org.apache.cayenne.query.QueryMetadata Maven / Gradle / Ivy
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package org.apache.cayenne.query;
import java.util.List;
import java.util.Map;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.DbEntity;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.Procedure;
import org.apache.cayenne.reflect.ClassDescriptor;
/**
* Provides a common interface for accessing query metadata.
*
* @since 1.2
*/
public interface QueryMetadata {
/**
* Defines the name of the property for the query {@link #getFetchLimit() fetch limit}
* .
*/
public static final String FETCH_LIMIT_PROPERTY = "cayenne.GenericSelectQuery.fetchLimit";
/**
* Defines default query fetch limit, which is zero, meaning that all matching rows
* should be fetched.
*/
public static final int FETCH_LIMIT_DEFAULT = 0;
/**
* Defines the name of the property for the query {@link #getFetchOffset() fetch
* offset}.
*
* @since 3.0
*/
public static final String FETCH_OFFSET_PROPERTY = "cayenne.GenericSelectQuery.fetchOffset";
/**
* Defines default query fetch start index, which is 0, meaning that matching rows
* selected starting from the first.
*
* @since 3.0
*/
public static final int FETCH_OFFSET_DEFAULT = 0;
/**
* Defines the name of the property for the query {@link #getPageSize() page size}.
*/
public static final String PAGE_SIZE_PROPERTY = "cayenne.GenericSelectQuery.pageSize";
/**
* Defines default query page size, which is zero for no pagination.
*/
public static final int PAGE_SIZE_DEFAULT = 0;
public static final String FETCHING_DATA_ROWS_PROPERTY = "cayenne.GenericSelectQuery.fetchingDataRows";
public static final boolean FETCHING_DATA_ROWS_DEFAULT = false;
/**
* @since 3.0
*/
public static final String CACHE_STRATEGY_PROPERTY = "cayenne.GenericSelectQuery.cacheStrategy";
/**
* @since 3.0
*/
public static final String CACHE_GROUPS_PROPERTY = "cayenne.GenericSelectQuery.cacheGroups";
/**
* Defines the name of the property for the query {@link #getStatementFetchSize() fetch
* size}.
*
* @since 3.0
*/
public static final String STATEMENT_FETCH_SIZE_PROPERTY = "cayenne.GenericSelectQuery.statementFetchSize";
/**
* Defines default query fetch start index, which is 0, meaning that matching rows
* selected starting from the first.
*
* @since 3.0
*/
public static final int STATEMENT_FETCH_SIZE_DEFAULT = 0;
/**
* @since 3.0
*/
ClassDescriptor getClassDescriptor();
/**
* Returns an ObjEntity associated with a query or null if no such entity exists.
*/
ObjEntity getObjEntity();
/**
* Returns a DbEntity associated with a query or null if no such entity exists.
*/
DbEntity getDbEntity();
/**
* Returns a Procedure associated with a query or null if no such procedure exists.
*/
Procedure getProcedure();
/**
* Returns a DataMap associated with a query or null if no such DataMap exists.
*/
DataMap getDataMap();
/**
* Returns a caching strategy for this query.
*
* @since 3.0
*/
QueryCacheStrategy getCacheStrategy();
/**
* Returns a String that uniquely identifies this query for the purposes of result
* caching. If null is returned, no caching is performed.
*/
String getCacheKey();
/**
* Returns an optional array of cache "groups". Cache groups allow to invalidate query
* caches in bulk on different events. Usually the first group in the array is
* considered to be the "main" group that is used for declarative cache invalidation
* with some cache providers.
*
* @since 3.0
*/
String[] getCacheGroups();
/**
* Returns true if this query should produce a list of data rows as
* opposed to DataObjects, false for DataObjects. This is a hint to
* QueryEngine executing this query.
*/
boolean isFetchingDataRows();
/**
* Returns true if the query results should replace any currently cached
* values, returns false otherwise. If {@link #isFetchingDataRows()}
* returns true, this setting is not applicable and has no effect.
*/
boolean isRefreshingObjects();
/**
* Returns query page size. Page size is a hint to Cayenne that query should be
* performed page by page, instead of retrieving all results at once. If the value
* returned is less than or equal to zero, no paging should occur.
*/
int getPageSize();
/**
* Specifies a start of a range when fetching a subset of records.
*
* @since 3.0
*/
int getFetchOffset();
/**
* Returns the limit on the maximum number of records that can be returned by this
* query. If the actual number of rows in the result exceeds the fetch limit, they
* will be discarded. One possible use of fetch limit is using it as a safeguard
* against large result sets that may lead to the application running out of memory,
* etc. If a fetch limit is greater or equal to zero, all rows will be returned.
*
* @return the limit on the maximum number of records that can be returned by this
* query
*/
int getFetchLimit();
/**
* Returns a query that originated this query. Originating query is a query whose
* result is needed to obtain the result of the query owning this metadata. Most often
* than not the returned value is null. One example of non-null originating query is a
* query for a range of objects in a previously fetched paginated list. The query that
* fetched the original paginated list is an "originated" query. It may be used to
* restore a list that got lost due to a cache overflow, etc.
*
* @since 3.0
*/
Query getOrginatingQuery();
/**
* Returns a root node of prefetch tree used by this query, or null of no prefetches
* are configured.
*/
PrefetchTreeNode getPrefetchTree();
/**
* Returns a map of aliases vs. expression subpaths that is used to build split joins.
*
* @since 3.0
*/
Map getPathSplitAliases();
/**
* Returns an optional list of result set mapping hints. Elements in the list can be
* either {@link EntityResultSegment} or {@link ScalarResultSegment}. The returned
* list can be null.
*
* @since 3.0
*/
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