Tagged Questions

MySQL : Open-Source, Relational Database Management System

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0
votes
1answer
28 views

Useful guide & FAQ for Application+SQL [closed]

Of course when you are making your first application for fun it doesn't matter that much how you deal with things. But when you need everything to be up to the current standards you don't always know ...
0
votes
0answers
61 views

Change a query so it no longer takes 20 mins and uses a 93G tmp table

Edit: So how would I go about changing this query to something more sane (given that I can work around the hibernate madness) This might be a whole different problem, but Hiberate has created a ...
0
votes
1answer
52 views

Can a primary key of one table be a foreign key of another table?

I am working on a scenario like this : I have an employee table which has columns like this Employee_ID First_Name Last_Name Employee_Designation Also I have a Joining_Vital table Employee_ID ...
2
votes
1answer
56 views

Innodb DB Consuming IO even when no operations are being done

I am currently doing some stress testing where I am pushing inserts to the database as fast as I can. The simulation inserts 10000 records per second. After inserting around 200 million records I ...
2
votes
2answers
221 views

“All joins can be rewritten to sub queries”, is this statement true?

I wonder if there any case that a join can not be converted to a sub-query. BTW: I am not discussing advantages and disadvantage of using sub-query or using join.
1
vote
1answer
46 views

How to change rows to columns in mysql?

I have data as following(it is just an sample, I have 100+ different types.): advertiser_id activity_type counts 1 1 2 1 2 5 2 1 ...
0
votes
2answers
63 views

Retrieving row ranking in a table

I'm aware there are already many questions alike however none of those answers helped me achieve row rankings in a table. I have a table set up as so: ...
0
votes
0answers
24 views

mysqldump replace option - ubuntu / mediawiki

I know this is probably a silly question, but I'd like to be sure, rather than make assumptions. There's the option to use 'replace' in a mysqldump, which uses the 'REPLACE' rather than the 'INSERT' ...
4
votes
1answer
292 views

How to setup complex multi-column index for massive table

I've searched what I could search on Google, SO, etc and haven't found an answer that would seem to fit what I'm looking for. I'm hesitant to make a post about this as I'm sure the answer is out there ...
0
votes
1answer
111 views

Can't restore from mysql dump file

I used mysqldump command to export/dump .sql file with rows like: String cmd1 = mysqldump + " -h" + host + " -u" + username + " -p" + password + " " + "--compact --no-create-info " + "--where=ID=" + ...
1
vote
1answer
41 views

mysqldump - select table in database only if it contains a specific string

(I'm new to Database Administrators, and am not a Database Administrator. However I originally asked this question on Stack Overflow (here) but didn't get any answers. Sorry if this is not the right ...
3
votes
2answers
106 views

0xDBE how to connect over local socket?

I want to connect to mysql over socket. This is what I'm trying to do: and it's not working. This is how it works in mysql workbench:
0
votes
1answer
43 views

how to setup [master] - [master-slave] - [slave] mysql replication

i am trying to setup a mysql replication architacture between 3 mysql server. (by following some tuto like ...
0
votes
1answer
45 views

duplicate entry issue with large mysql database table

I have a very large my sql database table. The other day, for no apparent reason, I now keep getting :- Duplicate entry '148245' for key 'PRIMARY' If I remove the entry at with primary of 148245, ...
0
votes
4answers
120 views

How to subtract fields and insert the value in other field automatically?

id val1 val2 total 1 10 4 10-4(automatically get the value) . . . . I am using php and mysql. I have a total column I need to make calculation automatically in a field, how it ...
1
vote
1answer
46 views

MySQL Delete Rows from Slave

I want to truncate the majority of data on a slave such that it only has the most recent records. I'll eventually demote the current master, making it a read-only archive, and promote the truncated ...
0
votes
2answers
30 views

How to delete a column named grave accent in MySQL

As title. Every time when i try to execute the query: ALTER TABLE tablename DROP COLUMN ```, got syntax error, which is understandable. So, what should i do to delete this column whose name is the ...
0
votes
2answers
142 views

Getting a Deadlock,

I have this code : public void saveItems(List<Pair<Item, MapleInventoryType>> items, int id) throws SQLException { PreparedStatement ps = null; PreparedStatement pse = null; ...
0
votes
0answers
37 views

MySQL loading XML

Hello i have this XML format (illustration) [Im using MySQL 5.6] <ROWS xmlns:xsi="..." xmlns="..." xsi:schemaLocation="..."> <TABLE col1="7169340714" col2="2" col3="2013-09-05T15:19:42" ...
2
votes
3answers
298 views

Why MAX() of SUM() giving wrong output?

I have a table employee id name salary city 1 ram 50000 c1 2 sham 20000 c2 3 jadu 80000 c1 4 madhu 90000 c4 5 hari 10000 c2 6 gopal 34000 c3 7 ...
0
votes
2answers
65 views

left join not working [closed]

CREATE TABLE `table1` ( `id` INT(10) NOT NULL ) ENGINE=InnoDB; CREATE TABLE `table2` ( `id` INT(10) NOT NULL, `value` INT(10) NOT NULL ) ENGINE=InnoDB; INSERT INTO table1 VALUES (1), (2), (3), (4); ...
0
votes
0answers
53 views

MySQL DATE vs DATETIME read/write performace

Did anyone perform accurate read/write performance comparisons of MySQL's DATE vs DATETIME column types? Please do not bother writing "It should be faster" or "I think it's faster". I am looking for ...
0
votes
2answers
53 views

Need Help maintaining multiple databases for a multi-tenant application?

i need some information about multiple databases for a multi-tenant application ? I am working on a project in which we are maintaining separate database for every company? The Companies Database ...
0
votes
1answer
34 views

Mysql speed issues with SHOW COLUMNS or SHOW FIELDS

To avoid making code changes every time we have a database change, we just use the SHOW FIELDS (Alias of SHOW COLUMNS) to get all of the columns for Inserts. We call this multiple times for multiple ...
0
votes
1answer
35 views

Schema check or “DATE as separate table”

I'm dusting of my SQL, and would love to know if I've got my mental ER-diagram right. http://sqlfiddle.com/#!2/c5c59 Basically, I've got 10-15 different datasets (actividades) from several locations ...
0
votes
1answer
287 views

how to sync local mysql database and live server database?

My plan is to store data in my local MySQL database and after a time interval it will update my live MySQL database remotely. Is it possible? I'm planing a inventory management script in PHP MySQL. ...
0
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0answers
40 views

Infinite loop in MySQL when connecting to database

I am running xampp on Windows - Apache and MySQL start fine, but when I try to go to the directory where I have my example app, it loops infinitely waiting for localhost: The log shows: 2014-08-22 ...
0
votes
2answers
106 views

How to break table into two without losing performance?

According to http://stackoverflow.com/a/174047/14731, splitting away infrequently-needed columns frees up the cache allowing faster retrieval of the commonly-used columns. I've got a table whose ...
0
votes
1answer
92 views

Multi-Column Full Text Search Going Very Slow

I have a full text index on a table articles for the columns content, title and keywords When doing the search on each of the columns, like so select count(1) from articles where ...
0
votes
1answer
9 views

Determining which database instance makes biggest IO

Assuming that I have a dedicated server on which I am running multiple instances of mysql and postresql servers. How without iotop determine which instance in particular time (proc/pid/io shows data ...
0
votes
0answers
21 views

Combining 2queries: One filtered Users on Role, One Select users with only one specific role

First query: Selects All users with specific rid ( 3 or 4 or 19 or ...). SELECT u.uid AS uid, u.name AS name, fn.field_full_name_value AS field_full_name_value FROM users u LEFT OUTER ...
6
votes
1answer
210 views

Huge differences of performance of MySQL in two servers

We have a MySQL server installed in two different machines, a testing server and a production server, both windows, which is used by a web application. The problem is that there are HUGE performance ...
1
vote
1answer
102 views

Revoke write privileges vs setting database to readonly

I am planning to do a database migration to a new server. During the transition stage, I do not want Apache user to be able to write anything to the database. I have two options. Revoke write ...
-1
votes
1answer
51 views

What makes yum difficult with RAID [closed]

I as working with someone on a redhat server using RAID 10 with MySQL, and they mentioned it is hard to use yum when having a raid setup. Is this true? If so, what actually makes it 'difficult'?
1
vote
2answers
174 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
votes
1answer
62 views

MySQL configuration to connect to multiple local applications [closed]

I've installed FreeRADIUS, MySQL and FreeRADIUS management (a web-based app) on the same machine, with both FreeRADIUS and FreeRADIUS management using same user to connect MySQL. My problem is when I ...
2
votes
2answers
54 views

Copying datadir directory enough for backing up a database with InnoDB tables?

I have an innodb table with 80 million rows and it's extremely slow with mysqldump so I'm thinking of copying the datadir directory for a backup / transfer. I used to copy database with only MyISAM ...
0
votes
0answers
18 views

If I were to peak under the hood, how does MySQL's GET_LOCK function work?

I am curious about how MySQL's GET_LOCK function actually works. I understand what it means when I ask for a lock, and what the potential return values are. But I want to get a better understanding ...
1
vote
0answers
25 views

MySQL Memory & max_connections Performance Tuning

So, our site runs WordPress and in the past few days we have been getting tons of spam comments etc. I believe that we are becoming the victims of some kind of bot army that has been crashing our ...
0
votes
2answers
61 views

average record hourly

I have one table, here is the schema CREATE TABLE `table_200901` ( `id` int(11) NOT NULL AUTO_INCREMENT, `carType` bigint(20) DEFAULT NULL, `dateTime` datetime DEFAULT NULL, `distance` ...
0
votes
0answers
10 views

SQL Select a rolling count of total transactions over time [duplicate]

I need to get a set of total transactions over time on a weekly interval. Essentially I need a total-transactions-to-date column. When I group by WEEK(Date) I get the amount of transactions for that ...
2
votes
3answers
86 views

Rolling count of total transactions over time

I need to get a set of total transactions over time on a weekly interval. Essentially I need a total-transactions-to-date column. When I group by WEEK(Date) I get the amount of transactions for that ...
0
votes
2answers
51 views

Best way to store few rows of data every minute without creating 1440 columns a day?

I will be calling a server that returns some JSON data every minute. The values are along the lines of Value, Currency, DateTime, and maybe 1 or 2 more values. What is the best way to keep save these ...
0
votes
1answer
32 views

Why does mysql treat “<” like it was “<=”?

I've tried the following command: SELECT * FROM `mi_schedule` WHERE `day`<=(DATE_ADD(NOW(),INTERVAL 7 DAY)) AND `day`>=NOW() Got 8 rows. Then I changed the <= to <, and nothing changed, ...
1
vote
0answers
65 views

How to measure bandwidth requirements for MySQL, Postgres, …?

TLTR: how to configure MySQL/Postgres to get a fair measurement of the I/O requirments for analytical queries? Hello, for certain database and especially database hardware experiments for want to ...
1
vote
1answer
46 views

Error 2003: Setting up MySQL Replication

Trying to setup MySQL Replication using this guide here : http://wpguru.co.uk/2013/05/how-to-setup-mysql-masterslave-replication-with-existing-data/ I was able to do this on two random VMs running the ...
0
votes
1answer
30 views

How to do Mysql migration from 5.0 (320bit windows) to 5.6 (64 bit windows)?

I want migrate My Mysql 5.0 windows 32 bit to Mysql 5.6 Windows 64 bit? Please suggest me the best way to do migration, i have around 10gb of data present in Mysql 5.0.
2
votes
0answers
38 views

Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL 5.1.73 database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. ...
1
vote
1answer
49 views

Java Spring application Database triggers auditing - how to provide the right user that made the change

We are developing a new web application. one of the most basic requirement is to audit all entities changes into a separate table. We would like to use DB triggers for that purpose. We use MySQL as ...
0
votes
0answers
180 views

SQL Server to MySQL migration using MySQL workbench

I tried to migrate database from SQL Server 2012 to MySQL v5.5. I used MySQL workbench v6.1 community edition. What I was migrating is just schema only, not for the data. I got this error Reverse ...