Linked Questions

15
votes
2answers
6k views

Must an index cover all selected columns for it to be used for ORDER BY?

Over at SO, someone recently asked Why isn't ORDER BY using the index? The situation involved a simple InnoDB table in MySQL comprising three columns and 10k rows. One of the columns, an integer, ...
5
votes
1answer
10k views

Mysql fulltext search my.cnf optimization

I have open a question on https://serverfault.com/questions/353888/mysql-full-text-search-cause-high-usage-cpu Some user recommended asking here. We built a news site. Every day we will input tens of ...
6
votes
2answers
2k views

Is there a way to hint to query optimizer to MySQL which constraints should be done first?

This is my current query: SELECT BusinessID as ID, 111151.29341326*SQRT(pow(-6.186751-X(LatLong),2)+pow(106.772835-Y(LatLong),2)*0.98838574205337) AS Distance from ( SELECT * FROM ...
5
votes
3answers
7k views

slow query with fulltext and left join

I have 3 tables about 250,000 records. table1 is MyISAM, add fullindex with title and content, add index with pid. table2 and table3 are InnoDB, add index with pid. Only query table3, just cost 0.04 ...
6
votes
2answers
621 views

Less restrictive query return less result due to simple removing one additional constraint

Look at this query SELECT DISTINCT TB.ID, TB.Latitude, TB.Longitude, 111151.29341326*SQRT(pow(-6.185-TB.Latitude,2)+pow(106.773-TB.Longitude,2)*0.98839228980165) AS Distance FROM `...
0
votes
1answer
1k views

Mysql Fulltext search doesn't return any results

I have an issue with a full text search in a MySQL table. MATCH AGAINST returns no results even I if have 7 records containing the words I'm looking for. What can I do to make it return the rows? ...
3
votes
2answers
1k views

Joining two Mysql VIEWs takes a very long time

I have a textbox (for which I used jQuery auto-completion) in my PHP form where user can insert an actor/actress name and then by clicking "Search" button, a new window is opened showing list of ...
0
votes
1answer
854 views

How can I rewrite the following removing the date_format function?

I have a table with a column when that is of type datetime. I am doing the following filter which can not use and index: AND DATE_FORMAT(t1.when, '%Y-%m-%d') <= LAST_DAY(now() - interval 1 month ) ...
2
votes
2answers
243 views

MySQL - Small table popping up in slowlog, refuses to use index

So I have two very very small tables (~20 rows) that are hit very frequently and pop up in the slowlog (I'm also logging tables not using indexes). I tested using a large multipart index (that's just ...
2
votes
2answers
148 views

Optimizing index creation

One thing that has bothered me for awhile is creating many many indexes for the one table where the query only differs slightly or contains many of the same columns. An example case would be: table1 ...
1
vote
2answers
163 views

Will moving the MATCH…AGAINST part in different part of the query (e.g. before evaluation of JOIN) will improve the performance?

Basically, I have the following query: select `t`.* from `tracking` `t` where exists ( select `ti`.`id` from `tracking_items` `ti` inner join `cars` `c` on (`c`.`car_id` = `ti`.`...