The unit test `JdbcDataSourceTest.java` was originally
implemented using the H2 database, which is no longer
available in Impala's environment. The test code was
also outdated and erroneous.
This commit addresses and fixes the failure of
JdbcDataSourceTest.java and rewrites it in
Postgres, hence ensures compatibility with Impala's
current environment and aligns with JDBC and external
data source APIs. Please note, this test is moved to fe
folder to fix the BackendConfig instance not initialized
error.
To test this file, run the following command:
pushd fe && mvn -fae test -Dtest=JdbcDataSourceTest
Please note that the tests in JdbcDataSourceTest have a
dependency on previous tests and individual tests cannot be
ran separately for this class.
Change-Id: Ie07173d256d73c88f5a6c041f087db16b6ff3127
Reviewed-on: http://gerrit.cloudera.org:8080/21805
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
This patch uses the "external data source" mechanism in Impala to
implement data source for querying JDBC.
It has some limitations due to the restrictions of "external data
source":
- It is not distributed, e.g, fragment is unpartitioned. The queries
are executed on coordinator.
- Queries which read following data types from external JDBC tables
are not supported:
BINARY, CHAR, DATETIME, and COMPLEX.
- Only support binary predicates with operators =, !=, <=, >=,
<, > to be pushed to RDBMS.
- Following data types are not supported for predicates:
DECIMAL, TIMESTAMP, DATE, and BINARY.
- External tables with complex types of columns are not supported.
- Support is limited to the following databases:
MySQL, Postgres, Oracle, MSSQL, H2, DB2, and JETHRO_DATA.
- Catalog V2 is not supported (IMPALA-7131).
- DataSource objects are not persistent (IMPALA-12375).
Additional fixes are planned on top of this patch.
Source files under jdbc/conf, jdbc/dao and jdbc/exception are
replicated from Hive JDBC Storage Handler.
In order to query the RDBMS tables, the following steps should be
followed (note that existing data source table will be rebuilt):
1. Make sure the Impala cluster has been started.
2. Copy the jar files of JDBC drivers and the data source library into
HDFS.
${IMPALA_HOME}/testdata/bin/copy-ext-data-sources.sh
3. Create an `alltypes` table in the Postgres database.
${IMPALA_HOME}/testdata/bin/load-ext-data-sources.sh
4. Create data source tables (alltypes_jdbc_datasource and
alltypes_jdbc_datasource_2).
${IMPALA_HOME}/bin/impala-shell.sh -f\
${IMPALA_HOME}/testdata/bin/create-ext-data-source-table.sql
5. It's ready to run query to access data source tables created
in last step. Don't need to restart Impala cluster.
Testing:
- Added unit-test for Postgres and ran unit-test with JDBC driver
postgresql-42.5.1.jar.
- Ran manual unit-test for MySql with JDBC driver
mysql-connector-j-8.1.0.jar.
- Ran core tests successfully.
Change-Id: I8244e978c7717c6f1452f66f1630b6441392e7d2
Reviewed-on: http://gerrit.cloudera.org:8080/17842
Reviewed-by: Wenzhe Zhou <wzhou@cloudera.com>
Reviewed-by: Kurt Deschler <kdeschle@cloudera.com>
Reviewed-by: Riza Suminto <riza.suminto@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
