| <!-- |
| |
| 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. |
| |
| --> |
| |
| # Thrift-based Apache connectors |
| |
| This library contains code for ADBC drivers built on top of the Thrift protocol with Arrow support: |
| |
| - Hive |
| - Impala |
| - Spark |
| |
| Each driver is at a different state of implementation. |
| |
| ## Custom generation |
| |
| Typically, [Thrift](https://thrift.apache.org/) code is generated from the Thrift compiler. And that is mostly true here as well. However, some files were further edited to include Arrow support. These contain the phrase `BUT THIS FILE HAS BEEN HAND EDITED TO SUPPORT ARROW SO REGENERATE AT YOUR OWN RISK` at the top. Some of these files include: |
| |
| ``` |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TBinaryColumn.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TBoolColumn.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TByteColumn.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TDoubleColumn.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TI16Column.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TI32Column.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TI64Column.cs |
| arrow-adbc/csharp/src/Drivers/Apache/Thrift/Service/Rpc/Thrift/TStringColumn.cs |
| ``` |
| |
| # Hive |
| |
| The Hive classes serve as the base class for Spark and Impala, since both of those platform implement Hive capabilities. |
| |
| Core functionality of the Hive classes beyond the base library implementation is under development, has limited functionality, and may produce errors. |
| |
| # Impala |
| |
| The Imapala classes are under development, have limited functionality, and may produce errors. |
| |
| # Spark |
| |
| The Spark classes are intended for use against native Spark. |
| |
| For more details, see [Spark Driver](Spark/README.md) |
| |
| ## Known Limitations |
| |
| 1. The API `SparkConnection.GetObjects` is not fully tested at this time |
| 1. It may not return all catalogs and schema in the server. |
| 1. It may throw an exception when returning object metadata from multiple catalog and schema. |
| 1. When a `NULL` value is returned for a `BINARY` type it is instead being returned as an empty array instead of the expected `null`. |
| 1. Result set metadata does not provide information about the nullability of each column. They are marked as `nullable` by default, which may not be accurate. |
| 1. The **Impala** driver is untested and is currently unsupported. |
| 1. The underlying Thrift interface only supports little-endian platforms. |
