nessie-gc truncate table to avoid increasing storage of DB

gc/gc-repository-jdbc/src/main/java/org/projectnessie/gc/contents/jdbc/JdbcHelper.java

@@ -55,6 +55,20 @@ public static void dropTables(Connection connection) throws SQLException {
     }
   }
 
+  public static int truncateTable(Connection connection) throws SQLException {
+    int numOfTruncatedTables = 0;
+    try (Statement st = connection.createStatement()) {
+      for (String tableName : SqlDmlDdl.ALL_CREATES.keySet()) {
+        if (tableExists(connection, tableName)) {
+          st.executeUpdate("TRUNCATE TABLE " + tableName);
+          numOfTruncatedTables++;
+        }
+      }
+      connection.commit();
+    }
+    return numOfTruncatedTables;
+  }
+
   private static boolean tableExists(Connection connection, String tableName) throws SQLException {
     DatabaseMetaData meta = connection.getMetaData();
     if (meta.storesUpperCaseIdentifiers()) {

gc/gc-repository-jdbc/src/test/java/org/projectnessie/gc/contents/jdbc/TestJdbcHelper.java

@@ -68,4 +68,24 @@ void dropTables() {
         .as("dropping tables again should not throw")
         .doesNotThrowAnyException();
   }
+
+  @Test
+  @Order(2)
+  void truncateTables() {
+    assertThatCode(
+            () -> {
+              try (Connection conn = dataSource.getConnection()) {
+                JdbcHelper.truncateTable(conn);
+              }
+            })
+        .doesNotThrowAnyException();
+    assertThatCode(
+            () -> {
+              try (Connection conn = dataSource.getConnection()) {
+                JdbcHelper.truncateTable(conn);
+              }
+            })
+        .as("truncating tables again should not throw")
+        .doesNotThrowAnyException();
+  }
 }

gc/gc-tool/src/main/java/org/projectnessie/gc/tool/cli/CLI.java

@@ -26,6 +26,7 @@
 import org.projectnessie.gc.tool.cli.commands.DeleteLiveSets;
 import org.projectnessie.gc.tool.cli.commands.JdbcCreateSchema;
 import org.projectnessie.gc.tool.cli.commands.JdbcDumpSchema;
+import org.projectnessie.gc.tool.cli.commands.JdbcTruncateTables;
 import org.projectnessie.gc.tool.cli.commands.ListDeferredDeletions;
 import org.projectnessie.gc.tool.cli.commands.ListLiveSets;
 import org.projectnessie.gc.tool.cli.commands.MarkAndSweep;
@@ -57,7 +58,8 @@
       JdbcDumpSchema.class,
       JdbcCreateSchema.class,
       CompletionScript.class,
-      ThirdPartyLicenses.class
+      ThirdPartyLicenses.class,
+      JdbcTruncateTables.class
     })
 public class CLI {
 

gc/gc-tool/src/main/java/org/projectnessie/gc/tool/cli/commands/JdbcTruncateTables.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2025 Dremio
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.projectnessie.gc.tool.cli.commands;
+
+import static java.lang.System.out;
+
+import java.sql.Connection;
+import javax.sql.DataSource;
+import org.projectnessie.gc.contents.jdbc.JdbcHelper;
+import org.projectnessie.gc.tool.cli.Closeables;
+import org.projectnessie.gc.tool.cli.options.EnvironmentDefaultProvider;
+import org.projectnessie.gc.tool.cli.options.JdbcOptions;
+import picocli.CommandLine;
+
+@CommandLine.Command(
+    name = "truncate",
+    aliases = {"clean-tables"},
+    mixinStandardHelpOptions = true,
+    defaultValueProvider = EnvironmentDefaultProvider.class,
+    description =
+        "Truncate nessie-gc tables to avoid increasing storage of DB, "
+            + "must not be used with the in-memory contents-storage.")
+public class JdbcTruncateTables extends BaseCommand {
+  @CommandLine.ArgGroup(multiplicity = "1", exclusive = false)
+  JdbcOptions jdbc;
+
+  @Override
+  protected Integer call(Closeables closeables) throws Exception {
+    DataSource dataSource = closeables.maybeAdd(jdbc.createDataSource());
+    int truncateTableCount;
+    try (Connection conn = dataSource.getConnection()) {
+      truncateTableCount = JdbcHelper.truncateTable(conn);
+    }
+    out.printf("number of `%s` tables truncated", truncateTableCount);
+    return truncateTableCount > 0 ? 0 : 1;
+  }
+}

gc/gc-tool/src/test/java/org/projectnessie/gc/tool/TestCLI.java

@@ -128,6 +128,9 @@ static Stream<Arguments> optionErrors() {
         arguments(
             asList("list-deferred", "--live-set-id=00000000-0000-0000-0000-000000000000"),
             "Error: Missing required argument (specify one of these): ([--inmemory] | [[--jdbc]"),
+        arguments(
+            singletonList("truncate"),
+            "Error: Missing required argument(s): ([--jdbc] --jdbc-url=<url>"),
         // No live-set-id
         arguments(
             asList("sweep", "--jdbc-url", "jdbc:foo//bar"),
@@ -470,4 +473,11 @@ public void completionScript(@TempDir Path dir) throws Exception {
     soft.assertThat(run.getExitCode()).as(run::getErr).isEqualTo(1);
     soft.assertThat(run.getErr()).contains("File already exists.");
   }
+
+  @Test
+  @Order(10)
+  public void truncateTables() throws Exception {
+    RunCLI run = RunCLI.run("truncate", "--jdbc-url", JDBC_URL);
+    soft.assertThat(run.getExitCode()).as(run::getErr).isEqualTo(0);
+  }
 }