org.apache.metamodel.jdbc.dialects

Class DefaultQueryRewriter

java.lang.Object

org.apache.metamodel.jdbc.dialects.AbstractQueryRewriter

org.apache.metamodel.jdbc.dialects.DefaultQueryRewriter

All Implemented Interfaces:

IQueryRewriter

Direct Known Subclasses:

DB2QueryRewriter, HiveQueryRewriter, HsqldbQueryRewriter, LimitOffsetQueryRewriter, OracleQueryRewriter, SQLiteQueryRewriter, SQLServerQueryRewriter

public class DefaultQueryRewriter
extends AbstractQueryRewriter

Generic query rewriter that adds syntax enhancements that are only possible to resolve just before execution time.

Field Summary

Fields inherited from class org.apache.metamodel.jdbc.dialects.AbstractQueryRewriter

logger

Constructor Summary

Constructors

Constructor and Description
DefaultQueryRewriter(JdbcDataContext dataContext)

Method Summary

Modifier and Type	Method and Description
protected Query	beforeRewrite(Query query) Method to modify query before rewriting begins.
String	escapeQuotes(String item) Escapes the quotes within a String literal of a query item.
boolean	isAggregateFunctionSupported(AggregateFunction function) Determines whether a specific aggregate function is supported by the database or not.
boolean	isFirstRowSupported() Gets whether this query rewriter is able to write the "First row" query property to the query string.
boolean	isMaxRowsSupported() Gets whether this query rewriter is able to write the "Max rows" query property to the query string.
boolean	isScalarFunctionSupported(ScalarFunction function) Determines whether a specific scalar function is supported by the database or not.
String	rewriteColumnType(ColumnType columnType, Integer columnSize) Rewrites the name of a column type, as it is written in CREATE TABLE statements.
String	rewriteFilterItem(FilterItem item)
protected String	rewriteFilterItemWithOperandLiteral(FilterItem item, String operandLiteral) Rewrites a (non-compound) FilterItem when it's operand has already been rewritten into a SQL literal.
protected String	rewriteTimestamp(Timestamp ts) Rewrites a Timestamp into it's literal representation as known by this SQL dialect.

Methods inherited from class org.apache.metamodel.jdbc.dialects.AbstractQueryRewriter

getColumnType, getDataContext, isSchemaIncludedInColumnPaths, isTransactional, rewriteColumnTypeInternal, rewriteFromClause, rewriteFromItem, rewriteFromItem, rewriteGroupByClause, rewriteGroupByItem, rewriteHavingClause, rewriteOrderByClause, rewriteOrderByItem, rewriteQuery, rewriteSelectClause, rewriteSelectItem, rewriteWhereClause

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultQueryRewriter

public DefaultQueryRewriter(JdbcDataContext dataContext)

Method Detail

beforeRewrite

protected Query beforeRewrite(Query query)

Description copied from class: AbstractQueryRewriter

Method to modify query before rewriting begins. Overwrite this method if you want to change parts of the query that are not just rendering related. Cloning the query before modifying is recommended in order to not violate referential integrity of clients (the query is mutable).

Overrides:

beforeRewrite in class AbstractQueryRewriter

Returns:

the modified query

rewriteColumnType

public String rewriteColumnType(ColumnType columnType,
                                Integer columnSize)

Description copied from interface: IQueryRewriter

Rewrites the name of a column type, as it is written in CREATE TABLE statements. Some databases dont support all column types, or have different names for them. The implementation of this method will do that conversion.

Specified by:

rewriteColumnType in interface IQueryRewriter

Overrides:

rewriteColumnType in class AbstractQueryRewriter

Parameters:

columnType - the (non-null) ColumnType to rewrite

columnSize - the (possibly null) column size that may or may not have been specified

Returns:

rewriteFilterItem

public String rewriteFilterItem(FilterItem item)

Specified by:

rewriteFilterItem in interface IQueryRewriter

Overrides:

rewriteFilterItem in class AbstractQueryRewriter

rewriteFilterItemWithOperandLiteral

protected String rewriteFilterItemWithOperandLiteral(FilterItem item,
                                                     String operandLiteral)

Rewrites a (non-compound) FilterItem when it's operand has already been rewritten into a SQL literal.

Parameters:

item -

operandLiteral -

Returns:

rewriteTimestamp

protected String rewriteTimestamp(Timestamp ts)

Rewrites a Timestamp into it's literal representation as known by this SQL dialect. This default implementation returns the JDBC spec's escape syntax for a timestamp: {ts 'yyyy-mm-dd hh:mm:ss.f . . .'}

Parameters:

ts -

Returns:

isScalarFunctionSupported

public boolean isScalarFunctionSupported(ScalarFunction function)

Description copied from interface: IQueryRewriter

Determines whether a specific scalar function is supported by the database or not. If the function is not supported then MetaModel will handle the function on the client side.

Returns:

isAggregateFunctionSupported

public boolean isAggregateFunctionSupported(AggregateFunction function)

Description copied from interface: IQueryRewriter

Determines whether a specific aggregate function is supported by the database or not. If the function is not supported then MetaModel will handle the function on the client side.

Returns:

isFirstRowSupported

public boolean isFirstRowSupported()

Description copied from interface: IQueryRewriter

Gets whether this query rewriter is able to write the "First row" query property to the query string.

Returns:

whether this query rewriter is able to write the "First row" query property to the query string.

isMaxRowsSupported

public boolean isMaxRowsSupported()

Description copied from interface: IQueryRewriter

Gets whether this query rewriter is able to write the "Max rows" query property to the query string.

Returns:

whether this query rewriter is able to write the "Max rows" query property to the query string.

escapeQuotes

public String escapeQuotes(String item)

Description copied from interface: IQueryRewriter

Escapes the quotes within a String literal of a query item.

Returns:

String item with quotes escaped.