Contents
- 1 What does it mean if a function is deterministic?
- 2 What are the implications of using non deterministic functions?
- 3 How do you know if a function is deterministic?
- 4 What is difference between hash and checksum?
- 5 When does a deterministic function return the same result?
- 6 What makes a nondeterministic function deterministic in SQL?
What does it mean if a function is deterministic?
Deterministic functions always return the same result any time they are called with a specific set of input values and given the same state of the database. The determinism of a function is one such property.
What are the implications of using non deterministic functions?
Nondeterministic functions result in different output each time they are called with a fixed set of input values even if the database state that they access remains the same. For example, GETDATE() function, results the current date and time value, always a different value.
How do you know if a function is deterministic?
Function Determinism
- A function is considered deterministic if it always returns the same result set when it’s called with the same set of input values.
- A function is considered nondeterministic if it doesn’t return the same result set when it’s called with the same set of input values.
Is checksum deterministic?
The reason why checksums and hashing functions (the algorithms that produce checksums) work is because they are deterministic: if they weren’t so, our life would be much harder! Hashes are omnipresent, in fact they help us: detecting data corruption during a data transfer.
Can a function be non deterministic?
Functions can be either deterministic or nondeterministic. A deterministic function always returns the same results if given the same input values. A nondeterministic function may return different results every time it is called, even when the same input values are provided.
What is difference between hash and checksum?
A checksum is intended to verify (check) the integrity of data and identify data-transmission errors, while a hash is designed to create a unique digital fingerprint of the data. A checksum protects against accidental changes. A cryptographic hash protects against a very motivated attacker.
When does a deterministic function return the same result?
Deterministic functions always return the same result any time they are called with a specific set of input values and given the same state of the database.
What makes a nondeterministic function deterministic in SQL?
Source or target type is datetime or smalldatetime, the other source or target type is a character string, and a nondeterministic style is specified. To be deterministic, the style parameter must be a constant.
How to make a computed column non deterministic?
Target type is sql_variant and its source type is nondeterministic. Source or target type is datetime or smalldatetime, the other source or target type is a character string, and a nondeterministic style is specified. To be deterministic, the style parameter must be a constant.
When is a rand function a nondeterministic function?
RAND is deterministic only when a seed parameter is specified. All the configuration, cursor, metadata, security, and system statistical functions are nondeterministic.