-3
votes
2answers
87 views

how to solve slow running sub query TSQL

I have a problem with a slow running query. I have analysed the query with the sql server profiler but I can't seem to find a good solution. I did find why it is running slow. If ask the full ...
0
votes
1answer
39 views

How to optimise very simple query with subquery that only needs to execute once

SELECT products_id, products_model, products_iban_no, products_allocation_number FROM products WHERE products_model IN (SELECT products_model FROM products GROUP BY products_model HAVING ...
0
votes
0answers
47 views

Latest of group in subquery is bottleneck, how to optimizing query?

See Original question I'm fetching the activity data for the latest activity for each company as part of a bigger query. I've been using the method provided by ypercube, and it works fine, but I find ...
0
votes
1answer
56 views

Take query results and insert into new table [closed]

So I have the following query: DECLARE @tbl TABLE(value int) *--The same function but with the number of the random numbers ;WITH Nbrs (n) AS ( SELECT 1 UNION ALL SELECT 1 + n FROM ...
1
vote
2answers
113 views

optimization of expensive subquery

The following query gets the last report (where latitude and longitude and secs are <> 0) associated with the specified units: SELECT reports.* FROM reports INNER JOIN ...
1
vote
1answer
670 views

UPDATE a column by COUNT of another table

It might be a naive question, but what is the difference of these two queries and which is preferred? UPDATE table1, (SELECT id,COUNT(*) idcount FROM table2 GROUP BY id) AS B SET table1.Freq = ...
1
vote
1answer
402 views

Using OFFSET in a large table by a simple sub-query

The slow performance for using OFFSET in large table has been widely discussed in various blogs, and the most efficient way is to use an INNER JOIN as SELECT * FROM table INNER JOIN ( SELECT id FROM ...
0
votes
1answer
288 views

Find nearest values from MySQL Table

I want to fetch nearest rates for a given value from below table. mysql> select * from rates; +------+----------+----------+ | ID | Type | Rate | +------+---------------------+ | 1 | ...
1
vote
2answers
347 views

Improve performance with the WHERE NOT IN sub-select clause

In the following query, I have to count transactions for each customer. [EDIT]However, I have to exclude from the result set entirely, customers that have a transaction older than one year. ...
1
vote
1answer
101 views

Minimizing Page Fetches

I have a complicated database structure and am trying to use it to retrieve Records based on multiple selection criteria from several tables. As a general rule, is it better to attempt to use ...
1
vote
3answers
2k 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 ...
0
votes
2answers
711 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 ...
2
votes
2answers
151 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 ...
-3
votes
2answers
645 views

Optimisation sub query SQL Server

I would like to optimise the query below because it's actually taking 40% of the time in the real one. I HAVE to get the first line in the table 2 for each line in the table 1. The relationship is 1 ...
3
votes
1answer
5k views

MySQL: Optimize UNION with “ORDER BY” in inner queries

I just set up a logging system which consists of multiple tables with the same layout. There is one table for each data source. For the log viewer, I want to UNION all the log tables, filter them ...
3
votes
2answers
238 views

Do MySQL sub-queries essentially use as much overhead as separate queries?

If I have a query like this: SELECT name FROM ( SELECT * FROM `table` WHERE id IN (1,40,300) ORDER BY AnotherColumn ) From a bandwidth and overhead standpoint, is that the same thing as doing ...
1
vote
1answer
1k views

PostgreSQL 9.1 - Query on VIEWS taking a lot of time

Using PostgreSQL 9.1, we are having problems while executing queries on a VIEW of PostgreSQL. Following is the situation: We have a partitioned Table "buz_scdr" over which we have built a VIEW ...
3
votes
5answers
442 views

Query optimization [Oracle]

The Query: select JOIN_RESULT.batch_id as BATCH_ID, JOIN_RESULT.unique_doc_id as DOCUMENT_ID, JOIN_RESULT.brand as BRAND, JOIN_RESULT.message_date_time as UPLOAD_DATE, ...
4
votes
1answer
4k views

mySQL query optimisation — multiple joins or select … where not in (select distinct…)?

Background I have a Drupal install accessing a large users database (~200k rows) and my "People finder" functionality needs to access all those rows (in a random order). I don't seem to be able to ...
4
votes
3answers
293 views

Which is the most efficient way to run a particular select query?

If I run the following code: select PolicyNumber, MAX(decpageid) as decpageid, Risk from StatRiskDecpages where PolicyNumber = 'AR-0000301132-04' group by PolicyNumber, Risk I get the following ...
5
votes
4answers
2k views

MySQL subquery slows down drastically, but they work fine independently

Query 1: select distinct email from mybigtable where account_id=345 takes 0.1s Query 2: Select count(*) as total from mybigtable where account_id=123 and email IN (<include all from above ...