Motivation At present, many customers need to access the external table through Doris, but Doris only supports accessing the external table of MySQL at present. This problem makes it difficult for users of other databases to use Doris.
Open Database Connectivity (ODBC) is a standard application programming interface for accessing database management systems:https://en.wikipedia.org/wiki/Open_Database_Connectivity So should we support ODBC Scan node as a general external table access method, it is provided to users. user can use Driver Manager of ODBC to determine the databases that need to be accessed. It can bring us the following benefits: 1. First, Doris can eazily support a variety of different databases as external table, likes: Oracle, PostgreSQL, SQLServer. Not only RDMS, ODBC also support some NoSQL database. likes: Redis, MongoDB. 1. ODBC help Doris have a unified development interface instead of focusing on the connection implementation of different databases. 2. UNIX ODBC is a static library based on LGPL, which can avoid the commercial risk of using different database client APIs How To Use It is very similar to the previous use of MySQL external table. The table creation statement is as follows. CREATE EXTERNAL TABLE `baseall_oracle` ( `k1` decimal(9, 3) NOT NULL COMMENT "", `k2` char(10) NOT NULL COMMENT "", `k3` datetime NOT NULL COMMENT "", `k5` varchar(20) NOT NULL COMMENT "", `k6` double NOT NULL COMMENT "" ) ENGINE=ODBC PROPERTIES ( "host" = "192.168.1.2", "port" = "4234", "user" = "happenlee", "password" = "happenlee", "database" = "happen", "table" = "baseall", "driver" = "Oracle 19 ODBC driver", "type" = "oracle" ); Noted that it needs to add some additional info： * type： To identify which database the table belongs to. For different databases, there are some differences in ODBC connection and query. * driver： To identify which odbc driver the table use. Use should installed proper driver and config it in be/conf/odbcinst.ini like： # Example driver definitions # Driver from the postgresql-odbc package # Setup from the unixODBC package [PostgreSQL] Description = ODBC for PostgreSQL Driver = /usr/lib/psqlodbc.so Setup = /usr/lib/libodbcpsqlS.so Driver64 = /usr/lib64/psqlodbc.so Setup64 = /usr/lib64/libodbcpsqlS.so FileUsage = 1 # Driver from the mysql-connector-odbc package # Setup from the unixODBC package [MySQL ODBC 8.0 Unicode Driver] Description = ODBC for MySQL Driver = /home/happen/mysql/mysql_odbc_rpm/usr/lib64/libmyodbc8w.so FileUsage = 1 [Oracle 19 ODBC driver] Description=Oracle ODBC driver for Oracle 19 Driver=/usr/lib/oracle/19.8/client64/lib/libsqora.so.19.1 Setup= FileUsage= CPTimeout= CPReuse= Implementation 1. First, we should add third party static library of Unix ODBC. 2. Second，Modify thrift file to determine the interface of ODBC scan node. like： 1. Modify the code of be part, implementation ODBC_SCAN_NODE and ODBC_SCANNER 2. Modify the code of FE part to support adding external tables of ODBC engine. Some Problem Need To Talk 1. Now the odbc driver of mysql have a function library conflict with mysql-server-mysql-5.7.18，which may cause core of BE. So we should disable WITH_MYSQL compile options，when we need to use ODBC_SCAN_NODE to connect mysql. 2. odbc scan node should support old external table of MySQL. Best Wish HappenLee
