[GitHub] [arrow] lidavidm commented on a change in pull request #9368: [WIP] [POC] Flight SQL

[GitBox <gi...@apache.org>]

lidavidm commented on a change in pull request #9368:
URL: https://github.com/apache/arrow/pull/9368#discussion_r654545089



##########
File path: format/FlightSQL.proto
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@@ -0,0 +1,337 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+
+syntax = "proto3";
+
+option java_package = "org.apache.arrow.flight.sql.impl";
+package arrow.flight.protocol.sql;
+
+/*
+ * Wrapper for the result of a "GetSQLInfo" action.
+ */
+message ActionGetSQLInfoResult {
+  /*
+   * Values are modelled after ODBC's SQLGetInfo() function. This information is intended to provide
+   * Flight SQL clients with basic, SQL syntax and SQL functions related information.
+   * More information types can be added in future releases.
+   * E.g. more SQL syntax support types, scalar functions support, type conversion support etc.
+   *
+   * Initially, Flight SQL will support the following information types:
+   * - Server Information
+   * -
+   *
+   * 1. Server Information: Provides basic information about the Flight SQL Server.
+   *
+   * The name of the Flight SQL Server.
+   * FLIGHT_SQL_SERVER_NAME
+   *
+   * The native version of the Flight SQL Server.
+   * FLIGHT_SQL_SERVER_VERSION
+   *
+   * The Arrow version of the Flight SQL Server.
+   * FLIGHT_SQL_SERVER_ARROW_VERSION
+   *
+   * Indicates whether the Flight SQL Server is read only.
+   * FLIGHT_SQL_SERVER_READ_ONLY
+   *
+   * Indicates whether the Flight SQL Server supports both read and write.
+   * FLIGHT_SQL_SERVER_READ_WRITE
+   *
+   * 2. SQL Syntax Information: provides information about SQL syntax supported by the Flight SQL Server.
+   *
+   * Indicates whether the Flight SQL Server supports CREATE and DROP of catalogs.
+   * In a SQL environment, a catalog is a collection of schemas.
+   * SQL_DDL_CATALOG
+   *
+   * Indicates whether the Flight SQL Server supports CREATE and DROP of schemas.
+   * In a SQL environment, a catalog is a collection of tables, views, indexes etc.
+   * SQL_DDL_SCHEMA
+   *
+   * Indicates whether the Flight SQL Server supports CREATE and DROP of tables.
+   * In a SQL environment, a table is a collection of rows of information. Each row of information
+   * may have one or more columns of data.
+   * SQL_DDL_TABLE
+   *
+   * Indicates the case sensitivity of catalog, table and schema names.
+   * SQL_IDENTIFIER_CASE
+   *
+   * Indicates the supported character(s) used to surround a delimited identifier.
+   * SQL_IDENTIFIER_QUOTE_CHAR
+   *
+   * Indicates case sensitivity of quoted identifiers.
+   * SQL_QUOTED_IDENTIFIER_CASE
+   *
+   */
+  map<string, GetSQLInfoValue> flight_sql_info = 1;
+
+  // Implementation specific custom SQLInfo values.
+  map<string, GetSQLInfoValue> custom_info = 2;
+}
+
+/*
+ * Wrapper for values returned in ActionGetSQLInfoResult.
+ */
+message GetSQLInfoValue {
+  oneof value {
+    string string_value = 1;
+    int32 integer_value = 2;
+    int32 integer_bitmask = 3;
+    int32 integer_flag = 4;
+    bytes binary_value = 5;
+    int64 long_value = 6;
+  }
+}
+
+/*
+ * Request message for the "GetCatalogs" action on a 
+ * Flight SQL enabled backend. 
+ * Requests a list of catalogs available in the server.
+ */
+message ActionGetCatalogsRequest {
+  /*
+   * Specifies the order of result values.
+   */ 
+  ResultsOrder order = 1;
+}
+
+/*
+ * Wrap the result of a "GetCatalogs" action.
+ */
+message ActionGetCatalogsResult {
+  repeated string catalog = 1;
+}
+
+/*
+ * Request message for the "GetSchemas" action on a 
+ * Flight SQL enabled backend. 
+ * Requests a list of schemas available in the server.
+ */
+message ActionGetSchemasRequest {
+  /*
+   * Specifies the order of result values with precedence:
+   *  - catalog
+   *  - schema
+   */
+  ResultsOrder order = 1;
+
+  /*
+   * Specifies the Catalog to search for schemas.
+   * If omitted, then schemas for all catalogs are searched.
+   */ 
+  string catalog = 2;
+
+  /*
+   * Specifies a filter pattern for schemas to search for.
+   * When no schema_filter_pattern is provided, the pattern will not be used to narrow the search.
+   * In the pattern string, two special characters can be used to denote matching rules:
+   *    - "%" means to match any substring with 0 or more characters.
+   *    - "_" means to match any one character.
+   */
+  string schema_filter_pattern = 3;
+}
+
+/*
+ * Wrap the result of a "GetSchemas" action.
+ */
+message ActionGetSchemasResult {
+  string catalog = 1;
+  string schema = 2;
+}
+
+/*
+ * Request message for the "GetTables" action on a 
+ * Flight SQL enabled backend. 
+ * Requests a list of tables available in the server.
+ */
+message ActionGetTablesRequest {
+  /*
+   * Specifies the order of result values with prescendence:
+   *  - catalog
+   *  - schema
+   *  - table_type
+   *  - table
+   */
+  ResultsOrder order = 1;
+
+  // Specifies the Catalog to search for schemas.
+  string catalog = 2;
+
+  /* Specifies a filter pattern for schemas to search for.
+   * When no schema_filter_pattern is provided, the pattern will not be used to narrow the search.
+   * In the pattern string, two special characters can be used to denote matching rules:
+   *    - "%" means to match any substring with 0 or more characters.
+   *    - "_" means to match any one character.
+   */
+  string schema_filter_pattern = 3;
+
+  /* Specifies a filter pattern for tables to search for.
+   * When no schema_filter_pattern is provided, the pattern will not be used to narrow the search.
+   * In the pattern string, two special characters can be used to denote matching rules:
+   *    - "%" means to match any substring with 0 or more characters.
+   *    - "_" means to match any one character.
+   */
+  string table_name_filter_pattern = 4;
+
+  // Specifies a filter of table types which must match.
+  repeated string table_types = 5;
+
+  // Specifies if the schema should be returned for found tables.
+  bool include_schema = 6; 
+}
+
+/*
+ * Wrap the result of a "GetTables" action.
+ */
+message ActionGetTablesResult {
+  string catalog = 1;
+  string schema = 2;
+  string table = 3;
+  string table_type = 4;
+
+  /*
+   * Schema of the dataset as described in Schema.fbs::Schema, it is serialized as an IPC message.
+   * Null if include_schema on request is false.
+   */
+  bytes arrow_metadata = 5; 
+}
+
+/*
+ * Wrap the result of a "GetTableTypes" action.
+ */
+message ActionGetTableTypesResult {
+  /*
+   * Indicates the type of the table. E.g. table (regular data table) , view, system table etc.
+   */
+  string table_type = 1;
+}
+
+// SQL Execution Action Messages
+
+/*
+ * Request message for the "GetPreparedStatement" action on a 
+ * Flight SQL enabled backend.
+ */
+message ActionGetPreparedStatementRequest {
+  // The valid SQL string to get a prepared statement for.
+  string query = 1;
+}
+
+/*
+ * Wrap the result of a "GetPreparedStatement" action.
+ */
+message ActionGetPreparedStatementResult {
+
+  // Opaque handle for the prepared statement on the server.
+  bytes prepared_statement_handle = 1;
+
+  // If a result set generating query was provided, dataset_schema contains the 
+  // schema of the dataset as described in Schema.fbs::Schema, it is serialized as an IPC message.
+  bytes dataset_schema = 2;
+
+  // If the query provided contained parameters, parameter_schema contains the 
+  // Schema of the expected parameters as described in Schema.fbs::Schema.
+  bytes parameter_schema = 3;
+}
+
+/*
+ * Request message for the "ClosePreparedStatement" action on a 
+ * Flight SQL enabled backend. 
+ * Closes server resources associated with the prepared statement handle.
+ */
+message ActionClosePreparedStatementRequest {
+  // Opaque handle for the prepared statement on the server.
+  string prepared_statement_handle = 1;
+}
+
+
+// SQL Execution Messages.
+
+/*
+ * Represents a SQL query. Used in the command member of FlightDescriptor
+ * for the following RPC calls:
+ *  - GetSchema: return the schema of the query.
+ *  - GetFlightInfo: execute the query.
+ */
+message CommandStatementQuery {
+  // The SQL syntax.
+  string query = 1;
+}
+
+/*
+ * Represents an instance of executing a prepared statement. Used in the 
+ * command member of FlightDescriptor for the following RPC calls:
+ * TODO: Is the idea that a Put with parameter values would execute multiple bound versions of the prepared statement

Review comment:
       It 'just' needs someone to write it up and propose it. I'll have to check in on the existing thread. I would very much prefer not to require more statefulness if we don't have to, since it'll complicate implementations. (Also, if it's before DoGet, that means the server might have to execute the same query in response to either of two distinct RPC calls?)




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