Package mondrian.spi.impl

Class PostgreSqlDialect

    • Constructor Detail

      • PostgreSqlDialect

        public PostgreSqlDialect​(Connection connection)
                  throws SQLException
        Creates a PostgreSqlDialect.
        Parameters:
        connection - Connection
        Throws:
        SQLException

    • Method Detail

      • 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.

      • 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.

      • getType

        public SqlStatement.Type getType​(ResultSetMetaData metaData,
                                 int columnIndex)
                          throws SQLException
        Description copied from interface: Dialect

        Chooses the most appropriate type for accessing the values of a column in a result set for a dialect.

        Dialect-specific nuances involving type representation should be encapsulated in implementing methods. For example, if a dialect has implicit rules involving scale or precision, they should be handled within this method so the client can simply retrieve the "best fit" SqlStatement.Type for the column.

        Specified by:
        getType in interface Dialect
        Overrides:
        getType in class JdbcDialectImpl
        Parameters:
        metaData - Results set metadata
        columnIndex - Column ordinal (0-based)
        Returns:
        the most appropriate SqlStatement.Type for the column
        Throws:
        SQLException