Module expr

Expressions in RisingWave.

All expressions are implemented under the Expression trait.

Construction

Expressions can be constructed by build_func() function, which returns a BoxedExpression.

They can also be transformed from the prost ExprNode using the build_from_prost() function.

Evaluation

Expressions can be evaluated using the eval function.

Re-exports

• pub use super::ExprError;
• pub use super::Result;

Modules

• and_or 🔒
  For expression that only accept two nullable arguments as input.
• build 🔒
• expr_input_ref 🔒
• expr_literal 🔒
• expr_some_all 🔒
• expr_udf 🔒
• test_utils
  Helper functions to construct prost ExprNode for test.
• value 🔒
• wrapper 🔒

Structs

• Context
  An optional context that can be used in a function.
• InputRefExpression
  A reference to a column in input relation.
• LiteralExpression
  A literal expression.
• LogReport
  Log the error to report an error during evaluation.
• NonStrictExpression
  An type-safe wrapper that indicates the inner expression can be evaluated in a non-strict manner, i.e., developers can directly call eval_infallible and eval_row_infallible without checking the result.

Enums

• ValueImpl
  The type-erased return value of an expression.
• ValueRef
  The generic reference type of ValueImpl. Used as the arguments of expressions.

Traits

• EvalErrorReport
  Report an error during evaluation.
• Expression
  Interface of an expression.
• ExpressionBoxExt
  Extension trait for boxing expressions.

Functions

• build_from_pretty
  Build an expression from a string.
• build_from_prost
  Build an expression from protobuf.
• build_func
  Build an expression in FuncCall variant.
• build_func_non_strict
  Build an expression in FuncCall variant in non-strict mode.
• build_non_strict_from_prost
  Build an expression from protobuf in non-strict mode.

Type Aliases

• BoxedExpression
  An owned dynamically typed Expression.