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SELECT Top (100) a lot faster than Top (1)


SELECT Top (100) a lot faster than Top (1)

By : urmila
Date : November 22 2020, 04:01 AM
it helps some times Solution:
After checking out the green information message in the SSMS execution plan window, there was a missing index with a INCLUDE of the selected Column.
code :


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Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc

Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc


By : Ryan
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , One reason that selecting specific columns is better is that it raises the probability that SQL Server can access the data from indexes rather than querying the table data.
Here's a post I wrote about it: The real reason select queries are bad index coverage
Why is Select 1 faster than Select count(*)?

Why is Select 1 faster than Select count(*)?


By : user1446942
Date : March 29 2020, 07:55 AM
I wish this help you Since Oracle doesn't support IF EXISTS in PL/SQL, CodeByMidnight's suggestion to use EXISTS would normally be done with something like
code :
SELECT 1 
  INTO l_local_variable 
  FROM dual 
 WHERE EXISTS( 
    SELECT 1 
      FROM some_table 
     WHERE some_column = some_condition ); 
The faster of two SQL queries, sort and select top 1, or select MAX

The faster of two SQL queries, sort and select top 1, or select MAX


By : user1721756
Date : March 29 2020, 07:55 AM
wish help you to fix your issue With an index on order_date, they are of same performance.
Without an index, MAX is a little bit faster, since it will use Stream Aggregation rather than Top N Sort.
MYSQL: Why SELECT [explicit column names] is faster than SELECT *

MYSQL: Why SELECT [explicit column names] is faster than SELECT *


By : user3414526
Date : March 29 2020, 07:55 AM
Does that help When you do select * the rdbms has to expand the * to the column names and do the select after words. When you provide explicit column names that step isnt necessary.
Why select count(*) is faster the select * even if table has no indexes?

Why select count(*) is faster the select * even if table has no indexes?


By : user2341256
Date : March 29 2020, 07:55 AM
I wish this help you The execution time difference is due to the fact that SELEC * will show the entire content of your table and the SELECT COUNT(*) will only count how many rows are present without showing them.
Answer about optimisation
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