Does the number of columns been selected affect query speed?
27174
"SELECT *" why is it an antipattern
8316
Do frequent DML operations on a table with indexes and huge data affect SELECT query performance?
80282
count(*) vs count(column-name) - which is more correct?
138284
Are individual queries faster than joins?
148344
Can you prevent more than X number of rows being updated in SQL Server?
31259
Re-arranging / selecting of a data table very slow in For loop
46470
Can MySQL reasonably perform queries on billions of rows?
27414
Postgres 10 - Query slows down with order by
11223
quick selection of a random row from a large table in mysql
37820
MySQL - varchar length and performance
86649
What's the most efficient way to select the last n rows in a table without changing the table's structure?
96974
How can adding a Subselect make a SOQL query non-selective?
33417
Tune a simple inner join query
41314
Is there a REAL performance difference between INT and VARCHAR primary keys?
39136
System.QueryException: Non-selective query against large object type (more than 200000 rows)
72529
Why insert-select to variable table from XML variable so slow?
20965
How to limit columns returned by Django query?