[IMPALA-7715] "Impala Conditional Functions" documentation errata

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Impala 3.0
• Fix Version/s: Impala 3.1.0
• Component/s: Docs
• Epic Color: ghx-label-1
• Assignee: Alexandra Rodoni
• Reporter: Paul Rogers
• Created: 16/Oct/18 20:11
• Updated: 23/Oct/18 18:12
• Resolved: 17/Oct/18 19:19

Description

Consider the documentation page Impala Conditional Functions.

Multiple functions have ambiguous descriptions. For example:

isfalse(boolean)

Purpose: Tests if a Boolean expression is false or not. Returns true if so.

The above is confusing, it essentially means: "Returns true if a Boolean expression is false or not." This obviously means the function always returns false, which is not accurate.

Reword to say: "Returns true if the expression is false. Returns false if the expression is true or NULL."

Other ambiguous descriptions:

istrue(boolean)

Purpose: Tests if a Boolean expression is true or not. Returns true if so.

Better: "Returns true if an expression is true. Returns false if the expression is false or NULL."

Others:

nonnullvalue(expression)

Purpose: Tests if an expression (of any type) is NULL or not. Returns false if so.

Better: "Returns true if the expression is non-null, tase if the expression is null. Same as expression IS NOT NULL."

nullvalue(expression)

Purpose: Tests if an expression (of any type) is NULL or not. Returns true if so.

Better: "Returns true if the expression is NULL, false otherwise. Same as expression IS NULL"

Issue Links

• is part of: IMPALA-7747 Clean up the Expression Rewriter