MySQL 5.5 brought many performance enhancements and expanded the feature set of the popular open-source RDBMS.

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90 views

Table Design for Student Attendance hourly for each day

I have created a table(attendance_details) for storing every day attendance of Students in MySQL. Need to capture attendance for hourly(1-8hrs) for every day. I have the student details in separate ...
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3answers
3k views

MySQL Table not repairing

Table info: Database name: user_motiva Table name: wp_options.frm wp_options.MYD wp_options.MYI wp_options.TMD when I do a mysqlcheck -r --all-databases it gets hung on that table even if you ...
3
votes
2answers
12k views

ALTER TABLE - Rename a column

This got me nuts! I want to rename a column from read-more to read_more in blog table Tried all this: ALTER TABLE blog RENAME COLUMN read-more to read_more; ALTER TABLE blog CHANGE COLUMN ...
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2answers
3k views

Difference between On Delete Cascade & On Update Cascade in mysql

I have two tables in MySQL database- parent, child. I'm trying to add foreign key references to my child table based on the parent table. Is there any significant difference between ON UPDATE CASCADE ...
0
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1answer
28 views

How to turn Event Scheduler On permenantly in mysql

How do i turn on the event scheduler in mysql permanently. I'm using phpmyadmin and i have scheduled an event to copy records from one table to another everyday at a specific time, but the records are ...
0
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1answer
42 views

MySQL: How to write a recursive function to show menu tree?

I try to build a menu tree inside the SQL with this function: DROP FUNCTION IF EXISTS hello_world; DELIMITER $$ CREATE FUNCTION hello_world(_typeId INT, _typeText TEXT) RETURNS TEXT BEGIN ...
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0answers
10 views

MySQL 5.5 only use 1 thread and 30% cpu

i have a big issue, every day i need to update or insert like 3.3 milion rows, i have trying to do what ever i can but it still only run like 605 query/s i use VirtualBox so my setup are testing on 1, ...
0
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1answer
213 views

Change MAMP to use a lower Mysql 5.1 version

I need to have the same development environment for my PHP program. My clients test server is running on Mysql 5.1 while my local is using MAMP running Mysql 5.5. How do downgrade my mysql database ...
0
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1answer
37 views

mySQL running on 100% CPU both on RDS and EC2

How do we troubleshoot an issue with Amazon wherein my database queries (PHP/MySQL) are eating 100% CPU most of the day? Traffic=200 connections average mySQL version = 5.5.40 The ...
2
votes
1answer
47 views

mysqldump doesn't restore database. why not?

Why doesn't my restore operation work? I created a dumpfile for a database using: mysqldump -u root -p databasename > /home/databasename_bkup.sql I then opened the dumfile and confirmed ...
3
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0answers
53 views

Is it a waste to set innodb_buffer_pool_instances greater than the # of CPUs?

I set the innodb_buffer_pool_size to 20GB on a server with 12 CPU cores. My full database is 11gb, however most of it is archived tables that are almost never used. The total queried data is around 3 ...
14
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4answers
2k views

effective mysql table/index design for 35 million rows+ table, with 200+ corresponding columns (double), any combination of which may be queried

I am looking for advice on table/index design for the following situation: I have a large table (stock price history data, InnoDB, 35 million rows and growing) with a compound primary key (assetid ...
0
votes
1answer
30 views

Slow query while selecting a higher offset from millions of rows

I have sort of security log files containing millions of rows. On my current testing I imported the data for one month which is the sum of ~14,000,000 records. The table contains several set of fields ...
1
vote
1answer
379 views

Unable to use mysql_upgrade:

I updated mysql recently and found problem related to privileges and backup. When I am using mysql_upgrade command it says- mysqlcheck: Got error: 1064: You have an error in your SQL syntax; check ...
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0answers
17 views

Alternative to using subqueries

Anyone please help me to optimize this query SELECT COUNT(csd.search_id) AS searches,count(distinct cd.cust_phone) as unique_searches, (SELECT COUNT(csd.product_type) FROM ...
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0answers
135 views

Centos 5.11 mysql-server 5.0.95 upgrade to mysql55w-server

Here's my thought process on my upgrade: mysqldump --all-databases > backup.sql service mysqld stop yum remove mysql mysql-server yum install mysql55w mysql55w-server service mysqld start ...
10
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2answers
13k views

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 ...
0
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1answer
24 views

MySQL - Is it possible to assign permission to count the number of tables in a database without permissions on individual tables?

As part of a script I am trying to count the number of tables that exist in a particular MySql schema. Using my own user I am using the query SELECT COUNT(*) FROM information_schema.tables WHERE ...
2
votes
1answer
1k views

Mysql 5.5.38 ERROR 1062 (23000): Duplicate entry '' for key 'anykey'

I dropped my UNIQUE KEY index 'myindex' on a table and I wanted to change the UNIQUE KEY to something else, so after dropping it I did: alter table mytable add unique key anykey (add1, city, state); ...
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0answers
21 views

Does creating an empty table in MySql have any effect(downtime) on production?

Disclaimer: I am, in all probability, paranoid about pushing a patch on a production server. The patch alters the schema, by creating a new table (which is empty), and changes some stored procedures ...
1
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2answers
683 views

Can I disable an account in mysql after x failed login attempts?

The question is in the title. I would like to disable accounts after x failed login attempts. Is it possible? Thank you
3
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3answers
2k views

MySQL information_schema doesn't update

I have a database, say abc, in mysql server. It has only one table named test. test uses innodb engine and I've set innodb_file_per_table to true. After I run the query delete from abc.test, I want ...
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1answer
1k views

MYSQL query to find records between two date range

I am working in a web application using PHP and MySQL. I have two tables Employee employee_id email_id 3 tl1@jasmine.com 4 agent1@jasmine.com 5 ...
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2answers
44 views

Need to convert date to word using trigger

I have created a datetoword function in Mysql. Checked the function working fine. Now using this function need to convert the date from field1 (date-datetype) to field2 (Varchar-datatype) within the ...
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1answer
36 views

How to only display a variable in PHP inside a MySQL query when it has a content or when a condition is true?

How do I only display $mon or any variable when it has content? whenever i use this syntax and for example, monday must contain the number 1 and tuesday would contain number 2 and the other ones have ...
0
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1answer
38 views

Large query with subquery runs indefinitely after mysql update

We recently did a big server update, in the process migrating from mysql-5.0 to 5.5.40 Several of the queries, which had been running well on the old server, now grind everything to a screeching halt. ...
1
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1answer
83 views

Why are tiny Innodb row updates causing so much disk IO?

This is a followup question to my earlier How can I determine which Innodb table is being written? Using the accepted answer from the above-referenced question I was able to determine which (two) of ...
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0answers
27 views

Different Auto-increment values Mysql schema Replication

I have 6 Slave set up (EC-2, linux) and a Master ; 2 schemas getting replicated. Version info: mysql Ver 14.14 Distrib 5.5.34, for Linux (x86_64) using readline 5.1 Once in few months in one of the ...
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1answer
49 views

Can MySQL log lock waits?

Is it possible to have MySQL log queries or transactions where lock waits occur? One can debug specific application errors generated from lock wait timeout errors from the DB but without the ability ...
7
votes
2answers
11k views

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. ...
0
votes
1answer
125 views

MySQL always writes simple temporary/memory tables to disk (both tmp_table_size and max_heap_table_size are set to 8GB)

I'm struggling with this issue and just can't figure out why this is happening. CREATE TABLE sitecache._test ENGINE=MEMORY SELECT * FROM website.gallery_likes WHERE 1=0; Every time I execute this ...
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0answers
26 views

Use join to aggregate data from various normalized tables

I have a database as follows: tbl_clients (Primary Key: client_id, Foreign Keys:place_id,district_id,zone_id,country_id) tbl_places (Primary Key: place_id) tbl_districts (Primary key: district_id) ...
1
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1answer
32 views

Purge mysql log bins older than two weeks automatically

I have to manually write purge binary logs bin to "mysql-bin.somenumbers" ; Once in a while, I need to reduce the spaces that binlogs are taking on my web server. Is it possible to purge binary ...
0
votes
1answer
55 views

Add linked server from SQL-Server to MySQL: “Data source name not found” (Error:7303)

I'm trying to link my SQL-Server 2005 on Windows Server 2008 R2 with MySQL 5.5.40 on a different computer. I have followed this guide: ...
2
votes
2answers
273 views

MySQL user without SUPER privilege

This may be a simple question and may not be the right place to ask but I couldn't find any useful information from Google. Here is my question. When creating users in mysql using grant all ...
1
vote
1answer
42 views

MySQL Data Files Missing?

We are upgrading our website and I was checking on the size of the new database compared to the old one and was really surprised to find that in the /var/lib/mysql/ directory, the only files there ...
1
vote
1answer
29 views

Mysql Master-Slave replication catchup and bin_logs

I have set up MYSql Replication using 2x 128gig ram 24 core cloud servers. we have a massive live database that cannot experience down time due to the high volume of data input. I have found while ...
2
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0answers
3k views

Why does CAST(1 AS SIGNED INTEGER) return a BIGINT on MySQL?

If I do CAST(1 AS SIGNED INTEGER) I always end up getting a BIGINT returned, for example: $ mysql -u root -p --column-type-info Enter password: --- Copyright and help message snipped for brevity --- ...
0
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1answer
26 views

how to overcome these type of issues where null value inserted into primary key not null column in table

how to overcome these type of issues where null value inserted into primary key not null column in table
2
votes
2answers
139 views

How to batch multiple insert statements for database dump with MySQL?

I have a MySQL database with some large tables. In particular, the largest table (by far) currently has ~11,000,000 rows. According to the a query I ran, the table clocks in at around 1.7GB, but it's ...
1
vote
1answer
67 views

Why does this ALTER TABLE ADD FOREIGN KEY query create two foreign key constraints

I am attempting to add a foreign key constraint to existing tables via an ALTER TABLE statement: CREATE TABLE `blog` ( `blogid` int(11) NOT NULL AUTO_INCREMENT, `deptid` int(11) NOT NULL DEFAULT ...
0
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0answers
61 views

MySQL Dynamic columns duplicate value workaround

As the title suggests i have the following code which transposes certain row values into field names, however the problem im having is that the values "closed" & "reopened" may appear in several ...
2
votes
4answers
833 views

Getting 0KB of size file while backup mysql database using mysql dump [closed]

I am using below code to backup my database using php script but I am getting 0KB size file. How can I backup my full database with all routines and functions? $dbhost = 'localhost'; $dbuser = ...
10
votes
2answers
146 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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0answers
184 views

Are there any caveats to installing MySQL 5.5 on CentOS 5?

I need to install MySQL 5.5 in CentOS 5. As CentOS 5 is a little bit old is there any odd behavior when you want to install MySQL 5.5 on CentOS 5?
2
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1answer
66 views

How can I determine which Innodb table is being written?

I am running Mysql 5.5. I have about 100 Innodb tables spread over 10 DB's (mostly wordpress sites) and I am recently seeing a lot more disk IO than I have been, without any increase in traffic. The ...
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2answers
93 views

MYSQL: Join with many to many

I'm trying to create a view and trying to see what can be done, I have a main table a table I want to join to and also a junction table. Event table (it's very big so it's just dummy data): ...
5
votes
2answers
115 views

Is there a (non-binary) MySQL collation that doesn't treat different mathematical symbols as the same character?

I've run into a real headache with MySQL's collations and non-BMP characters (ones with Unicode codepoints above U+FFFF). Basically, given a table and data like: CREATE TABLE `math` ( `id` int(11) ...
0
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0answers
61 views

How to use a subquery that returns multiple rows?

I am getting Error 1242 : Subquery returns more than 1 row. Basically, I have to do this : select data from my database based on a time criterion (between 2 dates) and then apply a filter on the ...
0
votes
1answer
42 views

Unique constraint for new values only

I have a large table with a column that contains duplicates. I want to add a unique constraint on this column for future entries only (not the old data). Is this possible?