I'm doing a database query but it's taking a while, I believe it's for the group by and the order by, but I couldn't get better.
SET #CODIGO_EMPRESA = 1;
SET #CODIGO_FILIAL = 2;
SET #DATA_INICIAL = '2021-06-16 21:59:17';
SET #DATA_FINAL = '2021-09-20 21:59:16';
SET #SITUACAO_SUP_SANG = 0;
SELECT *
FROM
(
SELECT
CODIGO_BOMBA, CODIGO_BICO, ENCERRANTE_FINAL
FROM
MOVIMENTO_COMB_ABASTECIDAS
WHERE
CODIGO_EMPRESA = #CODIGO_EMPRESA
AND CODIGO_FILIAL = #CODIGO_FILIAL
AND DATAHORA < #DATA_INICIAL
ORDER BY DATAHORA DESC , ENCERRANTE_INICIAL DESC
) A GROUP BY CODIGO_BOMBA, CODIGO_BICO
You need a multicolumn index to help this query run fast. It should contain the two columns you mention in WHERE ... = ... and then the column you mention in WHERE ... < ....
Try this:
CREATE INDEX MCA_CE_CF_D
ON MOVIMENTO_COMB_ABASTECIDAS
(CODIGO_EMPRESA, CODIGO_FILIAL, DATAHORA);
You didn't ask about this, but your query has some other problems. You're misusing MySQL's notorious nonstandard extension to GROUP BY. So its SELECT clause is interpreted as if ANY_VALUE() appeared on the third column.
SELECT CODIGO_BOMBA, CODIGO_BICO, ANY_VALUE(ENCERRANTE_FINAL)
And, because SQL is a set-processing language, it is free to ignore ORDER BY clauses in subqueries unless they're accompanied by LIMIT clauses. If it somehow is not ignoring your ORDER BY clause, that is nothing but luck.
Related
I have the following mysql query that I think should be faster. The database table has 1 million records and the query table 3.5 seconds
set #numberofdayssinceexpiration = 1;
set #today = DATE(now());
set #start_position = (#pagenumber-1)* #pagesize;
SELECT *
FROM (SELECT ad.id,
title,
description,
startson,
expireson,
ad.appuserid UserId,
user.email UserName,
ExpiredCount.totalcount
FROM advertisement ad
LEFT JOIN (SELECT servicetypeid,
Count(*) AS TotalCount
FROM advertisement
WHERE Datediff(#today,expireson) =
#numberofdayssinceexpiration
AND sendreminderafterexpiration = 1
GROUP BY servicetypeid) AS ExpiredCount
ON ExpiredCount.servicetypeid = ad.servicetypeid
LEFT JOIN aspnetusers user
ON user.id = ad.appuserid
WHERE Datediff(#today,expireson) = #numberofdayssinceexpiration
AND sendreminderafterexpiration = 1
ORDER BY ad.id) AS expiredAds
LIMIT 20 offset 1;
Here's the execution plan:
Here are the indexes defined on the table:
I wonder what I am doing wrong.
Thanks for any help
First, I would like to point out some problems. Then I will get into your Question.
LIMIT 20 OFFSET 1 gives you 20 rows starting with the second row.
The lack of an ORDER BY in the outer query may lead to an unpredictable ordering. In particular, the Limit and Offset can pick whatever they want. New versions will actually throw away the ORDER BY in the subquery.
DATEDIFF, being a function, makes that part of the WHERE not 'sargeable'. That is it can't use an INDEX. The usual way (which is sargeable) to compare dates is (assuming expireson is of datatype DATE):
WHERE expireson >= CURDATE() - INTERVAL 1 DAY
Please qualify each column name. With that, I may be able to advise on optimal indexes.
Please provide SHOW CREATE TABLE so that we can see what column(s) are in each index.
I'm new in sql and I have some problems with complex selection. How can I delete two rows with smallest base_amount with base_currency 'USD'?
In MySQL, you can use ORDER BY and LIMIT in a DELETE:
delete from t
where base_currency = 'USD'
order by base_amount asc
limit 2;
I have a SQL query like this, and it takes high amount of loading...
Not sure what is happening here...if anyone could help me with this.
SELECT `posts`.* FROM `posts`
WHERE `posts`.`type`
IN ('MySubDomainSitePost')
AND `posts`.`aasm_state` = 'published'
AND (published_at <= '2015-05-12 01:01:01')
AND `posts`.`on_frontpage` = 1
AND `posts`.`is_pinned` = 0
ORDER BY published_at DESC LIMIT 16
You need to check the query performance using explain select. Now for large data-set the query will perform very poorly if the columns are not indexed.
From the given query you may need to add the following indexes
alter table posts
add index p_search_idx(type,aasm_state,published_at,on_frontpage,is_pinned);
This will boost up the speed of the query.
Make sure to take a backup of the table before applying the index.
And no need to use IN in the query it could be as
SELECT `posts`.* FROM `posts`
WHERE `posts`.`type` = 'MySubDomainSitePost'
AND `posts`.`aasm_state` = 'published'
AND (published_at <= '2015-05-12 01:01:01')
AND `posts`.`on_frontpage` = 1
AND `posts`.`is_pinned` = 0
ORDER BY published_at DESC LIMIT 16
I have the following query:
SELECT *
FROM products
INNER JOIN product_meta
ON products.id = product_meta.product_id
JOIN sales_rights
ON product_meta.product_id = sales_rights.product_id
WHERE ( products.categories REGEXP '[[:<:]]5[[:>:]]' )
AND ( active = '1' )
AND ( products.show_browse = 1 )
AND ( product_meta.software_platform_mac IS NOT NULL )
AND ( sales_rights.country_id = '240'
OR sales_rights.country_id = '223' )
GROUP BY products.id
ORDER BY products.avg_rating DESC
LIMIT 0, 18;
Running the query with the omission of the ORDER BY section and the query runs in ~90ms, with the ORDER BY section and the query takes ~8s.
I've browsed around SO and have found the reason for this could be that the sort is being executed before all the data is returned, and instead we should be running ORDER BY on the result set instead? (See this post: Slow query when using ORDER BY)
But I can't quite figure out the definitive way on how I do this?
I've browsed around SO and have found the reason for this could be
that the sort is being executed before all the data is returned, and
instead we should be running ORDER BY on the result set instead?
I find that hard to believe, but if that's indeed the issue, I think you'll need to do something like this. (Note where I put the parens.)
select * from
(
SELECT products.id, products.avg_rating
FROM products
INNER JOIN product_meta
ON products.id = product_meta.product_id
JOIN sales_rights
ON product_meta.product_id = sales_rights.product_id
WHERE ( products.categories REGEXP '[[:<:]]5[[:>:]]' )
AND ( active = '1' )
AND ( products.show_browse = 1 )
AND ( product_meta.software_platform_mac IS NOT NULL )
AND ( sales_rights.country_id = '240'
OR sales_rights.country_id = '223' )
GROUP BY products.id
) as X
ORDER BY avg_rating DESC
LIMIT 0, 18;
Also, edit your question and include a link to that advice. I think many of us would benefit from reading it.
Additional, possibly unrelated issues
Every column used in a WHERE clause should probably be indexed somehow. Multi-column indexes might perform better for this particular query.
The column products.categories seems to be storing multiple values that you filter with regular expressions. Storing multiple values in a single column is usually a bad idea.
MySQL's GROUP BY is indeterminate. A standard SQL statement using a GROUP BY might return fewer rows, and it might return them faster.
If you can, you may want to index your ID columns so that the query will run quicker. This is a DBA-level solution, rather than a SQL solution - tuning the database will help overall performance.
The issue in the instance of this query, was that by using GROUP BY and ORDER BY in a query, MySQL is unable to use the index if the GROUP BY and ORDER BY expressions are different.
Related Reading:
http://dev.mysql.com/doc/refman/5.0/en/order-by-optimization.html
http://mysqldba.blogspot.co.uk/2008/06/how-to-pick-indexes-for-order-by-and.html
I have an existing mysql query that I need to add to and I'm not sure how to go about it.
Here is my current sql query.
SELECT tbl_brokerage_names.brokerage_id, tbl_brokerage_names.short_name,
b.indication, b.max_indication
FROM tbl_brokerage_names
LEFT JOIN (
SELECT * FROM tbl_recommendation_brokerages
WHERE recommendation_id = {$_GET['id']}
) b ON (tbl_brokerage_names.brokerage_id = b.brokerage_id)
ORDER BY tbl_brokerage_names.short_name ASC
Here is the query that I need to work into the previous query.
SELECT * , COUNT( * )
FROM tbl_streetaccounts
JOIN tbl_brokerage_names
WHERE tbl_brokerage_names.brokerage_id = tbl_streetaccounts.brokerage_id
Basically I need to return a count, so I need to combine these two queries.
You should run these as two separate queries.
The COUNT(*) query will return a single row, so there's no way to "combine" it with the first query while preserving the multi-row result of the first query.
Also, when you SELECT *, COUNT(*) you will get columns from some arbitrary row.
By the way, you have a glaring SQL injection vulnerability. Don't interpolate $_GET parameters directly in your SQL query. Instead, coerce it to an integer:
<?php
$id = (int) $_GET['id'];
$sql = "SELECT ... WHERE recommendation_id = {$id}";
Like #Bill said, you cannot get the count in every row without really weird syntax, but you can get an overall count using GROUP BY ... WITH ROLLUP.
e.g.:
<?php
$id = mysql_real_escape_string($_GET['id']); //works with anything, not just numbers
$query = "
SELECT tbl_brokerage_names.brokerage_id
, tbl_brokerage_names.short_name
, b.indication
, b.max_indication
, count(*) as rowcount
FROM tbl_brokerage_names
LEFT JOIN (
SELECT * FROM tbl_recommendation_brokerages
WHERE recommendation_id = '$id' //The single quotes are essential for safety!
) b ON (tbl_brokerage_names.brokerage_id = b.brokerage_id)
GROUP BY tbl_brokerage_names.brokerage_id WITH ROLLUP
ORDER BY tbl_brokerage_names.short_name ASC
";
The GROUP BY .. WITH ROLLUP will add an extra line to the result with all NULL's for the non aggregated columns and a grand total count.
If you have any lines where rowcount > 0 then you need to add extra clauses from table b to the group by clause to prevent MySQL from hiding arbitrary rows.
Table tbl_brokerage_names is already fully defined because you are grouping by the primary key.