Add support for reading parquet file thanks to arrow-dataset Kotlin#576

Author: fb64

dataframe-arrow/build.gradle.kts

@@ -19,6 +19,7 @@ dependencies {
     implementation(libs.arrow.vector)
     implementation(libs.arrow.format)
     implementation(libs.arrow.memory)
+    implementation(libs.arrow.dataset)
     implementation(libs.commonsCompress)
     implementation(libs.kotlin.reflect)
     implementation(libs.kotlin.datetimeJvm)

dataframe-arrow/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/arrowReading.kt

@@ -1,5 +1,6 @@
 package org.jetbrains.kotlinx.dataframe.io
 
+import org.apache.arrow.dataset.file.FileFormat
 import org.apache.arrow.memory.RootAllocator
 import org.apache.arrow.vector.ipc.ArrowReader
 import org.apache.commons.compress.utils.SeekableInMemoryByteChannel
@@ -184,3 +185,11 @@ public fun DataFrame.Companion.readArrow(
  */
 public fun ArrowReader.toDataFrame(nullability: NullabilityOptions = NullabilityOptions.Infer): AnyFrame =
     DataFrame.Companion.readArrowImpl(this, nullability)
+
+/**
+ * Read [Parquet](https://parquet.apache.org/) data from existing [url] by using [Arrow Dataset](https://arrow.apache.org/docs/java/dataset.html)
+ */
+public fun DataFrame.Companion.readParquet(
+    url: URL,
+    nullability: NullabilityOptions = NullabilityOptions.Infer,
+): AnyFrame = readArrowDataset(url.toString(), FileFormat.PARQUET, nullability)

dataframe-arrow/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/arrowReadingImpl.kt

@@ -6,6 +6,11 @@ import kotlinx.datetime.LocalTime
 import kotlinx.datetime.toKotlinLocalDate
 import kotlinx.datetime.toKotlinLocalDateTime
 import kotlinx.datetime.toKotlinLocalTime
+import org.apache.arrow.dataset.file.FileFormat
+import org.apache.arrow.dataset.file.FileSystemDatasetFactory
+import org.apache.arrow.dataset.jni.DirectReservationListener
+import org.apache.arrow.dataset.jni.NativeMemoryPool
+import org.apache.arrow.dataset.scanner.ScanOptions
 import org.apache.arrow.memory.RootAllocator
 import org.apache.arrow.vector.BigIntVector
 import org.apache.arrow.vector.BitVector
@@ -390,3 +395,27 @@ internal fun DataFrame.Companion.readArrowImpl(
         return flattened.concatKeepingSchema()
     }
 }
+
+internal fun DataFrame.Companion.readArrowDataset(
+    fileUri: String,
+    fileFormat: FileFormat,
+    nullability: NullabilityOptions = NullabilityOptions.Infer,
+): AnyFrame {
+    val scanOptions = ScanOptions(32768)
+    RootAllocator().use { allocator ->
+        FileSystemDatasetFactory(
+            allocator,
+            NativeMemoryPool.createListenable(DirectReservationListener.instance()),
+            fileFormat,
+            fileUri,
+        ).use { datasetFactory ->
+            datasetFactory.finish().use { dataset ->
+                dataset.newScan(scanOptions).use { scanner ->
+                    scanner.scanBatches().use { reader ->
+                        return readArrow(reader, nullability)
+                    }
+                }
+            }
+        }
+    }
+}

dataframe-arrow/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/ArrowKtTest.kt

@@ -629,4 +629,17 @@ internal class ArrowKtTest {
             DataFrame.readArrow(dbArrowReader) shouldBe expected
         }
     }
+
+    @Test
+    fun testReadParquet() {
+        val path = testResource("test.arrow.parquet").path
+        val dataFrame = DataFrame.readParquet(URL("file:$path"))
+        dataFrame.rowsCount() shouldBe 300
+        assertEstimations(
+            exampleFrame = dataFrame,
+            expectedNullable = false,
+            hasNulls = false,
+            fromParquet = true,
+        )
+    }
 }

dataframe-arrow/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/exampleEstimatesAssertions.kt

@@ -24,7 +24,12 @@ import java.time.LocalTime as JavaLocalTime
  * Assert that we have got the same data that was originally saved on example creation.
  * Example generation project is currently located at https://github.com/Kopilov/arrow_example
  */
-internal fun assertEstimations(exampleFrame: AnyFrame, expectedNullable: Boolean, hasNulls: Boolean) {
+internal fun assertEstimations(
+    exampleFrame: AnyFrame,
+    expectedNullable: Boolean,
+    hasNulls: Boolean,
+    fromParquet: Boolean = false,
+) {
     /**
      * In [exampleFrame] we get two concatenated batches. To assert the estimations, we should transform frame row number to batch row number
      */
@@ -142,16 +147,27 @@ internal fun assertEstimations(exampleFrame: AnyFrame, expectedNullable: Boolean
         assertValueOrNull(iBatch(i), element, JavaLocalDate.ofEpochDay(iBatch(i).toLong() * 30).toKotlinLocalDate())
     }
 
-    val datetimeCol = exampleFrame["date64"] as DataColumn<LocalDateTime?>
-    datetimeCol.type() shouldBe typeOf<LocalDateTime>().withNullability(expectedNullable)
-    datetimeCol.forEachIndexed { i, element ->
-        assertValueOrNull(
-            rowNumber = iBatch(i),
-            actual = element,
-            expected = JavaLocalDateTime
-                .ofEpochSecond(iBatch(i).toLong() * 60 * 60 * 24 * 30, 0, ZoneOffset.UTC)
-                .toKotlinLocalDateTime(),
-        )
+    if (fromParquet) {
+        // parquet format have only one type of date: https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#date without time
+        val datetimeCol = exampleFrame["date64"] as DataColumn<LocalDate?>
+        datetimeCol.type() shouldBe typeOf<LocalDate>().withNullability(expectedNullable)
+        datetimeCol.forEachIndexed { i, element ->
+            assertValueOrNull(iBatch(i), element, JavaLocalDate.ofEpochDay(iBatch(i).toLong() * 30).toKotlinLocalDate())
+        }
+    } else {
+        val datetimeCol = exampleFrame["date64"] as DataColumn<LocalDateTime?>
+        datetimeCol.type() shouldBe typeOf<LocalDateTime>().withNullability(expectedNullable)
+        datetimeCol.forEachIndexed { i, element ->
+            assertValueOrNull(
+                rowNumber = iBatch(i),
+                actual = element,
+                expected = JavaLocalDateTime.ofEpochSecond(
+                    iBatch(i).toLong() * 60 * 60 * 24 * 30,
+                    0,
+                    ZoneOffset.UTC,
+                ).toKotlinLocalDateTime(),
+            )
+        }
     }
 
     val timeSecCol = exampleFrame["time32_seconds"] as DataColumn<LocalTime?>

dataframe-arrow/src/test/resources/test.arrow.parquet

@@ -104,6 +104,7 @@ jsoup = { group = "org.jsoup", name = "jsoup", version.ref = "jsoup" }
 arrow-format = { group = "org.apache.arrow", name = "arrow-format", version.ref = "arrow" }
 arrow-vector = { group = "org.apache.arrow", name = "arrow-vector", version.ref = "arrow" }
 arrow-memory = { group = "org.apache.arrow", name = "arrow-memory-unsafe", version.ref = "arrow" }
+arrow-dataset = { group = "org.apache.arrow", name = "arrow-dataset", version.ref = "arrow" }
 arrow-c-data = { group = "org.apache.arrow", name = "arrow-c-data", version.ref = "arrow" }