liurenjie1024 commented on code in PR #309:
URL: https://github.com/apache/iceberg-rust/pull/309#discussion_r1872463255
##########
crates/iceberg/src/spec/transform.rs:
##########
@@ -261,6 +269,323 @@ impl Transform {
_ => self == other,
}
}
+
+ /// Projects a given predicate according to the transformation
+ /// specified by the `Transform` instance.
+ ///
+ /// This allows predicates to be effectively applied to data
+ /// that has undergone transformation, enabling efficient querying
+ /// and filtering based on the original, untransformed data.
+ ///
+ /// # Example
+ /// Suppose, we have row filter `a = 10`, and a partition spec
+ /// `bucket(a, 37) as bs`, if one row matches `a = 10`, then its partition
+ /// value should match `bucket(10, 37) as bs`, and we project `a = 10` to
+ /// `bs = bucket(10, 37)`
+ pub fn project(&self, name: String, predicate: &BoundPredicate) ->
Result<Option<Predicate>> {
+ let func = create_transform_function(self)?;
+
+ match self {
+ Transform::Identity => match predicate {
+ BoundPredicate::Unary(expr) => Self::project_unary(expr.op(),
name),
+ BoundPredicate::Binary(expr) =>
Ok(Some(Predicate::Binary(BinaryExpression::new(
+ expr.op(),
+ Reference::new(name),
+ expr.literal().to_owned(),
+ )))),
+ BoundPredicate::Set(expr) =>
Ok(Some(Predicate::Set(SetExpression::new(
+ expr.op(),
+ Reference::new(name),
+ expr.literals().to_owned(),
+ )))),
+ _ => Ok(None),
+ },
+ Transform::Bucket(_) => match predicate {
+ BoundPredicate::Unary(expr) => Self::project_unary(expr.op(),
name),
+ BoundPredicate::Binary(expr) => self.project_eq_operator(name,
expr, &func),
+ BoundPredicate::Set(expr) => self.project_in_operator(expr,
name, &func),
+ _ => Ok(None),
+ },
+ Transform::Truncate(width) => match predicate {
+ BoundPredicate::Unary(expr) => Self::project_unary(expr.op(),
name),
+ BoundPredicate::Binary(expr) => {
+ self.project_binary_with_adjusted_boundary(name, expr,
&func, Some(*width))
+ }
+ BoundPredicate::Set(expr) => self.project_in_operator(expr,
name, &func),
+ _ => Ok(None),
+ },
+ Transform::Year | Transform::Month | Transform::Day |
Transform::Hour => {
+ match predicate {
+ BoundPredicate::Unary(expr) =>
Self::project_unary(expr.op(), name),
+ BoundPredicate::Binary(expr) => {
+ self.project_binary_with_adjusted_boundary(name, expr,
&func, None)
+ }
+ BoundPredicate::Set(expr) =>
self.project_in_operator(expr, name, &func),
+ _ => Ok(None),
+ }
+ }
+ _ => Ok(None),
+ }
+ }
+
+ /// Check if `Transform` is applicable on datum's `PrimitiveType`
+ fn can_transform(&self, datum: &Datum) -> bool {
+ let input_type = datum.data_type().clone();
+ self.result_type(&Type::Primitive(input_type)).is_ok()
+ }
+
+ /// Creates a unary predicate from a given operator and a reference name.
+ fn project_unary(op: PredicateOperator, name: String) ->
Result<Option<Predicate>> {
+ Ok(Some(Predicate::Unary(UnaryExpression::new(
+ op,
+ Reference::new(name),
+ ))))
+ }
+
+ /// Attempts to create a binary predicate based on a binary expression,
+ /// if applicable.
+ ///
+ /// This method evaluates a given binary expression and, if the operation
+ /// is equality (`Eq`) and the literal can be transformed, constructs a
+ /// `Predicate::Binary`variant representing the binary operation.
+ fn project_eq_operator(
+ &self,
+ name: String,
+ expr: &BinaryExpression<BoundReference>,
+ func: &BoxedTransformFunction,
+ ) -> Result<Option<Predicate>> {
+ if expr.op() != PredicateOperator::Eq ||
!self.can_transform(expr.literal()) {
+ return Ok(None);
+ }
+
+ Ok(Some(Predicate::Binary(BinaryExpression::new(
+ expr.op(),
+ Reference::new(name),
+ func.transform_literal_result(expr.literal())?,
+ ))))
+ }
+
+ /// Projects a binary expression to a predicate with an adjusted boundary.
+ ///
+ /// Checks if the literal within the given binary expression is
+ /// transformable. If transformable, it proceeds to potentially adjust
+ /// the boundary of the expression based on the comparison operator (`op`).
+ /// The potential adjustments involve incrementing or decrementing the
+ /// literal value and changing the `PredicateOperator` itself to its
+ /// inclusive variant.
+ fn project_binary_with_adjusted_boundary(
+ &self,
+ name: String,
+ expr: &BinaryExpression<BoundReference>,
+ func: &BoxedTransformFunction,
+ width: Option<u32>,
+ ) -> Result<Option<Predicate>> {
+ if !self.can_transform(expr.literal()) {
+ return Ok(None);
+ }
+
+ let op = &expr.op();
+ let datum = &expr.literal();
+
+ if let Some(boundary) = Self::adjust_boundary(op, datum)? {
+ let transformed_projection =
func.transform_literal_result(&boundary)?;
+
+ let adjusted_projection =
+ self.adjust_time_projection(op, datum,
&transformed_projection);
+
+ let adjusted_operator = Self::adjust_operator(op, datum, width);
+
+ if let Some(op) = adjusted_operator {
+ let predicate = match adjusted_projection {
+ None => Predicate::Binary(BinaryExpression::new(
+ op,
+ Reference::new(name),
+ transformed_projection,
+ )),
+ Some(AdjustedProjection::Single(d)) => {
+ Predicate::Binary(BinaryExpression::new(op,
Reference::new(name), d))
+ }
+ Some(AdjustedProjection::Set(d)) =>
Predicate::Set(SetExpression::new(
+ PredicateOperator::In,
+ Reference::new(name),
+ d,
+ )),
+ };
+ return Ok(Some(predicate));
+ }
+ };
+
+ Ok(None)
+ }
+
+ /// Projects a set expression to a predicate,
+ /// applying a transformation to each literal in the set.
+ fn project_in_operator(
+ &self,
+ expr: &SetExpression<BoundReference>,
+ name: String,
+ func: &BoxedTransformFunction,
+ ) -> Result<Option<Predicate>> {
+ if expr.op() != PredicateOperator::In
+ || expr.literals().iter().any(|d| !self.can_transform(d))
+ {
+ return Ok(None);
+ }
+
+ let mut new_set = FnvHashSet::default();
+
+ for lit in expr.literals() {
+ let datum = func.transform_literal_result(lit)?;
+
+ if let Some(AdjustedProjection::Single(d)) =
+ self.adjust_time_projection(&PredicateOperator::In, lit,
&datum)
+ {
+ new_set.insert(d);
+ };
+
+ new_set.insert(datum);
+ }
+
+ Ok(Some(Predicate::Set(SetExpression::new(
+ expr.op(),
+ Reference::new(name),
+ new_set,
+ ))))
+ }
+
+ /// Adjusts the boundary value for comparison operations
+ /// based on the specified `PredicateOperator` and `Datum`.
+ ///
+ /// This function modifies the boundary value for certain comparison
+ /// operators (`LessThan`, `GreaterThan`) by incrementing or decrementing
+ /// the literal value within the given `Datum`. For operators that do not
+ /// imply a boundary shift (`Eq`, `LessThanOrEq`, `GreaterThanOrEq`,
+ /// `StartsWith`, `NotStartsWith`), the original datum is returned
+ /// unmodified.
+ fn adjust_boundary(op: &PredicateOperator, datum: &Datum) ->
Result<Option<Datum>> {
+ let literal = datum.literal();
+
+ let adjusted_boundary = match op {
+ PredicateOperator::LessThan => match literal {
+ PrimitiveLiteral::Int(v) => Some(Datum::int(v - 1)),
+ PrimitiveLiteral::Long(v) => Some(Datum::long(v - 1)),
+ PrimitiveLiteral::Decimal(v) => Some(Datum::decimal(v - 1)?),
+ PrimitiveLiteral::Date(v) => Some(Datum::date(v - 1)),
+ PrimitiveLiteral::Timestamp(v) =>
Some(Datum::timestamp_micros(v - 1)),
+ _ => Some(datum.to_owned()),
+ },
+ PredicateOperator::GreaterThan => match literal {
+ PrimitiveLiteral::Int(v) => Some(Datum::int(v + 1)),
+ PrimitiveLiteral::Long(v) => Some(Datum::long(v + 1)),
+ PrimitiveLiteral::Decimal(v) => Some(Datum::decimal(v + 1)?),
+ PrimitiveLiteral::Date(v) => Some(Datum::date(v + 1)),
+ PrimitiveLiteral::Timestamp(v) =>
Some(Datum::timestamp_micros(v + 1)),
+ _ => Some(datum.to_owned()),
+ },
+ PredicateOperator::Eq
+ | PredicateOperator::LessThanOrEq
+ | PredicateOperator::GreaterThanOrEq
+ | PredicateOperator::StartsWith
+ | PredicateOperator::NotStartsWith => Some(datum.to_owned()),
+ _ => None,
+ };
+
+ Ok(adjusted_boundary)
+ }
+
+ /// Adjusts the comparison operator based on the specified datum and an
+ /// optional width constraint.
+ ///
+ /// This function modifies the comparison operator for `LessThan` and
+ /// `GreaterThan` cases to their inclusive counterparts (`LessThanOrEq`,
+ /// `GreaterThanOrEq`) unconditionally. For `StartsWith` and
+ /// `NotStartsWith` operators acting on string literals, the operator may
+ /// be adjusted to `Eq` or `NotEq` if the string length matches the
+ /// specified width, indicating a precise match rather than a prefix
+ /// condition.
+ fn adjust_operator(
+ op: &PredicateOperator,
+ datum: &Datum,
+ width: Option<u32>,
+ ) -> Option<PredicateOperator> {
+ match op {
+ PredicateOperator::LessThan =>
Some(PredicateOperator::LessThanOrEq),
+ PredicateOperator::GreaterThan =>
Some(PredicateOperator::GreaterThanOrEq),
+ PredicateOperator::StartsWith => match datum.literal() {
+ PrimitiveLiteral::String(s) => {
+ if let Some(w) = width {
+ if s.len() == w as usize {
+ return Some(PredicateOperator::Eq);
+ };
+ };
+ Some(*op)
+ }
+ _ => Some(*op),
+ },
+ PredicateOperator::NotStartsWith => match datum.literal() {
+ PrimitiveLiteral::String(s) => {
+ if let Some(w) = width {
+ let w = w as usize;
+
+ if s.len() == w {
+ return Some(PredicateOperator::NotEq);
+ }
+
+ if s.len() < w {
+ return Some(*op);
+ }
+
+ return None;
+ };
+ Some(*op)
+ }
+ _ => Some(*op),
+ },
+ _ => Some(*op),
+ }
+ }
+
+ /// Adjust projection for temporal transforms, align with Java
+ /// implementation:
https://github.com/apache/iceberg/blob/main/api/src/main/java/org/apache/iceberg/transforms/ProjectionUtil.java#L275
+ fn adjust_time_projection(
Review Comment:
Is it breaking new things? If it only have benefits of improving compability
with old version, then I would prefer to keep it.
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