[feature](Show) add one show type cast command (#15137)

docs/en/docs/sql-manual/sql-reference/Show-Statements/SHOW-TYPECAST.md

@@ -0,0 +1,71 @@
+---
+{
+    "title": "SHOW-TYPECAST",
+    "language": "en"
+}
+---
+
+<!--
+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.
+-->
+
+## SHOW-TYPECAST
+
+### Name
+
+SHOW TYPECAST
+
+### Description
+
+View all type cast under the database. If the user specifies a database, then view the corresponding database, otherwise directly query the database where the current session is located
+
+Requires `SHOW` permission on this database
+
+grammar
+
+```sql
+SHOW TYPE_CAST [IN|FROM db]
+````
+
+ Parameters
+
+>`db`: database name to query
+
+### Example
+
+````sql
+mysql> show type_cast in testDb\G
+**************************** 1. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+**************************** 2. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+**************************** 3. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+
+3 rows in set (0.00 sec)
+````
+
+### Keywords
+
+    SHOW, TYPECAST
+
+### Best Practice
+

docs/sidebars.json

@@ -880,6 +880,7 @@
                                 "sql-manual/sql-reference/Show-Statements/SHOW-EXPORT",
                                 "sql-manual/sql-reference/Show-Statements/SHOW-ENCRYPT-KEY",
                                 "sql-manual/sql-reference/Show-Statements/SHOW-FUNCTIONS",
+                                "sql-manual/sql-reference/Show-Statements/SHOW-TYPECAST",
                                 "sql-manual/sql-reference/Show-Statements/SHOW-FILE",
                                 "sql-manual/sql-reference/Show-Statements/SHOW-GRANTS",
                                 "sql-manual/sql-reference/Show-Statements/SHOW-LAST-INSERT",

docs/zh-CN/docs/sql-manual/sql-reference/Show-Statements/SHOW-TYPECAST.md

@@ -0,0 +1,71 @@
+---
+{
+    "title": "SHOW-TYPECAST",
+    "language": "zh-CN"
+}
+---
+
+<!--
+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.
+-->
+
+## SHOW-TYPECAST
+
+### Name
+
+SHOW TYPECAST
+
+### Description
+
+查看数据库下所有的类型转换。如果用户指定了数据库，那么查看对应数据库的，否则直接查询当前会话所在数据库
+
+需要对这个数据库拥有 `SHOW` 权限
+
+语法
+
+```sql
+SHOW TYPE_CAST [IN|FROM db]
+````
+
+ Parameters
+
+>`db`: database name to query
+
+### Example
+
+````sql
+mysql> show type_cast in testDb\G
+**************************** 1. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+**************************** 2. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+**************************** 3. row ******************** ******
+Origin Type: TIMEV2
+  Cast Type: TIMEV2
+
+3 rows in set (0.00 sec)
+````
+
+### Keywords
+
+    SHOW, TYPECAST
+
+### Best Practice
+

fe/fe-core/src/main/cup/sql_parser.cup

@@ -602,7 +602,8 @@ terminal String
     KW_WORK,
     KW_WRITE,
     KW_YEAR,
-    KW_MTMV;
+    KW_MTMV,
+    KW_TYPECAST;
 
 terminal COMMA, COLON, DOT, DOTDOTDOT, AT, STAR, LPAREN, RPAREN, SEMICOLON, LBRACKET, RBRACKET, DIVIDE, MOD, ADD, SUBTRACT;
 terminal BITAND, BITOR, BITXOR, BITNOT;
@@ -3667,6 +3668,10 @@ show_param ::=
     {:
         RESULT = new ShowFunctionsStmt(dbName, isBuiltin, parser.isVerbose, parser.wild, parser.where);
     :}
+    | KW_TYPECAST opt_db:dbName
+    {:
+        RESULT = new ShowTypeCastStmt(dbName, parser.where);
+    :}
     | KW_FILE opt_db:dbName
     {:
         RESULT = new ShowSmallFilesStmt(dbName);

fe/fe-core/src/main/java/org/apache/doris/analysis/ShowTypeCastStmt.java

@@ -0,0 +1,101 @@
+// 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.doris.analysis;
+
+import org.apache.doris.catalog.Column;
+import org.apache.doris.catalog.Env;
+import org.apache.doris.catalog.ScalarType;
+import org.apache.doris.cluster.ClusterNamespace;
+import org.apache.doris.common.AnalysisException;
+import org.apache.doris.common.ErrorCode;
+import org.apache.doris.common.ErrorReport;
+import org.apache.doris.common.UserException;
+import org.apache.doris.mysql.privilege.PrivPredicate;
+import org.apache.doris.qe.ConnectContext;
+import org.apache.doris.qe.ShowResultSetMetaData;
+
+import com.google.common.base.Strings;
+
+public class ShowTypeCastStmt extends ShowStmt {
+    private static final ShowResultSetMetaData META_DATA =
+            ShowResultSetMetaData.builder()
+                    .addColumn(new Column("Origin Type", ScalarType.createVarchar(32)))
+                    .addColumn(new Column("Cast Type", ScalarType.createVarchar(32)))
+                    .build();
+
+    @Override
+    public ShowResultSetMetaData getMetaData() {
+        return META_DATA;
+    }
+
+    private String dbName;
+
+    private Expr expr;
+
+    public ShowTypeCastStmt(String dbName, Expr expr) {
+        this.dbName = dbName;
+        this.expr = expr;
+    }
+
+    public String getDbName() {
+        return dbName;
+    }
+
+    public Expr getExpr() {
+        return expr;
+    }
+
+    @Override
+    public void analyze(Analyzer analyzer) throws UserException {
+        super.analyze(analyzer);
+
+        if (Strings.isNullOrEmpty(dbName)) {
+            dbName = analyzer.getDefaultDb();
+            if (Strings.isNullOrEmpty(dbName)) {
+                ErrorReport.reportAnalysisException(ErrorCode.ERR_NO_DB_ERROR);
+            }
+        } else {
+            dbName = ClusterNamespace.getFullName(getClusterName(), dbName);
+        }
+
+        if (!Env.getCurrentEnv().getAuth().checkDbPriv(ConnectContext.get(), dbName, PrivPredicate.SHOW)) {
+            ErrorReport.reportAnalysisException(
+                    ErrorCode.ERR_DBACCESS_DENIED_ERROR, ConnectContext.get().getQualifiedUser(), dbName);
+        }
+
+        if (expr != null) {
+            throw new AnalysisException("Only support like 'function_pattern' syntax.");
+        }
+    }
+
+    @Override
+    public String toSql() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("SHOW ");
+        sb.append("TypeCast FROM ");
+        if (!Strings.isNullOrEmpty(dbName)) {
+            sb.append("`").append(dbName).append("` ");
+        }
+        return sb.toString();
+    }
+
+    @Override
+    public String toString() {
+        return toSql();
+    }
+}

fe/fe-core/src/main/java/org/apache/doris/catalog/PrimitiveType.java

@@ -94,6 +94,10 @@ public enum PrimitiveType {
 
     private static ImmutableSetMultimap<PrimitiveType, PrimitiveType> implicitCastMap;
 
+    public static ImmutableSetMultimap<PrimitiveType, PrimitiveType> getImplicitCastMap() {
+        return implicitCastMap;
+    }
+
     static {
         ImmutableSetMultimap.Builder<PrimitiveType, PrimitiveType> builder = ImmutableSetMultimap.builder();
         // Nulltype

fe/fe-core/src/main/java/org/apache/doris/qe/ShowExecutor.java

@@ -92,6 +92,7 @@ import org.apache.doris.analysis.ShowTabletStmt;
 import org.apache.doris.analysis.ShowTransactionStmt;
 import org.apache.doris.analysis.ShowTrashDiskStmt;
 import org.apache.doris.analysis.ShowTrashStmt;
+import org.apache.doris.analysis.ShowTypeCastStmt;
 import org.apache.doris.analysis.ShowUserPropertyStmt;
 import org.apache.doris.analysis.ShowVariablesStmt;
 import org.apache.doris.analysis.ShowViewStmt;
@@ -117,6 +118,7 @@ import org.apache.doris.catalog.MaterializedIndexMeta;
 import org.apache.doris.catalog.MetadataViewer;
 import org.apache.doris.catalog.OlapTable;
 import org.apache.doris.catalog.Partition;
+import org.apache.doris.catalog.PrimitiveType;
 import org.apache.doris.catalog.Replica;
 import org.apache.doris.catalog.ReplicaAllocation;
 import org.apache.doris.catalog.ScalarType;
@@ -196,6 +198,7 @@ import org.apache.doris.transaction.TransactionStatus;
 
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import org.apache.commons.lang3.tuple.Triple;
@@ -387,6 +390,8 @@ public class ShowExecutor {
             handleMTMVJobs();
         } else if (stmt instanceof ShowMTMVTaskStmt) {
             handleMTMVTasks();
+        } else if (stmt instanceof ShowTypeCastStmt) {
+            handleShowTypeCastStmt();
         } else {
             handleEmtpy();
         }
@@ -2472,4 +2477,26 @@ public class ShowExecutor {
         }
         resultSet = new ShowResultSet(showStmt.getMetaData(), results);
     }
+
+    private void handleShowTypeCastStmt() throws AnalysisException {
+        ShowTypeCastStmt showStmt = (ShowTypeCastStmt) stmt;
+
+        Util.prohibitExternalCatalog(ctx.getDefaultCatalog(), stmt.getClass().getSimpleName());
+        DatabaseIf db = ctx.getCurrentCatalog().getDbOrAnalysisException(showStmt.getDbName());
+
+        List<List<String>> resultRowSet = Lists.newArrayList();
+        ImmutableSetMultimap<PrimitiveType, PrimitiveType> castMap = PrimitiveType.getImplicitCastMap();
+        if (db instanceof Database) {
+            resultRowSet = castMap.entries().stream().map(primitiveTypePrimitiveTypeEntry -> {
+                List<String> list = Lists.newArrayList();
+                list.add(primitiveTypePrimitiveTypeEntry.getKey().toString());
+                list.add(primitiveTypePrimitiveTypeEntry.getValue().toString());
+                return list;
+            }).collect(Collectors.toList());
+        }
+
+        // Only success
+        ShowResultSetMetaData showMetaData = showStmt.getMetaData();
+        resultSet = new ShowResultSet(showMetaData, resultRowSet);
+    }
 }

fe/fe-core/src/main/jflex/sql_scanner.flex

@@ -235,6 +235,7 @@ import org.apache.doris.qe.SqlModeHelper;
         keywordMap.put("full", new Integer(SqlParserSymbols.KW_FULL));
         keywordMap.put("function", new Integer(SqlParserSymbols.KW_FUNCTION));
         keywordMap.put("functions", new Integer(SqlParserSymbols.KW_FUNCTIONS));
+        keywordMap.put("type_cast", new Integer(SqlParserSymbols.KW_TYPECAST));
         keywordMap.put("global", new Integer(SqlParserSymbols.KW_GLOBAL));
         keywordMap.put("grant", new Integer(SqlParserSymbols.KW_GRANT));
         keywordMap.put("grants", new Integer(SqlParserSymbols.KW_GRANTS));