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.

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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.

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Constant Field Values

LOCAL_CACHE_REFRESH

static final java.lang.String LOCAL_CACHE_REFRESH

Same as LOCAL_CACHE, only forcing any current cache expiration.

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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.

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Constant Field Values

SHARED_CACHE_REFRESH

static final java.lang.String SHARED_CACHE_REFRESH

Same as SHARED_CACHE, only forcing any current cache expiration.

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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.

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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.

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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.

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Constant Field Values

PAGE_SIZE_DEFAULT

static final int PAGE_SIZE_DEFAULT

Defines default query page size, which is zero for no pagination.

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Constant Field Values

FETCHING_DATA_ROWS_PROPERTY

static final java.lang.String FETCHING_DATA_ROWS_PROPERTY

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Constant Field Values

FETCHING_DATA_ROWS_DEFAULT

static final boolean FETCHING_DATA_ROWS_DEFAULT

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Constant Field Values

REFRESHING_OBJECTS_PROPERTY

static final java.lang.String REFRESHING_OBJECTS_PROPERTY

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Constant Field Values

REFRESHING_OBJECTS_DEFAULT

static final boolean REFRESHING_OBJECTS_DEFAULT

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Constant Field Values

RESOLVING_INHERITED_PROPERTY

static final java.lang.String RESOLVING_INHERITED_PROPERTY

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Constant Field Values

RESOLVING_INHERITED_DEFAULT

static final boolean RESOLVING_INHERITED_DEFAULT

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Constant Field Values

CACHE_POLICY_PROPERTY

static final java.lang.String CACHE_POLICY_PROPERTY

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Constant Field Values

CACHE_POLICY_DEFAULT

static final java.lang.String CACHE_POLICY_DEFAULT

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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.