0
votes
2answers
22 views

Sorting of results is slow some times but fast at other times

I have a mysql query that is joining a few tables and then uses order by field for sorting. It sometimes runs quite fast at other times it is slow. While it was slow i profiled the query to find that ...
1
vote
1answer
19 views

How to store temp tables in memory during table “optimize”?

When optimizing tables, SHOW PROCESSLIST lists it as "copying to tmp table". I'm trying to ensure the copy takes place in memory to speed up the process. I've tried adjusting the tmp_table_size to ...
4
votes
1answer
67 views

sql indexing and performance

I am using mysql5.1, i have table which has about 15 lakh (1.5 million) records.This table has records for different entities i.e child records for all master entities. There are 8 columns in this ...
1
vote
2answers
39 views

What's the best way to translate a website [on hold]

I have a website in Django using MySQL, and I have more than 4.000 entries that I want to translate. What's the best way to do it? Create a new database for every language? Create other table for ...
0
votes
1answer
25 views

MySQL Query Cache - what type of queue is used?

I am wondering what type of queue is MySQL Query Cache using. When there is new query and cache is full which query is deleted? Oldest one? One with fewer number of hits? Or maybe there is some ...
0
votes
1answer
30 views

How to make make my query run fast?

How to make this query run faster? Table contains over 2 million rows of data and takes around 30 to 120 seconds to process the query. SELECT INET_NTOA(blocks.startIpNum), ...
2
votes
2answers
206 views

Optimized query to fetch a record from 10 million entries

A table has 2 fields | UniqueKey | TimeStamp | ------------------------- | xfsddddq | 1024125412 | | xfstttdx | 1024125413 |< | xfsdxxau | 1024125415 | Estimated, there are 10 million ...
0
votes
1answer
44 views

MYSQL Stock Database Optimization

I am downloading a bulk of stock data: Ticker symbol, company name, industry sector, Open, high, low, close I was wondering performance-wise if separating the ticker, company name, industry sector ...
1
vote
0answers
49 views

Tagged questions

I have similar to StackExchange network that utilises tagged questions. In my web application Users also can find questions by tags. The query below returns a set of tagged questions: SELECT ...
0
votes
0answers
29 views

How can the performance of a query that has a condition on two fields of each row be improved?

I have an images table with approximately 5 million rows in it. For the purposes of this question lets say the table looks like this: CREATE TABLE `images` ( `id` int(11) NOT NULL AUTO_INCREMENT, ...
0
votes
0answers
26 views

MySQL: Large data slow reads

I have very large table with 17,044,833 Rows and 6.4 GB in size. I am running the simple query below and it takes like 5 seconds. Any ideas what optimizations can I do to improve the speed of this ...
0
votes
0answers
53 views

Opimizing Mysql

Below is a Snapshot of my Server info. And the results of mysqltuner.pl Some help with commands would be appreciated. I'm new to this and have gotten pretty far, but I'm having issue with Mysql ...
0
votes
0answers
25 views

Why is adding a FK constraint slow in MySQL?

I'm doing some experimentation in MySQL 5.1.53 and I've run across a case that I just don't understand. CREATE TABLE A ( `pk` INT(11) NOT NULL, `fk` INT(11) NOT NULL, PRIMARY KEY `pk_A` ...
1
vote
1answer
54 views

mysql optimize group by having count

I have 2 mysql table: table t1: CREATE TABLE IF NOT EXISTS `t1` ( `id` bigint(20) NOT NULL, `url` varchar(255) DEFAULT NULL, `title` varchar(255) DEFAULT NULL, `type` varchar(255) DEFAULT ...
0
votes
1answer
50 views

Can this where in subquery be optimized?

Currently the query takes ~ 0.2 seconds. Is this the best it gets? Because it feels rather slow for the amount of data I have in my database. I've tried creating an inner join out of it but I can't ...
1
vote
1answer
191 views

Can I rely on this SQL shortcut to save a query?

Consider a table with a status field that holds one of two values: | status | set('active','default') | YES | | active | I need to know how many records are in the table, and additionally how ...
0
votes
0answers
19 views

Optimization for a dynamic M2M value field

I'm using a Configurable Product methodology in my system. Everything works great, but I have one thing I think that might strongly impact the performance in the future. This is a dynamic linking ...
1
vote
1answer
28 views

MySQL hangs in killed state

I have a strange situation where a mysql OPTIMIZE query will never end. After killinh it, it remains in the "killed" state. Scenario to reproduce: OS: CentOS 6.5 MySQL: 5.6 Engine: MyISAM (with at ...
0
votes
0answers
32 views

query comes in slow query when log_queries_not_using_indexes is enabled

This query comes in slow query log when log_queries_not_using_indexes is enabled. SELECT a.id, d.id AS city_id, d.city FROM booking a, sub_area_master b, area_master c, city_master d WHERE ...
1
vote
1answer
51 views

How can I optimize this query?

I'm trying to select the time field from five tables and return the oldest time. The userid field in every table is indexed. Here's the query: ( SELECT `time` FROM `eventlog` WHERE userid = ...
0
votes
0answers
30 views

Which of these two queries is better - can be optimized more?

With regards to the usage of the IF statement, which is better to use? Query #1: SELECT whatever FROM auctions AS a LEFT JOIN ............... WHERE ............... ORDER BY ...
0
votes
0answers
46 views

How do I perform a batch update on the first n matching rows?

I need to perform a large number of updates at the same time. Each update needs to only affect up to a specific number of rows even though the WHERE clause might match to many more rows. So far, I'm ...
0
votes
1answer
88 views

INSERT take too much time

I have in my MySQL DB a few tables Most of the time, I'm only doing INSERT in my db. I have up to 4 connections to the DB, each one inserting into a different table. There cannot be two connections ...
0
votes
0answers
47 views

Alternatives for subquery

There are three tables: product_hits, products, and product_subcategory_map. I want to count the number of product_hits and for each product. There could be more than one subcategory in the ...
1
vote
1answer
147 views

InnoDB: very bad performance on INSERT/UPDATE

Lately I have really big problems with INSERTs and UPDATEs. On my website 80% of all queries are SELECTs but in query slow log there are only INSERTs and UPDATEs. My dedicated server has 32GB RAM, ...
0
votes
1answer
47 views

Optimize query to minimize tmp copying time

I have this mega query : SELECT s.eleve_id, crs.id_cours as 'cours_id', mc.code as cours_code, s.employe_id, s.id_seance, '0' as theorique, s.statut, s.type_vehicule_id, s.type_conduite_id, ...
2
votes
1answer
80 views

Optimize table and query, aggregate by date or date-hour

I have a table storing sensor data (100M rows currently) from stations from different sites. In my case, sites may have many stations. Create table statement is as follows: CREATE TABLE sensor_data ( ...
1
vote
2answers
216 views

Optimize a MySQL Database using MySQL Workbench

I actually have a few issues. First, I found this information about optimizing: MySQL OPTIMIZE all tables? The problem is, I don't seem to have a mysqlcheck program anywhere. I'm using MySQL ...
1
vote
1answer
74 views

Need to optimize simple SELECT query for InnoDB table with 2million rows

I'd like to make this query the fastest possible, since it's called really often. SELECT login_events.id FROM login_events WHERE ( DATE(created_at) >= DATE(CURRENT_DATE) AND person_id = 1 ) ...
3
votes
1answer
496 views

Maximum possible memory usage: 16.2G (874% of installed RAM)

Why the MySQL is saying that can use about 16GB of RAM even if my server has only about 2GB? # ./mysqltuner.pl >> MySQLTuner 1.2.0 - Major Hayden <major@mhtx.net> >> Bug ...
4
votes
4answers
80 views

Optimize MySQL Query using LEFT JOIN

I have a query with execution plan as below and is taking more than 20 seconds to execute how can i optimize it EXPLAIN SELECT c.coupon_id as c_id, `c` . *, `st`.`name` AS `store` FROM `coupon` AS ...
3
votes
1answer
81 views

Simple SELECT takes forever, but works as a subquery. Why?

I'm running a MySQL 5.1 server and I have a MyISAM table called my_table with nearly 5 million records. Its structure is the following: ...
0
votes
0answers
99 views

how I can set tmp_table_size for 16GB long table?

I am posting the same question as I posted in SO, but somebody advice me to post it here. I have a 16GB big table with 8 partition. And RAM 4 GB. I am running a query - SELECT ...
0
votes
0answers
30 views

Tips for improving my particular batch processing

I'm working with mail data from the USPS, which contains 10 related tables to make up a single mailing, as well as a single table containing all of the scans that each mail piece may receive. Once per ...
0
votes
1answer
96 views

On which fields to index? Fields queried (WHERE) or fields returned (SELECT)

I have a large MySQL database table (~1 million rows and growing) on an AWS RDS Medium instance: mysql> describe clients; ...
0
votes
0answers
39 views

is it good to add index on column used in group by clause?

I have a query like- select x, sum(y) from xyz where z>=100 group by x order by sum(y) desc; will it be faster if I am going to add index on x?
0
votes
0answers
29 views

How to make a process use all the power of the machine (MySQL process)

I need to do a serious migration of data from MySQL to MongoDB. I have dumped the actual database from its server to the Amazon AWS box. I set up a powerful Amazon AWS Ubuntu EC2 12.04.3 type ...
1
vote
1answer
59 views

DROP TABLE on a huge InnoDB table

I have an innodb table with over 140 million rows taking 26GB. I would like to drop this table however this is taking way too long, probably days. How can I speed up this query? processor: Intel® ...
1
vote
2answers
77 views

MySQL (InnoDB) UPDATE SET performance with value in WHERE AND clause

If an UPDATE query is performed where the values being SET are also part of the WHERE clause, in the form of an additional AND statement on the column being set's value, is there a significant ...
0
votes
2answers
173 views

Which is better? A join or a SELECT IN? [closed]

I have a set of ids that I extract using a join of 2 tables. Now I need some information from 2 other tables. What would normally be the best approach? So a SELECT IN using the set of ids I already ...
1
vote
1answer
64 views

How is the number of records on a select determined as high or low by optimizer?

What is the threshold between using the index and doing an direct access to the database? I assume this decision is related to the number of index access (and subsequent access to the tables). If this ...
0
votes
1answer
121 views

Optimizing multiple MySQL sub-queries and joins for multiple runs

The query (below) that's running is taking ~0.6 sec which normally would be fine but it gets run almost 1300 times for different custids. How can I make it run faster? Setup: Mac OS X 10.7.5 MySQL ...
0
votes
0answers
27 views

Large-query optimization: given my “explain” results, what stands out?

I've got a monster query, which runs quite quick in many cases, but in some cases very much slower. The EXPLAIN output below is from one of the slow cases. I'm guessing that the slowdown is related ...
0
votes
2answers
980 views

How to force higher values of open_files_limit or table_open_cache?

I'm having a frustrating problem where setting my.cnf to values higher than I currently have them does not 'take'. This is MySQL 5.6.14 on MacOS X 10.8.3 I'm trying to address dropped connections ...
0
votes
1answer
108 views

Optimize MySQL Self JOIN Query

I have a query which is running in 15+ seconds SELECT t1.`ST_StockCode`, t2.`SM_StockCode`, t2.`ST_ItemSize` FROM `stocks` AS t1, `stocks` AS t2 WHERE ...
0
votes
0answers
68 views

can this mysql query be optimized further?

I have this query select counterparty_id, max(id) max_id from client_administrations where counterparty_type = 1 and effective_on <= '2013-10-22' group by counterparty_id When I ...
2
votes
2answers
103 views

Convert to Self JOIN

I have a correlated sub query, which is taking 16 Minutes to execute. How can I convert it to join or optimize it. SELECT SSF.SM_StockCode, SSF.ST_ItemSize FROM Stock AS SSF WHERE ...
1
vote
2answers
47 views

Convert to JOIN [duplicate]

I have a correlated sub query, which is taking 16 Minutes to execute how can i convert it to join or optimize it. SELECT SSF.SM_StockCode, SSF.ST_ItemSize FROM Stock AS SSF WHERE SSF.SM_StockCode = ...
0
votes
2answers
63 views

Filesort while using primary key for orderby

I have been breaking my head for the past two days now for this. CREATE TABLE `clients` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `guarantor_name` varchar(50) NOT NULL, ...
0
votes
1answer
126 views

How to optimize indexes on MySQL query with various sorts

I have an INNODB table levels: +--------------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | ...