoDB has done its "crash recovery". ...
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2answers
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Why is MySQL is creating so many temporary tables on disk?

Can any configuration mistake lead to creating too many temp tables by mysql..mysql tuner shows Current max_heap_table_size = 200 M Current tmp_table_size = 200 M Of 17158 temp tables, 30% were ...
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2answers
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PostgreSQL vs. MySQL - Advantages / Disadvantages with a spatial component

We are the in the process of building out a web application that has a spatial data component. In the beginning our spatial data comparisons will take a given point and return matched overlapping ...
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5answers
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Alternatives to MySQL Workbench [closed]

I've been running into some problems with MySQL Workbench that I'm not sure will be able to be fixed (namely, what appears to be an old bug that may have resurfaced), so I'd like to be able to find a ...
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1answer
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Clarification on MySQL innodb_flush_method variable

Let me begin by admitting that I'm very ignorant of the inner workings of hard disks. So when I read over the manual for the variable innodb_flush_method, it confused me. Can I get an explanation in ...
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Is a 5+ column primary key bad for large (100 million+) table?

I was reading about some real life DB issues, and one project had a 100 million row plus table that had 5 columns as its primary. I'm thinking this is bad, but can anyone tell me exactly why? EDIT: ...
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What is the reason of Host 'host_name' is blocked in MySQL?

When I use incorrect password to connect to mysql server, and the test count is over the max_connect_errors, and I find the Aborted_connects is also arise as the count I test, but the host is still ...
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181 views

Find total duration of each consecutive series of rows

MySQL Version The code will run in MySQL 5.5 Background I have a table like the following one CREATE TABLE t ( id INT NOT NULL AUTO_INCREMENT , patient_id INT NOT NULL , bed_id INT NOT NULL , ...
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1answer
587 views

Disable explicit commits in JDBC, detect them in SQL, or put the database in a readonly state

Background: I'm working on http://sqlfiddle.com (my site), and am trying to prevent one avenue of abuse possible there. I'm hoping that by asking about a problem I'm currently addressing, I don't ...
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Matching single column against multiple values without self-joining table in MySQL

We have a table that we use to store answers to questions. We need to be able to find users that have certain answers to particular questions. So, if our table consists of the following data: user_id ...
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5answers
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Why using innodb_file_per_table?

There are many articles exaggerating (IMHO of course) the need for innodb_file_per_table. I understand that with innodb_file_per_table, there should be a better control over the individual tables; ...
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3answers
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Modify DEFINER on Many Views

I have am having problems backing up my databases after an update. I have been poking around on my system trying to figure out why. One query I ran returned this result. Got error: 1449: The user ...
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3answers
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How to estimate/predict data size and index size of a table in MySQL

I am finding what is the best way to estimate size of a table for that i have studied lot of blogs and forums but unable to find any accurate answer For an example we have a table City with InnoDB ...
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4answers
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Cannot open table mysql/innodb_index_stats

After a fresh install of XAMPP and import from my linux live db that is working to the windows Dev-stage, I started encountering problems with INSERT. Everything else seems to work well. The errors I ...
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2answers
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InnoDB: Error: Table “mysql”.“innodb_table_stats” not found after upgrade to mysql 5.6

I upgraded to mysql 5.6 from 5.5, and now my logs are littered with such messages on startup I found a possible solution here, but it does not seem official. ...
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3answers
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Best of MyISAM and InnoDB

Is it possible to make InnoDB to use indexes same as MyISAM instead of clustered index due to limitation of RAM while getting benefit of its concurrency performance?
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What is the difference between optimize table and analyze table in mysql

What is the difference between optimize table and analyze table in mysql? I have read the online docs, but not sure what the difference is.
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mysql wont start after increasing innodb_buffer_pool_size and innodb_log_file_size

I am following this solution here http://stackoverflow.com/questions/3927690/howto-clean-a-mysql-innodb-storage-engine/4056261#comment14041132_4056261 and tried to increase my innodb_buffer_pool_size ...
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3answers
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Installing default MySQL Tables in Windows (mysql_install_db)

In Linux, the default MySQL grant tables can be created with the mysql_install_db script, but that does not work on Windows. How can the default grant tables be installed on Windows? (No, I’m not ...
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What tools are there for data masking? (MySQL, Linux) [closed]

I'm looking for (ideally free, open-source) data masking tools. Do any such exist? Note: this related question deals with tools for generating test data, but in this question I'm more interested in ...
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2answers
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InnoDB create table error: “Row size too large”

We have some engineers that flatten a normalized db structure into a temporary table for the purposes of generating a report. The columns are specified as TEXT NOT NULL (I know "why are they doing ...
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3answers
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Replicate RDS-MySQL to a non-amazon host?

I have a fairly large MySQL (5.1) database running in Amazon as an RDS instance. I'm working on migrating it out of Amazon. To do that smoothly I'd like to set up the new hardware as a read-only ...
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How to use prepared statements within MySQL stored procedures?

I'm using mysql and I need to somehow use the column curid returned by the prepared statement in the later query. I use prepared statements because as I've read, it is the only way to pass a variable ...
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1answer
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changing mysql table comment

i know that: mysql table comment can be defined while creating it: create table (...)comment='table_comment'; and how to display it: show table status where name='table_name'; and i know how to ...
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3answers
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How to convert mysql to postgresql? [closed]

I am desperately looking for a conversion tool to convert a big mysql database to postgresql. I need the tool/script to be: Free Works under Linux Simple to use and not buggy You actually tried and ...
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1answer
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Error creating foreign key from MySQL Workbench

I'm trying to synchronize schema changes from MySQL Workbench to my database. I'm getting the following error when it tries to create a foreign key: Executing SQL script in server ERROR: Error 1005: ...
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1answer
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CREATE INDEX vs ALTER TABLE ADD INDEX - MySQLism, or SQL Standard?

Just came across a weird issue, whereby depending on how I create an index, an index name is required. http://dev.mysql.com/doc/refman/5.5/en/create-index.html ...
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3answers
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Monitor MySQL activity per database?

What is the best way to monitor activity on each database of my server ? I tried mtop/mytop which display activity in real time but aren't very practical to see all the queries executed on it. I ...
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1answer
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Cannot drop anonymous user from mysql.user

I am trying to DROP the anonymous users from my mysql.users database. However, I have been getting odd behavior. When I enter the command: DROP User ''@'WOPR'; I was getting a generic error ...
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1answer
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Does mysqldump export indices, by default?

I played around a little with mysqldump and I was wondering, if it does export indices (FULLTEXT, INDEX,...) by default. I read up on it and I found this option: --disable-keys, -K which suggests, ...
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Audit logins on MySQL database

Is there a way to audit logins to MySQL? I'd like to be able to create a username for each employee and thereby create an audit trail of logins. However, googling has turned up no good results. The ...
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1answer
240 views

Power went out - Did query finish?

Is there a way to check and see if a query finished? I ran 3 very long running update queries (+/- 25 hours each) as I went out the door for vacation last week. Unfortunately, somewhere during the ...
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3answers
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MySQL High Performance for Lots of SELECTs/INSERTs/UPDATEs/DELETEs

I am creating a module where every user often gets a record into a table for 10 to 300 seconds. When the time expires a record gets deleted. The case is: there will be a lot of users and records will ...
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3answers
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How to get the most out of MySQL on a QuadCore machine with 16 GB of RAM?

I'm running a MySQL 5.5 server on my workstation for scientific data analysis and wonder how to configure MySQL in order to get the most out of it performance-wise. The types of query that I typically ...
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1answer
8k views

Autoincrement primary key in CREATE TABLE … AS SELECT

I created table using a complicated select query via CREATE TABLE ... AS SELECT.... How can I add an autoincrement primary key in this query? For example: create table `user_mv` select ...
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1answer
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How does MySQL return a result set from a stored procedure?

I'm trying to get my head around stored procedures for use in a web application. It seems to me that whatever the last statement is in a MySQL stored procedure is seems to be what gets treated as that ...
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1answer
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Is there such thing as Custom Data Types?

Does MySQL have any support for custom data types? For example, zip codes might be stored in a varchar(10) field, but they could be compacted in to an int, with options for blank, and a flag as to ...
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MySQL status variable Handler_read_rnd_next is growing a lot

In MYSQL status, Handler_read_rnd_next value is very high. I am aware that, this value will be incremented when a query is executed which is not having proper indexes. But, even when we execute ...
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What are the benefits of using MySQL Cluster?

I have never dipped my hands in MySQL Cluster and want to know how it can benefit me. When is it best to use it, and does it have performance benefits?
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Adding an index very slow…is there a mysql cmd to get an ETA or show progress?

I'm currently running an alter query on my table (20M entries) in order to add an index. it's running for more than 3 days already (stuck on 'copy to tmp table'). is there a way I can see the ...
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1answer
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How to speed up queries on a large 220 million rows table (9 gig data)?

The issue: We have a social site where members can rate each other for compatibility or matching. This user_match_ratings table contains over 220 million rows (9 gig data or almost 20 gig in ...
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1answer
694 views

Calculate MATCH() AGAINST() scores from UNIFIED QUERY not FOR EACH TABLE

I am trying to have a score for entire section of SELECT statements SELECT *,MATCH(`result`) AGAINST('keyword') as `score` FROM `table1` WHERE MATCH(`result`) AGAINST('keyword') UNION SELECT ...
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9answers
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Which DBMS are fast enough for an online game (few thousand players)?

I'm currently making an MMORPG game, which could have a few thousand players online at the same time (probably not; just wishful thinking). First we wanted to use MySQL, but I have heard it isn't fast ...
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How to update one table based on another table's values on the fly?

I have a table in the name of ips as below: CREATE TABLE `ips` ( `id` int(10) unsigned NOT NULL DEFAULT '0', `begin_ip_num` int(11) unsigned DEFAULT NULL, `end_ip_num` int(11) unsigned DEFAULT ...
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One Big Database vs. Several Smaller Ones

We have a situation were we can (A) deploy instances of an applications in one MySQL database using table prefixing or (B) use different MySQL databases for each instance of the application, for e.g., ...
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What to set innodb_buffer_pool and why..?

I have 170GB of InnoDB index and Data. I have to readjust the innodb_buffer_pool size for better performance.The Max table size of a InnoDB table(Index+data) is 28GB. So what should be the optimal ...
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How do I show the binlog_format on a MySQL server?

How do I show the binlog_format on a MySQL server? And if I dont like it how do I set it to XX permanently? Where XX is STATEMENT, ROW or MIXED.
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For absolute performance, is SUM faster or COUNT?

This relates to counting the number of records that match a certain condition, e.g. invoice amount > $100. I tend to prefer COUNT(CASE WHEN invoice_amount > 100 THEN 1 END) However, this is ...