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 36317 2009-06-23 14:19:19Z michiel $

Author:

Rob van Maris

Constructor Summary

PostgreSqlSqlHandler()
Constructor.

Method Summary

protected void	appendDateField(StringBuilder sb, Step step, String fieldName, boolean multipleSteps, int datePart) date time functions
protected StringBuilder	appendLikeOperator(StringBuilder sb, FieldConstraint constraint) Appends the 'LIKE' operator for the given case sensitiviy.
protected StringBuilder	appendRegularExpressionOperator(StringBuilder sb, FieldConstraint constraint)
protected StringBuilder	appendSortOrderField(StringBuilder sb, SortOrder sortOrder, boolean multipleSteps, SearchQuery query) Normally, Postgresql does not sort case senstively, so we should not sort on UPPER(fieldname).
protected void	appendTableName(StringBuilder 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(FieldConstraint 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, appendField, appendField, appendFieldValue, appendLowerField, appendPreField, appendQueryBodyToSql, appendRelationConstraints, appendSortOrderDirection, appendSortOrderField, appendSortOrders, appendTableAlias, forceEncode, 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(FieldConstraint 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 StringBuilder appendLikeOperator(StringBuilder sb,
                                           FieldConstraint constraint)

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 StringBuilder appendSortOrderField(StringBuilder sb,
                                             SortOrder sortOrder,
                                             boolean multipleSteps,
                                             SearchQuery query)

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

appendRegularExpressionOperator

protected StringBuilder appendRegularExpressionOperator(StringBuilder sb,
                                                        FieldConstraint constraint)

Overrides:

appendRegularExpressionOperator in class BasicSqlHandler

appendDateField

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

date time functions

Overrides:

appendDateField in class BasicSqlHandler

Javadoc:

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

Parameters:

query - The searchquery.

firstInChain - The first element in the chain of handlers. At some point appendQueryBodyToSql() will have to be called on this handler, to generate the body of the query.

Returns:

SQL string representation of the query.

Throws:

SearchQueryException

appendTableName

protected void appendTableName(StringBuilder 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

See Also:

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