Improve unparser MySQL compatibility (apache#11589)

* Configurable date field extraction style for unparsing (#21)

* Add support for IntervalStyle::MySQL (#18)

* Support alternate format for Int64 unparsing (SIGNED for MySQL) (#22)

* Alternate format support for Timestamp casting (DATETIME for MySQL) (#23)

* Improve

* Fix clippy and docs

Author: sgrebnov

datafusion/sql/src/unparser/dialect.rs

@@ -15,8 +15,14 @@
 // specific language governing permissions and limitations
 // under the License.
 
+use std::sync::Arc;
+
+use arrow_schema::TimeUnit;
 use regex::Regex;
-use sqlparser::{ast, keywords::ALL_KEYWORDS};
+use sqlparser::{
+    ast::{self, Ident, ObjectName, TimezoneInfo},
+    keywords::ALL_KEYWORDS,
+};
 
 /// `Dialect` to use for Unparsing
 ///
@@ -36,8 +42,8 @@ pub trait Dialect: Send + Sync {
         true
     }
 
-    // Does the dialect use TIMESTAMP to represent Date64 rather than DATETIME?
-    // E.g. Trino, Athena and Dremio does not have DATETIME data type
+    /// Does the dialect use TIMESTAMP to represent Date64 rather than DATETIME?
+    /// E.g. Trino, Athena and Dremio does not have DATETIME data type
     fn use_timestamp_for_date64(&self) -> bool {
         false
     }
@@ -46,23 +52,50 @@ pub trait Dialect: Send + Sync {
         IntervalStyle::PostgresVerbose
     }
 
-    // Does the dialect use DOUBLE PRECISION to represent Float64 rather than DOUBLE?
-    // E.g. Postgres uses DOUBLE PRECISION instead of DOUBLE
+    /// Does the dialect use DOUBLE PRECISION to represent Float64 rather than DOUBLE?
+    /// E.g. Postgres uses DOUBLE PRECISION instead of DOUBLE
     fn float64_ast_dtype(&self) -> sqlparser::ast::DataType {
         sqlparser::ast::DataType::Double
     }
 
-    // The SQL type to use for Arrow Utf8 unparsing
-    // Most dialects use VARCHAR, but some, like MySQL, require CHAR
+    /// The SQL type to use for Arrow Utf8 unparsing
+    /// Most dialects use VARCHAR, but some, like MySQL, require CHAR
     fn utf8_cast_dtype(&self) -> ast::DataType {
         ast::DataType::Varchar(None)
     }
 
-    // The SQL type to use for Arrow LargeUtf8 unparsing
-    // Most dialects use TEXT, but some, like MySQL, require CHAR
+    /// The SQL type to use for Arrow LargeUtf8 unparsing
+    /// Most dialects use TEXT, but some, like MySQL, require CHAR
     fn large_utf8_cast_dtype(&self) -> ast::DataType {
         ast::DataType::Text
     }
+
+    /// The date field extract style to use: `DateFieldExtractStyle`
+    fn date_field_extract_style(&self) -> DateFieldExtractStyle {
+        DateFieldExtractStyle::DatePart
+    }
+
+    /// The SQL type to use for Arrow Int64 unparsing
+    /// Most dialects use BigInt, but some, like MySQL, require SIGNED
+    fn int64_cast_dtype(&self) -> ast::DataType {
+        ast::DataType::BigInt(None)
+    }
+
+    /// The SQL type to use for Timestamp unparsing
+    /// Most dialects use Timestamp, but some, like MySQL, require Datetime
+    /// Some dialects like Dremio does not support WithTimeZone and requires always Timestamp
+    fn timestamp_cast_dtype(
+        &self,
+        _time_unit: &TimeUnit,
+        tz: &Option<Arc<str>>,
+    ) -> ast::DataType {
+        let tz_info = match tz {
+            Some(_) => TimezoneInfo::WithTimeZone,
+            None => TimezoneInfo::None,
+        };
+
+        ast::DataType::Timestamp(None, tz_info)
+    }
 }
 
 /// `IntervalStyle` to use for unparsing
@@ -80,6 +113,19 @@ pub enum IntervalStyle {
     MySQL,
 }
 
+/// Datetime subfield extraction style for unparsing
+///
+/// `<https://www.postgresql.org/docs/current/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT>`
+/// Different DBMSs follow different standards; popular ones are:
+/// date_part('YEAR', date '2001-02-16')
+/// EXTRACT(YEAR from date '2001-02-16')
+/// Some DBMSs, like Postgres, support both, whereas others like MySQL require EXTRACT.
+#[derive(Clone, Copy, PartialEq)]
+pub enum DateFieldExtractStyle {
+    DatePart,
+    Extract,
+}
+
 pub struct DefaultDialect {}
 
 impl Dialect for DefaultDialect {
@@ -133,6 +179,22 @@ impl Dialect for MySqlDialect {
     fn large_utf8_cast_dtype(&self) -> ast::DataType {
         ast::DataType::Char(None)
     }
+
+    fn date_field_extract_style(&self) -> DateFieldExtractStyle {
+        DateFieldExtractStyle::Extract
+    }
+
+    fn int64_cast_dtype(&self) -> ast::DataType {
+        ast::DataType::Custom(ObjectName(vec![Ident::new("SIGNED")]), vec![])
+    }
+
+    fn timestamp_cast_dtype(
+        &self,
+        _time_unit: &TimeUnit,
+        _tz: &Option<Arc<str>>,
+    ) -> ast::DataType {
+        ast::DataType::Datetime(None)
+    }
 }
 
 pub struct SqliteDialect {}
@@ -151,6 +213,10 @@ pub struct CustomDialect {
     float64_ast_dtype: sqlparser::ast::DataType,
     utf8_cast_dtype: ast::DataType,
     large_utf8_cast_dtype: ast::DataType,
+    date_field_extract_style: DateFieldExtractStyle,
+    int64_cast_dtype: ast::DataType,
+    timestamp_cast_dtype: ast::DataType,
+    timestamp_tz_cast_dtype: ast::DataType,
 }
 
 impl Default for CustomDialect {
@@ -163,6 +229,13 @@ impl Default for CustomDialect {
             float64_ast_dtype: sqlparser::ast::DataType::Double,
             utf8_cast_dtype: ast::DataType::Varchar(None),
             large_utf8_cast_dtype: ast::DataType::Text,
+            date_field_extract_style: DateFieldExtractStyle::DatePart,
+            int64_cast_dtype: ast::DataType::BigInt(None),
+            timestamp_cast_dtype: ast::DataType::Timestamp(None, TimezoneInfo::None),
+            timestamp_tz_cast_dtype: ast::DataType::Timestamp(
+                None,
+                TimezoneInfo::WithTimeZone,
+            ),
         }
     }
 }
@@ -206,6 +279,26 @@ impl Dialect for CustomDialect {
     fn large_utf8_cast_dtype(&self) -> ast::DataType {
         self.large_utf8_cast_dtype.clone()
     }
+
+    fn date_field_extract_style(&self) -> DateFieldExtractStyle {
+        self.date_field_extract_style
+    }
+
+    fn int64_cast_dtype(&self) -> ast::DataType {
+        self.int64_cast_dtype.clone()
+    }
+
+    fn timestamp_cast_dtype(
+        &self,
+        _time_unit: &TimeUnit,
+        tz: &Option<Arc<str>>,
+    ) -> ast::DataType {
+        if tz.is_some() {
+            self.timestamp_tz_cast_dtype.clone()
+        } else {
+            self.timestamp_cast_dtype.clone()
+        }
+    }
 }
 
 /// `CustomDialectBuilder` to build `CustomDialect` using builder pattern
@@ -230,6 +323,10 @@ pub struct CustomDialectBuilder {
     float64_ast_dtype: sqlparser::ast::DataType,
     utf8_cast_dtype: ast::DataType,
     large_utf8_cast_dtype: ast::DataType,
+    date_field_extract_style: DateFieldExtractStyle,
+    int64_cast_dtype: ast::DataType,
+    timestamp_cast_dtype: ast::DataType,
+    timestamp_tz_cast_dtype: ast::DataType,
 }
 
 impl Default for CustomDialectBuilder {
@@ -248,6 +345,13 @@ impl CustomDialectBuilder {
             float64_ast_dtype: sqlparser::ast::DataType::Double,
             utf8_cast_dtype: ast::DataType::Varchar(None),
             large_utf8_cast_dtype: ast::DataType::Text,
+            date_field_extract_style: DateFieldExtractStyle::DatePart,
+            int64_cast_dtype: ast::DataType::BigInt(None),
+            timestamp_cast_dtype: ast::DataType::Timestamp(None, TimezoneInfo::None),
+            timestamp_tz_cast_dtype: ast::DataType::Timestamp(
+                None,
+                TimezoneInfo::WithTimeZone,
+            ),
         }
     }
 
@@ -260,6 +364,10 @@ impl CustomDialectBuilder {
             float64_ast_dtype: self.float64_ast_dtype,
             utf8_cast_dtype: self.utf8_cast_dtype,
             large_utf8_cast_dtype: self.large_utf8_cast_dtype,
+            date_field_extract_style: self.date_field_extract_style,
+            int64_cast_dtype: self.int64_cast_dtype,
+            timestamp_cast_dtype: self.timestamp_cast_dtype,
+            timestamp_tz_cast_dtype: self.timestamp_tz_cast_dtype,
         }
     }
 
@@ -293,6 +401,7 @@ impl CustomDialectBuilder {
         self
     }
 
+    /// Customize the dialect with a specific SQL type for Float64 casting: DOUBLE, DOUBLE PRECISION, etc.
     pub fn with_float64_ast_dtype(
         mut self,
         float64_ast_dtype: sqlparser::ast::DataType,
@@ -301,16 +410,44 @@ impl CustomDialectBuilder {
         self
     }
 
+    /// Customize the dialect with a specific SQL type for Utf8 casting: VARCHAR, CHAR, etc.
     pub fn with_utf8_cast_dtype(mut self, utf8_cast_dtype: ast::DataType) -> Self {
         self.utf8_cast_dtype = utf8_cast_dtype;
         self
     }
 
+    /// Customize the dialect with a specific SQL type for LargeUtf8 casting: TEXT, CHAR, etc.
     pub fn with_large_utf8_cast_dtype(
         mut self,
         large_utf8_cast_dtype: ast::DataType,
     ) -> Self {
         self.large_utf8_cast_dtype = large_utf8_cast_dtype;
         self
     }
+
+    /// Customize the dialect with a specific date field extract style listed in `DateFieldExtractStyle`
+    pub fn with_date_field_extract_style(
+        mut self,
+        date_field_extract_style: DateFieldExtractStyle,
+    ) -> Self {
+        self.date_field_extract_style = date_field_extract_style;
+        self
+    }
+
+    /// Customize the dialect with a specific SQL type for Int64 casting: BigInt, SIGNED, etc.
+    pub fn with_int64_cast_dtype(mut self, int64_cast_dtype: ast::DataType) -> Self {
+        self.int64_cast_dtype = int64_cast_dtype;
+        self
+    }
+
+    /// Customize the dialect with a specific SQL type for Timestamp casting: Timestamp, Datetime, etc.
+    pub fn with_timestamp_cast_dtype(
+        mut self,
+        timestamp_cast_dtype: ast::DataType,
+        timestamp_tz_cast_dtype: ast::DataType,
+    ) -> Self {
+        self.timestamp_cast_dtype = timestamp_cast_dtype;
+        self.timestamp_tz_cast_dtype = timestamp_tz_cast_dtype;
+        self
+    }
 }