All versions of MySQL (not Microsoft SQL Server). Please also add a version-specific tag like mysql-5.7 if that is relevant to the question.

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7
votes
2answers
9k views

How can you have two auto-incremental columns in one table?

I have a MySQL table that contains information on invoices of a company. However, this company has two branches, and each of them has a unique invoicing sequence; a "Serie A" and "Serie B", so to ...
5
votes
2answers
2k views

Data type for currency 'type' column, e.g. usd, cat, etc.

I am setting up a MySQL database for accounting software. One of the fields is to save the currency used for each transaction. What field type would you recommend? Details: No more than 10 different ...
11
votes
3answers
17k views

Why is 'LOAD DATA INFILE' faster than normal INSERT statements?

I've read an article that mentioned we can achieve 60,000 inserts per second by LOAD DATA IN FILE statement that read from csv files and insert it into database. Why should it differ from normal ...
2
votes
2answers
5k views

MySQL Table level Replication

I have 3 servers, say A,B &C. All have the equivalent data(same data). Now what I want is to make A as the master and B,C the slaves. But the scenario is that I only want to replicate some of the ...
5
votes
1answer
165 views

For MySQL, is there tool to dump a set of rows from one tables and all related (by foreign key) rows from all related tables?

I'm using MySQL db. I want to dump a set of rows from one table and if these rows have foriegn keys that point to rows on some other tables, I want to dump those too. Then I want to load these dumps ...
1
vote
1answer
132 views

create more logs in Mysql, pros and cons?

I just install XAMP in my mac and I'm trying to learn by my own, with books, tutorials and you guys. I'm working in the backup part and I saw I have only a LOG "mysql-bin.000001' : What happen when ...
2
votes
1answer
238 views

How to change the create and use statement in a large sql file without opening it

I need a way to change the schema name which appears in create statement and use statement of mysql dump file. The goal is having the database restored with a different database name on another ...
3
votes
2answers
297 views

What's the latest on MySQL Proxy?

Does somebody here know the latest state of the development of MySQL Proxy? Most materials I found on web are outdated.
2
votes
0answers
327 views

MYSQL & Access ODBC

I am trying to connect mysql with access, i am settings up the ODBC correctly from the data sources, however i get a driver error. I am using access 2010 and the driver version of the ODBC conector ...
1
vote
0answers
292 views

MySQL suddenly running very very slowly

I run a PHP/MySQL website on a fairly large server with 16GB RAM and 3 vCPUs. Everything was flying along until this morning when I noticed MySQL down. I tried to restart MySQL and first got the ...
1
vote
2answers
21k views

MySql - Clean ibdata1

I have a database that its entire size is ~44GB, out of it ibdata1 is ~35GB that doesnt make sense, the size of the data shouldnt be more then 10GB. i use the following query to get an esstimation of ...
2
votes
2answers
2k views

MySQL Server is Restarting automatically after some minutes

I am getting an Issue after everey 2-3 minutes mysql> show tables; ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect... Connection id: 57 I am really not able ...
2
votes
4answers
225 views

MySql Database solution for specific web app problem

Well, I need to create a comment system for posts that people add to my web app. This web app is just like facebook or myspace posts. Users add posts and people can comment on them. But the problem is ...
2
votes
1answer
364 views

MySQL : Does 'bytes_sent' and 'bytes_received' include mysqldump data?

I'm trying to estimate my db traffic not including backups (mysql 5.1.41). I use show global status; to get the parameters bytes_sent and bytes_received. Questions Do these numbers include ...
-3
votes
2answers
585 views

How can I generate Cassandra data model from a MySQL schema?

Is there a tool for generating a Cassandra model from a MySQL database?
3
votes
2answers
10k views

Is SELECT COUNT GROUP BY more efficient than counting a result set?

I have a table with a rank column which can be either 1, 2 or 3. I need to count the number of records for each rank, but I also need to display all the data ordered by rank. From my perspective, the ...
4
votes
2answers
2k views

Select rows where value of second column is not present in first column

I have this table structure: id1 id2 1 2 1 3 1 4 2 1 2 5 I need to build a query to select id2 where id1 is not in id2. For example if id1 = 1 then only id2=3 and id2=4. I tried ...
3
votes
1answer
175 views

Human relations between users

I'm involve in a development of a tiny Social Network where users must be able to establish relations between them and also have permissions over contents. For a example: I add one user as my friend ...
4
votes
2answers
872 views

Difference between backup methods: Oracle and MySQL

I was reading that Oracle databases have cold, warm, full and redo backups. Questions How is it possible that MySQL doesn't have as many options? I have read that MySQL has cold backups (it puts ...
1
vote
2answers
571 views

Managing features for a real estate agency [duplicate]

I have a database table real_estate where the basic information is held (id, status, sku, address, building_type, sales_status) and now I want to attach features to that real_estate table. The data ...
5
votes
4answers
5k views

Prevent reset of auto_increment id in Innodb database after server restart

I recently read that because of how InnoDB recalculates the AUTO_INCREMENT value when the server restarts, any records on the high end of the ID list may have their IDs reused. Normally, this isn't a ...
1
vote
1answer
779 views

Which Optimistic Concurrency Control method will work out best in the long run?

These are the options I've thought of: DotNet Dave: UPDATE mytable set f1=newval where id=666 and f1 := f1ValueFromSelect Charlie Checksum: UPDATE mytable set f1=newval where id=666 and ...
1
vote
1answer
284 views

GUID as reason for MySQL import slowness

We faced MySQL restores DB VERY slow: ~3 min for 15 MB dump. This is a new dedicated server with a lot of RAM. We were told the most possible reason is GUID is uded as primary key in many tables: ...
1
vote
1answer
2k views

My SQL 5.6.4 DATETIME column milliseconds is not getting stored

Beginning from MySQL 5.6.4, milliseconds support is provided for date columns like DATETIME etc. I just created a table to check if its working: create table testdata(startime DATETIME(5)); ...
3
votes
1answer
76 views

How to avoid listing FIELD/IN twice?

I have SELECT field(foo,'this','that','bar','baz') FROM t WHERE f1 IN ('this','that','bar','baz') How can I avoid listing ('this','that','bar','baz') twice?
0
votes
1answer
4k views

How can I select the latest record having one state where no later records exist with any other state?

I want to select the last record (by datetime) having a given state where no later records exist with any other state for each given "widget". widget state timestamp ------ ----- ...
1
vote
2answers
2k views

Do I need SQL_NO_CACHE for write intensive query?

When I establish a connection to DB, I have to write about 30,000 records with an INSERT statement. I've read in a book that I should do it ! Questions Do I need to do SQL_NO_CACHE ? Is it gonna ...
4
votes
2answers
3k views

What happens when InnoDB hits its tablespace autoextend max?

The latest version of High Performance MySQL (3rd ed.) recommends that one: ...place an upper limit on the tablespace's size to keep it from growing very large, because once it grows, it doesn't ...
12
votes
1answer
23k views

Mysql Innodb: InnoDB: ERROR: the age of the last checkpoint is InnoDB: which exceeds the log group capacity

I really need some mysql expertize. I am a newbi to mysql and I am seeing some server crash of my db in the past 1 week. I am using mysql 5.1.36 on Ubuntu. This is a dedicated mysql server with Dual ...
5
votes
1answer
4k views

SELECT with large WHERE IN clause taking long time

I'm pretty new at all this so be gentle :). I have large medical DB where I need to extract data for patients based on selected doctor(s). Right now I build a patient list by SELECT patID FROM ...
5
votes
3answers
809 views

How can I select using the same fields from an undetermined number of tables using MySQL?

I'm dealing with a MySQL database where I have an undetermined amount of identically structured tables that look like this: foo_reference1 foo_reference2 foo_referencea foo_referenceb .... ...
0
votes
1answer
366 views

horizontal partitioning or multiple tables?

I'm developing an application and need to propose a database schema. We plan for a MySQL database with millions of records which should be distributed over multiple machines for performance and ...
0
votes
1answer
8k views

MySQL: Why is DATEDIFF and TIMEDIFF/60.0/60.0/24.0 results different?

I have a database with two DATETIME values, and then I generate some new values from them: tdiff = timediff(d1,d2)+0 day1 = truncate(tdiff/60.0/60.0/24.0,0) day2 = datediff(d1,d2)+0 All three of ...
2
votes
1answer
10k views

How to compare (in MySQL) a DATETIME value to a TIMESTAMP value?

I'm trying to understand how to compare a DATETIME value (ostensibly inserted as GMT) and a TIMESTAMP value (automatically generated at INSERT time). As I understand it, the DATETIME is set to ...
2
votes
2answers
2k views

Will an ALTER TABLE ADD COLUMN on a slave break replication?

I need to add a last_modified column to a MyISAM table tbl_items. The crux of this problem is that tbl_items houses several gigabytes of data. Also of note, I am using a master-slave deployment with ...
2
votes
0answers
325 views

How to seperate sensitive data in database(MySql) [closed]

I need to design a database that will contains information about personal disease of users. What can be the approach in order to implement the columns of the DB's tables: encrypt the information, ...
1
vote
2answers
143 views

How to restructure this slow query

For the following query: SELECT l.* FROM `leads` AS `l` INNER JOIN `users` AS `u` ON l.client_id = u.id WHERE (`l`.`lender_id` = 1) AND (l.claimed_date IS NULL) AND (`l`.`disabled` = 0) AND ...
2
votes
2answers
1k views

Model a family tree database in Access 2007

I designed my database with the intention of implementing it with MySQL, but have now decided to implement it in Access 2007 using form and subforms. While creating my UML diagram, I realised I have ...
5
votes
4answers
26k views

Cannot GRANT privileges as root

Because of having some problems, I decided to re-create all users except for root@localhost. This works fine, but the newly created user has no right to do anything. What I want is to simply give all ...
5
votes
5answers
16k views

Mysql: Insert performance INNODB vs MYISAM

I am inserting into a simple small table with 5 attributes and 1000 rows. I observed when the engine is INNODB, each insert is taking 0.03 - 0.05 seconds. I changed the engine to MYISAM, then the ...
4
votes
3answers
2k views

How can I write a proper query to JOIN all of these tables without duplicates?

Let's say I have four tables: TABLE: players COLUMNS: id, first_name, last_name TABLE: passing_stats COLUMNS: id, year, passing_yards (several other passing columns) TABLE: rushing_stats ...
26
votes
2answers
34k views

When to use views in MySQL?

When creating tables from multiple joins for use in analysis, when is it preferred to use views versus creating a new table? One reason that I would prefer to use views is that the database schema ...
2
votes
2answers
827 views

mysql products db design

I am building a products site with php and mysql(no shopping cart). I have 400k products, the main site with 2 methods for query. query for products types, all the query by menu, cloud tags (no ...
2
votes
2answers
136 views

Why isn't the following query using the `always` index?

This morning I started receiving load warnings on one of the MySQL servers I manage. SHOW FULL PROCESSLIST revealed that the culprit was the following (poorly written) query: SELECT * FROM movies, ...
2
votes
2answers
2k views

Is there a benefit/drawback to adding LIMIT 0,1 when performing SELECT on unique key field?

I am using a MySQL database and perform many select like these: SELECT MyField FROM MyTable WHERE MyKey = 'some_value'; The purpose is to retrieve a field a value if the corresponding row exists. ...
7
votes
2answers
26k views

How do you remove fragmentation from InnoDB tables?

I have a Database having number of tables. I want to delete some records from the tables say the no of records are more than 20K or 50K. The All the Tables are InnoDB. And file_per_table is off. ...
1
vote
1answer
2k views

MySQL flush logs, unknown error

I gave been trying to solve this for few days now, and cant seem to figure this out. I have been trying to set log rotation for mysql slow using linux logrotate feature, and my script seems to get ...
1
vote
2answers
732 views

Strange behaviour with MySQL 5.1 TO_DAYS partitioning schema

I have this table definition: CREATE TABLE `va_ventas` ( `ID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `Date` DATE NOT NULL, `Time` TIME NULL DEFAULT NULL, `Country` VARCHAR(3) NULL DEFAULT NULL, ...
1
vote
2answers
3k views

Slave settings not working

I have this machine as slave. Below is the command I ran and stuck. I done the change on the config file and set the id=2 too. Anything else I am missing here? slave start; ERROR 1201 (HY000): Could ...
1
vote
2answers
419 views

why can I only install MySQL 5.1 on cent OS 6.2?

I had Ubuntu 10.10 on my server and MySQL 5.1 version. But since i wanted to update the system, I installed a fresh version of Cent OS 6 only so I could install the latest version of MySQL. But after ...