Add earliest partition date stat to table stats collector

apps/spark/src/main/java/com/linkedin/openhouse/jobs/util/TableStatsCollector.java

@@ -22,7 +22,7 @@ public IcebergTableStats collectTableStats() {
     IcebergTableStats stats = IcebergTableStats.builder().build();
 
     IcebergTableStats statsWithMetadataData =
-        TableStatsCollectorUtil.populateTableMetadata(table, stats);
+        TableStatsCollectorUtil.populateTableMetadata(table, spark, stats);
     IcebergTableStats statsWithReferenceFiles =
         TableStatsCollectorUtil.populateStatsOfAllReferencedFiles(
             fqtn, table, spark, statsWithMetadataData);

apps/spark/src/main/java/com/linkedin/openhouse/jobs/util/TableStatsCollectorUtil.java

@@ -21,9 +21,11 @@
 import org.apache.iceberg.ReachableFileUtil;
 import org.apache.iceberg.Table;
 import org.apache.iceberg.spark.SparkTableUtil;
+import org.apache.iceberg.types.Types;
 import org.apache.spark.sql.Dataset;
 import org.apache.spark.sql.Row;
 import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.functions;
 
 /** Utility class to collect stats for a given table. */
 @Slf4j
@@ -172,9 +174,11 @@ protected static IcebergTableStats populateStorageStats(
    * Collect table metadata for a given table.
    *
    * @param table
+   * @param spark
    * @param stats
    */
-  protected static IcebergTableStats populateTableMetadata(Table table, IcebergTableStats stats) {
+  protected static IcebergTableStats populateTableMetadata(
+      Table table, SparkSession spark, IcebergTableStats stats) {
     Map<String, Object> policyMap = getTablePolicies(table);
     return stats
         .builder()
@@ -197,6 +201,13 @@ protected static IcebergTableStats populateTableMetadata(Table table, IcebergTab
         .sharingEnabled(
             policyMap.containsKey("sharingEnabled") && (Boolean) policyMap.get("sharingEnabled"))
         .retentionPolicies(buildRetentionStats(policyMap))
+        .earliestPartitionDate(
+            getEarliestPartitionDate(
+                table,
+                spark,
+                policyMap.containsKey("columnName")
+                    ? (String) policyMap.get("columnName")
+                    : getPartitionColumnName(table)))
         .build();
   }
 
@@ -247,6 +258,43 @@ private static long getSumOfFileSizeBytes(Dataset<Row> allDataFiles) {
         .getLong(0);
   }
 
+  /**
+   * Get the earliest partition date on a table.
+   *
+   * @param table
+   * @param spark
+   * @param partitionColumnName
+   * @return
+   */
+  private static String getEarliestPartitionDate(
+      Table table, SparkSession spark, String partitionColumnName) {
+    if (partitionColumnName == null) {
+      return null;
+    }
+
+    Dataset<Row> partitionData =
+        SparkTableUtil.loadMetadataTable(spark, table, MetadataTableType.PARTITIONS);
+    String partitionColumn = String.format("partition.%s", partitionColumnName);
+
+    String earliestPartitionDate =
+        partitionData
+            .select(partitionColumn)
+            .orderBy(functions.asc(partitionColumn))
+            .first()
+            .get(0)
+            .toString();
+
+    return earliestPartitionDate;
+  }
+
+  private static String getPartitionColumnName(Table table) {
+    return StreamSupport.stream(table.spec().partitionType().fields().spliterator(), false)
+        .filter(field -> field.type() instanceof Types.DateType)
+        .map(Types.NestedField::name)
+        .findFirst()
+        .orElse(null);
+  }
+
   /**
    * Get table policies.
    *

apps/spark/src/test/java/com/linkedin/openhouse/jobs/spark/OperationsTest.java

@@ -9,6 +9,8 @@
 import com.linkedin.openhouse.tables.client.model.Retention;
 import com.linkedin.openhouse.tablestest.OpenHouseSparkITest;
 import io.opentelemetry.api.metrics.Meter;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -527,6 +529,40 @@ private static Path prepareOrphanTableDirectory(Operations ops, String tableName
     return tbLoc;
   }
 
+  @Test
+  public void testCollectEarliestPartitionDateStat() throws Exception {
+    final String tableName = "db.test_collect_earliest_partition_date";
+    List<String> rowValue = new ArrayList<>();
+
+    try (Operations ops = Operations.withCatalog(getSparkSession(), meter)) {
+      // Test table with no partition
+      prepareTable(ops, tableName);
+      IcebergTableStats stats = ops.collectTableStats(tableName);
+      Assertions.assertNull(stats.getEarliestPartitionDate());
+
+      // Test yyyy-mm-dd format on table with multiple partitioned columns
+      prepareTableWithPoliciesWithMultipleStringPartition(ops, tableName, "30d", false);
+      rowValue.add("202%s-07-16");
+      rowValue.add("202%s-07-17");
+      rowValue.add("202%s-08-16");
+      rowValue.add("202%s-09-16");
+      populateTableWithMultipleStringColumn(ops, tableName, 1, rowValue);
+      stats = ops.collectTableStats(tableName);
+      Assertions.assertEquals(stats.getEarliestPartitionDate(), "202%s-07-16");
+      rowValue.clear();
+
+      // Test timestamp format
+      prepareTableWithPolicies(ops, tableName, "30d", false);
+      populateTable(ops, tableName, 1, 2);
+      populateTable(ops, tableName, 1, 1);
+      populateTable(ops, tableName, 1, 0);
+      stats = ops.collectTableStats(tableName);
+      Assertions.assertEquals(
+          stats.getEarliestPartitionDate(),
+          LocalDate.now().minusDays(2).format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
+    }
+  }
+
   @Test
   public void testCollectTablePolicyStats() throws Exception {
     final String tableName = "db.test_collect_table_stats_with_policy";
@@ -662,6 +698,20 @@ private static void populateTableWithStringColumn(
     }
   }
 
+  private static void populateTableWithMultipleStringColumn(
+      Operations ops, String tableName, int numRows, List<String> dataFormats) {
+    for (String dataFormat : dataFormats) {
+      for (int row = 0; row < numRows; ++row) {
+        ops.spark()
+            .sql(
+                String.format(
+                    "INSERT INTO %s VALUES ('%s', '%s', %d)",
+                    tableName, dataFormat, String.format(dataFormat, row), row))
+            .show();
+      }
+    }
+  }
+
   private static void prepareTable(Operations ops, String tableName) {
     prepareTable(ops, tableName, false);
   }
@@ -739,6 +789,24 @@ private static void prepareTableWithPoliciesWithStringPartition(
     ops.spark().sql(String.format("DESCRIBE %s", tableName)).show();
   }
 
+  private static void prepareTableWithPoliciesWithMultipleStringPartition(
+      Operations ops, String tableName, String retention, boolean sharing) {
+    ops.spark().sql(String.format("DROP TABLE IF EXISTS %s", tableName)).show();
+    ops.spark()
+        .sql(
+            String.format(
+                "CREATE TABLE %s (datepartition string, data string, num int) PARTITIONED BY (datepartition, num)",
+                tableName))
+        .show();
+    ops.spark()
+        .sql(
+            String.format(
+                "ALTER TABLE %s SET POLICY (RETENTION=%s ON COLUMN datepartition)",
+                tableName, retention));
+    ops.spark().sql(String.format("ALTER TABLE %s SET POLICY (SHARING=%s)", tableName, sharing));
+    ops.spark().sql(String.format("DESCRIBE %s", tableName)).show();
+  }
+
   private static void prepareTableWithPoliciesWithCustomStringPartition(
       Operations ops, String tableName, String retention, String pattern) {
     ops.spark().sql(String.format("DROP TABLE IF EXISTS %s", tableName)).show();

services/common/src/main/java/com/linkedin/openhouse/common/stats/model/BaseTableMetadata.java

@@ -35,4 +35,6 @@ public class BaseTableMetadata {
   private Boolean sharingEnabled;
 
   private RetentionStatsSchema retentionPolicies;
+
+  private String earliestPartitionDate;
 }