org.mmbase.storage.search.implementation.database
Class PostgreSqlSqlHandler

java.lang.Object
  org.mmbase.storage.search.implementation.database.BasicSqlHandler
      org.mmbase.storage.search.implementation.database.PostgreSqlSqlHandler

All Implemented Interfaces:

SqlHandler

public class PostgreSqlSqlHandler

extends BasicSqlHandler

implements SqlHandler

The PostgreSQL query handler, implements SqlHandler for standard PostgreSql functionality.
Derived from BasicSqlHandler, overrides

• toSql(), implements FEATURE_MAX_NUMBER and FEATURE_OFFSET, by adding a construct like "LIMIT 20" or "LIMIT 20 OFFSET 80" after the body, when appropriate.
• getSupportLevel(int,SearchQuery), returns SUPPORT_OPTIMAL for these features, delegates to the superclass for other features.

Since:

MMBase-1.7

Version:

$Id: PostgreSqlSqlHandler.java,v 1.23 2006/07/05 20:06:16 michiel Exp $

Author:

Rob van Maris

Constructor Summary

PostgreSqlSqlHandler()
Constructor.

Method Summary

protected void	appendDateField(StringBuffer sb, Step step, String fieldName, boolean multipleSteps, int datePart) date time functions
protected StringBuffer	appendLikeOperator(StringBuffer sb, boolean caseSensitive) Appends the 'LIKE' operator for the given case sensitiviy.
protected StringBuffer	appendSortOrderField(StringBuffer sb, SortOrder sortOrder, boolean multipleSteps) Normally, Postgresql does not sort case senstively, so we should not sort on UPPER(fieldname).
protected void	appendTableName(StringBuffer sb, Step step) Optimizes postgresql queries by adding the ONLY keyword to a relation-table, provided that the role was given (and therefor the selection only applies to the given table).
int	getSupportLevel(int feature, SearchQuery query) Gets the level at which a feature is supported for a query by this handler.
String	toSql(SearchQuery query, SqlHandler firstInChain) Represents a SearchQuery object as a string in SQL format, using the database configuration.
protected boolean	useLower(FieldCompareConstraint constraint) Wether the 'LOWER' function needs to be used to implement case insensitivity.

Methods inherited from class org.mmbase.storage.search.implementation.database.BasicSqlHandler

appendCompositeConstraintToSql, appendConstraintToSql, appendDateValue, appendField, appendFieldValue, appendQueryBodyToSql, appendRelationConstraints, appendSortOrderDirection, appendSortOrders, appendTableAlias, getAllowedValue, getSupportLevel, toSqlString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.mmbase.storage.search.implementation.database.SqlHandler

appendConstraintToSql, appendQueryBodyToSql, getAllowedValue, getSupportLevel

Constructor Detail

PostgreSqlSqlHandler

public PostgreSqlSqlHandler()

Constructor.

Method Detail

getSupportLevel

public int getSupportLevel(int feature,
                           SearchQuery query)
                    throws SearchQueryException

Description copied from interface: SqlHandler

Gets the level at which a feature is supported for a query by this handler. This is one of either:

• SUPPORT_NONE
• SUPPORT_WEAK
• SUPPORT_NORMAL
• SUPPORT_OPTIMAL

Given the choice, the query handler with the highest level of support is prefered.

Specified by:

getSupportLevel in interface SqlHandler

Overrides:

getSupportLevel in class BasicSqlHandler

Throws:

SearchQueryException

useLower

protected boolean useLower(FieldCompareConstraint constraint)

Description copied from class: BasicSqlHandler

Wether the 'LOWER' function needs to be used to implement case insensitivity. This is not always the case, because some database only match case insensitively, in which case it does not make sense to lowercase.

Overrides:

useLower in class BasicSqlHandler

appendLikeOperator

protected StringBuffer appendLikeOperator(StringBuffer sb,
                                          boolean caseSensitive)

Description copied from class: BasicSqlHandler

Appends the 'LIKE' operator for the given case sensitiviy. Some databases support a case insensitive LIKE ('ILIKE'). Implementations for those database can override this method.

Overrides:

appendLikeOperator in class BasicSqlHandler

Returns:

The string buffer.

appendSortOrderField

protected StringBuffer appendSortOrderField(StringBuffer sb,
                                            SortOrder sortOrder,
                                            boolean multipleSteps)

Normally, Postgresql does not sort case senstively, so we should not sort on UPPER(fieldname). This is mainly very bad if the query is also distinct. (ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list), may occur.

Overrides:

appendSortOrderField in class BasicSqlHandler

appendDateField

protected void appendDateField(StringBuffer sb,
                               Step step,
                               String fieldName,
                               boolean multipleSteps,
                               int datePart)

date time functions

Overrides:

appendDateField in class BasicSqlHandler

Warning: No Java Documentation Available.

toSql

public String toSql(SearchQuery query,
                    SqlHandler firstInChain)
             throws SearchQueryException

Description copied from interface: SqlHandler

Represents a SearchQuery object as a string in SQL format, using the database configuration.

Specified by:

toSql in interface SqlHandler

Overrides:

toSql in class BasicSqlHandler

Throws:

SearchQueryException

appendTableName

protected void appendTableName(StringBuffer sb,
                               Step step)

Optimizes postgresql queries by adding the ONLY keyword to a relation-table, provided that the role was given (and therefor the selection only applies to the given table).

Overrides:

appendTableName in class BasicSqlHandler

Parameters:

sb -

step -

See Also:

BasicSqlHandler.appendTableName(java.lang.StringBuffer, org.mmbase.storage.search.Step)