JDBC Query Consumer
The JDBC Query Consumer origin reads database data using a user-defined SQL query through a JDBC connection. The origin returns data as a map with column names and field values. For information about supported versions, see Supported Systems and Versions.
Data Collector includes database-specific origins, such as the Oracle Bulkload origin. When available, use a database-specific origin. Data Collector also provides CDC origins to process changed data and the JDBC Multitable Consumer origin to perform database replication or to read from multiple tables in the same database.
When you configure the JDBC Query Consumer origin, you define the SQL query that the origin uses to read data from a single table or from a join of tables.
When you configure the origin, you specify connection information, query interval, and custom JDBC configuration properties to determine how the origin connects to the database. You configure the query mode and SQL query to define the data returned by the database. When in full query mode and reading from certain databases, you can use a stored procedure instead of a SQL query. When the source database has high-precision timestamps, such as IBM Db2 TIMESTAMP(9) fields, you can configure the origin to write strings rather than datetime values to maintain the precision.
You can configure the JDBC Query Consumer origin to perform change data capture for databases that store the information in a table. And you can specify what the origin does when encountering an unsupported data type.
You can specify custom properties that your driver requires. You can configure advanced connection properties. To use a JDBC version older than 4.0, you specify the driver class name and define a health check query.
By default, the origin generates JDBC record header and field attributes that provide additional information about each record and field.
You can also use a connection to configure the origin.
The origin can generate events for an event stream. For more information about dataflow triggers and the event framework, see Dataflow Triggers Overview.
Database Vendors and Drivers
The JDBC Query Consumer origin can read database data from multiple database vendors.
Database Vendor | Supported Versions | Tested Versions |
---|---|---|
MySQL | MySQL 5.7 and later |
|
Oracle |
Also supported:
|
|
PostgreSQL | PostgreSQL 9.x and later |
|
Microsoft SQL Server |
|
|
MySQL Data Types
The JDBC Query Consumer origin converts MySQL data types into Data Collector data types.
MySQL Data Type | Data Collector Data Type |
---|---|
Bigint | Long |
Bigint Unsigned | Decimal |
Binary | Byte Array |
Blob | Byte Array |
Char | String |
Date | Date |
Datetime | Datetime |
Decimal | Decimal |
Double | Double |
Enum | String |
Float | Float |
Int | Integer |
Int Unsigned | Long |
Json | String |
Linestring | Byte Array |
Medium Int | Integer |
Medium Int Unsigned | Long |
Numeric | Decimal |
Point | Byte Array |
Polygon | Byte Array |
Set | String |
Smallint | Short |
Smallint Unsigned | Integer |
Text | String |
Time | Time |
Timestamp | Datetime |
Tinyint, Tinyint Unsigned | Short |
Varbinary | Byte Array |
Varchar | String |
Year | Date |
Oracle Data Types
The JDBC Query Consumer origin converts Oracle data types into Data Collector data types.
Oracle Data Type | Data Collector Data Type |
---|---|
Number | Decimal |
Char | String |
Varchar, Varchar2 | String |
Nchar, NvarChar2 | String |
Binary_float | Float |
Binary_double | Double |
Date | Datetime |
Timestamp | Datetime |
Timestamp with time zone | Zoned_datetime |
Timestamp with local time zone | Zoned_datetime |
Long | String |
Blob | Byte_array |
Clob | String |
Nclob | String |
XMLType | String |
PostgreSQL Data Types
The JDBC Query Consumer origin converts PostgreSQL data types into Data Collector data types.
PostgreSQL Data Type | Data Collector Data Type |
---|---|
Bigint | Long |
Boolean | Boolean |
Bytea | Byte Array |
Char | String |
Date | Date |
Decimal | Decimal |
Double Precision | Double |
Enum | String |
Integer | Integer |
Money | Double |
Numeric | Decimal |
Real | Float |
Smallint | Short |
Text | String |
Time, Time with Time Zone | Time |
Timestamp, Timestamp with Time Zone | Time |
Varchar | String |
SQL Server Data Types
The JDBC Query Consumer origin converts SQL Server data types into Data Collector data types.
SQL Server Data Type | Data Collector Data Type |
---|---|
Bigint | Long |
Binary | Byte_Array |
Bit | Boolean |
Char | String |
Date | Date |
Datetime, Datetime2 | Datetime |
Datetimeoffset | Zoned_datetime |
Decimal | Decimal |
Float | Double |
Image | Byte_Array |
Int | Integer |
Money | Decimal |
Nchar | String |
Ntext | String |
Numeric | Decimal |
Nvarchar | String |
Real | Float |
Smalldatetime | Datetime |
Smallint | Short |
Smallmoney | Decimal |
Text | String |
Time | Time |
Tinyint | Short |
Varbinary | Byte_Array |
Varchar | String |
XML | String |
Unsupported Data Types
- Stops the pipeline
- If the stage encounters an unsupported data type, the stage stops the
pipeline after completing the processing of the previous records and
displays the following
error:
JDBC_37 - Unsupported type 1111 for column.
- Converts to string
- If the stage encounters an unsupported data type, the stage converts the data to string when possible, and then continues processing. Not all unsupported data types can successfully be converted to string. When using this option, verify that the data is converted to string as expected.
Installing the JDBC Driver
You install the driver into the JDBC stage library, streamsets-datacollector-jdbc-lib
, which includes the origin.
To use the JDBC driver
with multiple stage libraries, install the driver into each stage library associated
with the stages.
For example, if you want to use a MySQL JDBC driver with the JDBC Lookup processor
and with the MySQL Binary Log origin, you install the driver as an external library
for the JDBC stage library, streamsets-datacollector-jdbc-lib
, and for the MySQL Binary Log stage library, streamsets-datacollector-mysql-binlog-lib
.
For information about installing additional drivers, see Install External Libraries.
Offset Column and Offset Value
The JDBC Query Consumer origin uses an offset column and initial offset value to determine where to start reading data within a table. Include both the offset column and the offset value in the WHERE clause of the SQL query.
The offset column must be a column in the table with unique non-null values, such as a primary key or indexed column. The initial offset value is a value within the offset column where you want the origin to start reading.
When the origin performs an incremental query, you must configure the offset column and offset value. For full queries, you can optionally configure them.
Full and Incremental Mode
The JDBC Query Consumer origin can perform queries in two modes:
- Incremental mode
- To use incremental mode, you must select the Incremental Mode property and configure an offset column and initial offset value for the origin. When you define the SQL query, you must use the ${OFFSET} parameter to represent the offset value in the WHERE clause.
- Full mode
- To use full mode, you must clear the Incremental Mode property for the origin. You can optionally configure an offset column and initial offset value and can define any type of SQL query.
Recovery
The JDBC Query Consumer origin supports recovery after a deliberate or unexpected stop when it performs incremental queries. Recovery is not supported for full queries.
In incremental mode, the origin uses offset values in the offset column to determine where to continue processing after a deliberate or unexpected stop. To ensure seamless recovery in incremental mode, use a primary key or indexed column as the offset column. As the JDBC Query Consumer origin processes data, it tracks the offset value internally. When the pipeline stops, the origin notes where it stopped processing data. When you restart the pipeline, it continues from the last-saved offset.
When the JDBC Query Consumer origin performs full queries, the origin runs the full query again after you restart the pipeline.
SQL Query
The SQL query defines the data returned from the database. You define the query in the SQL Query property on the JDBC tab.
runtime:loadResource
function in the SQL Query property to load the query from the resource file at runtime.
For example, you might enter the following expression for the
property:${runtime:loadResource("myquery.sql", false)}
When running the origin in full query mode and reading from certain databases, you can define a stored procedure, then call the stored procedure using the SQL Query property.
SQL Query for Incremental Mode
When you define the SQL query for incremental mode, the JDBC Query Consumer origin requires a WHERE and ORDER BY clause in the query.
Use the following guidelines when you define the WHERE and ORDER BY clauses in the query:
- In the WHERE clause, include the offset column and the offset value
- The origin uses an offset column and value to determine the data that is returned. Include both in the WHERE clause of the query.
- Use the OFFSET parameter to represent the offset value
- In the WHERE clause, use ${OFFSET} to represent the offset value.
- In the ORDER BY clause, include the offset column as the first column
- To avoid returning duplicate data, use the offset column as the first column in the ORDER BY clause.
invoice
table where the ID column is the offset column. The query
returns all data where the ID is greater than the offset and orders the data by the
ID: SELECT * FROM invoice WHERE id > ${OFFSET} ORDER BY id
SQL Query for Full Mode
You can define any type of SQL query for full mode.
invoice
table:SELECT * FROM invoice
When you define the SQL query for full mode, you can optionally include the WHERE and ORDER BY clauses using the same guidelines as for incremental mode. However, using these clauses to read from large tables can cause performance issues.
Stored Procedure in Full Mode
When reading from certain databases, you can call a stored procedure from the JDBC Query Consumer origin. Currently, you can use stored procedures with MySQL, PostgreSQL, and SQL Server databases.
You can call a stored procedure when using the JDBC Query Consumer origin in full mode. Using stored procedures in other modes is not supported.
- In your database, define the stored procedure.
- In the origin, on the JDBC tab, configure the SQL Query property to call the stored procedure. Use the appropriate syntax for your database.
- Also on the JDBC tab, clear the Incremental Mode property, which is selected by default.
- Test the pipeline to ensure that the procedure performs as expected.
Examples
- MySQL database
- To read all data from a MySQL table, you might create a stored procedure
as
follows:
CREATE PROCEDURE <procedure_name>() BEGIN SELECT * FROM <table_name>; END;
- PostgreSQL database
- To read all data from a PostgreSQL table, you might create a stored
procedure as
follows:
create or replace function <procedure_name>() returns table (id int) language plpgsql as $$ begin return query select * from <table_name>; end;$$
- SQL Server database
- To read all data from a SQL Server table, you might create a stored
procedure as
follows:
CREATE PROCEDURE <procedure_name> AS SELECT * FROM <table_name> RETURN
JDBC Attributes
The JDBC Query Consumer origin generates record header attributes and field attributes that provide additional information about each record and field. The origin receives these details from the JDBC driver.
JDBC Header Attributes
By default, the JDBC Query Consumer origin generates JDBC record header attributes that provide additional information about each record, such as the original data type of a field or the source tables for the record. The origin receives these details from the JDBC driver.
You can use the record:attribute
or
record:attributeOrDefault
functions to access the information
in the attributes. For more information about working with record header attributes,
see Working with Header Attributes.
JDBC header attributes include a user-defined prefix to
differentiate the JDBC header attributes from other record header attributes. By
default, the prefix is jdbc
.
You can change the prefix that the origin uses and you can configure the origin not to create JDBC header attributes with the Create JDBC Header Attributes and JDBC Header Prefix properties on the Advanced tab.
JDBC Header Attribute | Description |
---|---|
<JDBC prefix>.tables |
Provides a
comma-separated list of source tables for the fields in the
record.
Note: Not all JDBC drivers
provide this information.
For example, at this time, the MySQL MariaDB and PostgreSQL drivers provide a comma-separated list of source tables in random order. In contrast, the Oracle and Microsoft SQL Server drivers provide only an empty string. |
<JDBC prefix>.<column name>.jdbcType | Provides the numeric value of the original SQL data type for each field in the record. See the Java documentation for a list of the data types that correspond to numeric values. |
<JDBC prefix>.<column name>.precision | Provides the original precision for all numeric and decimal fields. |
<JDBC prefix>.<column name>.scale | Provides the original scale for all numeric and decimal fields. |
Header Attributes with the Drift Synchronization Solution
When you use the JDBC Query Consumer origin with the Drift Synchronization Solution, ensure that the origin creates JDBC header attributes. JDBC header attributes allow the Hive Metadata processor to use the precision and scale information in the attributes to define decimal fields. The origin creates JDBC header attributes, by default.
- In the origin, on the Advanced tab, make sure that the Create JDBC Header Attributes property is selected.
- On the same tab, you can optionally change the default for the JDBC Header Prefix property.
- If you changed the default value for the JDBC Header Prefix property, then on
the Hive tab of the Hive Metadata processor, configure
the Decimal Precision Expression and Decimal
Scale Expression properties. Update the
jdbc.
string in each property to match the specified JDBC header prefix.If you did not change the JDBC Header Prefix default value, then use the default expressions for the properties.
JDBC Field Attributes
The JDBC Query Consumer origin generates field attributes for columns converted to the Decimal or Datetime data types in Data Collector. The attributes provide additional information about each field.
- Decimal and Numeric data types are converted to the Data Collector Decimal data type, which does not store scale and precision.
- The Timestamp data type is converted to the Data Collector Datetime data type, which does not store nanoseconds.
Data Collector Data Type | Generated Field Attribute | Description |
---|---|---|
Decimal | precision | Provides the original precision for every decimal or numeric column. |
Decimal | scale | Provides the original scale for every decimal or numeric column. |
Datetime | nanoSeconds | Provides the original nanoseconds for every timestamp column. |
You can use the record:fieldAttribute
or
record:fieldAttributeOrDefault
functions to access the information
in the attributes. For more information about working with field attributes, see Field Attributes.
Event Generation
The JDBC Query Consumer origin can generate events that you can use in an event stream. When you enable event generation, the origin generates an event when it completes processing the data returned by the specified query. The origin also generates an event when a query completes successfully and when it fails to complete.
- With the Pipeline Finisher executor to stop the pipeline and
transition the pipeline to a Finished state when the origin completes processing
available data.
When you restart a pipeline stopped by the Pipeline Finisher executor, the origin processes data based on how you configured the origin. For example, if you configure the origin to run in incremental mode, the origin saves the offset when the executor stops the pipeline. When it restarts, the origin continues processing from the last-saved offset. In contrast, if you configure the origin to run in full mode, when you restart the pipeline, the origin uses the initial offset, if specified.
For an example, see Stopping a Pipeline After Processing All Available Data.
- With the Email executor to send a custom email
after receiving an event.
For an example, see Sending Email During Pipeline Processing.
-
With a destination to store information about completed queries.
For an example, see Preserving an Audit Trail of Events.
For more information about dataflow triggers and the event framework, see Dataflow Triggers Overview.
Event Record
Record Header Attribute | Description |
---|---|
sdc.event.type | Event type. Uses one of the following types:
|
sdc.event.version | Integer that indicates the version of the event record type. |
sdc.event.creation_timestamp | Epoch timestamp when the stage created the event. |
- No-more-data
- The origin generates a no-more-data event record when it completes processing all data returned by a query.
- Query success
- The origin generates a query success event record when it completes processing the data returned from a query.
- Query failure
- The origin generates a query failure event record when it fails to complete processing the data returned from a query.
Configuring a JDBC Query Consumer
Configure a JDBC Query Consumer origin to use a single configured SQL query to read database data through a JDBC connection.