yiguolei commented on a change in pull request #7940: URL: https://github.com/apache/incubator-doris/pull/7940#discussion_r800350506
########## File path: fe/fe-core/src/main/java/org/apache/doris/tablefunction/TableFunction.java ########## @@ -0,0 +1,50 @@ +// 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.tablefunction; + +import org.apache.doris.analysis.TupleDescriptor; +import org.apache.doris.catalog.Column; +import org.apache.doris.catalog.Table; +import org.apache.doris.catalog.Table.TableType; +import org.apache.doris.common.UserException; +import org.apache.doris.planner.PlanNodeId; +import org.apache.doris.planner.ScanNode; + +import java.util.List; + +public abstract class TableFunction { Review comment: No, the table function really generate a temporary table during the query. It has scan operations and also has table schemas. Actually there are 2 kinds of table functions(https://spark.apache.org/docs/latest/sql-ref-syntax-qry-select-tvf.html.): 1. TVF that can be specified in a FROM clause, e.g. range; 2. TVF that can be specified in SELECT/LATERAL VIEW clauses, e.g. explode. Currently Clickhouse only support from clause table function https://clickhouse.com/docs/en/sql-reference/table-functions. >>>For a "table function", it should support common expr as its parameter, such as referring a column from a table, or an Expression. This is not a problem, we could treat the string literal as a common expr and extend the parameter type in the future. But I think StringLiteral as parameter will meet many cases because the actual table function could parse the string parameter as real db name or column names. For example in clickhouse, https://clickhouse.com/docs/en/sql-reference/table-functions/merge/ the merge table function use dbname and table name as string parameters and the file table function also use column type as tring parameters https://clickhouse.com/docs/en/sql-reference/table-functions/file/. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
