JDBC

JDBC

JDBC Catalogs in Doris are connected to external data sources using the standard JDBC protocol.

Once connected, Doris will ingest metadata of databases and tables from the external data sources in order to enable quick access to external data.

Usage

1. Supported datas sources include MySQL, PostgreSQL, Oracle, SQLServer, Clickhouse, Doris, SAP HANA, Trino and OceanBase.

Create Catalog

1. MySQL

SinceVersion 1.2.0

CREATE CATALOG jdbc_mysql PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:mysql://127.0.0.1:3306/demo",
    "driver_url" = "mysql-connector-java-5.1.47.jar",
    "driver_class" = "com.mysql.jdbc.Driver"
)

2. PostgreSQL

SinceVersion 1.2.2

CREATE CATALOG jdbc_postgresql PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:postgresql://127.0.0.1:5449/demo",
    "driver_url" = "postgresql-42.5.1.jar",
    "driver_class" = "org.postgresql.Driver"
);

Doris obtains all schemas that PG user can access through the SQL statement: select nspname from pg_namespace where has_schema_privilege('<UserName>', nspname, 'USAGE'); and map these schemas to doris database.

As for data mapping from PostgreSQL to Doris, one Database in Doris corresponds to one schema in the specified database in PostgreSQL (for example, "demo" in jdbc_url above), and one Table in that Database corresponds to one table in that schema. To make it more intuitive, the mapping relations are as follows:

Doris	PostgreSQL
Catalog	Database
Database	Schema
Table	Table

3. Oracle

SinceVersion 1.2.2

CREATE CATALOG jdbc_oracle PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:oracle:thin:@127.0.0.1:1521:helowin",
    "driver_url" = "ojdbc6.jar",
    "driver_class" = "oracle.jdbc.driver.OracleDriver"
);

As for data mapping from Oracle to Doris, one Database in Doris corresponds to one User, and one Table in that Database corresponds to one table that the User has access to. In conclusion, the mapping relations are as follows:

Doris	Oracle
Catalog	Database
Database	User
Table	Table

4. Clickhouse

SinceVersion 1.2.2

CREATE CATALOG jdbc_clickhouse PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:clickhouse://127.0.0.1:8123/demo",
    "driver_url" = "clickhouse-jdbc-0.3.2-patch11-all.jar",
    "driver_class" = "com.clickhouse.jdbc.ClickHouseDriver"
);

5. SQLServer

SinceVersion 1.2.2

CREATE CATALOG sqlserver_catalog PROPERTIES (
    "type"="jdbc",
    "user"="SA",
    "password"="Doris123456",
    "jdbc_url" = "jdbc:sqlserver://localhost:1433;DataBaseName=doris_test",
    "driver_url" = "mssql-jdbc-11.2.3.jre8.jar",
    "driver_class" = "com.microsoft.sqlserver.jdbc.SQLServerDriver"
);

As for data mapping from SQLServer to Doris, one Database in Doris corresponds to one schema in the specified database in SQLServer (for example, "doris_test" in jdbc_url above), and one Table in that Database corresponds to one table in that schema. The mapping relations are as follows:

Doris	SQLServer
Catalog	Database
Database	Schema
Table	Table

6. Doris

SinceVersion 1.2.3

Jdbc Catalog also support to connect another Doris database:

CREATE CATALOG doris_catalog PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:mysql://127.0.0.1:9030?useSSL=false",
    "driver_url" = "mysql-connector-java-5.1.47.jar",
    "driver_class" = "com.mysql.jdbc.Driver"
);

Currently, Jdbc Catalog only support to use 5.x version of JDBC jar package to connect another Doris database. If you use 8.x version of JDBC jar package, the data type of column may not be matched.

7. SAP_HANA

SinceVersion 1.2.3

CREATE CATALOG hana_catalog PROPERTIES (
    "type"="jdbc",
    "user"="SYSTEM",
    "password"="SAPHANA",
    "jdbc_url" = "jdbc:sap://localhost:31515/TEST",
    "driver_url" = "ngdbc.jar",
    "driver_class" = "com.sap.db.jdbc.Driver"
)

Doris	SAP_HANA
Catalog	Database
Database	Schema
Table	Table

8. Trino

SinceVersion 1.2.4

CREATE CATALOG trino_catalog PROPERTIES (
    "type"="jdbc",
    "user"="hadoop",
    "password"="",
    "jdbc_url" = "jdbc:trino://localhost:9000/hive",
    "driver_url" = "trino-jdbc-389.jar",
    "driver_class" = "io.trino.jdbc.TrinoDriver"
);

When Trino is mapped, Doris's Database corresponds to a Schema in Trino that specifies Catalog (such as "hive" in the 'jdbc_url' parameter in the example). The Table in Doris's Database corresponds to the Tables in Trino's Schema. That is, the mapping relationship is as follows:

Doris	Trino
Catalog	Catalog
Database	Schema
Table	Table

9. OceanBase

<<<<<<< HEAD

CREATE CATALOG jdbc_oceanbase_mysql PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:oceanbase://127.0.0.1:2881/demo",
    "driver_url" = "oceanbase-client-2.4.2.jar",
    "driver_class" = "com.oceanbase.jdbc.Drive",
    "oceanbase_mode" = "mysql"
)

CREATE CATALOG jdbc_oceanbase_oracle PROPERTIES (
    "type"="jdbc",
    "user"="root",
    "password"="123456",
    "jdbc_url" = "jdbc:oceanbase://127.0.0.1:2881/demo",
    "driver_url" = "oceanbase-client-2.4.2.jar",
    "driver_class" = "com.oceanbase.jdbc.Drive",
    "oceanbase_mode" = "oracle"
)

Parameter Description

Parameter	Required or Not	Default Value	Description
user	Yes		Username in relation to the corresponding database
password	Yes		Password for the corresponding database
jdbc_url	Yes		JDBC connection string
driver_url	Yes		JDBC Driver Jar
driver_class	Yes		JDBC Driver Class
only_specified_database	No	"false"	Whether only the database specified to be synchronized.
lower_case_table_names	No	"false"	Whether to synchronize jdbc external data source table names in lower case.
oceanbase_mode	No	""	When the connected external data source is OceanBase, the mode must be specified as mysql or oracle
include_database_list	No	""	When only_specified_database=true，only synchronize the specified databases. split with ','. db name is case sensitive.
exclude_database_list	No	""	When only_specified_database=true，do not synchronize the specified databases. split with ','. db name is case sensitive.

driver_url can be specified in three ways:

1. File name. For example, mysql-connector-java-5.1.47.jar. Please place the Jar file package in jdbc_drivers/ under the FE/BE deployment directory in advance so the system can locate the file. You can change the location of the file by modifying jdbc_drivers_dir in fe.conf and be.conf.

2. Local absolute path. For example, file:///path/to/mysql-connector-java-5.1.47.jar. Please place the Jar file package in the specified paths of FE/BE node.

3. HTTP address. For example, https://doris-community-test-1308700295.cos.ap-hongkong.myqcloud.com/jdbc_driver/mysql-connector-java-5.1.47.jar. The system will download the Driver file from the HTTP address. This only supports HTTP services with no authentication requirements.

only_specified_database: When the JDBC is connected, you can specify which database/schema to connect. For example, you can specify the DataBase in mysql jdbc_url; you can specify the CurrentSchema in PG jdbc_url.

include_database_list: When only_specified_database=true, only synchronize the specified databases. split with ',', default value is '', means no filter takes effect, synchronizes all databases. db name is case sensitive.

exclude_database_list: When only_specified_database=true, specify databases that do not need to synchronize. split with ',', default value is '', means no filter takes effect, synchronizes all databases. db name is case sensitive.

When include_database_list and exclude_database_list specify overlapping databases, exclude_database_list would take effect with higher privilege over include_database_list.

If you connect the Oracle database when using this property, please use the version of the jar package above 8 or more (such as ojdbc8.jar).

Query

select * from mysql_catalog.mysql_database.mysql_table where k1 > 1000 and k3 ='term';

In some cases, the keywords in the database might be used as the field names. For queries to function normally in these cases, Doris will add escape characters to the field names and tables names in SQL statements based on the rules of different databases, such as (``) for MySQL, ([]) for SQLServer, and ("") for PostgreSQL and Oracle. This might require extra attention on case sensitivity. You can view the query statements sent to these various databases via explain sql.

Write Data

SinceVersion 1.2.2After creating a JDBC Catalog in Doris, you can write data or query results to it using the `insert into` statement. You can also ingest data from one JDBC Catalog Table to another JDBC Catalog Table.

Example:

insert into mysql_catalog.mysql_database.mysql_table values(1, "doris");
insert into mysql_catalog.mysql_database.mysql_table select * from table;

Transaction

In Doris, data is written to External Tables in batches. If the ingestion process is interrupted, rollbacks might be required. That's why JDBC Catalog Tables support data writing transactions. You can utilize this feature by setting the session variable: enable_odbc_transcation .

set enable_odbc_transcation = true; 

The transaction mechanism ensures the atomicity of data writing to JDBC External Tables, but it reduces performance to a certain extent. You may decide whether to enable transactions based on your own tradeoff.

Column Type Mapping

MySQL

MYSQL Type	Doris Type	Comment
BOOLEAN	BOOLEAN
TINYINT	TINYINT
SMALLINT	SMALLINT
MEDIUMINT	INT
INT	INT
BIGINT	BIGINT
UNSIGNED TINYINT	SMALLINT	Doris does not support UNSIGNED data types so UNSIGNED TINYINT will be mapped to SMALLINT.
UNSIGNED MEDIUMINT	INT	Doris does not support UNSIGNED data types so UNSIGNED MEDIUMINT will be mapped to INT.
UNSIGNED INT	BIGINT	Doris does not support UNSIGNED data types so UNSIGNED INT will be mapped to BIGINT.
UNSIGNED BIGINT	LARGEINT
FLOAT	FLOAT
DOUBLE	DOUBLE
DECIMAL	DECIMAL
DATE	DATE
TIMESTAMP	DATETIME
DATETIME	DATETIME
YEAR	SMALLINT
TIME	STRING
CHAR	CHAR
VARCHAR	VARCHAR
TINYTEXT、TEXT、MEDIUMTEXT、LONGTEXT、TINYBLOB、BLOB、MEDIUMBLOB、LONGBLOB、TINYSTRING、STRING、MEDIUMSTRING、LONGSTRING、BINARY、VARBINARY、JSON、SET、BIT	STRING
Other	UNSUPPORTED

PostgreSQL

POSTGRESQL Type	Doris Type	Comment
boolean	BOOLEAN
smallint/int2	SMALLINT
integer/int4	INT
bigint/int8	BIGINT
decimal/numeric	DECIMAL
real/float4	FLOAT
double precision	DOUBLE
smallserial	SMALLINT
serial	INT
bigserial	BIGINT
char	CHAR
varchar/text	STRING
timestamp	DATETIME
date	DATE
time	STRING
interval	STRING
point/line/lseg/box/path/polygon/circle	STRING
cidr/inet/macaddr	STRING
bit/bit(n)/bit varying(n)	STRING	bit will be mapped to STRING in Doris. It will be read as true/false instead of 1/0
uuid/josnb	STRING
Other	UNSUPPORTED

Oracle

ORACLE Type	Doris Type	Comment
number(p) / number(p,0)	TINYINT/SMALLINT/INT/BIGINT/LARGEINT	Doris will determine the type to map to based on the value of p: p < 3 -> TINYINT; p < 5 -> SMALLINT; p < 10 -> INT; p < 19 -> BIGINT; p > 19 -> LARGEINT
number(p,s), [ if(s>0 && p>s) ]	DECIMAL(p,s)
number(p,s), [ if(s>0 && p < s) ]	DECIMAL(s,s)
number(p,s), [ if(s<0) ]	TINYINT/SMALLINT/INT/BIGINT/LARGEINT	if s<0, Doris will set p to `p+
number		Doris does not support Oracle NUMBER type that does not specified p and s
float/real	DOUBLE
DATE	DATETIME
TIMESTAMP	DATETIME
CHAR/NCHAR	STRING
VARCHAR2/NVARCHAR2	STRING
LONG/ RAW/ LONG RAW/ INTERVAL	STRING
Other	UNSUPPORTED

SQLServer

SQLServer Type	Doris Type	Comment
bit	BOOLEAN
tinyint	SMALLINT	The tinyint type in SQLServer is an unsigned number so it will be mapped to SMALLINT in Doris.
smallint	SMALLINT
int	INT
bigint	BIGINT
real	FLOAT
float	DOUBLE
money	DECIMAL(19,4)
smallmoney	DECIMAL(10,4)
decimal/numeric	DECIMAL
date	DATE
datetime/datetime2/smalldatetime	DATETIMEV2
char/varchar/text/nchar/nvarchar/ntext	STRING
binary/varbinary	STRING
time/datetimeoffset	STRING
Other	UNSUPPORTED

Clickhouse

ClickHouse Type	Doris Type	Comment
Bool	BOOLEAN
String	STRING
Date/Date32	DATEV2	JDBC CATLOG uses Datev2 type default when connecting ClickHouse
DateTime/DateTime64	DATETIMEV2	JDBC CATLOG uses DateTimev2 type default when connecting ClickHouse
Float32	FLOAT
Float64	DOUBLE
Int8	TINYINT
Int16/UInt8	SMALLINT	Doris does not support UNSIGNED data types so UInt8 will be mapped to SMALLINT.
Int32/UInt16	INT	Doris does not support UNSIGNED data types so UInt16 will be mapped to INT.
Int64/Uint32	BIGINT	Doris does not support UNSIGNED data types so UInt32 will be mapped to BIGINT.
Int128/UInt64	LARGEINT	Doris does not support UNSIGNED data types so UInt64 will be mapped to LARGEINT.
Int256/UInt128/UInt256	STRING	Doris does not support data types of such orders of magnitude so these will be mapped to STRING.
DECIMAL	DECIMAL/DECIMALV3/STRING	The Data type is based on the DECIMAL field's (precision, scale) and the enable_decimal_conversion configuration.
Enum/IPv4/IPv6/UUID	STRING	Data of IPv4 and IPv6 type will be displayed with an extra / as a prefix. To remove the /, you can use the split_partfunction.
Array	ARRAY	Array internal basic type adaptation logic refers to the preceding types. Nested types are not supported
Other	UNSUPPORTED

Doris

Doris Type	Jdbc Catlog Doris Type	Comment
BOOLEAN	BOOLEAN
TINYINT	TINYINT
SMALLINT	SMALLINT
INT	INT
BIGINT	BIGINT
LARGEINT	LARGEINT
FLOAT	FLOAT
DOUBLE	DOUBLE
DECIMAL / DECIMALV3	DECIMAL/DECIMALV3/STRING	The Data type is based on the DECIMAL field's (precision, scale) and the enable_decimal_conversion configuration
DATE	DATEV2	JDBC CATLOG uses Datev2 type default when connecting DORIS
DATEV2	DATEV2
DATETIME	DATETIMEV2	JDBC CATLOG uses DATETIMEV2 type default when connecting DORIS
DATETIMEV2	DATETIMEV2
CHAR	CHAR
VARCHAR	VARCHAR
STRING	STRING
TEXT	STRING
Other	UNSUPPORTED

SAP HANA

SAP HANA Type	Doris Type	Comment
BOOLEAN	BOOLEAN
TINYINT	TINYINT
SMALLINT	SMALLINT
INTERGER	INT
BIGINT	BIGINT
SMALLDECIMAL	DECIMALV3
DECIMAL	DECIMAL/DECIMALV3/STRING	The Data type is based on the DECIMAL field's (precision, scale) and the enable_decimal_conversion configuration
REAL	FLOAT
DOUBLE	DOUBLE
DATE	DATEV2	JDBC CATLOG uses Datev2 type default when connecting HANA
TIME	TEXT
TIMESTAMP	DATETIMEV2	JDBC CATLOG uses DATETIMEV2 type default when connecting HANA
SECONDDATE	DATETIMEV2	JDBC CATLOG uses DATETIMEV2 type default when connecting HANA
VARCHAR	TEXT
NVARCHAR	TEXT
ALPHANUM	TEXT
SHORTTEXT	TEXT
CHAR	CHAR
NCHAR	CHAR
Other	UNSUPPORTED

Trino

Trino Type	Doris Type	Comment
boolean	BOOLEAN
tinyint	TINYINT
smallint	SMALLINT
integer	INT
bigint	BIGINT
decimal	DECIMAL/DECIMALV3/STRING	The Data type is based on the DECIMAL field's (precision, scale) and the enable_decimal_conversion configuration
real	FLOAT
double	DOUBLE
date	DATE/DATEV2	JDBC CATLOG uses Datev2 type default when connecting Trino
timestamp	DATETIME/DATETIMEV2	JDBC CATLOG uses DATETIMEV2 type default when connecting Trino
varchar	TEXT
char	CHAR
array	ARRAY	Array internal basic type adaptation logic refers to the preceding types. Nested types are not supported
others	UNSUPPORTED

Note: Currently, only Hive connected to Trino has been tested. Other data sources connected to Trino have not been tested.

OceanBase

For MySQL mode, please refer to MySQL type mapping For Oracle mode, please refer to Oracle type mapping

FAQ

1. Are there any other databases supported besides MySQL, Oracle, PostgreSQL, SQLServer, ClickHouse, SAP HANA, Trino and OceanBase?

   Currently, Doris supports MySQL, Oracle, PostgreSQL, SQLServer, ClickHouse, SAP HANA, Trino and OceanBase. We are planning to expand this list. Technically, any databases that support JDBC access can be connected to Doris in the form of JDBC external tables. You are more than welcome to be a Doris contributor to expedite this effort.

2. Why does Mojibake occur when Doris tries to read emojis from MySQL external tables?

   In MySQL, utf8mb3 is the default utf8 format. It cannot represent emojis, which require 4-byte encoding. To solve this, when creating MySQL external tables, you need to set utf8mb4 encoding for the corresponding columns, set the server encoding to utf8mb4, and leave the characterEncoding in JDBC URl empty (because utf8mb4 is not supported for this property, and anything other than utf8mb4 will cause a failure to write the emojis).

   You can modify the configuration items globally:

   Modify the my.ini file in the mysql directory (for linux system, modify the my.cnf file in the etc directory)
   [client]
   default-character-set=utf8mb4
   
   [mysql]
   Set the mysql default character set
   default-character-set=utf8mb4
   
   [mysqld]
   Set the mysql character set server
   character-set-server=utf8mb4
   collation-server=utf8mb4_unicode_ci
   init_connect='SET NAMES utf8mb4
   
   Modify the type for the corresponding tables and columns
   ALTER TABLE table_name MODIFY  colum_name  VARCHAR(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
   ALTER TABLE table_name CHARSET=utf8mb4;
   SET NAMES utf8mb4

3. Why does the error message "CAUSED BY: DataReadException: Zero date value prohibited" pop up when DateTime="0000:00:00 00:00:00" while reading MySQL external tables?

   This error occurs because of an illegal DateTime. It can be fixed by modifying the zeroDateTimeBehavior parameter.

   The options for this parameter include: EXCEPTION,CONVERT_TO_NULL,ROUND. Respectively, they mean to report error, convert to null, and round the DateTime to "0001-01-01 00:00:00" when encountering an illegal DateTime.

   You can add "jdbc_url"="jdbc:mysql://IP:PORT/doris_test?zeroDateTimeBehavior=convertToNull" to the URL.

4. Why do loading failures happen when reading MySQL or other external tables?

   For example:

   failed to load driver class com.mysql.jdbc.driver in either of hikariconfig class loader

   Such errors occur because the driver_class has been wrongly put when creating the Resource. The problem with the above example is the letter case. It should be corrected as "driver_class" = "com.mysql.jdbc.Driver".

5. How to fix communication link failures?

   If you run into the following errors:

   ERROR 1105 (HY000): errCode = 2, detailMessage = PoolInitializationException: Failed to initialize pool: Communications link failure
   
   The last packet successfully received from the server was 7 milliseconds ago.  The last packet sent successfully to the server was 4 milliseconds ago.
   CAUSED BY: CommunicationsException: Communications link failure
       
   The last packet successfully received from the server was 7 milliseconds ago.  The last packet sent successfully to the server was 4 milliseconds ago.
   CAUSED BY: SSLHandshakeExcepti

   Please check the be.out log of BE.

   If it contains the following message:

   WARN: Establishing SSL connection without server's identity verification is not recommended. 
   According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. 
   For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. 
   You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

   You can add ?useSSL=false to the end of the JDBC connection string when creating Catalog. For example, "jdbc_url" = "jdbc:mysql://127.0.0.1:3306/test?useSSL=false".

6. What to do with the OutOfMemoryError when querying MySQL databases?

   To reduce memory usage, Doris obtains one batch of query results at a time, and has a size limit for each batch. However, MySQL conducts one-off loading of all query results by default, which means the "loading in batches" method won't work. To solve this, you need to specify "jdbc_url"="jdbc:mysql://IP:PORT/doris_test?useCursorFetch=true" in the URL.

7. What to do with errors such as "CAUSED BY: SQLException OutOfMemoryError" when performing JDBC queries?

   If you have set useCursorFetch for MySQL, you can increase the JVM memory limit by modifying the value of jvm_max_heap_size in be.conf. The current default value is 1024M.

8. When using JDBC to query MySQL large data volume, if the query can occasionally succeed, occasionally report the following errors, and all the MySQL connections are completely disconnected when the error occurs:

    ERROR 1105 (HY000): errCode = 2, detailMessage = [INTERNAL_ERROR]UdfRuntimeException: JDBC executor sql has error:
    CAUSED BY: CommunicationsException: Communications link failure
    The last packet successfully received from the server was 4,446 milliseconds ago. The last packet sent successfully to the server was 4,446 milliseconds ago.

   When the above phenomenon appears, it may be that mysql server's own memory or CPU resources are exhausted and the MySQL service is unavailable. You can try to increase the memory or CPU resources of MySQL Server.