Implicit Conversion Performance Impact
in SQL Server
This post can help you to understand Implicit Conversion Performance Impact in SQL Server. First let’s understand the implicit conversion and then we’ll see how it impacts the performance.
Q. Why Conversion Required?
Data conversion has to be occurred whenever we need to compare data with two different datatypes. This comparison happens based on the data type precedence, lower precedence data types will always be implicitly converted up to the higher precedence type.
Q. What are the types of conversions?
There are two types of data conversions:
Explicit Conversion: When you explicitly convert data using data conversion functions CAST or CONVERT is known as explicit conversion. This conversion is clearly visible to the user.
Ex: WHERE Col1 = CAST($698.4 AS VARCHAR(10));
Implicit Conversion: SQL Server internally converts data from one data type to another. This conversion can’t be visible to the user. For example an INT type column is compared with TINYINT type column then SQL Server internally converts TINYINT to INT as INT have the higher precedence than TINYINT.
— Col1 – TINYINT and Col2 INT
EX: WHERE Col1 = Col2
Q. What is datatype Precedence?
SQL Server Update Statistics Performance Impact
The post “SQL Server Update Statistics Performance Impact” shows some interesting points on how statistics impact the query performance in SQL Server. Now before look into the impact we’ll quickly go through the essential basics:
Index statistics contain information about the distribution of index key values. By distribution, I mean the number of rows associated with each key value. SQL Server uses this information to determine what kind of execution plan to use when processing a query.
Types of Statistics:
- Statistics created by optimizer.
- Statistics created due to index creation.
- User defined statistics created from “CREATE STATISTICS”
- Query statistics generated from SET options. i.e SET STATISTICS IO / TIME ON / OFF;
Basic Awareness on Ransomware
This post can help you to understand the Basic Awareness on Ransomware. Since Jan 2017 “Ransomware” has been taking the top position in the world’s technology security concern list. When it comes to hacking it’s a different story but this “Ransomware” can make an immediate effect on your business. After the recent malicious “WannaCrypt” software attack customers have been asking the question “Are we ready to handle Ransomware?” This is a just to provide basic awareness on “Ransomware” attack especially for the Database people.
Q. What is Ransomware?
Highly speaking, Ransomware is malicious software that locks (Locker-ransomware) or encrypts (Crypto-ransomware) your data and demand money to get your data back (decrypt).
Q. How it actually attacks your machine?