From 0f53f11c5b9fb4252b90111a3a9fd1b62277bd19 Mon Sep 17 00:00:00 2001
From: Sumeet Varma <sumeet.varma@databricks.com>
Date: Tue, 12 Mar 2024 22:51:42 -0700
Subject: [PATCH] Vacuum changes

---
 .../apache/spark/sql/delta/TableFeature.scala | 16 ++++++++++-
 .../sql/delta/DeltaTableFeatureSuite.scala    | 27 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/spark/src/main/scala/org/apache/spark/sql/delta/TableFeature.scala b/spark/src/main/scala/org/apache/spark/sql/delta/TableFeature.scala
index 91d32f4e0b5..8acb32d536e 100644
--- a/spark/src/main/scala/org/apache/spark/sql/delta/TableFeature.scala
+++ b/spark/src/main/scala/org/apache/spark/sql/delta/TableFeature.scala
@@ -357,7 +357,8 @@ object TableFeature {
         // Row IDs are still under development and only available in testing.
         RowTrackingFeature,
         InCommitTimestampTableFeature,
-        TypeWideningTableFeature)
+        TypeWideningTableFeature,
+        VacuumProtocolCheckTableFeature)
     }
     val featureMap = features.map(f => f.name.toLowerCase(Locale.ROOT) -> f).toMap
     require(features.size == featureMap.size, "Lowercase feature names must not duplicate.")
@@ -656,6 +657,19 @@ object InCommitTimestampTableFeature
   }
 }
 
+/**
+ * A ReaderWriter table feature for VACUUM. If this feature is enabled:
+ * A writer should follow one of the following:
+ *   1. Non-Support for Vacuum: Writers can explicitly state that they do not support VACUUM for
+ *      any table, regardless of whether the Vacuum Protocol Check Table feature exists.
+ *   2. Implement Writer Protocol Check: Ensure that the VACUUM implementation includes a writer
+ *      protocol check before any file deletions occur.
+ * Readers don't need to understand or change anything new; they just need to acknowledge the
+ * feature exists
+ */
+object VacuumProtocolCheckTableFeature
+  extends ReaderWriterFeature(name = "vacuumProtocolCheck-dev")
+
 /**
  * Features below are for testing only, and are being registered to the system only in the testing
  * environment. See [[TableFeature.allSupportedFeaturesMap]] for the registration.
diff --git a/spark/src/test/scala/org/apache/spark/sql/delta/DeltaTableFeatureSuite.scala b/spark/src/test/scala/org/apache/spark/sql/delta/DeltaTableFeatureSuite.scala
index 46f31d151d0..17067000616 100644
--- a/spark/src/test/scala/org/apache/spark/sql/delta/DeltaTableFeatureSuite.scala
+++ b/spark/src/test/scala/org/apache/spark/sql/delta/DeltaTableFeatureSuite.scala
@@ -459,6 +459,33 @@ class DeltaTableFeatureSuite
     }
   }
 
+  for(commandName <- Seq("ALTER", "CLONE", "REPLACE", "CREATE OR REPLACE")) {
+    test(s"Vacuum Protocol Check is disabled by default but can be enabled during $commandName") {
+      val table = "tbl"
+      withTable(table) {
+        spark.range(0).write.format("delta").saveAsTable(table)
+        val log = DeltaLog.forTable(spark, TableIdentifier(table))
+        val protocol = log.update().protocol
+        assert(!protocol.readerAndWriterFeatureNames.contains(VacuumProtocolCheckTableFeature.name))
+
+        val tblProperties1 = Seq(s"'delta.minWriterVersion' = $TABLE_FEATURES_MIN_WRITER_VERSION")
+        sql(buildTablePropertyModifyingCommand(
+          commandName, targetTableName = table, sourceTableName = table, tblProperties1))
+        val newProtocol1 = log.update().protocol
+        assert(!newProtocol1.readerAndWriterFeatureNames.contains(
+          VacuumProtocolCheckTableFeature.name))
+
+        val tblProperties2 = Seq(s"'$FEATURE_PROP_PREFIX${VacuumProtocolCheckTableFeature.name}' " +
+          s"= 'supported', 'delta.minWriterVersion' = $TABLE_FEATURES_MIN_WRITER_VERSION")
+        sql(buildTablePropertyModifyingCommand(
+          commandName, targetTableName = table, sourceTableName = table, tblProperties2))
+        val newProtocol2 = log.update().protocol
+        assert(newProtocol2.readerAndWriterFeatureNames.contains(
+          VacuumProtocolCheckTableFeature.name))
+      }
+    }
+  }
+
   private def buildTablePropertyModifyingCommand(
       commandName: String,
       targetTableName: String,