sqlperformance Questions
4
I have a database in SQL Azure which is not taking between 15 and 30 minutes to do a simple:
select count(id) from mytable
The database is about 3.3GB and the count is returning approx 2,000,000...
Zebe asked 14/9, 2014 at 7:47
9
When should I use KEY, PRIMARY KEY, UNIQUE KEY and INDEX?
Caldarium asked 2/10, 2010 at 8:5
1
Solved
What happens if two transactions try to modify the same row simultaneously? Normally, once the row is modified, the other transaction waits until the first one performs commit or rollback. But what...
Cm asked 3/5, 2021 at 6:48
1
We had a weird issue in development and are looking for an explanation on a self-deadlock issue with a SELECT INTO on a temp table.
We have a routine to transform some fairly complicated JSON docum...
Vargas asked 17/9, 2020 at 13:59
2
Solved
I have a table with 10 millions rows that I need to join with another table and update all data. This is taking more than 1 one hour and it is increasing my transaction log in 10+ GBs. Is there ano...
Tampon asked 13/1, 2015 at 23:44
4
Solved
this a poor performancing query I have ... what have I done so wrong?
Please help me it is executed tons of times in my system, solving that will give me a ladder to heaven
I gave a check on the s...
Gangrel asked 21/12, 2018 at 12:1
3
Solved
I have the following Chained CTE query (simplified):
;WITH CTE1
AS(
SELECT * FROM TableA
),
CTE2
AS(
SELECT * FROM TableB b INNER JOIN CTE1 c ON b.id = c.id
)
SELECT * FROM CTE2
If I break C...
Soto asked 2/11, 2018 at 17:7
1
I have a presto cluster configured with 12 workers that is being queried by Java applications. The cluster is capable of performing 30 concurrent requests (if there are more, they are queued).
The...
Datha asked 12/7, 2018 at 9:20
1
Solved
This is a follow-up question to Retrieving last record in each group from database - SQL Server 2005/2008
In the answers, this example was provided to retrieve last record for a group of parameter...
Fully asked 22/5, 2018 at 11:56
2
I have following queries:
DECLARE @application_number CHAR(8)= '37832904';
SELECT
la.LEASE_NUMBER AS lease_number,
la.[LEASE_APPLICATION] AS application_number,
tnu.[FOLLOWUP_CODE] AS note_type...
Beldam asked 6/9, 2017 at 7:29
3
This started off as this question but now seems more appropriately asked specifically since I realised it is a DTU related question.
Basically, running:
select count(id) from mytable
EDIT: Addi...
Contrastive asked 27/9, 2014 at 9:5
2
Solved
I have a web application that use a SQL Server database that is shared with others web applications (over which I have no control). I must know when any of the web apps makes changes to some tables...
Modiolus asked 26/9, 2016 at 17:58
1
I have a table of books :
CREATE TABLE `books` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`nameOfBook` VARCHAR(32),
`releaseDate` DATETIME NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `Index 2` ...
Yahiya asked 8/11, 2016 at 14:26
2
I have a performance query nearest stores:
We have a table that contains around 50,000 records (stores/point of sale locations) in one country.
Each record has location columns of type "geography...
Ermey asked 23/12, 2016 at 15:2
1
Solved
Given the next SQL statement:
Select *
from A join B
on A.id1=B.id1 and
A.id2=B.id2
where A.year=2016
and B.year=2016
and knowing table A is much smaller than table B, so I need the datab...
Modal asked 21/12, 2016 at 12:56
5
Solved
summary: I've seen a lot of advice against using SELECT * in MS SQL, due to both performance and maintainability concerns. however, many of these posts are very old - 5 to 10 years! it seems, from ...
Tungstic asked 2/9, 2016 at 15:29
1
Solved
Is writing
session.createCriteria(Person.class)
.add(Restrictions.eq("id", personId))
.setMaxResults(1)
.uniqueResult();
better than writing
session.createCriteria(Person.class)
.add(Restric...
Hulen asked 23/3, 2016 at 10:24
8
Solved
So, recently a DBA is trying to tell us that we cannot use the syntax of
SELECT X, Y, Z
INTO #MyTable
FROM YourTable
To create temporary tables in our environment, because that syntax causes a l...
Parting asked 19/8, 2009 at 21:18
5
Solved
SELECT Trade.TradeId, Trade.Type, Trade.Symbol, Trade.TradeDate,
SUM(TradeLine.Notional) / 1000 AS Expr1
FROM Trade INNER JOIN
TradeLine ON Trade.TradeId = TradeLine.TradeId
WHERE (TradeLine.Id ...
Smith asked 11/5, 2011 at 20:39
2
Solved
The documentation for sys.dm_db_missing_index_group_stats uses the terms "user queries" and "system queries" but it doesn't define what those mean. For example:
user_seeks: "Number of seeks cause...
Rhizotomy asked 12/8, 2015 at 23:56
3
I have one small doubt in query performance. Basically, I have a table with more than 1C records. sl_id is the primary key in that table. Currently, I am updating the table column status to true (d...
Minh asked 9/7, 2014 at 7:17
1
Solved
Up until now my foreign keys have always been uniqueidentifiers or an int.
Would it impact performance negatively if I used a nvarchar field as a foreign key? Are there any other considerations I ...
Allantois asked 26/2, 2014 at 5:21
1
Solved
I've just recently become aware of the fact that you can now index your views in SQL Server (see http://technet.microsoft.com/en-us/library/cc917715.aspx). I'm now trying to figure out when I'd get...
Freeze asked 24/12, 2013 at 15:20
1
Solved
Does the order of the values in a WHERE IN clause matter? (this is on Firebird SQL if that is important)
Such as does:
where field1 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
offer a performance increa...
Swords asked 29/4, 2013 at 1:39
1
Solved
I'm running some aggregation queries on some very large tables in an OLAP environment. I'm currently bottlenecked by disk IO at 200 MB/s.
I'm doing these queries on a machine with 92 GB of RAM. Is...
Crookes asked 26/2, 2013 at 17:41
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