org.apache.spark.sql.jdbc

Class JdbcDialect

Object

org.apache.spark.sql.jdbc.JdbcDialect

All Implemented Interfaces:

java.io.Serializable, org.apache.spark.internal.Logging

Direct Known Subclasses:

AggregatedDialect

public abstract class JdbcDialect
extends Object
implements scala.Serializable, org.apache.spark.internal.Logging

:: DeveloperApi :: Encapsulates everything (extensions, workarounds, quirks) to handle the SQL dialect of a certain database or jdbc driver. Lots of databases define types that aren't explicitly supported by the JDBC spec. Some JDBC drivers also report inaccurate information---for instance, BIT(n>1) being reported as a BIT type is quite common, even though BIT in JDBC is meant for single-bit values. Also, there does not appear to be a standard name for an unbounded string or binary type; we use BLOB and CLOB by default but override with database-specific alternatives when these are absent or do not behave correctly.

Currently, the only thing done by the dialect is type mapping. getCatalystType is used when reading from a JDBC table and getJDBCType is used when writing to a JDBC table. If getCatalystType returns null, the default type handling is used for the given JDBC type. Similarly, if getJDBCType returns (null, None), the default type handling is used for the given Catalyst type.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.spark.internal.Logging

org.apache.spark.internal.Logging.SparkShellLoggingFilter

Constructor Summary

Constructors

Constructor and Description
JdbcDialect()

Method Summary

Modifier and Type	Method and Description
String[]	alterTable(String tableName, scala.collection.Seq<org.apache.spark.sql.connector.catalog.TableChange> changes, int dbMajorVersion) Alter an existing table.
void	beforeFetch(java.sql.Connection connection, scala.collection.immutable.Map<String,String> properties) Override connection specific properties to run before a select is made.
abstract boolean	canHandle(String url) Check if this dialect instance can handle a certain jdbc url.
AnalysisException	classifyException(String message, Throwable e) Gets a dialect exception, classifies it and wraps it by AnalysisException.
scala.Option<String>	compileAggregate(org.apache.spark.sql.connector.expressions.aggregate.AggregateFunc aggFunction) Deprecated. use org.apache.spark.sql.jdbc.JdbcDialect.compileExpression instead. Since 3.4.0.
scala.Option<String>	compileExpression(org.apache.spark.sql.connector.expressions.Expression expr) Converts V2 expression to String representing a SQL expression.
Object	compileValue(Object value) Converts value to SQL expression.
scala.Function1<Object,java.sql.Connection>	createConnectionFactory(org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options) Returns a factory for creating connections to the given JDBC URL.
String	createIndex(String indexName, org.apache.spark.sql.connector.catalog.Identifier tableIdent, org.apache.spark.sql.connector.expressions.NamedReference[] columns, java.util.Map<org.apache.spark.sql.connector.expressions.NamedReference,java.util.Map<String,String>> columnsProperties, java.util.Map<String,String> properties) Build a create index SQL statement.
void	createSchema(java.sql.Statement statement, String schema, String comment) Create schema with an optional comment.
String	dropIndex(String indexName, org.apache.spark.sql.connector.catalog.Identifier tableIdent) Build a drop index SQL statement.
String	dropSchema(String schema, boolean cascade)
scala.collection.Seq<scala.Tuple2<String,org.apache.spark.sql.connector.catalog.functions.UnboundFunction>>	functions() List the user-defined functions in jdbc dialect.
String	getAddColumnQuery(String tableName, String columnName, String dataType)
scala.Option<DataType>	getCatalystType(int sqlType, String typeName, int size, MetadataBuilder md) Get the custom datatype mapping for the given jdbc meta information.
String	getDeleteColumnQuery(String tableName, String columnName)
scala.Option<JdbcType>	getJDBCType(DataType dt) Retrieve the jdbc / sql type for a given datatype.
String	getLimitClause(Integer limit) returns the LIMIT clause for the SELECT statement
String	getOffsetClause(Integer offset) returns the OFFSET clause for the SELECT statement
String	getRenameColumnQuery(String tableName, String columnName, String newName, int dbMajorVersion)
String	getSchemaCommentQuery(String schema, String comment)
String	getSchemaQuery(String table) The SQL query that should be used to discover the schema of a table.
String	getTableCommentQuery(String table, String comment)
String	getTableExistsQuery(String table) Get the SQL query that should be used to find if the given table exists.
String	getTableSample(org.apache.spark.sql.execution.datasources.v2.TableSampleInfo sample)
String	getTruncateQuery(String table) The SQL query that should be used to truncate a table.
String	getTruncateQuery(String table, scala.Option<Object> cascade) The SQL query that should be used to truncate a table.
String	getUpdateColumnNullabilityQuery(String tableName, String columnName, boolean isNullable)
String	getUpdateColumnTypeQuery(String tableName, String columnName, String newDataType)
boolean	indexExists(java.sql.Connection conn, String indexName, org.apache.spark.sql.connector.catalog.Identifier tableIdent, org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options) Checks whether an index exists
scala.Option<Object>	isCascadingTruncateTable() Return Some[true] iff TRUNCATE TABLE causes cascading default.
boolean	isSupportedFunction(String funcName) Returns whether the database supports function.
org.apache.spark.sql.connector.catalog.index.TableIndex[]	listIndexes(java.sql.Connection conn, org.apache.spark.sql.connector.catalog.Identifier tableIdent, org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options) Lists all the indexes in this table.
String[][]	listSchemas(java.sql.Connection conn, org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options) Lists all the schemas in this table.
String	quoteIdentifier(String colName) Quotes the identifier.
String	removeSchemaCommentQuery(String schema)
String	renameTable(String oldTable, String newTable) Rename an existing table.
boolean	schemasExists(java.sql.Connection conn, org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options, String schema) Check schema exists or not.
boolean	supportsTableSample()

Methods inherited from class Object

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

Methods inherited from interface org.apache.spark.internal.Logging

$init$, initializeForcefully, initializeLogIfNecessary, initializeLogIfNecessary, initializeLogIfNecessary$default$2, initLock, isTraceEnabled, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning, org$apache$spark$internal$Logging$$log__$eq, org$apache$spark$internal$Logging$$log_, uninitialize

Constructor Detail

JdbcDialect

public JdbcDialect()

Method Detail

alterTable

public String[] alterTable(String tableName,
                           scala.collection.Seq<org.apache.spark.sql.connector.catalog.TableChange> changes,
                           int dbMajorVersion)

Alter an existing table.

Parameters:

tableName - The name of the table to be altered.

changes - Changes to apply to the table.

dbMajorVersion - (undocumented)

Returns:

The SQL statements to use for altering the table.

beforeFetch

public void beforeFetch(java.sql.Connection connection,
                        scala.collection.immutable.Map<String,String> properties)

Override connection specific properties to run before a select is made. This is in place to allow dialects that need special treatment to optimize behavior.

Parameters:

connection - The connection object

properties - The connection properties. This is passed through from the relation.

canHandle

public abstract boolean canHandle(String url)

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

Parameters:

url - the jdbc url.

Returns:

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

Throws:

NullPointerException - if the url is null.

classifyException

public AnalysisException classifyException(String message,
                                           Throwable e)

Gets a dialect exception, classifies it and wraps it by AnalysisException.

Parameters:

message - The error message to be placed to the returned exception.

e - The dialect specific exception.

Returns:

AnalysisException or its sub-class.

compileAggregate

public scala.Option<String> compileAggregate(org.apache.spark.sql.connector.expressions.aggregate.AggregateFunc aggFunction)

Deprecated. use org.apache.spark.sql.jdbc.JdbcDialect.compileExpression instead. Since 3.4.0.

Converts aggregate function to String representing a SQL expression.

Parameters:

aggFunction - The aggregate function to be converted.

Returns:

Converted value.

compileExpression

public scala.Option<String> compileExpression(org.apache.spark.sql.connector.expressions.Expression expr)

Converts V2 expression to String representing a SQL expression.

Parameters:

expr - The V2 expression to be converted.

Returns:

Converted value.

compileValue

public Object compileValue(Object value)

Converts value to SQL expression.

Parameters:

value - The value to be converted.

Returns:

Converted value.

createConnectionFactory

public scala.Function1<Object,java.sql.Connection> createConnectionFactory(org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options)

Returns a factory for creating connections to the given JDBC URL. In general, creating a connection has nothing to do with JDBC partition id. But sometimes it is needed, such as a database with multiple shard nodes.

Parameters:

options - - JDBC options that contains url, table and other information.

Returns:

The factory method for creating JDBC connections with the RDD partition ID. -1 means the connection is being created at the driver side.

Throws:

IllegalArgumentException - if the driver could not open a JDBC connection.

createIndex

public String createIndex(String indexName,
                          org.apache.spark.sql.connector.catalog.Identifier tableIdent,
                          org.apache.spark.sql.connector.expressions.NamedReference[] columns,
                          java.util.Map<org.apache.spark.sql.connector.expressions.NamedReference,java.util.Map<String,String>> columnsProperties,
                          java.util.Map<String,String> properties)

Build a create index SQL statement.

Parameters:

indexName - the name of the index to be created

tableIdent - the table on which index to be created

columns - the columns on which index to be created

columnsProperties - the properties of the columns on which index to be created

properties - the properties of the index to be created

Returns:

the SQL statement to use for creating the index.

createSchema

public void createSchema(java.sql.Statement statement,
                         String schema,
                         String comment)

Create schema with an optional comment. Empty string means no comment.

Parameters:

statement - (undocumented)

schema - (undocumented)

comment - (undocumented)

dropIndex

public String dropIndex(String indexName,
                        org.apache.spark.sql.connector.catalog.Identifier tableIdent)

Build a drop index SQL statement.

Parameters:

indexName - the name of the index to be dropped.

tableIdent - the table on which index to be dropped.

Returns:

the SQL statement to use for dropping the index.

dropSchema

public String dropSchema(String schema,
                         boolean cascade)

functions

public scala.collection.Seq<scala.Tuple2<String,org.apache.spark.sql.connector.catalog.functions.UnboundFunction>> functions()

List the user-defined functions in jdbc dialect.

Returns:

a sequence of tuple from function name to user-defined function.

getAddColumnQuery

public String getAddColumnQuery(String tableName,
                                String columnName,
                                String dataType)

getCatalystType

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

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

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.

getDeleteColumnQuery

public String getDeleteColumnQuery(String tableName,
                                   String columnName)

getJDBCType

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

Retrieve the jdbc / sql type for a given datatype.

Parameters:

dt - The datatype (e.g. StringType)

Returns:

The new JdbcType if there is an override for this DataType

getLimitClause

public String getLimitClause(Integer limit)

returns the LIMIT clause for the SELECT statement

Parameters:

limit - (undocumented)

Returns:

(undocumented)

getOffsetClause

public String getOffsetClause(Integer offset)

returns the OFFSET clause for the SELECT statement

Parameters:

offset - (undocumented)

Returns:

(undocumented)

getRenameColumnQuery

public String getRenameColumnQuery(String tableName,
                                   String columnName,
                                   String newName,
                                   int dbMajorVersion)

getSchemaCommentQuery

public String getSchemaCommentQuery(String schema,
                                    String comment)

getSchemaQuery

public String getSchemaQuery(String table)

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.

Parameters:

table - The name of the table.

Returns:

The SQL query to use for discovering the schema.

getTableCommentQuery

public String getTableCommentQuery(String table,
                                   String comment)

getTableExistsQuery

public String getTableExistsQuery(String table)

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.

Parameters:

table - The name of the table.

Returns:

The SQL query to use for checking the table.

getTableSample

public String getTableSample(org.apache.spark.sql.execution.datasources.v2.TableSampleInfo sample)

getTruncateQuery

public String getTruncateQuery(String table)

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.

Parameters:

table - The table to truncate

Returns:

The SQL query to use for truncating a table

getTruncateQuery

public String getTruncateQuery(String table,
                               scala.Option<Object> cascade)

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.

Parameters:

table - The table to truncate

cascade - Whether or not to cascade the truncation

Returns:

The SQL query to use for truncating a table

getUpdateColumnNullabilityQuery

public String getUpdateColumnNullabilityQuery(String tableName,
                                              String columnName,
                                              boolean isNullable)

getUpdateColumnTypeQuery

public String getUpdateColumnTypeQuery(String tableName,
                                       String columnName,
                                       String newDataType)

indexExists

public boolean indexExists(java.sql.Connection conn,
                           String indexName,
                           org.apache.spark.sql.connector.catalog.Identifier tableIdent,
                           org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options)

Checks whether an index exists

Parameters:

indexName - the name of the index

tableIdent - the table on which index to be checked

options - JDBCOptions of the table

conn - (undocumented)

Returns:

true if the index with indexName exists in the table with tableName, false otherwise

isCascadingTruncateTable

public scala.Option<Object> isCascadingTruncateTable()

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).

Returns:

(undocumented)

isSupportedFunction

public boolean isSupportedFunction(String funcName)

Returns whether the database supports function.

Parameters:

funcName - Upper-cased function name

Returns:

True if the database supports function.

listIndexes

public org.apache.spark.sql.connector.catalog.index.TableIndex[] listIndexes(java.sql.Connection conn,
                                                                             org.apache.spark.sql.connector.catalog.Identifier tableIdent,
                                                                             org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options)

Lists all the indexes in this table.

Parameters:

conn - (undocumented)

tableIdent - (undocumented)

options - (undocumented)

Returns:

(undocumented)

listSchemas

public String[][] listSchemas(java.sql.Connection conn,
                              org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options)

Lists all the schemas in this table.

Parameters:

conn - (undocumented)

options - (undocumented)

Returns:

(undocumented)

quoteIdentifier

public String quoteIdentifier(String colName)

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).

Parameters:

colName - (undocumented)

Returns:

(undocumented)

removeSchemaCommentQuery

public String removeSchemaCommentQuery(String schema)

renameTable

public String renameTable(String oldTable,
                          String newTable)

Rename an existing table.

Parameters:

oldTable - The existing table.

newTable - New name of the table.

Returns:

The SQL statement to use for renaming the table.

schemasExists

public boolean schemasExists(java.sql.Connection conn,
                             org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions options,
                             String schema)

Check schema exists or not.

Parameters:

conn - (undocumented)

options - (undocumented)

schema - (undocumented)

Returns:

(undocumented)

supportsTableSample

public boolean supportsTableSample()