feat: The octet function is implemented to calculate the number of bytes of the input value. And fixed the charlength function so that it correctly outputs the number of characters instead of bytes (#264)

Author: wszhdshys

src/db.rs

@@ -8,6 +8,7 @@ use crate::function::char_length::CharLength;
 use crate::function::current_date::CurrentDate;
 use crate::function::lower::Lower;
 use crate::function::numbers::Numbers;
+use crate::function::octet_length::OctetLength;
 use crate::function::upper::Upper;
 use crate::optimizer::heuristic::batch::HepBatchStrategy;
 use crate::optimizer::heuristic::optimizer::HepOptimizer;
@@ -61,6 +62,7 @@ impl DataBaseBuilder {
             builder.register_scala_function(CharLength::new("character_length".to_lowercase()));
         builder = builder.register_scala_function(CurrentDate::new());
         builder = builder.register_scala_function(Lower::new());
+        builder = builder.register_scala_function(OctetLength::new());
         builder = builder.register_scala_function(Upper::new());
         builder = builder.register_table_function(Numbers::new());
         builder

src/function/char_length.rs

@@ -43,7 +43,7 @@ impl ScalarFunctionImpl for CharLength {
         }
         let mut length: u64 = 0;
         if let DataValue::Utf8 { value, ty, unit } = &mut value {
-            length = value.len() as u64;
+            length = value.chars().count() as u64;
         }
         Ok(DataValue::UInt64(length))
     }

src/function/mod.rs

@@ -2,4 +2,5 @@ pub(crate) mod char_length;
 pub(crate) mod current_date;
 pub(crate) mod lower;
 pub(crate) mod numbers;
+pub(crate) mod octet_length;
 pub(crate) mod upper;

src/function/octet_length.rs

@@ -0,0 +1,63 @@
+use crate::catalog::ColumnRef;
+use crate::errors::DatabaseError;
+use crate::expression::function::scala::FuncMonotonicity;
+use crate::expression::function::scala::ScalarFunctionImpl;
+use crate::expression::function::FunctionSummary;
+use crate::expression::ScalarExpression;
+use crate::types::tuple::Tuple;
+use crate::types::value::DataValue;
+use crate::types::LogicalType;
+use serde::Deserialize;
+use serde::Serialize;
+use sqlparser::ast::CharLengthUnits;
+use std::sync::Arc;
+
+#[derive(Debug, Serialize, Deserialize)]
+pub(crate) struct OctetLength {
+    summary: FunctionSummary,
+}
+
+impl OctetLength {
+    pub(crate) fn new() -> Arc<Self> {
+        let function_name = "octet_length".to_lowercase();
+        let arg_types = vec![LogicalType::Varchar(None, CharLengthUnits::Characters)];
+        Arc::new(Self {
+            summary: FunctionSummary {
+                name: function_name,
+                arg_types,
+            },
+        })
+    }
+}
+
+#[typetag::serde]
+impl ScalarFunctionImpl for OctetLength {
+    #[allow(unused_variables, clippy::redundant_closure_call)]
+    fn eval(
+        &self,
+        exprs: &[ScalarExpression],
+        tuples: Option<(&Tuple, &[ColumnRef])>,
+    ) -> Result<DataValue, DatabaseError> {
+        let mut value = exprs[0].eval(tuples)?;
+        if !matches!(value.logical_type(), LogicalType::Varchar(_, _)) {
+            value = value.cast(&LogicalType::Varchar(None, CharLengthUnits::Characters))?;
+        }
+        let mut length: u64 = 0;
+        if let DataValue::Utf8 { value, ty, unit } = &mut value {
+            length = value.len() as u64;
+        }
+        Ok(DataValue::UInt64(length))
+    }
+
+    fn monotonicity(&self) -> Option<FuncMonotonicity> {
+        todo!()
+    }
+
+    fn return_type(&self) -> &LogicalType {
+        &LogicalType::Varchar(None, CharLengthUnits::Characters)
+    }
+
+    fn summary(&self) -> &FunctionSummary {
+        &self.summary
+    }
+}

tests/slt/sql_2016/E021_04.slt

@@ -5,8 +5,17 @@ SELECT CHARACTER_LENGTH ( 'foo' )
 ----
 3
 
-
 query I
 SELECT CHAR_LENGTH ( 'foo' )
 ----
 3
+
+query I
+SELECT CHARACTER_LENGTH ( '测试' )
+----
+2
+
+query I
+SELECT CHAR_LENGTH ( '测试' )
+----
+2

tests/slt/sql_2016/E021_05.slt

@@ -1,8 +1,11 @@
-# E021-05: OCTET_LENGTH function
+#E021-05: OCTET_LENGTH function
 
-# TODO: OCTET_LENGTH()
+query I
+SELECT OCTET_LENGTH ( 'foo' )
+----
+3
 
-# query I
-# SELECT OCTET_LENGTH ( 'foo' )
-# ----
-# 3
+query I
+SELECT OCTET_LENGTH ( '测试' )
+----
+6