mondrian.spi.impl

Class PostgreSqlDialect

java.lang.Object

mondrian.spi.impl.JdbcDialectImpl

mondrian.spi.impl.PostgreSqlDialect

All Implemented Interfaces:

Dialect

Direct Known Subclasses:

GreenplumDialect, NetezzaDialect

public class PostgreSqlDialect
extends JdbcDialectImpl

Implementation of Dialect for the PostgreSQL database.

Since:

Nov 23, 2008

Author:

jhyde

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
PostgreSqlDialect(Connection connection) Creates a PostgreSqlDialect.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	allowsRegularExpressionInWhereClause() Informs Mondrian if the dialect supports regular expressions when creating the 'where' or the 'having' clause.
protected String	generateOrderByNulls(String expr, boolean ascending, boolean collateNullsLast) Generates SQL to force null values to collate last.
String	generateRegularExpression(String source, String javaRegex) Must generate a String representing a regular expression match operation between a string literal and a Java regular expression.
Dialect.DatabaseProduct	getDatabaseProduct() Returns the database for this Dialect, or Dialect.DatabaseProduct.UNKNOWN if the database is not a common database.
static boolean	isGreenplum(DatabaseMetaData databaseMetaData) Detects whether this database is Greenplum.
boolean	requiresAliasForFromQuery() Returns whether this Dialect requires subqueries in the FROM clause to have an alias.

Methods inherited from class mondrian.spi.impl.JdbcDialectImpl

allowsAs, allowsCompoundCountDistinct, allowsCountDistinct, allowsDdl, allowsDialectSharing, allowsFromQuery, allowsJoinOn, allowsMultipleCountDistinct, allowsMultipleDistinctSqlMeasures, allowsOrderByAlias, allowsSelectNotInGroupBy, appendHintsAfterFromClause, caseWhenElse, deduceIdentifierQuoteString, deduceMaxColumnNameLength, deduceProductName, deduceProductVersion, deduceReadOnly, deduceSupportedResultSetStyles, deduceSupportsSelectNotInGroupBy, generateCountExpression, generateInline, generateInlineForAnsi, generateInlineGeneric, generateOrderByNullsAnsi, generateOrderItem, generateOrderItem, getMaxColumnNameLength, getProduct, getQuoteIdentifierString, needsExponent, quote, quoteBooleanLiteral, quoteDateLiteral, quoteDateLiteral, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteNumericLiteral, quoteStringLiteral, quoteTimeLiteral, quoteTimestampLiteral, requiresGroupByAlias, requiresHavingAlias, requiresOrderByAlias, requiresUnionOrderByExprToBeInSelectClause, requiresUnionOrderByOrdinal, 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

PostgreSqlDialect

public PostgreSqlDialect(Connection connection)
                  throws SQLException

Creates a PostgreSqlDialect.

Parameters:

connection - Connection

Throws:

SQLException

Method Detail

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()

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.

isGreenplum

public static boolean isGreenplum(DatabaseMetaData databaseMetaData)

Detects whether this database is Greenplum.

Greenplum uses the Postgres driver and appears to be a Postgres instance. The key difference is the presence of 'greenplum' in 'select version()'.

Parameters:

databaseMetaData - Database metadata

Returns:

Whether this is a Greenplum database

getDatabaseProduct

public Dialect.DatabaseProduct getDatabaseProduct()

Description copied from interface: Dialect

Returns the database for this Dialect, or Dialect.DatabaseProduct.UNKNOWN if the database is not a common database.

Specified by:

getDatabaseProduct in interface Dialect

Overrides:

getDatabaseProduct in class JdbcDialectImpl

Returns:

Database

allowsRegularExpressionInWhereClause

public boolean allowsRegularExpressionInWhereClause()

Description copied from interface: Dialect

Informs Mondrian if the dialect supports regular expressions when creating the 'where' or the 'having' clause.

Specified by:

allowsRegularExpressionInWhereClause in interface Dialect

Overrides:

allowsRegularExpressionInWhereClause in class JdbcDialectImpl

Returns:

True if regular expressions are supported.

generateRegularExpression

public String generateRegularExpression(String source,
                               String javaRegex)

Description copied from interface: Dialect

Must generate a String representing a regular expression match operation between a string literal and a Java regular expression. The string literal might be a column identifier or some other identifier, but the implementation must presume that it is already escaped and fit for use. The regular expression is not escaped and must be adapted to the proper dialect rules.

Postgres / Greenplum example:

generateRegularExpression( "'foodmart'.'customer_name'", "(?i).*oo.*") -> 'foodmart'.'customer_name' ~ "(?i).*oo.*"

Oracle example:

generateRegularExpression( "'foodmart'.'customer_name'", ".*oo.*") -> REGEXP_LIKE('foodmart'.'customer_name', ".*oo.*")

Dialects are allowed to return null if the dialect cannot convert that particular regular expression into something that the database would support.

Specified by:

generateRegularExpression in interface Dialect

Overrides:

generateRegularExpression in class JdbcDialectImpl

Parameters:

source - A String identifying the column to match against.

javaRegex - A Java regular expression to match against.

Returns:

A dialect specific matching operation, or null if the dialect cannot convert that particular regular expression into something that the database would support.