Implemented the count database in table model

integration-test/src/test/java/org/apache/iotdb/relational/it/schema/IoTDBDatabaseIT.java

@@ -815,6 +815,12 @@ public void testMixedDatabase() throws SQLException {
     try (final Connection connection =
             EnvFactory.getEnv().getConnection(BaseEnv.TABLE_SQL_DIALECT);
         final Statement statement = connection.createStatement()) {
+      TestUtils.assertResultSetEqual(
+          statement.executeQuery("count databases"), "count,", Collections.singleton("3,"));
+      TestUtils.assertResultSetEqual(
+          statement.executeQuery("select count(*) from information_schema.databases"),
+          "_col0,",
+          Collections.singleton("3,"));
       statement.execute("drop database test");
     }
 
@@ -825,6 +831,23 @@ public void testMixedDatabase() throws SQLException {
     }
   }
 
+  @Test
+  public void testCountDatabases() throws SQLException {
+    try (final Connection connection =
+            EnvFactory.getEnv().getConnection(BaseEnv.TABLE_SQL_DIALECT);
+        final Statement statement = connection.createStatement()) {
+      statement.execute("create database db1");
+      statement.execute("create database db2");
+
+      TestUtils.assertResultSetEqual(
+          statement.executeQuery("count databases"), "count,", Collections.singleton("3,"));
+      TestUtils.assertResultSetEqual(
+          statement.executeQuery("select count(*) from information_schema.databases"),
+          "_col0,",
+          Collections.singleton("3,"));
+    }
+  }
+
   @Test
   public void testDBAuth() throws SQLException {
     try (final Connection adminCon = EnvFactory.getEnv().getConnection(BaseEnv.TABLE_SQL_DIALECT);
@@ -838,6 +861,8 @@ public void testDBAuth() throws SQLException {
     try (final Connection userCon =
             EnvFactory.getEnv().getConnection("test", "password123456", BaseEnv.TABLE_SQL_DIALECT);
         final Statement userStmt = userCon.createStatement()) {
+      TestUtils.assertResultSetEqual(
+          userStmt.executeQuery("count databases"), "count,", Collections.singleton("1,"));
       TestUtils.assertResultSetEqual(
           userStmt.executeQuery("show databases"),
           "Database,TTL(ms),SchemaReplicationFactor,DataReplicationFactor,TimePartitionInterval,",
@@ -869,6 +894,8 @@ public void testDBAuth() throws SQLException {
     try (final Connection userCon =
             EnvFactory.getEnv().getConnection("test", "password123456", BaseEnv.TABLE_SQL_DIALECT);
         final Statement userStmt = userCon.createStatement()) {
+      TestUtils.assertResultSetEqual(
+          userStmt.executeQuery("count databases"), "count,", Collections.singleton("2,"));
       try (final ResultSet resultSet = userStmt.executeQuery("SHOW DATABASES")) {
         final ResultSetMetaData metaData = resultSet.getMetaData();
         assertEquals(showDBColumnHeaders.size(), metaData.getColumnCount());

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/Coordinator.java

@@ -78,6 +78,7 @@
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.AlterColumnDataType;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.AlterDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ClearCache;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateExternalService;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateFunction;
@@ -610,6 +611,7 @@ private IQueryExecution createQueryExecutionForTableModel(
     queryContext.setTimeOut(timeOut);
     queryContext.setStartTime(startTime);
     if (statement instanceof DropDB
+        || statement instanceof CountDB
         || statement instanceof ShowDB
         || statement instanceof CreateDB
         || statement instanceof AlterDB

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/TableConfigTaskVisitor.java

@@ -99,6 +99,7 @@
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.AlterTableRenameTableTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.AlterTableSetPropertiesTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.ClearCacheTask;
+import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.CountDBTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.CreateDBTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.CreateTableTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.CreateTableViewTask;
@@ -156,6 +157,7 @@
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.AstVisitor;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ClearCache;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ColumnDefinition;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateExternalService;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateFunction;
@@ -424,6 +426,15 @@ public IConfigTask visitShowDB(final ShowDB node, final MPPQueryContext context)
             canShowDB(accessControl, context.getSession().getUserName(), databaseName, context));
   }
 
+  @Override
+  public IConfigTask visitCountDB(final CountDB node, final MPPQueryContext context) {
+    context.setQueryType(QueryType.READ);
+    return new CountDBTask(
+        node,
+        databaseName ->
+            canShowDB(accessControl, context.getSession().getUserName(), databaseName, context));
+  }
+
   public static boolean canShowDB(
       final AccessControl accessControl,
       final String userName,

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/executor/ClusterConfigTaskExecutor.java

@@ -229,6 +229,7 @@
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.region.MigrateRegionTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.region.ReconstructRegionTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.region.RemoveRegionTask;
+import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.CountDBTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.DeleteDeviceTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.DescribeTableDetailsTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational.DescribeTableTask;
@@ -255,6 +256,7 @@
 import org.apache.iotdb.db.queryengine.plan.expression.Expression;
 import org.apache.iotdb.db.queryengine.plan.expression.visitor.TransformToViewExpressionVisitor;
 import org.apache.iotdb.db.queryengine.plan.planner.plan.node.metadata.write.view.AlterLogicalViewNode;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.DeleteDevice;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.DropDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ShowCluster;
@@ -2335,7 +2337,7 @@
   }
 
   @Override
   public SettableFuture<ConfigTaskResult> alterPipe(final AlterPipeStatement alterPipeStatement) {
     final SettableFuture<ConfigTaskResult> future = SettableFuture.create();
 
     // Validate pipe name
@@ -4140,6 +4142,24 @@
     return future;
   }
 
+  @Override
+  public SettableFuture<ConfigTaskResult> countDatabases(
+      final CountDB countDB, final Predicate<String> canSeenDB) {
+    final SettableFuture<ConfigTaskResult> future = SettableFuture.create();
+    final List<String> databasePathPattern = Arrays.asList(ALL_RESULT_NODES);
+    try (final ConfigNodeClient client =
+        CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
+      final TGetDatabaseReq req =
+          new TGetDatabaseReq(databasePathPattern, ALL_MATCH_SCOPE.serialize())
+              .setIsTableModel(true);
+      final TShowDatabaseResp resp = client.showDatabase(req);
+      CountDBTask.buildTSBlock(resp.getDatabaseInfoMap(), future, canSeenDB);
+    } catch (final IOException | ClientManagerException | TException e) {
+      future.setException(e);
+    }
+    return future;
+  }
+
   @Override
   public SettableFuture<ConfigTaskResult> showCluster(final ShowCluster showCluster) {
     // As the implementation is identical, we'll simply translate to the

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/executor/IConfigTaskExecutor.java

@@ -41,6 +41,7 @@
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.region.ReconstructRegionTask;
 import org.apache.iotdb.db.queryengine.plan.execution.config.metadata.region.RemoveRegionTask;
 import org.apache.iotdb.db.queryengine.plan.planner.plan.node.metadata.write.view.AlterLogicalViewNode;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.DeleteDevice;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.DropDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ShowCluster;
@@ -333,6 +334,9 @@ SettableFuture<ConfigTaskResult> showThrottleQuota(
   SettableFuture<ConfigTaskResult> showDatabases(
       final ShowDB showDB, final Predicate<String> canSeenDB);
 
+  SettableFuture<ConfigTaskResult> countDatabases(
+      final CountDB countDB, final Predicate<String> canSeenDB);
+
   SettableFuture<ConfigTaskResult> showCluster(ShowCluster showCluster);
 
   SettableFuture<ConfigTaskResult> useDatabase(final Use useDB, final IClientSession clientSession);

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/metadata/relational/CountDBTask.java

@@ -0,0 +1,82 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.iotdb.db.queryengine.plan.execution.config.metadata.relational;
+
+import org.apache.iotdb.commons.conf.IoTDBConstant;
+import org.apache.iotdb.commons.schema.column.ColumnHeader;
+import org.apache.iotdb.db.queryengine.common.header.DatasetHeader;
+import org.apache.iotdb.db.queryengine.plan.execution.config.ConfigTaskResult;
+import org.apache.iotdb.db.queryengine.plan.execution.config.IConfigTask;
+import org.apache.iotdb.db.queryengine.plan.execution.config.executor.IConfigTaskExecutor;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
+import org.apache.iotdb.rpc.TSStatusCode;
+
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.SettableFuture;
+import org.apache.tsfile.enums.TSDataType;
+import org.apache.tsfile.read.common.block.TsBlockBuilder;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.function.Predicate;
+
+import static org.apache.iotdb.commons.schema.table.InformationSchema.INFORMATION_DATABASE;
+
+public class CountDBTask implements IConfigTask {
+
+  private final CountDB node;
+  private final Predicate<String> canSeenDB;
+
+  public CountDBTask(final CountDB node, final Predicate<String> canSeenDB) {
+    this.node = node;
+    this.canSeenDB = canSeenDB;
+  }
+
+  @Override
+  public ListenableFuture<ConfigTaskResult> execute(final IConfigTaskExecutor configTaskExecutor)
+      throws InterruptedException {
+    return configTaskExecutor.countDatabases(node, canSeenDB);
+  }
+
+  public static void buildTSBlock(
+      final Map<String, ?> databaseInfoMap,
+      final SettableFuture<ConfigTaskResult> future,
+      final Predicate<String> canSeenDB) {
+    // information_schema is synthesized in table model rather than returned from ConfigNode.
+    final long databaseCount =
+        databaseInfoMap.keySet().stream()
+                .filter(databaseName -> !INFORMATION_DATABASE.equals(databaseName))
+                .filter(canSeenDB::test)
+                .count()
+            + (canSeenDB.test(INFORMATION_DATABASE) ? 1 : 0);
+
+    final TsBlockBuilder builder = new TsBlockBuilder(Collections.singletonList(TSDataType.INT32));
+    builder.getTimeColumnBuilder().writeLong(0L);
+    builder.getColumnBuilder(0).writeInt((int) databaseCount);
+    builder.declarePosition();
+
+    final DatasetHeader datasetHeader =
+        new DatasetHeader(
+            Collections.singletonList(
+                new ColumnHeader(IoTDBConstant.COLUMN_COUNT, TSDataType.INT32)),
+            true);
+    future.set(new ConfigTaskResult(TSStatusCode.SUCCESS_STATUS, builder.build(), datasetHeader));
+  }
+}

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/sql/ast/AstVisitor.java

@@ -79,6 +79,10 @@ default R visitShowDB(final ShowDB node, final C context) {
     return visitStatement(node, context);
   }
 
+  default R visitCountDB(final CountDB node, final C context) {
+    return visitStatement(node, context);
+  }
+
   default R visitCreateTable(final CreateTable node, final C context) {
     return visitStatement(node, context);
   }

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/sql/ast/CountDB.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.iotdb.db.queryengine.plan.relational.sql.ast;
+
+import org.apache.iotdb.commons.queryengine.plan.relational.sql.ast.AstMemoryEstimationHelper;
+import org.apache.iotdb.commons.queryengine.plan.relational.sql.ast.IAstVisitor;
+import org.apache.iotdb.commons.queryengine.plan.relational.sql.ast.Node;
+import org.apache.iotdb.commons.queryengine.plan.relational.sql.ast.NodeLocation;
+import org.apache.iotdb.commons.queryengine.plan.relational.sql.ast.Statement;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.tsfile.utils.RamUsageEstimator;
+
+import java.util.List;
+
+import static java.util.Objects.requireNonNull;
+
+public class CountDB extends Statement {
+
+  private static final long INSTANCE_SIZE = RamUsageEstimator.shallowSizeOfInstance(CountDB.class);
+
+  public CountDB(final NodeLocation location) {
+    super(requireNonNull(location, "location is null"));
+  }
+
+  @Override
+  public <R, C> R accept(final IAstVisitor<R, C> visitor, final C context) {
+    return ((AstVisitor<R, C>) visitor).visitCountDB(this, context);
+  }
+
+  @Override
+  public List<Node> getChildren() {
+    return ImmutableList.of();
+  }
+
+  @Override
+  public int hashCode() {
+    return getClass().hashCode();
+  }
+
+  @Override
+  public boolean equals(final Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    return (obj != null) && (getClass() == obj.getClass());
+  }
+
+  @Override
+  public String toString() {
+    return "COUNT DATABASES";
+  }
+
+  @Override
+  public long ramBytesUsed() {
+    long size = INSTANCE_SIZE;
+    size += AstMemoryEstimationHelper.getEstimatedSizeOfNodeLocation(getLocationInternal());
+    return size;
+  }
+}

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/sql/parser/AstBuilder.java

@@ -162,6 +162,7 @@
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ClearCache;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ColumnDefinition;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CopyTo;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDevice;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountStatement;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateDB;
@@ -406,6 +407,12 @@
     return new ShowDB(getLocation(ctx), Objects.nonNull(ctx.DETAILS()));
   }
 
+  @Override
+  public Node visitCountDatabasesStatement(
+      final RelationalSqlParser.CountDatabasesStatementContext ctx) {
+    return new CountDB(getLocation(ctx));
+  }
+
   @Override
   public Node visitCreateDbStatement(final RelationalSqlParser.CreateDbStatementContext ctx) {
     List<Property> properties = ImmutableList.of();
@@ -1993,7 +2000,7 @@
   }
 
   @Override
   public Node visitGrantStatement(RelationalSqlParser.GrantStatementContext ctx) {
     boolean toUser;
     String name;
     toUser = ctx.holderType().getText().equalsIgnoreCase("user");
@@ -2078,7 +2085,7 @@
     throw new SemanticException(DataNodeQueryMessages.AUTHOR_STATEMENT_PARSER_ERROR);
   }
 
   public Node visitRevokeStatement(RelationalSqlParser.RevokeStatementContext ctx) {
     boolean fromUser;
     String name;
     fromUser = ctx.holderType().getText().equalsIgnoreCase("user");

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/sql/util/DataNodeSqlFormatter.java

@@ -32,6 +32,7 @@
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.AstVisitor;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.ColumnDefinition;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CopyTo;
+import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CountDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateDB;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreateFunction;
 import org.apache.iotdb.db.queryengine.plan.relational.sql.ast.CreatePipe;
@@ -134,7 +135,13 @@ public Void visitExplainAnalyze(ExplainAnalyze node, Integer indent) {
 
   @Override
   public Void visitShowDB(ShowDB node, Integer indent) {
-    builder.append("SHOW DATABASE");
+    builder.append("SHOW DATABASES");
+    return null;
+  }
+
+  @Override
+  public Void visitCountDB(CountDB node, Integer indent) {
+    builder.append("COUNT DATABASES");
     return null;
   }