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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1answer
128 views

Issues with a Table having 120 fields in mysql

I am creating a table with 120 fields in MySQL. It will have 50 varchar(255) fields, other are maximum fields with char(1) , 1 date field and 5 double fields and others are int(11) fields. My ...
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3answers
208 views

Where can I learn about MySQL master/slave, master/master, or clustering setups?

What are the best resources you've read or watched about setting up master/slave or clustering for database replication? I don't know much about this. I have a database that is getting rather large ...
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2answers
1k views

How to GROUP_CONCAT between given rows?

I have a table as id diary 1 breakfast 2 walk 3 start 4 office works 5 office projects 6 end 7 taxi 8 start 9 preparing for meeting 10 doing the meeting 11 end 12 night I want ...
2
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1answer
357 views

Improve the performance and stability of a MySQL server

We provide a B2B solution, which is doing quite a lot of UPDATE, INSERT an DELETE operations. Our infrastructure at the moment looks like this: Home-Server ( MySQL (INNODB) + website ) 5 worker ...
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1answer
56 views

Is it possible to CREATE EVENT to another server?

I have serverA and ServerB. I need ServerA to copy a database to ServerB and UPDATE/INSERT/DELETE as it changes. I think this can be done with replication but I don't want to continually open a ...
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1answer
246 views

Server load discrepency in Slave with Master load being low and constant

We have MySQL Replication Master/Slave Setup db01 Master db02 Slave (ReadOnly) We are getting load discrepency on the Slave (db02), but the Master's (db01) server load is low. MySQL is the only ...
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1answer
370 views

My SQL Replication to an online database server

I have two MySQL Databases: On a local machine (connected to internet via a static IP) My SQL database on my webserver (JustHost, which I can access remotely) I want a replicate my local database ...
2
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1answer
554 views

Analysis of MySQL database in real time Amazon RDS similar to phpMyAdmin

I'm using a single Amazon RDS instance (medium) to power several WordPress websites running on a single Amazon EC2 instance. I used to have my databases on another EC2 instance and installed ...
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1answer
1k views

Splitting a column to normalized table

I have a de-normalized table as Original De-Normalized Table id text 23 first,second|third,fourth,fifth|sixth I want to normalize the database to create the following tables Table 1: (Split by "...
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1answer
401 views

Simplify and optimize a complex query

Our site has a chronological event feed that uses MySQL. We have noticed that some of the queries tend to run for quite a bit longer than others. For example, some queries for our heaviest users take ...
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1answer
852 views

MariaDB allowing select only user to create databases

I'm baffled. I have a select only user, but somehow, the user can create a new database, and create table inside the new database. It can't create tables inside other db. It's really odd. This is ...
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4answers
4k views

MySQL InnoDB locks primary key on delete even in READ COMMITTED

Preface Our application runs several threads that execute DELETE queries in parallel. The queries affect isolated data, i.e. there should be no possibility that concurrent DELETE occurs on the same ...
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2answers
12k views

Getting last row for each day in MySQL

I have problem in selecting other columns for the max(datetime) records. In layman terms I need to get relevant columns where max(DialDateTime) records for all the dates in Mysql. mysql> select ...
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1answer
1k views

How to properly secure MySQL database?

We have a web application based on the famous triad apache + php + mysql which we sell to our customers and gets installed on their servers. Currently, we are using MySQL 5.1.41 which has only a ...
2
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1answer
2k views

how to improve query performance

## Only 1 query which returns 10 rows. ## It took about 66 secs mysql> explain SELECT al.log_id , al.user_id , al.page_name , al.section_name , al.submit_time , al.url , ...
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1answer
813 views

what's the optimal partition setup for a linux db server?

My host wants to know how I want to partition my server before installing CentOS. I need to be able to do use xtrabackup to create quick backups from 20-50GB databases. I know I need to use a LVM, but ...
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1answer
3k views

Where is the MySQL variable - innodb_flush_method?

I would like to tweak the value of innodb_flush_method to find out its performance impact on a database server. That variable is listed when I run the command SHOW VARIABLES. But I could not find it ...
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1answer
2k views

Issue with connecting to the mysql database

We have an outstanding issue with VCC in chicago, there is an issue connecting to the mysql database If an agent does a refresh of the monitor they will be logged out. This is the error we ...
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0answers
96 views

pt-table-checksum generates no output

I've been using pt-table-checksum on our staging server successfully, but when I run ./pt-table-checksum h=localhost,u=user --ask-pass --lock-wait-time=50 --databases prod It just sits there. No ...
2
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3answers
597 views

mariadb ignoring force index

I'm trying to tune a relatively simple query: select bt.col1,bt.col2 from bigtable bt join smalltable st on bt.smalltable_id = st.smalltable_id where st.name = 'some name occuring only once in st' ...
2
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2answers
463 views

Bin logs with high i/o

I'm DBA (IBM Informix) and already use MySQL with Drupal , where have low workload. So, my knowledge of MySQL is minimal. Few days ago I start use MySQL with a basic configuration as back-end for a ...
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2answers
5k views

Deleting MySQL table with pending transactions

Is there a way to delete an InnoDB table or database with pending transactions in MySQL (preferably on file system level)? What happened: I use MySQL 5.5.28 and ran LOAD DATA INFILE… to import a ...
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3answers
709 views

Which RDBMS has the most advanced “table-valued” functions?

Every Database Management System focuses on specific features and applications. I am using mysql, probably as it is popular and satisfies common needs. However, I came across a problem, which needs ...
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2answers
106 views

MySQL query slow even with indexes

Structure of my table mysql> show create table t_group_tag_relation\G *************************** 1. row *************************** Table: t_group_tag_relation Create Table: CREATE TABLE `...
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1answer
405 views

mysql freeze/crash on JOIN

here is query: SELECT nw.news_id, nw.title, nw.description, nw.url, nw.date, nw.image, nw.status, src.title as src_title, src.keyword as src_keyword, src.url as src_url, src.icon as ...
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1answer
108 views

Way to add referencing and referenced entities of a specific entity in E-R Diagram MYSQL

Is there any way to add entities that are referencing a specific entity in an E-R Diagram. I have a database containing 400 tables. I want to see a view containing a specific entity and its ...
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1answer
576 views

Database structure for affiliate system

I am creating affiliate tracking system and looking for best database structure to use on MySQL to place the lowest possible load on the server. There will be 1000 affiliates, and each will have ...
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4answers
9k views

Unable to access mysql database remotely

I ran this command- [root@dev-img mysql]# mysql -u root -h 192.168.1.181 -e "use mysql;" and this is the output I got- ERROR 1045 (28000): Access denied for user 'root'@'192.168.1.65' (using ...
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0answers
162 views

Why is this table structure so slow to CRUD?

I have a table that I am using for queuing emails. Unfortunately, adding to or reading from this table becomes horrendously slow after adding about 50 records. -- Table "mail_queue" DDL CREATE TABLE `...
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2answers
1k views

How to split a string to and get info from another table in mysql

I have a system to assign score for each sentence stored in a column: TABLE 1: word_scores word score this 3 is 4 a 5 test 1 another 0 sentence 8 TABLE 2: ...
5
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1answer
276 views

Which MySQL storage engine is the most similar to ARCHIVE when that is not available?

I have a table that contains a log of events that is written to often and read very infrequently by comparison. I would love to use the ARCHIVE engine, because it is basically designed for exactly ...
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2answers
214 views

How can I optimize this query and support multiple SKUs?

My current query only can select one SKU at a time. I can leave salesite_id constant. If there is a way to also have varying salesite_ids that would be good too, but not necessary. Also any ...
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2answers
3k views

Trouble with triggers and insert .. on duplicate key update

I have two tables with identical schemas. one is a "main" table that is pruned periodically and kept small. The other is a "reporting" table that is an archive of everything that ever was. For ...
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1answer
3k views

MySQL on RDS, data transfer from one instance to another as a production job

I have a MySQL RDS instance ("production") from which I need to copy incremental data to another MySQL RDS instance ("reporting"). “Incremental data” being the new rows in certain tables. Currently ...
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2answers
1k views

mysql replication delay very serious

We use a ssd disk for master database and SATA disk for slave. On high write load (300 writes/s), slave delay is very serious. I have set: innodb_flush_log_at_trx_commit = 0 increased ...
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5answers
8k views

Field types for columns in a MySQL query

Is it possible to get the field type from a MySQL query, in the same way you can get it from a table with the SHOW COLUMNS command? edit: i should clarify that a bit. I am aware that I can get the ...
2
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2answers
6k views

How do I force a JOIN to use a specific index in MySQL?

I have a query that JOINs 2 tables; lineitem and part, select sum(l_extendedprice* (1 - l_discount)) as revenue from lineitem force index for join (l_pk), part where ( ...
2
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2answers
3k views

Comparing dates in a BEFORE INSERT trigger

I need help making a TRIGGER that compares two dates being entered into a table, but I'm not 100% on the syntax I should use. Something like: CREATE TRIGGER chk_dates BEFORE INSERT ON `...
8
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1answer
16k views

Should a MySQL replication slave be set to read only?

I've got replication running on Percona Server 5.5 by following this guide and wondered if I should add read-only=1 to my slave's my.cnf to make it read only? The guide sets up replication for the ...
3
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1answer
5k views

Foreign key of multiple tables

I have the following 3 tables: ╔═════════════════╗ ║ Companies ║ ╠═════════════════╣ ║ id ║ ║ name ║ ║ type ║ ║ etc... ║ ╚═════════════════╝ ╔════════...
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2answers
2k views

MySQL Enterprise Backup error: Log scan was only able to reach xxxx

I use MySQL Enterprise Backup to make incremental backups, but when I apply a restore (copy-back), I can't remake a backup. I get this error: mysqlbackup: ERROR: Log scan was only able to reach ...
2
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2answers
376 views

MySQL “Limit” clause grabbing more results than requested

I'm trying to add pagination to my points system (100 results per page) and came up with this : SELECT A.username, A.points FROM users A INNER JOIN ( SELECT points FROM users WHERE points &...
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2answers
2k views

Best way to organize compound indexes on partitioned table (date by range)?

I have a table with an auto increment primary key, but in order to use the partition feature in MySQL I had to include the date in the primary key so I would use partition by range using the date ...
0
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0answers
65 views

How to check on my partitions?

I am a newbie into partition. First I have a table with auto increment with its primary key and many other fields. I wanted to partition based on dataInsertDateTime column. It have me error so I had ...
7
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1answer
795 views

LOAD DATA INFILE blocks on concurrent use against MyISAM tables

I'm having trouble loading data into MyISAM table(s) concurrently using LOAD DATA INFILE. The loading operation works fine in isolation. Trying to do LOAD DATA INFILE operations concurrently, blocks &...
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1answer
755 views

How to run this MySQL statement?

See the MySQL example on http://dev.mysql.com/doc/refman/5.5/en/loop.html: I copy it and paste on MySQL command line but it stop at every semicolon. I wonder how to make these sentences work? I ...
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2answers
2k views

how to reduce mysql overhead?

My machine has 2GB RAM, I have some cron job run every minute insert into some data. My mysql always overhead. I think it is very frequently, if some cron job mysql insert run, 5-10 minutes, the db ...
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1answer
292 views

Where are partitions defined in mysql

I have a large table that I want to spread across multiple disks/LUNs. It will contain blobs and I want to have it separated out from the other data. How do I go from new disks (lets call them ...
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1answer
222 views

MySQL user defined rollback procedure

I'm attempting to write my own mini-rollback procedure. I have a table that tracks any updates or deletes to another table using a trigger. I am attempting to make it possible to restore one or more ...
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2answers
13k views

Dynamic change to innodb_flush_log_at_trx_commit

This is related to this question. It does help to get better performance for InnoDB tables. According to MySQL manual, innodb_flush_log_at_trx_commit is a global dynamic variable. Thus, I can change ...