MySQL : Open-Source, Relational Database Management System

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5
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1answer
125 views

Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
3
votes
3answers
309 views

Finding differences between a master and slave when pt-table-sync fails

I have a table that's showing some differences on a master and slave according to pt-table-checksum (PTC). I've found some verifying differences beyond that. Certain tables in the mix have composite ...
1
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2answers
52 views

RAID configuration for mysql

I attached 4 10G disks to mysql Server and I used RAID 0 but still same mysql performance the same, Do I have to change configuration in my.cnf to let mysql know about RAID 0. this is my mount ...
0
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0answers
7 views

Adding time to an event that runs on a weekly basis

I have this event that runs every Thursday CREATE EVENT le_drop_database ON SCHEDULE EVERY 1 WEEK STARTS CURRENT_DATE + INTERVAL 3 - WEEKDAY(CURRENT_DATE) DAY DO BEGIN drop database carbon; ...
0
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1answer
2k views

MySQL relay log corrupted, how do I fix it? Tried but failed

A MySQL v5.1.61 relay got corrupted when the machine suddenly shut down. I tried to fix it but it didn't work. — How do I fix it? Did I do something wrong? As far as I've read, corrupted MySQL relay ...
0
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0answers
7 views

MySQL - Moving binary logs to Network Server On Windows

Is it possible to move the Binary logs for MySQL (on Windows), to a different physical server? My MySQL Databases are MySQL 5.5. (Bearing in mind that ultimately this will be a Master DB, and there ...
0
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1answer
29 views

What's faster: two UPDATEs with WHERE (in / not in) or one UPDATE with CASE?

What's best performance wise, two separate UPDATEs: UPDATE table1 SET enabled = 0 WHERE code NOT IN ( SELECT id FROM table2 ); UPDATE table1 SET enabled = 1 WHERE ...
0
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2answers
110 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
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1answer
30 views

MySQL JDBC does not behaves as the MySQL Workbench

I'm running the following from the MySQL Workbench, and from my local tomcat using jdbc. START TRANSACTION; CREATE SCHEMA IF NOT EXISTS `ROOT`; CREATE TABLE IF NOT EXISTS `ROOT`.`all_tables` ( ...
0
votes
1answer
44 views

Mysql database recovery in linux

Is there anyway to get back database if I deleted database. Is mysql creates temp file which contain temporary data from database and whether I can recover from that Edited: cp my.cnf my.cnf41 mv ...
1
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0answers
15 views

Table is dropped but ibd file still exists

I was dropping some unwanted tables I have in the MySQL. When I run a drop table, its showing table doesnot exists. But when a check in the data directory, the .ibd file exists and its almost 1GB. How ...
0
votes
1answer
185 views

MySQL max_connection value

Questions I got a 12 GB machine with apache & myqsl, i have may apache max_client set to 150 will this cause some bottlenecks with the 50 max_connection in mysql? What value should I set mysql ...
0
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2answers
21 views

Rank variable value in MySQL is always being set to null

In a sample procedure I am trying to find the rank the of the cities according to the number of offices. I have a Location Table and an Office Table and a location can have multiple offices ...
0
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2answers
75 views

Database Design Help: MySql/PostgreSQL Single Database/Multiple Databases

We are planning to build a web based custom business analytics tool using PHP and MySQL/PostgreSQL. In our application, we are planning to upload customer’s data using a Excel sheet and these data ...
1
vote
1answer
24 views

Indexing the difference between two columns in MySQL

Is there a way to optimize/index a query that sorts the difference between two columns. I have a modest sized table of 5 million rows that I'm trying to do the following: SELECT pk_column, column_x, ...
0
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0answers
21 views

Should I drop this column or is there a query that can achieve a results table without duplicate columns?

I use a column named active in several of my database tables to adjust whether a particular entry/row/user/etc should be included in future query result tables instead of deleting the information. ...
0
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0answers
10 views

long mysql insert and update script user variables appear to be lost while running script

I have a mysql database table called 'dash_something' dash_something ------------- date, DATE *this is the date of the summary type, CHAR(10) entity, CHAR(25) number_of_emails_1, INT ...
0
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3answers
24 views

PostgreSQL equivalent of MySQL query variables?

Hello Stack Overflow Exchange People Is there a straightforward way to adapt these types of mySQL queries to postgreSQL: setting variables in MySQL like set @aintconst = -333 set @arealconst = ...
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0answers
25 views

Many small queries or one single query

This is not exactly a question, more of a survey. Here at BlackBean we have a time series aggregation and analysis platform built on top of MySQL, where each client have your own database, and each ...
0
votes
1answer
186 views

slow writes on percona / mariadb server only when replication is running

Hi I am trying to migrate to percona server from mysql 5.6 on windows. In my development machine for percona is running of centos 6.5 which is installed on vmware 5.5 sphere. Our business ...
1
vote
2answers
147 views

How to duplicate related rows

Tables: Payments with auto-increment ID and one-to-many relationship to Projects such that one payment (say £10) has two records in Projects allocating the £10 between the projects. Now next month, ...
0
votes
1answer
24 views

queries for hierarchical data

This table is a questions and answers CMS and i want to know how data is fetched from these tables. +------+----------+-------+ | id | parentid | type | +------+----------+-------+ | 1 | 0 ...
0
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2answers
93 views

How to select the latest record of each hour in a day

I want to select the latest record of each hour in a given date, based on the datetime column 'reading_on' in my table , what is the best way to do it. I already tried group by HOUR(reading_on) with ...
0
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0answers
27 views

Storing DB credentials in an application source code?

I am making an app which connects to a DB, and the app will have plenty different userslogins. Is it a good design choice to have a specific DB login/password for the application, using which the ...
1
vote
1answer
31 views

Adding foreign keys constraint on databases used

We have a server with about 20 databases, all duplicates of the same original db, and we just noticed the original is missing all the foreign keys constraint for some unknown reason. So of course all ...
0
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1answer
47 views

Does “Connect” statement for every query indicate broken connection pooling?

there's only one client application running queries against a MySQL instance. After enabling MySQL's general query log (configured to log every query) I noticed that every query starts with a ...
0
votes
1answer
22 views

SymmetricDS not using Lookup Transform on primary key

I'm syncing records between two MySQL databases using SymmetricDS, but need to keep the primary key (fieldname = "id") fields unique. Symmetric doesn't seem to want to obey the "lookup" transform_type ...
0
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2answers
34 views

MySQL Replication: Seconds Behind Master super high

I've set up a slave db server for my production database, but when I checked the show slave status, I noticed a super big number in seconds behind master. This is the output: ...
1
vote
1answer
19 views

InnoDB deadlock with INSERT .. SELECT

I am trying to understand why a deadlock occurs when two workers in parallel are running INSERT .. SELECT queries on a table which has both 1) auto incremented primary key, 2) a unique index on ...
0
votes
1answer
61 views

Speed up a MySQL BETWEEN query

SELECT dateToFind FROM table1 INNER JOIN table2 ON dateToFind BETWEEN dateFrom AND dateTo I need to improve the performance of this kind of query. I added BTREE indexes on dateToFind, dateFrom, ...
2
votes
3answers
38 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
85 views

Anyway to optimize complex view?

In the system, Files can belong to either products, clearances, business_lines or titles. Clearances are records that represent a combination of a title and a product. Products are collections of ...
1
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0answers
29 views

MySQL 5.1 High Cpu usage on CentOS 6

I am running MySQL 5.1 on a CentOS 6 server with 16G ram. I got also apache on it. MySQL is constantly using too much cpu. top - 17:40:36 up 112 days, 12:13, 1 user, load average: 1.24, 1.72, 1.82 ...
0
votes
1answer
65 views

What is the strategy of query evaluation in DBMS when Limit is used in query?

I have following tables in database post(post_id , user_id , post_text , parsed_text) ; Comment(comment_id , post_id , user_id , comment_text) ; friend(id , user_id , friend_id ) ; group (id , ...
0
votes
1answer
183 views

MySQL DB structure with Main category and several nested sub categories

I am looking to create a set of fields on my webpage identical to what eBay uses on their category selection page when you are selling something. For my purposes I am doing motorcycles, power sports, ...
0
votes
1answer
54 views

GROUP BY performance

I have a query like this: SELECT HOUR(datetime) as Hour, COUNT(*) as hits, SUM(clicks) FROM visitors_log_table WHERE datetime >= CURDATE() GROUP BY Hour WITH ROLLUP It works fine. But I ...
0
votes
1answer
16 views

I cant figure out the error probably with the date field in this mysql stored procedure

This is my empDetails table I am trying to create a stored procedure on. mysql> describe empDetails; +---------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | ...
0
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0answers
6 views

How to migrate a mysql server in production to Percona XtraDB Cluster

I need some help : I have a mysql server in production and i want to migrate all the database to an existing cluster (percona xtradb). For now , my idea is : 1) Lock all tables 2) do a dump per ...
0
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0answers
9 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 ...
0
votes
1answer
20 views

Recovering MySQL root password (XAMPP)

I posted this on StackOverflow and was told to come here. I have an XAMPP MySQL installation and want to recover the root password. I am aware that questions have asked this already, however they are ...
0
votes
1answer
15 views

Best Mysql Settings for my server

I have The following server specification: RAM : 64GB CPU : 2 X 2.50GHz (total 8 cores) This server is only dedicated for mysql database with up to 30GB of data and to run complex queries that ...
0
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0answers
53 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 ...
1
vote
1answer
8 views

Not able to update MySQL table using Oracle: Unknown column in 'where clause' {42S22,NativeErr = 1054}

I have the following tables: MySQL table: jti_member_interact CREATE TABLE `jti_member_interact` ( `INT_MEMBER_ID` int(11) NOT NULL, `INT_ID` int(11) NOT NULL AUTO_INCREMENT, `INT_SOURCE` ...
1
vote
1answer
1k 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 ...
0
votes
1answer
33 views

Proposal: MySQL blob handling revision [on hold]

Why does MySQL store blobs in the direct table rather than off to the side so that if it needs to read the corresponding stuff it will read the stuff off to the side? Essentially it would create its ...
0
votes
1answer
45 views

How to prevent crashes connected with dropped tables during mysql import?

I have made a mysql dump with mysqldump, tables are dropped and re-created with DROP TABLE IF EXISTS `users`; CREATE TABLE `users` ( However for a read-intensive database I sometimes get crashes ...
0
votes
1answer
2k views

In place upgrade from MySQL 5.5 to 5.6.11 removes all users from user table

On Windows, I upgraded from 5.1 to 5.5 no problem. Copied my 5.1 data folder into my 5.5 instance Started mysqld skipping grants Ran mysql_upgrade All good, but going from 5.5 to 5.6: Copied ...
0
votes
2answers
92 views

MySQL incremental backups per database (not global)

While searching for free/open-source MySQL incremental backups solutions I have found a number of ways to do incremental backups and all of them seem to either rely on "logical" way of backups/restore ...
1
vote
1answer
257 views

How to rebuild entire MySQL data after server re install?

I have a MySQL server running with multiple databases in a 32 bit environment. I need to rebuild my system to a 64 bit environment. Is it possible to replicate the entire MySQL databases, users, ...
2
votes
1answer
97 views

poor and/or unreliable InnoDB performance

I recognize that there are a ton of posts like this, but after reading up on InnoDB performance problems, nothing I tried has helped. I have a database containing four InnoDB tables. The largest ...