MySQL : Open-Source, Relational Database Management System

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Get unique rows based on max of a column in mysql

I came across many solutions like the one in this question. However, they all are restricted to data from one table. I'm very very new to SQL. I'd like to get the same results as in the linked ...
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Poor performance filtering mysql spatial join

First of all, sorry for the crossposting. I ask this question in stackoverflow and they sent me here I have a mysql table with spatial references (GEOGRAPHIC_FILTER), like cities, countries, natural ...
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MySQL SSL using MariaDB JDBC Driver

We have the following setup: Ec2 instance running a jboss server with mariadb (1.1.7) datasources setup to connect to an rds instance running MySQL 5.6.21. We would like to turn on SSL on for this ...
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Limit relation one to many or one to one

In a relationship one to many or one to one you can limit the relationship of the related table? For example, I have a table 'cliente' and another 'acct', each 'cliente' can have thousands (perhaps ...
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How “relatively safe” is the data which was salvaged from corrupted MySQL InnoDB database?

I encountered the corruption like the following. 150208 14:27:52 InnoDB: Error: page 443375 log sequence number 8941 870477908 InnoDB: is in the future! Current system log sequence number 5968 ...
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InnoDB Deadlocks Involving Currency Transactions

We're dealing with InnoDB deadlocks that are affecting our virtual transaction system. LATEST DETECTED DEADLOCK 150210 20:51:03 *** (1) TRANSACTION: TRANSACTION 0 4240405649, ACTIVE 0 sec, process no ...
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MySQL ssl setup failed

I am following word by word of http://dev.mysql.com/doc/refman/5.0/en/creating-ssl-certs.html for creating SSL certificates to setup SSL enable replication but it is not working for me. Steps which I ...
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Help with ER design

So i am trying to create a db for a restaurant as a homework assignment.. However there is a spot that confuses me and involves the dish entity. "Every dish must belong to a category ...
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Database schema design for individual configurations

I'm trying to design a database schema that allows me to store customer custom built products. As a simplified example: A user can buy a cupboard, draws, boxes, and dividers. A cupboard has 2 tiers. ...
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MySQL - Cannot add new Foreign Key

I'm using magento and it does some re-index for a product flat table structure. In this process a new table is created. The SQL for that table is something like: CREATE TABLE ...
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How to set the trigger when field(contain json value) is updated?

I have one table in which there is one field called info.This field hold json value. I want to create trigger on this field.I want to split this json format string into record I mean I want to insert ...
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Custom cycling order in MySQL

Having following Foo table: id | name | group ===|=========|====== 1 | "John" | 1 2 | "Paul" | 1 3 | "Marry" | 1 4 | "Josh" | 1 5 | "Mike" | 2 6 | "Kevin" | 2 7 | "Ramon" | 2 8 | "Kim" ...
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MySQL InnoDB Configuration with 60Gb of Memory

I'm running a large MySQL Database, in the range of 30Gb in size. The MySQL 5.5 server is running on a dedicated server with 60GB of RAM, with no other processes installed apart from monitoring tools, ...
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Is there any way to improve this code?

SELECT tblstud.studid, tblsched.ip FROM tblstud LEFT JOIN tblstudsched ON (tblstud.studid=tblstudsched.studid) LEFT JOIN tblsched ON (tblstudsched.schedid=tblsched.schedid) ...
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Can MySql cause a Windows server to shutdown unexpectedly?

For the 3rd time, my server where my MySQL instance is running simply shutdown unexpectedly, this time, causing my tables to be corrupt as I had ALTER statements running. While in contact with my ...
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adding a new partition takes a long time

I am adding a new partition and it takes too long to get this task done. ALTER TABLE attribute_usage_information ADD PARTITION ( PARTITION AUI_2015001 VALUES LESS THAN (735964) ) I am new to MySql ...
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Connection error except with SQLYog

I have a problem connecting with the database with PHP or with MySQL in Linux . I can only connect to the DB with SQLYog. The error I'm getting is this: SQLSTATE[HY000] [2003] Can't connect to MySQL ...
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To configure MySQL Enterprise Workbench for Incremental Backup with Online Backup option

Could not acquire management access for administration RuntimeError:Could not initialize WMI interface: Workbench.wmiOpenSession():Could not connect to target machine. When i am trying to configure ...
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Using Netscaler datastream and MySQL

I configured MySQL service on a netscaler 10.5. When I perform some MySQL benchmarks using mysqlslap, the first time it runs correctly, the 2nd time I have an error message: When I run it the first ...
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Can MySQL Index Merge an Composite index with a single column index?

I am tuning a query and currently have an index as following : Index 1 : (col1, col2) An example query would be : SELECT * FROM t1 WHERE col1 = '1' AND col3 = '2'; I have created an index on ...
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25.000+ rows - MySQL SELECT consecutive numbers performance issue

I have tried to be as explicit as I could. Below you have the query explained in details What I want to obtain? - I want to SELECT start_number and end_number from a set of consecutive numbers from ...
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two column compare ,get count(*) of two column A value same cloumn B value

I have a Mysql table as --------------------- -- page - user -- --------------------- -- page a - user 1 -- -- page a - user 2 -- -- page a - user 3 -- -- page b - user 1 -- -- page b - user 3 -- ...
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MySQL calculate overlapping period excluding overlapping rules

I would like to calculate the period overlap in hours based on special rules. I created a test setup, that works as long as the rules themselves don't overlap. Example non overlapping rules: id ...
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Multilanguage category structure - standard vs. normalization?

I'm building a multilingual application and I need some advice on how to structure the table. Basically I have a category table based on nested set. There are 4 languages and I plan to enlarge this ...
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Sysbench insert data between a given range

I was trying to insert 1000000 records of data into 1000 tables in sysbench. But after installing about 278, sybench just crashed with the following error: FATAL: failed to execute function ...
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Are ZRM (Zmanda Recovery Manager) incremental backups reliable?

I had an issue while restoring incremental backups and I'm wondering if they are reliable. I'm making weekly full backups and daily incremental backups and I needed to restore a single database after ...
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Migration error: “Invalid date literal detected” when reading decimal

I'm attempting a migration from MSSQL to MySQL and keep coming across a "Invalid date literal detected" error when reading certain decimal columns. I'm running the following (all up-to-date as of ...
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Migrate from SQLite to MySQL (then back)

For various reasons, I must use a SQLite database with a local application. However, I wrote a Flask app that enables users to more easily classify items in the database, and it runs very slow on ...
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Need advice on optimizing database on a recurring basis

I have a search engine with approx 3.5 million rows in the searchable table. There are many suppliers that feed into the table each day, so primary keys are constantly being removed and added and the ...
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Handling this multi-threading scenario in the database?

I am working on sample bus ticket booking application,in I am facing these two multi-threading scenarios. Scenario 1 1: Let's say there are two users, they both pick a particular seat and submit ...
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MySQL - Transactions and causality

I'm new to MySQL's LOCK and TRANSACTION and have a question about different isolation levels of a transaction: Given two transactions executing the same code (auto-commit is false): (1) get data of ...
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Handling SQL updates for production deploys

I'm researching for quite a long time now (about two months) and haven't found a good approach for this, so I'll ask you experts out there in the hope of some enlightenment. I run a pretty ...
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Can't seem to optimize joined select query

Can't seem to figure this one out. Query is taking upwards of 7-8 seconds which is just not acceptable and seems as though it will get worse as the table(s) get larger. Without going into a ton of ...
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MySQL table partition strange behavior (slow query suddenly)

(I asked this question in "stack overflow" and was recommended to ask in here). (MySQL version: 5.6.15) I have a huge table (Table_A) with 10M rows, in entity-attribute-value model. It has a ...
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MySQL not using multicolumn index on self join

I'm trying to optimise a query that performs an inner join with itself. The table size is currently 10GB ~50 million rows. /* Count all occurrences between start and end site id of a given speed ...
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276 views

Lost Connection to mysql server at 'reading authorization packet', system error 0"

OK, this has been bugging me all afternoon now, I have a new MySQL Database '5.5.40-0+wheezy1-log' running on Debian Linux. It is to all extents and purposes a clean install. I have created two ...
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Any way to mitigate the large server load during LOAD DATA LOCAL INFILE operations?

I'm using MySQL LOAD DATA LOCAL INFILE to load csv files, and have noticed that during these loads, server output speed to other users diminishes eg long page download times, logins timeout. The LOAD ...
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Skipping stopwords (and indexing small words) for one fulltext index only, in MySQL

I have a rather odd situation where it might be preferable to not use stopwords and to have a value of ft_min_word_len equal to 1. The index in question would be dealing with only a few words per row ...
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Summing a column based on uniqueness of another column without using temporary table

I have a table like this: CREATE TABLE `files` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, `hash` char(40) DEFAULT NULL, `size` bigint(20) unsigned DEFAULT '0', ...
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ORA-00937 when calculating a sub-value in an aggregate select statement

The problem described below applies to Oracle 11g databases. I also tested the statements on MySQL and PostgreSQL with no problems of the kind mentioned in this question. I want to use an ...
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MySQL permissions or privileges (User does not have access to metadata required)

I am using MySQL and I need to give one user to web service for access database. The web service need all permission related to stored procedure, like procedure execution. I executed the following ...
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“Unexpected EOF” during SELECT on huge MyISAM table

When executing a SELECT query that uses filesort on a huge table (2 billion rows) the execution stops after ~30mins with the following error message: ERROR 9 (HY000) at line 1: Unexpected EOF found ...
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172 views

MySQL master slave replication not working

I had MySQL master slave running and working fine but suddenly it stopped. I don't know which commands have been executed but now replication is not working. I am very new to MySQL can anyone help me? ...
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How can I correct MySQL replication while using federated tables?

This is an overview of what I have going I have 2 server A (10.0.4.22) AND B (10.0.4.29) A is a replication of B and B is a replication of A (yes it is a ring replication) ON A I have 2 table uat and ...
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Combining fields to make a unique record or keeping them separated

I've been asked to implement what has before, been a bunch of CSV files, into a MySQL database. I'm at a point in the design where all the schemas, tables and fields have been mocked-up; however I'm ...
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Selecting most recent date when dates are stored in another table

Working in a MySQL database, I have tables set up like this: Table song_instances has song_id (int), meeting_instance_id (int) The meeting_instances table has columns meeting_instance_id (int), ...
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Copying to tmp table slow for query … but only sometimes

I have a query, and I admit it may not be the prettiest query in the world. Sometimes this query runs fairly fast (e.g. 200ms) and other times it runs super slow (e.g. 30s). I don't know why, and ...
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MySql Audit Changes from Db Admin, Security

I know that you can use triggers (before insert, update, delete) to track the changes in history tables. But this only works if the changes are made by the applications. But in some circumstance, ...
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How to calculate geographic distances using MySQL

Given a MySQL table with a series of latitude and longitude points, stored as strings, how can I find the distances between each point in the table and a given point, call it "originlat, originlon" ? ...
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Conversion to Barracuda/Compressed Rows Doesn't Free Disk Space

I'm currently converting large tables to the Barracuda file format. We are using file_per_table. I had one table that decreased from 4.3gb in size down to 1.8gb and we're very happy about this. ...