mondrian.spi.impl

Class HiveDialect

java.lang.Object

mondrian.spi.impl.JdbcDialectImpl

mondrian.spi.impl.HiveDialect

All Implemented Interfaces:

Dialect

Direct Known Subclasses:

ImpalaDialect

public class HiveDialect
extends JdbcDialectImpl

Implementation of Dialect for the Hive database.

Since:

Jan 10, 2011

Author:

Hongwei Fu

Nested Class Summary

Nested classes/interfaces inherited from interface mondrian.spi.Dialect

Dialect.DatabaseProduct, Dialect.Datatype

Field Summary

Fields

Modifier and Type	Field and Description
static JdbcDialectFactory	FACTORY

Fields inherited from class mondrian.spi.impl.JdbcDialectImpl

databaseProduct, permitsSelectNotInGroupBy, productVersion

Constructor Summary

Constructors

Constructor and Description
HiveDialect(Connection connection) Creates a HiveDialect.

Method Summary

Modifier and Type	Method and Description
boolean	allowsAs() Returns whether the SQL dialect allows "AS" in the FROM clause.
boolean	allowsCompoundCountDistinct() Returns whether this Dialect allows multiple arguments to the COUNT(DISTINCT ...) aggregate function, for example SELECT COUNT(DISTINCT x, y) FROM t
boolean	allowsJoinOn() Returns whether this dialect supports "ANSI-style JOIN syntax", FROM leftTable JOIN rightTable ON conditon.
boolean	allowsOrderByAlias() Returns true if aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.
protected String	deduceIdentifierQuoteString(DatabaseMetaData databaseMetaData)
protected int	deduceMaxColumnNameLength(DatabaseMetaData databaseMetaData)
protected boolean	deduceReadOnly(DatabaseMetaData databaseMetaData)
protected Set<List<Integer>>	deduceSupportedResultSetStyles(DatabaseMetaData databaseMetaData)
String	generateInline(List<String> columnNames, List<String> columnTypes, List<String[]> valueList) Generates a SQL statement to represent an inline dataset.
protected String	generateOrderByNulls(String expr, boolean ascending, boolean collateNullsLast) Generates SQL to force null values to collate last.
protected void	quoteDateLiteral(StringBuilder buf, String value, Date date) Helper method for JdbcDialectImpl.quoteDateLiteral(StringBuilder, String).
void	quoteTimestampLiteral(StringBuilder buf, String value) Appends to a buffer a timestamp literal.
boolean	requiresAliasForFromQuery() Returns whether this Dialect requires subqueries in the FROM clause to have an alias.
boolean	requiresGroupByAlias() Returns true if this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias.
boolean	requiresOrderByAlias() Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.
boolean	requiresUnionOrderByExprToBeInSelectClause() Returns true if this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause.
boolean	requiresUnionOrderByOrdinal() Returns true if this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query.

Methods inherited from class mondrian.spi.impl.JdbcDialectImpl

allowsCountDistinct, allowsCountDistinctWithOtherAggs, allowsDdl, allowsDialectSharing, allowsFromQuery, allowsMultipleCountDistinct, allowsMultipleDistinctSqlMeasures, allowsRegularExpressionInWhereClause, allowsSelectNotInGroupBy, appendHintsAfterFromClause, caseWhenElse, computeStatisticsProviders, deduceProductName, deduceProductVersion, deduceSupportsSelectNotInGroupBy, extractEmbeddedFlags, generateCountExpression, generateInlineForAnsi, generateInlineGeneric, generateOrderByNullsAnsi, generateOrderItem, generateRegularExpression, getDatabaseProduct, getMaxColumnNameLength, getProduct, getQuoteIdentifierString, getStatisticsProviders, getType, isDatabase, needsExponent, quote, quoteBooleanLiteral, quoteDateLiteral, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteNumericLiteral, quoteStringLiteral, quoteTimeLiteral, quoteTimestampLiteral, requiresHavingAlias, supportsGroupByExpressions, supportsGroupingSets, supportsMultiValueInExpr, supportsResultSetConcurrency, supportsUnlimitedValueList, toString, toUpper

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

FACTORY

public static final JdbcDialectFactory FACTORY

Constructor Detail

HiveDialect

public HiveDialect(Connection connection)
            throws SQLException

Creates a HiveDialect.

Parameters:

connection - Connection

Throws:

SQLException - on error

Method Detail

deduceIdentifierQuoteString

protected String deduceIdentifierQuoteString(DatabaseMetaData databaseMetaData)

Overrides:

deduceIdentifierQuoteString in class JdbcDialectImpl

deduceSupportedResultSetStyles

protected Set<List<Integer>> deduceSupportedResultSetStyles(DatabaseMetaData databaseMetaData)

Overrides:

deduceSupportedResultSetStyles in class JdbcDialectImpl

deduceReadOnly

protected boolean deduceReadOnly(DatabaseMetaData databaseMetaData)

Overrides:

deduceReadOnly in class JdbcDialectImpl

deduceMaxColumnNameLength

protected int deduceMaxColumnNameLength(DatabaseMetaData databaseMetaData)

Overrides:

deduceMaxColumnNameLength in class JdbcDialectImpl

allowsCompoundCountDistinct

public boolean allowsCompoundCountDistinct()

Description copied from interface: Dialect

Returns whether this Dialect allows multiple arguments to the COUNT(DISTINCT ...) aggregate function, for example

SELECT COUNT(DISTINCT x, y) FROM t

Specified by:

allowsCompoundCountDistinct in interface Dialect

Overrides:

allowsCompoundCountDistinct in class JdbcDialectImpl

Returns:

whether Dialect allows multiple arguments to COUNT DISTINCT

See Also:

Dialect.allowsCountDistinct(), Dialect.allowsMultipleCountDistinct()

requiresAliasForFromQuery

public boolean requiresAliasForFromQuery()

Description copied from interface: Dialect

Returns whether this Dialect requires subqueries in the FROM clause to have an alias.

Specified by:

requiresAliasForFromQuery in interface Dialect

Overrides:

requiresAliasForFromQuery in class JdbcDialectImpl

Returns:

whether dialewct requires subqueries to have an alias

See Also:

Dialect.allowsFromQuery()

requiresOrderByAlias

public boolean requiresOrderByAlias()

Description copied from interface: Dialect

Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.

For example, in such a dialect,

SELECT x FROM t ORDER BY x + y

would be illegal, but

SELECT x, x + y AS z FROM t ORDER BY z

would be legal.

MySQL, DB2 and Ingres are examples of such dialects.

Specified by:

requiresOrderByAlias in interface Dialect

Overrides:

requiresOrderByAlias in class JdbcDialectImpl

Returns:

Whether this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias

allowsOrderByAlias

public boolean allowsOrderByAlias()

Description copied from interface: Dialect

Returns true if aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.

For example, in such a dialect,

SELECT x, x + y AS z FROM t ORDER BY z

would be legal.

MySQL, DB2 and Ingres are examples of dialects where this is true; Access is a dialect where this is false.

Specified by:

allowsOrderByAlias in interface Dialect

Overrides:

allowsOrderByAlias in class JdbcDialectImpl

Returns:

Whether aliases defined in the SELECT clause can be used as expressions in the ORDER BY clause.

requiresGroupByAlias

public boolean requiresGroupByAlias()

Description copied from interface: Dialect

Returns true if this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias.

For example, in such a dialect,

SELECT x, x FROM t GROUP BY x

would be illegal, but

SELECT x AS a, x AS b FROM t ORDER BY a, b

would be legal.

Infobright is the only such dialect.

Specified by:

requiresGroupByAlias in interface Dialect

Overrides:

requiresGroupByAlias in class JdbcDialectImpl

Returns:

Whether this Dialect can include expressions in the GROUP BY clause only by adding an expression to the SELECT clause and using its alias

requiresUnionOrderByExprToBeInSelectClause

public boolean requiresUnionOrderByExprToBeInSelectClause()

Description copied from interface: Dialect

Returns true if this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause.

For example, SELECT x, y + z FROM t
UNION ALL
SELECT x, y + z FROM t
ORDER BY y + z is allowed but SELECT x, y, z FROM t
UNION ALL
SELECT x, y, z FROM t
ORDER BY y + z SELECT x, y, z FROM t ORDER BY y + z is not.

Access is an example of a dialect with this restriction.

Specified by:

requiresUnionOrderByExprToBeInSelectClause in interface Dialect

Overrides:

requiresUnionOrderByExprToBeInSelectClause in class JdbcDialectImpl

Returns:

whether this dialect allows an expression in the ORDER BY clause of a UNION (or other set operation) query only if it occurs in the SELECT clause

requiresUnionOrderByOrdinal

public boolean requiresUnionOrderByOrdinal()

Description copied from interface: Dialect

Returns true if this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query.

For example, SELECT x, y + z FROM t
UNION ALL
SELECT x, y + z FROM t
ORDER BY 1, 2 is allowed but SELECT x, y, z FROM t
UNION ALL
SELECT x, y, z FROM t
ORDER BY x is not.

Teradata is an example of a dialect with this restriction.

Specified by:

requiresUnionOrderByOrdinal in interface Dialect

Overrides:

requiresUnionOrderByOrdinal in class JdbcDialectImpl

Returns:

whether this dialect allows only integers in the ORDER BY clause of a UNION (or other set operation) query

generateInline

public String generateInline(List<String> columnNames,
                             List<String> columnTypes,
                             List<String[]> valueList)

Description copied from interface: Dialect

Generates a SQL statement to represent an inline dataset.

For example, for Oracle, generates

 SELECT 1 AS FOO, 'a' AS BAR FROM dual
 UNION ALL
 SELECT 2 AS FOO, 'b' AS BAR FROM dual
 

For ANSI SQL, generates:

 VALUES (1, 'a'), (2, 'b')
 

Specified by:

generateInline in interface Dialect

Overrides:

generateInline in class JdbcDialectImpl

Parameters:

columnNames - List of column names

columnTypes - List of column types ("String" or "Numeric")

valueList - List of rows values

Returns:

SQL string

quoteDateLiteral

protected void quoteDateLiteral(StringBuilder buf,
                                String value,
                                Date date)

Description copied from class: JdbcDialectImpl

Helper method for JdbcDialectImpl.quoteDateLiteral(StringBuilder, String).

Overrides:

quoteDateLiteral in class JdbcDialectImpl

Parameters:

buf - Buffer to append to

value - Value as string

date - Value as date

generateOrderByNulls

protected String generateOrderByNulls(String expr,
                                      boolean ascending,
                                      boolean collateNullsLast)

Description copied from class: JdbcDialectImpl

Generates SQL to force null values to collate last.

This default implementation makes use of the ANSI SQL 1999 CASE-WHEN-THEN-ELSE in conjunction with IS NULL syntax. The resulting SQL will look something like this:

CASE WHEN "expr" IS NULL THEN 0 ELSE 1 END

You can override this method for a particular database to use something more efficient, like ISNULL().

ANSI SQL provides the syntax "ASC/DESC NULLS LAST" and "ASC/DESC NULLS FIRST". If your database supports the ANSI syntax, implement this method by calling JdbcDialectImpl.generateOrderByNullsAnsi(java.lang.String, boolean, boolean).

This method is only called from JdbcDialectImpl.generateOrderItem(String, boolean, boolean, boolean). Some dialects override that method and therefore never call this method.

Overrides:

generateOrderByNulls in class JdbcDialectImpl

Parameters:

expr - Expression.

ascending - Whether ascending.

collateNullsLast - Whether nulls should appear first or last.

Returns:

Expression to force null values to collate last or first.

allowsAs

public boolean allowsAs()

Description copied from interface: Dialect

Returns whether the SQL dialect allows "AS" in the FROM clause. If so, "SELECT * FROM t AS alias" is a valid query.

Specified by:

allowsAs in interface Dialect

Overrides:

allowsAs in class JdbcDialectImpl

Returns:

whether dialect allows AS in FROM clause

allowsJoinOn

public boolean allowsJoinOn()

Description copied from interface: Dialect

Returns whether this dialect supports "ANSI-style JOIN syntax", FROM leftTable JOIN rightTable ON conditon.

Specified by:

allowsJoinOn in interface Dialect

Overrides:

allowsJoinOn in class JdbcDialectImpl

Returns:

Whether this dialect supports FROM-JOIN-ON syntax.

quoteTimestampLiteral

public void quoteTimestampLiteral(StringBuilder buf,
                                  String value)

Description copied from interface: Dialect

Appends to a buffer a timestamp literal.

For example, in the default dialect, quoteStringLiteral(buf, "1969-03-17 12:34:56") appends TIMESTAMP '1969-03-17 12:34:56'.

Specified by:

quoteTimestampLiteral in interface Dialect

Overrides:

quoteTimestampLiteral in class JdbcDialectImpl

Parameters:

buf - Buffer to append to

value - Literal