Tagged Questions
0
votes
2answers
46 views
How do I use subquery on the same table in MySQL?
I have a query like this which takes a really long time to run. The table is around 4 million rows.
DELETE FROM TABLE WHERE value_was IS NULL OR value_was <= value_now;
I'm hoping I could ...
2
votes
3answers
69 views
How can I improve this query?
About a year back I introduced a query which returns a sort of "Customers Also Purchased" data-set. At the time it ran reasonably fast however, as of late it's become very slow, sometimes taking up to ...
0
votes
2answers
48 views
How to use and optimize subquery on 100 million rows
What I'm trying to do is running a job on more than 100 million domains which haven't processed before.
I have two tables, "domain" and "domain_setting", on every batch (10.000 domains per batch) I'm ...
0
votes
0answers
46 views
MySQL query optimization when no row is returned
I am using explain to figure out what is happening in my query which is:
explain select t from c where u1_id = 1 group by t;
I see "Using where" in the Extra column of the resultset. But this only ...
0
votes
1answer
33 views
MySQL stored routine performance while using PREPARE
Instead of maintaining stored routines for each database in my current environment i have decided to create separate database just for stored routines storage. Mainly i am using them for reporting. ...
0
votes
1answer
19 views
Simple query not using indexes
My query is not using indexes.
It is a simple query.
Can someone explain why that's the case?
The query:
select TIME_FORMAT(start_time,'%H:%i') start_time,
TIME_FORMAT(end_time,'%H:%i') ...
0
votes
1answer
44 views
Optimizing ORDER BY for simple MySQL query
I'm trying to optimize this really simple query, and it gives me grief for a day now :(
Seems pretty straightforward, I need to select with a JOIN from 2 tables, and get top X results sorted in a ...
0
votes
1answer
46 views
MySQL database schema design help needed
I am developing a PHP application expecting millions of records both parent and children. My goal is to design an optimized database design to achieve high speed and performance.
This application ...
0
votes
2answers
69 views
speeding up a query on MySql
I have a table with more than 10 million rows and 10 fields(columns). There is an index on field_1 and I am running the following query.
create table t2
select field_1,
sum(ifnull(field_2,0)) ...
2
votes
1answer
160 views
How to speed up queries on a large 220 million rows table (9 gig data)?
The issue:
We have a social site where members can rate each other for compatibility or matching. This user_match_ratings table contains over 220 million rows (9 gig data or almost 20 gig in ...
0
votes
2answers
149 views
optimize big sql query
My query has to return a statistics for example for march containing productname and price and its sidedishes (1:n relation) with the right price of each sidedish and the right tax for each sidedish ...
0
votes
1answer
61 views
Speed efficient query for membership first joined, latest category from membership table (min, max)
I have the following table representing membership information:
CREATE TABLE IF NOT EXISTS `membership` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`organisation_id` int(11) NOT NULL,
...
0
votes
1answer
64 views
Second time query execution using different constants makes faster?
Can someone explain or direct me how execution on indexes happen with different constants at intervals in Mysql. I notice only for the first execution on the table it takes time, after that with ...
1
vote
2answers
76 views
Database and query optimizacion
I have a database containing three tables: tbl_database (main table is the primary), tbl_cmdatabase and tbl_blacklist. The three tables share the same structure but differ in the number of records ...
0
votes
1answer
56 views
query taking long time to execute.we are expecting result in very quickly anybody please rewrite it
Query is taking long time to execute.we are expecting result in 0 sec.If possible Please help me to rewrite it. Also suggest me to add any indexes on table.Also suggest me if optimization is needed.If ...
0
votes
2answers
110 views
MySQL: can not get rid of “Using filesort” in a simple query
Simple query but can not get rid of "using filesort":
CREATE TABLE IF NOT EXISTS `online` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`uid` int(11) NOT NULL,
`expiration` int(11) NOT NULL,
...
2
votes
0answers
30 views
How can one improve the performance of a query that selects on a low cardinality column in MySQL?
I have a "State" column that has a low cardinality (three possible value), on which most of my queries perform an equality selection (WHERE col = 'blah') AFAIK you need something like a bitmap index ...
0
votes
1answer
68 views
Mysql. Block/disconnect slow queries
I am experiencing issue.
Someone 'attacked' my server: simply by searching the same phrase with multiple requests.
As it is text search request and database indices are not used, the engine searches ...
2
votes
0answers
134 views
MySQL: Improve performance for one row insert into table with unique constraint
I have a table with ~ 40 mil records, with a unique index on the url collumn, of type varchar(255).
Now the insert speed is about 30/s, is this expected? how could I improve it?
I can't use bulk ...
1
vote
1answer
102 views
Query is not using indexes on third table in left join
My query is not using indexes on third table(pci promotion_coupon_images) .
i was tried with using index and force index in query but there is no change in result.
any body please suggest me how ...
0
votes
1answer
77 views
Create a VIEW that spans 3 tables
Sorry if the title is not clear - feel free to improve.
Here are 3 tables (not all data is relevant to the question):
CREATE TABLE `content` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
...
1
vote
1answer
33 views
simple query is not using indexes
My query is not using indexes.
it was taking around 5 seconds.
output is 500 rows only. it is a simple query
Please find the explain plan and table structure here.
Explain Plan
mysql> explain ...
0
votes
0answers
72 views
Performance Optimising MySQL query
I have this query in my mysql database, when i execute this, it takes about 4 sec. To give me the result (on xampp 1.8.0 with mysql 5.5)
I was wondering if there is any way to enhance this query so ...
1
vote
2answers
61 views
Efficient way to query set of rows from MySQL
I am using MySQL database engine. My Java application uses simple JDBC to retrieve data from database.
I have following database schema: main table with two columns: (INTEGER id, BLOB data). id is ...
0
votes
1answer
59 views
Query taking long time
My query is taking around 540 seconds to get result.
Please help me to rewrite it.
Query:
SELECT pd.domain, fd.passkeyid
FROM portfolio.domains AS pd,
fabulousdomains.domains AS fd
WHERE ...
1
vote
1answer
130 views
Slow query performance
My database contains 20,000 rows and the following query is slow. Please help me to speed this up:
SELECT r.report_id,
r.user_id,
u.user_name,
u.user_mail,
...
2
votes
2answers
103 views
Slow MySQL query with Order and Group by
I have a query that is taking a long time to execute (1.13s). The two tables user_articles and articles have around 25,000 records. This is the query:
SELECT `user_articles`.*
FROM `user_articles`
...
2
votes
1answer
223 views
Mysql - show results from 3 tables excluding NULL or EMPTY values for certain fields
I have 3 simple tables with polls, users and votes. I'd like to show all polls ordered by clean count of votes (sometimes either poll_id or user_id don't get inserted).
Furthermore I'd like to show ...
2
votes
1answer
71 views
Slow Query Gets Even Slower After Indexing
I have a MySQL database with just one table containing 8 million records. I need to query the table to find a single record that matches a specific number:
select * from my_table
where
...
1
vote
1answer
61 views
Performance impact of including result column in indexed columns
I have a database (in MySQL, using InnoDB) that I am using for texture identification in a 3D image. In it, there will be a table of texels(texture pixels) with hue included, in the form of:
texelid ...
2
votes
2answers
106 views
Query taking too much time
My query is taking too much time to execute. Please help me here.
mysql> explain
select pcm.catalog_id
from cat_produ_catal_map_defer pcm, cat_catal_catal_map_defer ccm, cat_catal_defer c
...
0
votes
1answer
57 views
Long running query
This is my long running query:
select *
from t_keyword
where id in
(
select rel.element_id
from t_event event
join t_event_element_rel rel on
event.id = rel.event_id
where
...
1
vote
2answers
105 views
How to optimize this query?
Query:
Select *
from `t_event`
where `create_user_id`=7
and (`event_create_date`)=('2012-12-18 00:00:00')
and `event_type_cd`=11
and `domain_id` =602
and `job_id` =1
limit 1
Table structure:
...
2
votes
2answers
68 views
MySQL index on column comparison
How do you go about setting an index to be used for a column comparison like WHERE col1 > col2?
col1 and col2 are of DATETIME type.
2
votes
1answer
174 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 ...
1
vote
1answer
130 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 ...
2
votes
1answer
103 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 ,
...
2
votes
3answers
91 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'
...
1
vote
1answer
71 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 ...
0
votes
1answer
80 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 ...
1
vote
2answers
133 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
(
...
0
votes
2answers
191 views
Slow query with straight_join for small result
I have a performance-problem with a query in my application and I don’t understand the behavior of mysql.
The query consists of different joins, especially the join to the mentioncache-table. If the ...
2
votes
2answers
105 views
Can I use a foreign key index as a shortcut to getting a row count in an INNODB table?
I have a table that has a large number of rows in it.
The primary key (an auto-incrementing integer) is, by default, indexed.
While waiting for a row count to be returned I did an EXPLAIN in another ...
2
votes
1answer
242 views
inner join on PK with extra criteria slow despite indices?
Given the two tables below I am struggling to understand:
why is the third query slow even though first two queries are fast
what exactly is EXPLAIN saying
can I do anything to significantly speed ...
0
votes
0answers
108 views
how to improve performance of my query it was taking more than one hour in my environment
How can I improve performance of below query? It was running more than one hour to execute in my production environment. Query plan:
mysql> explain
SELECT transaction_detail.trans_id,
...
1
vote
1answer
117 views
Optimizing User Defined Custom Columns
I am building a web based app that has the potential to have very high traffic and collect a lot of data. Most of this traffic will be utilizing the database. Database is MySQL InnoDB. I want to give ...
1
vote
1answer
84 views
Combining columns in index
With reference to RolandoMySQLDBA's answer on
MySQL: Index when joining to tables not being used (Performance optimizing question)
He mentioned
Make sure you build an index that involves the ...
2
votes
3answers
442 views
MySQL optimization - year column grouping - using temporary table, filesort
I have a transactions table which is having 600,000 records, I need to list the count for the dashboard on financial year basis. The table used is MyISAM. I tried adding index for the transaction date ...
1
vote
1answer
420 views
Slow complex query with group/order
I have a problem with a very important query in my application.
It is very slow when adding group and order to it.
So the full query is:
SELECT
m.id,
m.title,
m.title_text,
...
1
vote
2answers
304 views
Slow mysql fulltext query
I have a little problem with the performance of a mysql-query which uses a fulltext index.
The following query
SELECT Mention.id
FROM mentions AS Mention
WHERE (MATCH (`Mention`.`title_text`, ...
