Core: Retain current view version during expiration (#12067)

Co-authored-by: Christian Thiel <[email protected]>
apache · Jan 24, 2025 · 681ff57 · 681ff57
1 parent 026a9b0
commit 681ff57
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Showing 2 changed files with 58 additions and 7 deletions.
diff --git a/core/src/main/java/org/apache/iceberg/view/ViewMetadata.java b/core/src/main/java/org/apache/iceberg/view/ViewMetadata.java
@@ -469,7 +469,8 @@ public ViewMetadata build() {
       List<ViewVersion> retainedVersions;
       List<ViewHistoryEntry> retainedHistory;
       if (versions.size() > numVersionsToKeep) {
-        retainedVersions = expireVersions(versionsById, numVersionsToKeep);
+        retainedVersions =
+            expireVersions(versionsById, numVersionsToKeep, versionsById.get(currentVersionId));
         Set<Integer> retainedVersionIds =
             retainedVersions.stream().map(ViewVersion::versionId).collect(Collectors.toSet());
         retainedHistory = updateHistory(history, retainedVersionIds);
@@ -493,14 +494,24 @@ public ViewMetadata build() {
 
     @VisibleForTesting
     static List<ViewVersion> expireVersions(
-        Map<Integer, ViewVersion> versionsById, int numVersionsToKeep) {
+        Map<Integer, ViewVersion> versionsById, int numVersionsToKeep, ViewVersion currentVersion) {
       // version ids are assigned sequentially. keep the latest versions by ID.
       List<Integer> ids = Lists.newArrayList(versionsById.keySet());
       ids.sort(Comparator.reverseOrder());
 
       List<ViewVersion> retainedVersions = Lists.newArrayList();
+      // always retain the current version
+      retainedVersions.add(currentVersion);
+
       for (int idToKeep : ids.subList(0, numVersionsToKeep)) {
-        retainedVersions.add(versionsById.get(idToKeep));
+        if (retainedVersions.size() == numVersionsToKeep) {
+          break;
+        }
+
+        ViewVersion version = versionsById.get(idToKeep);
+        if (currentVersion.versionId() != version.versionId()) {
+          retainedVersions.add(version);
+        }
       }
 
       return retainedVersions;

diff --git a/core/src/test/java/org/apache/iceberg/view/TestViewMetadata.java b/core/src/test/java/org/apache/iceberg/view/TestViewMetadata.java
@@ -62,11 +62,11 @@ public void testExpiration() {
     ViewVersion v2 = newViewVersion(2, "select count(1) as count from t2");
     Map<Integer, ViewVersion> versionsById = ImmutableMap.of(1, v1, 2, v2, 3, v3);
 
-    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 3))
+    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 3, v1))
         .containsExactlyInAnyOrder(v1, v2, v3);
-    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 2))
-        .containsExactlyInAnyOrder(v2, v3);
-    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 1)).containsExactly(v3);
+    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 2, v1))
+        .containsExactlyInAnyOrder(v1, v3);
+    assertThat(ViewMetadata.Builder.expireVersions(versionsById, 1, v1)).containsExactly(v1);
   }
 
   @Test
@@ -1181,4 +1181,44 @@ public void droppingDialectAllowedAndThenDisallowed() {
                 + "Previous dialects: [trino]\n"
                 + "New dialects: [spark]");
   }
+
+  @Test
+  public void currentViewVersionIsNeverExpired() {
+    Map<String, String> properties = ImmutableMap.of(ViewProperties.VERSION_HISTORY_SIZE, "1");
+    ViewVersion viewVersionOne = newViewVersion(1, "select * from ns.tbl");
+    ViewVersion viewVersionTwo = newViewVersion(2, "select count(*) from ns.tbl");
+    ViewVersion viewVersionThree = newViewVersion(3, "select count(*) as count from ns.tbl");
+
+    ViewMetadata originalViewMetadata =
+        ViewMetadata.builder()
+            .setProperties(properties)
+            .setLocation("location")
+            .addSchema(new Schema(Types.NestedField.required(1, "x", Types.LongType.get())))
+            .addVersion(viewVersionOne)
+            .addVersion(viewVersionTwo)
+            .addVersion(viewVersionThree)
+            .setCurrentVersionId(1)
+            .build();
+
+    // the first build will not expire versions that were added in the builder
+    assertThat(originalViewMetadata.versions()).hasSize(3);
+    assertThat(originalViewMetadata.history())
+        .hasSize(1)
+        .element(0)
+        .extracting(ViewHistoryEntry::versionId)
+        .isEqualTo(1);
+
+    // rebuild the metadata to expire older versions
+    ViewMetadata viewMetadata = ViewMetadata.buildFrom(originalViewMetadata).build();
+    assertThat(viewMetadata.versions()).hasSize(1);
+
+    // make sure history and current version are retained
+    assertThat(viewMetadata.currentVersionId()).isEqualTo(1);
+    assertThat(viewMetadata.currentVersion()).isEqualTo(viewVersionOne);
+    assertThat(viewMetadata.history())
+        .hasSize(1)
+        .element(0)
+        .extracting(ViewHistoryEntry::versionId)
+        .isEqualTo(1);
+  }
 }