liurenjie1024 commented on code in PR #309:
URL: https://github.com/apache/iceberg-rust/pull/309#discussion_r1547649993
##########
crates/iceberg/src/spec/transform.rs:
##########
@@ -261,6 +269,300 @@ 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)?;
+
+ let projection = match predicate {
+ BoundPredicate::Unary(expr) => match self {
+ Transform::Identity
+ | Transform::Bucket(_)
+ | Transform::Truncate(_)
+ | Transform::Year
+ | Transform::Month
+ | Transform::Day
+ | Transform::Hour =>
Some(Predicate::Unary(UnaryExpression::new(
+ expr.op(),
+ Reference::new(name),
+ ))),
+ _ => None,
+ },
+ BoundPredicate::Binary(expr) => match self {
+ Transform::Identity =>
Some(Predicate::Binary(BinaryExpression::new(
+ expr.op(),
+ Reference::new(name),
+ expr.literal().to_owned(),
+ ))),
+ Transform::Bucket(_) => {
+ if expr.op() != PredicateOperator::Eq ||
!self.can_transform(expr.literal()) {
+ return Ok(None);
+ }
+
+ Some(Predicate::Binary(BinaryExpression::new(
+ expr.op(),
+ Reference::new(name),
+ func.transform_literal_result(expr.literal())?,
+ )))
+ }
+ Transform::Truncate(width) => {
+ if !self.can_transform(expr.literal()) {
+ return Ok(None);
+ }
+
+ self.transform_projected_boundary(
+ name,
+ expr.literal(),
+ &expr.op(),
+ &func,
+ Some(*width),
+ )?
+ }
+ Transform::Year | Transform::Month | Transform::Day |
Transform::Hour => {
+ if !self.can_transform(expr.literal()) {
+ return Ok(None);
+ }
+
+ self.transform_projected_boundary(
+ name,
+ expr.literal(),
+ &expr.op(),
+ &func,
+ None,
+ )?
+ }
+ _ => None,
+ },
+ BoundPredicate::Set(expr) => match self {
+ Transform::Identity => Some(Predicate::Set(SetExpression::new(
+ expr.op(),
+ Reference::new(name),
+ expr.literals().to_owned(),
+ ))),
+ Transform::Bucket(_)
+ | Transform::Truncate(_)
+ | Transform::Year
+ | Transform::Month
+ | Transform::Day
+ | Transform::Hour => {
+ if expr.op() != PredicateOperator::In
+ || expr.literals().iter().any(|d|
!self.can_transform(d))
+ {
+ return Ok(None);
+ }
+
+ Some(Predicate::Set(SetExpression::new(
+ expr.op(),
+ Reference::new(name),
+ self.transform_set(expr.literals(), &func)?,
+ )))
+ }
+ _ => None,
+ },
+ _ => None,
+ };
+
+ Ok(projection)
+ }
+
+ /// 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()
+ }
+
+ /// Transform each literal value of `FnvHashSet<Datum>`
+ fn transform_set(
+ &self,
+ literals: &FnvHashSet<Datum>,
+ func: &BoxedTransformFunction,
+ ) -> Result<FnvHashSet<Datum>> {
+ let mut new_set = FnvHashSet::default();
+
+ for lit in literals {
+ let datum = func.transform_literal_result(lit)?;
+
+ if let Some(AdjustedProjection::Single(d)) =
+ self.adjust_projection(&PredicateOperator::In, lit, &datum)
+ {
+ new_set.insert(d);
+ };
+
+ new_set.insert(datum);
+ }
+
+ Ok(new_set)
+ }
+
+ /// Apply transform on `Datum` with adjusted boundaries.
+ /// Returns Predicate with projection and possibly
+ /// rewritten `PredicateOperator`
+ fn transform_projected_boundary(
+ &self,
+ name: String,
+ datum: &Datum,
+ op: &PredicateOperator,
+ func: &BoxedTransformFunction,
+ width: Option<u32>,
+ ) -> Result<Option<Predicate>> {
+ if let Some(boundary) = self.projected_boundary(op, datum)? {
+ let transformed = func.transform_literal_result(&boundary)?;
+ let adjusted = self.adjust_projection(op, datum, &transformed);
+ let op = self.projected_operator(op, datum, width);
+
+ if let Some(op) = op {
+ let predicate = match adjusted {
+ None => Predicate::Binary(BinaryExpression::new(
+ op,
+ Reference::new(name),
+ transformed,
+ )),
+ 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)
+ }
+
+ /// Create a new `Datum` with adjusted projection boundary.
+ /// Returns `None` if `PredicateOperator` and `PrimitiveLiteral`
+ /// can not be projected
+ fn projected_boundary(&self, op: &PredicateOperator, datum: &Datum) ->
Result<Option<Datum>> {
+ let literal = datum.literal();
+
+ let projected_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(projected_boundary)
+ }
+
+ /// Create a new `PredicateOperator`, rewritten for projection
+ fn projected_operator(
Review Comment:
Reasonable to me.
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