org.apache.cayenne.query
Interface QueryMetadata


public interface QueryMetadata

Provides a common interface for accessing query metadata.

Since:
1.2
Author:
Andrus Adamchik

Field Summary
static java.lang.String CACHE_POLICY_DEFAULT
           
static java.lang.String CACHE_POLICY_PROPERTY
           
static int FETCH_LIMIT_DEFAULT
          Defines default query fetch limit, which is zero, meaning that all matching rows should be fetched.
static java.lang.String FETCH_LIMIT_PROPERTY
          Defines the name of the property for the query fetch limit.
static boolean FETCHING_DATA_ROWS_DEFAULT
           
static java.lang.String FETCHING_DATA_ROWS_PROPERTY
           
static java.lang.String LOCAL_CACHE
          A cache policy ruling that query results shall be cached separately for each DataContext.
static java.lang.String LOCAL_CACHE_REFRESH
          Same as LOCAL_CACHE, only forcing any current cache expiration.
static java.lang.String NO_CACHE
          A cache policy that disables caching of query results.
static int PAGE_SIZE_DEFAULT
          Defines default query page size, which is zero for no pagination.
static java.lang.String PAGE_SIZE_PROPERTY
          Defines the name of the property for the query page size.
static boolean REFRESHING_OBJECTS_DEFAULT
           
static java.lang.String REFRESHING_OBJECTS_PROPERTY
           
static boolean RESOLVING_INHERITED_DEFAULT
           
static java.lang.String RESOLVING_INHERITED_PROPERTY
           
static java.lang.String SHARED_CACHE
          A cache policy ruling that query results shall be stored in a shared cache accessible by all DataContexts.
static java.lang.String SHARED_CACHE_REFRESH
          Same as SHARED_CACHE, only forcing any current cache expiration.
 
Method Summary
 java.lang.String getCacheKey()
          Returns a String that uniquely identifies this query for the purposes of result caching.
 java.lang.String getCachePolicy()
          Returns query cache policy, which can be one of NO_CACHE, LOCAL_CACHE, or SHARED_CACHE.
 DataMap getDataMap()
          Returns a DataMap associated with a query or null if no such DataMap exists.
 DbEntity getDbEntity()
          Returns a DbEntity associated with a query or null if no such entity exists.
 int getFetchLimit()
          Returns the limit on the maximium number of records that can be returned by this query.
 int getFetchStartIndex()
          Specifies a start of a range when fetching a subset of records.
 ObjEntity getObjEntity()
          Returns an ObjEntity associated with a query or null if no such entity exists.
 int getPageSize()
          Returns query page size.
 PrefetchTreeNode getPrefetchTree()
          Returns a root node of prefetch tree used by this query, or null of no prefetches are configured.
 Procedure getProcedure()
          Returns a Procedure associated with a query or null if no such procedure exists.
 boolean isFetchingDataRows()
          Returns true if this query should produce a list of data rows as opposed to DataObjects, false for DataObjects.
 boolean isRefreshingObjects()
          Returns true if the query results should replace any currently cached values, returns false otherwise.
 boolean isResolvingInherited()
          Returns true if objects fetched via this query should be fully resolved according to the inheritance hierarchy.
 

Field Detail

NO_CACHE

static final java.lang.String NO_CACHE
A cache policy that disables caching of query results.

See Also:
Constant Field Values

LOCAL_CACHE

static final java.lang.String LOCAL_CACHE
A cache policy ruling that query results shall be cached separately for each DataContext.

See Also:
Constant Field Values

LOCAL_CACHE_REFRESH

static final java.lang.String LOCAL_CACHE_REFRESH
Same as LOCAL_CACHE, only forcing any current cache expiration.

See Also:
Constant Field Values

SHARED_CACHE

static final java.lang.String SHARED_CACHE
A cache policy ruling that query results shall be stored in a shared cache accessible by all DataContexts.

See Also:
Constant Field Values

SHARED_CACHE_REFRESH

static final java.lang.String SHARED_CACHE_REFRESH
Same as SHARED_CACHE, only forcing any current cache expiration.

See Also:
Constant Field Values

FETCH_LIMIT_PROPERTY

static final java.lang.String FETCH_LIMIT_PROPERTY
Defines the name of the property for the query fetch limit.

See Also:
Constant Field Values

FETCH_LIMIT_DEFAULT

static final int FETCH_LIMIT_DEFAULT
Defines default query fetch limit, which is zero, meaning that all matching rows should be fetched.

See Also:
Constant Field Values

PAGE_SIZE_PROPERTY

static final java.lang.String PAGE_SIZE_PROPERTY
Defines the name of the property for the query page size.

See Also:
Constant Field Values

PAGE_SIZE_DEFAULT

static final int PAGE_SIZE_DEFAULT
Defines default query page size, which is zero for no pagination.

See Also:
Constant Field Values

FETCHING_DATA_ROWS_PROPERTY

static final java.lang.String FETCHING_DATA_ROWS_PROPERTY
See Also:
Constant Field Values

FETCHING_DATA_ROWS_DEFAULT

static final boolean FETCHING_DATA_ROWS_DEFAULT
See Also:
Constant Field Values

REFRESHING_OBJECTS_PROPERTY

static final java.lang.String REFRESHING_OBJECTS_PROPERTY
See Also:
Constant Field Values

REFRESHING_OBJECTS_DEFAULT

static final boolean REFRESHING_OBJECTS_DEFAULT
See Also:
Constant Field Values

RESOLVING_INHERITED_PROPERTY

static final java.lang.String RESOLVING_INHERITED_PROPERTY
See Also:
Constant Field Values

RESOLVING_INHERITED_DEFAULT

static final boolean RESOLVING_INHERITED_DEFAULT
See Also:
Constant Field Values

CACHE_POLICY_PROPERTY

static final java.lang.String CACHE_POLICY_PROPERTY
See Also:
Constant Field Values

CACHE_POLICY_DEFAULT

static final java.lang.String CACHE_POLICY_DEFAULT
See Also:
Constant Field Values
Method Detail

getObjEntity

ObjEntity getObjEntity()
Returns an ObjEntity associated with a query or null if no such entity exists.


getDbEntity

DbEntity getDbEntity()
Returns a DbEntity associated with a query or null if no such entity exists.


getProcedure

Procedure getProcedure()
Returns a Procedure associated with a query or null if no such procedure exists.


getDataMap

DataMap getDataMap()
Returns a DataMap associated with a query or null if no such DataMap exists.


getCachePolicy

java.lang.String getCachePolicy()
Returns query cache policy, which can be one of NO_CACHE, LOCAL_CACHE, or SHARED_CACHE. NO_CACHE is generally a default policy.


getCacheKey

java.lang.String getCacheKey()
Returns a String that uniquely identifies this query for the purposes of result caching. If null is returned, no caching is performed.


isFetchingDataRows

boolean isFetchingDataRows()
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.


isRefreshingObjects

boolean isRefreshingObjects()
Returns true if the query results should replace any currently cached values, returns false otherwise. If isFetchingDataRows()returns true, this setting is not applicable and has no effect.


isResolvingInherited

boolean isResolvingInherited()
Returns true if objects fetched via this query should be fully resolved according to the inheritance hierarchy.


getPageSize

int getPageSize()
Returns query page size. Page size is a hint to Cayenne that query should be performed page by page, instead of retrieveing all results at once. If the value returned is less than or equal to zero, no paging should occur.


getFetchStartIndex

int getFetchStartIndex()
Specifies a start of a range when fetching a subset of records. The last index is determined by getFetchLimit().


getFetchLimit

int getFetchLimit()
Returns the limit on the maximium 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.

Returns:
the limit on the maximium number of records that can be returned by this query

getPrefetchTree

PrefetchTreeNode getPrefetchTree()
Returns a root node of prefetch tree used by this query, or null of no prefetches are configured.



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