org.apache.flink.connector.jdbc.dialect

Interface JdbcDialect

All Superinterfaces:

Serializable

All Known Implementing Classes:

AbstractDialect, MySqlDialect, PostgresDialect

@PublicEvolving
public interface JdbcDialect
extends Serializable

Represents a dialect of SQL implemented by a particular JDBC system. Dialects should be immutable and stateless.

See Also:

JdbcDialectFactory

Method Summary

Modifier and Type	Method and Description
default String	appendDefaultUrlProperties(String url) Appends default JDBC properties to url for current dialect.
default Optional<String>	defaultDriverName()
String	dialectName() Get the name of jdbc dialect.
String	getDeleteStatement(String tableName, String[] conditionFields) Constructs the dialects delete statement for a single row with the given condition.
String	getInsertIntoStatement(String tableName, String[] fieldNames) Generates a string that will be used as a PreparedStatement to insert a row into a database table.
String	getLimitClause(long limit) Get limit clause to limit the number of emitted row from the jdbc source.
JdbcRowConverter	getRowConverter(RowType rowType) Get converter that convert jdbc object and Flink internal object each other.
String	getRowExistsStatement(String tableName, String[] conditionFields) Generates a query to determine if a row exists in the table.
String	getSelectFromStatement(String tableName, String[] selectFields, String[] conditionFields) Constructs the dialects select statement for fields with given conditions.
String	getUpdateStatement(String tableName, String[] fieldNames, String[] conditionFields) Constructs the dialects update statement for a single row with the given condition.
Optional<String>	getUpsertStatement(String tableName, String[] fieldNames, String[] uniqueKeyFields) Constructs the dialects upsert statement if supported; such as MySQL's DUPLICATE KEY UPDATE, or PostgreSQL's {@code ON CONFLICT...
String	quoteIdentifier(String identifier) Quotes the identifier.
void	validate(RowType rowType) Check if this dialect instance support a specific data type in table schema.

Method Detail

dialectName

String dialectName()

Get the name of jdbc dialect.

Returns:

the dialect name.

getRowConverter

JdbcRowConverter getRowConverter(RowType rowType)

Get converter that convert jdbc object and Flink internal object each other.

Parameters:

rowType - the given row type

Returns:

a row converter for the database

getLimitClause

String getLimitClause(long limit)

Get limit clause to limit the number of emitted row from the jdbc source.

Parameters:

limit - number of row to emit. The value of the parameter should be non-negative.

Returns:

the limit clause.

validate

void validate(RowType rowType)
       throws ValidationException

Check if this dialect instance support a specific data type in table schema.

Parameters:

rowType - the physical table datatype of a row in the database table.

Throws:

ValidationException - in case of the table schema contains unsupported type.

defaultDriverName

default Optional<String> defaultDriverName()

Returns:

the default driver class name, if user has not configured the driver class name, then this one will be used.

quoteIdentifier

String quoteIdentifier(String identifier)

Quotes the identifier.

Used to put quotes around the identifier if the column name is a reserved keyword or contains characters requiring quotes (e.g., space).

Returns:

the quoted identifier.

getUpsertStatement

Optional<String> getUpsertStatement(String tableName,
                                    String[] fieldNames,
                                    String[] uniqueKeyFields)

Constructs the dialects upsert statement if supported; such as MySQL's DUPLICATE KEY UPDATE, or PostgreSQL's ON CONFLICT... DO UPDATE SET... If supported, the returned string will be used as a PreparedStatement. Fields in the statement must be in the same order as the fieldNames parameter.

If the dialect does not support native upsert statements, the writer will fallback to SELECT + UPDATE/INSERT which may have poor performance.

Returns:

The upsert statement if supported, otherwise None.

getRowExistsStatement

String getRowExistsStatement(String tableName,
                             String[] conditionFields)

Generates a query to determine if a row exists in the table. The returned string will be used as a PreparedStatement.

By default, the dialect will fallback to a simple SELECT query.

getInsertIntoStatement

String getInsertIntoStatement(String tableName,
                              String[] fieldNames)

Generates a string that will be used as a PreparedStatement to insert a row into a database table. Fields in the statement must be in the same order as the fieldNames parameter.

Returns:

the dialects INSERT INTO statement.

getUpdateStatement

String getUpdateStatement(String tableName,
                          String[] fieldNames,
                          String[] conditionFields)

Constructs the dialects update statement for a single row with the given condition. The returned string will be used as a PreparedStatement. Fields in the statement must be in the same order as the fieldNames parameter.

Returns:

A single row update statement.

getDeleteStatement

String getDeleteStatement(String tableName,
                          String[] conditionFields)

Constructs the dialects delete statement for a single row with the given condition. The returned string will be used as a PreparedStatement. Fields in the statement must be in the same order as the fieldNames parameter.

Returns:

A single row delete statement.

getSelectFromStatement

String getSelectFromStatement(String tableName,
                              String[] selectFields,
                              String[] conditionFields)

Constructs the dialects select statement for fields with given conditions. The returned string will be used as a PreparedStatement. Fields in the statement must be in the same order as the fieldNames parameter.

Returns:

A select statement.

appendDefaultUrlProperties

default String appendDefaultUrlProperties(String url)

Appends default JDBC properties to url for current dialect. Some database dialects will set default JDBC properties for performance or optimization consideration, such as MySQL dialect uses 'rewriteBatchedStatements=true' to enable execute multiple MySQL statements in batch mode.

Returns:

A JDBC url that has appended the default properties.