Date support

README.md

@@ -30,5 +30,5 @@ Use the `file://` protocol to load data into a file instead.
 
 ## Limitations
 
-- Supported datatypes: bool, char, int2, int4, int8, float4, float8, timestamp, timestamptz, text, bytea. Cast the columns in your query to `text` or another supported type if your query returns different types
+- Supported datatypes: bool, char, int2, int4, int8, float4, float8, timestamp, timestamptz, date, text, bytea. Cast the columns in your query to `text` or another supported type if your query returns different types
 - Doesn't support appending to tables, only writing new Delta Tables (pass `-o` to overwrite)

src/pg_arrow_source.rs

@@ -23,20 +23,43 @@ pub enum ArrowBuilder {
     Float32Builder(array::Float32Builder),
     Float64Builder(array::Float64Builder),
     TimestampMicrosecondBuilder(array::TimestampMicrosecondBuilder),
+    DateBuilder(array::Date32Builder),
     StringBuilder(array::StringBuilder),
     BinaryBuilder(array::BinaryBuilder),
 }
 use crate::{ArrowBuilder::*, DataLoadingError};
 
 // tokio-postgres provides awkward Rust type conversions for Postgres TIMESTAMP and TIMESTAMPTZ values
 // It's easier just to handle the raw values ourselves
+struct UnixEpochDayOffset(i32);
+// Number of days from 1970-01-01 to 2000-01-01
+const J2000_EPOCH_DAYS: i32 = 10957;
+
+impl FromSql<'_> for UnixEpochDayOffset {
+    fn from_sql(_ty: &Type, buf: &[u8]) -> Result<Self, Box<dyn std::error::Error + Sync + Send>> {
+        let byte_array: [u8; 4] = buf.try_into()?;
+        let offset = i32::from_be_bytes(byte_array) + J2000_EPOCH_DAYS;
+        Ok(Self(offset))
+    }
+
+    fn accepts(ty: &Type) -> bool {
+        *ty == Type::DATE
+    }
+}
+impl From<UnixEpochDayOffset> for i32 {
+    fn from(val: UnixEpochDayOffset) -> Self {
+        val.0
+    }
+}
+
 struct UnixEpochMicrosecondOffset(i64);
-const J2000_EPOCH_OFFSET: i64 = 946_684_800_000_000; // Number of us from 1970-01-01 to 2000-01-01
+// Number of us from 1970-01-01 (Unix epoch) to 2000-01-01 (Postgres epoch)
+const J2000_EPOCH_MICROSECONDS: i64 = J2000_EPOCH_DAYS as i64 * 86400 * 1000000;
 
 impl FromSql<'_> for UnixEpochMicrosecondOffset {
     fn from_sql(_ty: &Type, buf: &[u8]) -> Result<Self, Box<dyn std::error::Error + Sync + Send>> {
         let byte_array: [u8; 8] = buf.try_into()?;
-        let offset = i64::from_be_bytes(byte_array) + J2000_EPOCH_OFFSET;
+        let offset = i64::from_be_bytes(byte_array) + J2000_EPOCH_MICROSECONDS;
         Ok(Self(offset))
     }
 
@@ -69,6 +92,7 @@ impl ArrowBuilder {
                     Some("UTC".into()),
                 )),
             ),
+            Type::DATE => DateBuilder(array::Date32Builder::new()),
             Type::TEXT => StringBuilder(array::StringBuilder::new()),
             Type::BYTEA => BinaryBuilder(array::BinaryBuilder::new()),
             _ => panic!("Unsupported type: {}", pg_type),
@@ -102,6 +126,10 @@ impl ArrowBuilder {
                 row.get::<usize, Option<UnixEpochMicrosecondOffset>>(column_idx)
                     .map(UnixEpochMicrosecondOffset::into),
             ),
+            DateBuilder(ref mut builder) => builder.append_option(
+                row.get::<usize, Option<UnixEpochDayOffset>>(column_idx)
+                    .map(UnixEpochDayOffset::into),
+            ),
             StringBuilder(ref mut builder) => {
                 builder.append_option(row.get::<usize, Option<&str>>(column_idx))
             }
@@ -120,6 +148,7 @@ impl ArrowBuilder {
             Float32Builder(builder) => Arc::new(builder.finish()),
             Float64Builder(builder) => Arc::new(builder.finish()),
             TimestampMicrosecondBuilder(builder) => Arc::new(builder.finish()),
+            DateBuilder(builder) => Arc::new(builder.finish()),
             StringBuilder(builder) => Arc::new(builder.finish()),
             BinaryBuilder(builder) => Arc::new(builder.finish()),
         }
@@ -137,6 +166,7 @@ fn pg_type_to_arrow_type(pg_type: &Type) -> DataType {
         Type::FLOAT8 => DataType::Float64,
         Type::TIMESTAMP => DataType::Timestamp(TimeUnit::Microsecond, None),
         Type::TIMESTAMPTZ => DataType::Timestamp(TimeUnit::Microsecond, Some("UTC".into())),
+        Type::DATE => DataType::Date32,
         Type::TEXT => DataType::Utf8,
         Type::BYTEA => DataType::Binary,
         _ => panic!("Unsupported type: {}. Explicitly cast the relevant columns to text in order to store them as strings.", pg_type),
@@ -230,22 +260,32 @@ impl PgArrowSource {
 mod tests {
     use postgres::types::{FromSql, Type};
 
-    use super::UnixEpochMicrosecondOffset;
+    use super::*;
 
     #[test]
-    fn test_just_after_j2000() {
+    fn test_timestamp_just_after_j2000() {
         let offset =
             UnixEpochMicrosecondOffset::from_sql(&Type::TIMESTAMP, &[0, 0, 0, 0, 0, 0, 1, 2])
                 .unwrap();
         assert_eq!(offset.0, 946_684_800_000_000 + 256 + 2);
     }
     #[test]
-    fn test_just_before_j2000() {
+    fn test_timestamp_just_before_j2000() {
         let offset = UnixEpochMicrosecondOffset::from_sql(
             &Type::TIMESTAMP,
             &[255, 255, 255, 255, 255, 255, 255, 255],
         )
         .unwrap();
         assert_eq!(offset.0, 946_684_800_000_000 - 1);
     }
+    #[test]
+    fn test_date_just_after_j2000() {
+        let offset = UnixEpochDayOffset::from_sql(&Type::DATE, &[0, 0, 1, 2]).unwrap();
+        assert_eq!(offset.0, 10957 + 256 + 2);
+    }
+    #[test]
+    fn test_date_just_before_j2000() {
+        let offset = UnixEpochDayOffset::from_sql(&Type::DATE, &[255, 255, 255, 255]).unwrap();
+        assert_eq!(offset.0, 10957 - 1);
+    }
 }

tests/basic_integration.rs

@@ -1,6 +1,6 @@
 use arrow::array::{
-    Array, BinaryArray, BooleanArray, Float32Array, Float64Array, Int16Array, Int32Array,
-    Int64Array, Int8Array, StringArray, TimestampMicrosecondArray,
+    Array, BinaryArray, BooleanArray, Date32Array, Float32Array, Float64Array, Int16Array,
+    Int32Array, Int64Array, Int8Array, StringArray, TimestampMicrosecondArray,
 };
 use clap::Parser;
 use futures::{StreamExt, TryStreamExt};
@@ -195,9 +195,21 @@ async fn test_pg_arrow_source() {
         (elapsed_days * seconds_per_day + 2) * 1000000
     );
 
+    // THEN the first 3 date values should be as expected
+    let cdate_array = rb1
+        .column(10)
+        .as_any()
+        .downcast_ref::<Date32Array>()
+        .unwrap();
+    assert!(cdate_array.is_null(0));
+    assert!(!cdate_array.is_null(1));
+    assert_eq!(cdate_array.value(1), elapsed_days as i32 + 1);
+    assert!(!cdate_array.is_null(2));
+    assert_eq!(cdate_array.value(2), elapsed_days as i32 + 2);
+
     // THEN the first 3 text values should be as expected
     let ctext_array = rb1
-        .column(10)
+        .column(11)
         .as_any()
         .downcast_ref::<StringArray>()
         .unwrap();
@@ -209,7 +221,7 @@ async fn test_pg_arrow_source() {
 
     // THEN the first 3 bytea values should be as expected
     let cbytea_array = rb1
-        .column(11)
+        .column(12)
         .as_any()
         .downcast_ref::<BinaryArray>()
         .unwrap();

tests/postgres-init-scripts/init-pg-data.sql

@@ -9,6 +9,7 @@ CREATE TABLE t1(
   cfloat8 DOUBLE PRECISION,
   ctimestamp TIMESTAMP,
   ctimestamptz TIMESTAMPTZ,
+  cdate DATE,
   ctext TEXT,
   cbytea BYTEA
 );
@@ -25,6 +26,7 @@ INSERT INTO t1(
   cfloat8,
   ctimestamp,
   ctimestamptz,
+  cdate,
   ctext,
   cbytea
 ) SELECT
@@ -37,6 +39,7 @@ INSERT INTO t1(
   s + 0.5,
   '2024-01-01'::TIMESTAMP + s * INTERVAL '1 second',
   '2024-01-01 00:00:00+00'::TIMESTAMPTZ + s * INTERVAL '1 second',
+  '2024-01-01'::DATE + s,
   s::TEXT,
   int4send(s::INT)
 FROM generate_series(1, 25000) AS s;