org.apache.spark.sql.jdbc

Class AggregatedDialect

Object

org.apache.spark.sql.jdbc.JdbcDialect

org.apache.spark.sql.jdbc.AggregatedDialect

All Implemented Interfaces:

java.io.Serializable

public class AggregatedDialect
extends JdbcDialect

AggregatedDialect can unify multiple dialects into one virtual Dialect. Dialects are tried in order, and the first dialect that does not return a neutral element will win.

param: dialects List of dialects.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AggregatedDialect(scala.collection.immutable.List<JdbcDialect> dialects)

Method Summary

Modifier and Type	Method and Description
boolean	canHandle(String url) Check if this dialect instance can handle a certain jdbc url.
scala.Option<DataType>	getCatalystType(int sqlType, String typeName, int size, MetadataBuilder md) Get the custom datatype mapping for the given jdbc meta information.
scala.Option<JdbcType>	getJDBCType(DataType dt) Retrieve the jdbc / sql type for a given datatype.
String	getSchemaQuery(String table) The SQL query that should be used to discover the schema of a table.
String	getTableExistsQuery(String table) Get the SQL query that should be used to find if the given table exists.
String	getTruncateQuery(String table) The SQL query that should be used to truncate a table.
scala.Option<Object>	isCascadingTruncateTable() Return Some[true] iff TRUNCATE TABLE causes cascading default.
String	quoteIdentifier(String colName) Quotes the identifier.

Methods inherited from class org.apache.spark.sql.jdbc.JdbcDialect

beforeFetch, compileValue

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AggregatedDialect

public AggregatedDialect(scala.collection.immutable.List<JdbcDialect> dialects)

Method Detail

canHandle

public boolean canHandle(String url)

Description copied from class: JdbcDialect

Check if this dialect instance can handle a certain jdbc url.

Specified by:

canHandle in class JdbcDialect

Parameters:

url - the jdbc url.

Returns:

True if the dialect can be applied on the given jdbc url.

getCatalystType

public scala.Option<DataType> getCatalystType(int sqlType,
                                              String typeName,
                                              int size,
                                              MetadataBuilder md)

Description copied from class: JdbcDialect

Get the custom datatype mapping for the given jdbc meta information.

Overrides:

getCatalystType in class JdbcDialect

Parameters:

sqlType - The sql type (see java.sql.Types)

typeName - The sql type name (e.g. "BIGINT UNSIGNED")

size - The size of the type.

md - Result metadata associated with this type.

Returns:

The actual DataType (subclasses of DataType) or null if the default type mapping should be used.

getJDBCType

public scala.Option<JdbcType> getJDBCType(DataType dt)

Description copied from class: JdbcDialect

Retrieve the jdbc / sql type for a given datatype.

Overrides:

getJDBCType in class JdbcDialect

Parameters:

dt - The datatype (e.g. StringType)

Returns:

The new JdbcType if there is an override for this DataType

quoteIdentifier

public String quoteIdentifier(String colName)

Description copied from class: JdbcDialect

Quotes the identifier. This is used to put quotes around the identifier in case the column name is a reserved keyword, or in case it contains characters that require quotes (e.g. space).

Overrides:

quoteIdentifier in class JdbcDialect

Parameters:

colName - (undocumented)

Returns:

(undocumented)

getTableExistsQuery

public String getTableExistsQuery(String table)

Description copied from class: JdbcDialect

Get the SQL query that should be used to find if the given table exists. Dialects can override this method to return a query that works best in a particular database.

Overrides:

getTableExistsQuery in class JdbcDialect

Parameters:

table - The name of the table.

Returns:

The SQL query to use for checking the table.

getSchemaQuery

public String getSchemaQuery(String table)

Description copied from class: JdbcDialect

The SQL query that should be used to discover the schema of a table. It only needs to ensure that the result set has the same schema as the table, such as by calling "SELECT * ...". Dialects can override this method to return a query that works best in a particular database.

Overrides:

getSchemaQuery in class JdbcDialect

Parameters:

table - The name of the table.

Returns:

The SQL query to use for discovering the schema.

isCascadingTruncateTable

public scala.Option<Object> isCascadingTruncateTable()

Description copied from class: JdbcDialect

Return Some[true] iff TRUNCATE TABLE causes cascading default. Some[true] : TRUNCATE TABLE causes cascading. Some[false] : TRUNCATE TABLE does not cause cascading. None: The behavior of TRUNCATE TABLE is unknown (default).

Overrides:

isCascadingTruncateTable in class JdbcDialect

Returns:

(undocumented)

getTruncateQuery

public String getTruncateQuery(String table)

Description copied from class: JdbcDialect

The SQL query that should be used to truncate a table. Dialects can override this method to return a query that is suitable for a particular database. For PostgreSQL, for instance, a different query is used to prevent "TRUNCATE" affecting other tables.

Overrides:

getTruncateQuery in class JdbcDialect

Parameters:

table - The name of the table.

Returns:

The SQL query to use for truncating a table