0
votes
1answer
32 views

Take query results and insert into new table

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
80 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
116 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
106 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
148 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
283 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
89 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
1k 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
559 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
141 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
493 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
4k 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
214 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
355 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
283 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
1k 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 ...