org.apache.ignite.cache.query

Class SqlFieldsQuery

java.lang.Object

org.apache.ignite.cache.query.Query<List<?>>

org.apache.ignite.cache.query.SqlFieldsQuery

All Implemented Interfaces:

Serializable

public class SqlFieldsQuery
extends Query<List<?>>

SQL Fields query. This query can return specific fields of data based on SQL 'select' clause, as opposed to SqlQuery, which always returns the whole key and value objects back.

Collocated Flag

Collocation flag is used for optimization purposes. Whenever Ignite executes a distributed query, it sends sub-queries to individual cluster members. If you know in advance that the elements of your query selection are collocated together on the same node, usually based on some affinity-key, Ignite can make significant performance and network optimizations.

For example, in case of Word-Count example, we know that all identical words are processed on the same cluster member, because we use the word itself as affinity key. This allows Ignite to execute the 'limit' clause on the remote nodes and bring back only the small data set specified within the 'limit' clause, instead of the whole query result as would happen in a non-collocated execution.

See Also:

IgniteCache.query(Query), Serialized Form

Field Summary

Fields inherited from class org.apache.ignite.cache.query.Query

DFLT_PAGE_SIZE

Constructor Summary

Constructors

Constructor and Description
SqlFieldsQuery(SqlFieldsQuery qry) Copy constructs SQL fields query.
SqlFieldsQuery(String sql) Constructs SQL fields query.
SqlFieldsQuery(String sql, boolean collocated) Constructs SQL fields query.

Method Summary

Modifier and Type	Method and Description
SqlFieldsQuery	copy()
Object[]	getArgs() Gets SQL arguments.
@Nullable int[]	getPartitions() Gets partitions for query, in ascending order.
@Nullable String	getSchema() Get schema for the query.
String	getSql() Gets SQL clause.
int	getTimeout() Gets the query execution timeout in milliseconds.
boolean	isCollocated() Checks if this query is collocated.
boolean	isDistributedJoins() Check if distributed joins are enabled for this query.
boolean	isEnforceJoinOrder() Checks if join order of tables if enforced.
boolean	isLazy() Gets lazy query execution flag.
boolean	isReplicatedOnly() Deprecated. No longer used as of Apache Ignite 2.8.
SqlFieldsQuery	setArgs(Object... args) Sets SQL arguments.
SqlFieldsQuery	setCollocated(boolean collocated) Sets flag defining if this query is collocated.
SqlFieldsQuery	setDistributedJoins(boolean distributedJoins) Specify if distributed joins are enabled for this query.
SqlFieldsQuery	setEnforceJoinOrder(boolean enforceJoinOrder) Sets flag to enforce join order of tables in the query.
SqlFieldsQuery	setLazy(boolean lazy) Sets lazy query execution flag.
SqlFieldsQuery	setLocal(boolean loc) Sets whether this query should be executed on local node only.
SqlFieldsQuery	setPageSize(int pageSize) Sets optional page size, if 0, then default is used.
SqlFieldsQuery	setPartitions(int... parts) Sets partitions for a query.
SqlFieldsQuery	setReplicatedOnly(boolean replicatedOnly) Deprecated. No longer used as of Apache Ignite 2.8.
SqlFieldsQuery	setSchema(@Nullable String schema) Set schema for the query.
SqlFieldsQuery	setSql(String sql) Sets SQL clause.
SqlFieldsQuery	setTimeout(int timeout, TimeUnit timeUnit) Sets the query execution timeout.
String	toString()

Methods inherited from class org.apache.ignite.cache.query.Query

getPageSize, isLocal, prepare

Methods inherited from class java.lang.Object

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

Constructor Detail

SqlFieldsQuery

public SqlFieldsQuery(SqlFieldsQuery qry)

Copy constructs SQL fields query.

Parameters:

qry - SQL query.

SqlFieldsQuery

public SqlFieldsQuery(String sql)

Constructs SQL fields query.

Parameters:

sql - SQL query.

SqlFieldsQuery

public SqlFieldsQuery(String sql,
                      boolean collocated)

Constructs SQL fields query.

Parameters:

sql - SQL query.

collocated - Collocated flag.

Method Detail

getSql

public String getSql()

Gets SQL clause.

Returns:

SQL clause.

setSql

public SqlFieldsQuery setSql(String sql)

Sets SQL clause.

Parameters:

sql - SQL clause.

Returns:

this For chaining.

getArgs

public Object[] getArgs()

Gets SQL arguments.

Returns:

SQL arguments.

setArgs

public SqlFieldsQuery setArgs(Object... args)

Sets SQL arguments.

Parameters:

args - SQL arguments.

Returns:

this For chaining.

getTimeout

public int getTimeout()

Gets the query execution timeout in milliseconds.

Returns:

Timeout value.

setTimeout

public SqlFieldsQuery setTimeout(int timeout,
                                 TimeUnit timeUnit)

Sets the query execution timeout. Query will be automatically cancelled if the execution timeout is exceeded.

Parameters:

timeout - Timeout value. Zero value disables timeout.

timeUnit - Time unit.

Returns:

this For chaining.

isCollocated

public boolean isCollocated()

Checks if this query is collocated.

Returns:

true If the query is collocated.

setCollocated

public SqlFieldsQuery setCollocated(boolean collocated)

Sets flag defining if this query is collocated. Collocation flag is used for optimization purposes of queries with GROUP BY statements. Whenever Ignite executes a distributed query, it sends sub-queries to individual cluster members. If you know in advance that the elements of your query selection are collocated together on the same node and you group by collocated key (primary or affinity key), then Ignite can make significant performance and network optimizations by grouping data on remote nodes.

Parameters:

collocated - Flag value.

Returns:

this For chaining.

isEnforceJoinOrder

public boolean isEnforceJoinOrder()

Checks if join order of tables if enforced.

Returns:

Flag value.

setEnforceJoinOrder

public SqlFieldsQuery setEnforceJoinOrder(boolean enforceJoinOrder)

Sets flag to enforce join order of tables in the query. If set to true query optimizer will not reorder tables in join. By default is false.

It is not recommended to enable this property until you are sure that your indexes and the query itself are correct and tuned as much as possible but query optimizer still produces wrong join order.

Parameters:

enforceJoinOrder - Flag value.

Returns:

this For chaining.

setDistributedJoins

public SqlFieldsQuery setDistributedJoins(boolean distributedJoins)

Specify if distributed joins are enabled for this query.

Parameters:

distributedJoins - Distributed joins enabled.

Returns:

this For chaining.

isDistributedJoins

public boolean isDistributedJoins()

Check if distributed joins are enabled for this query.

Returns:

true If distributed joins enabled.

setPageSize

public SqlFieldsQuery setPageSize(int pageSize)

Sets optional page size, if 0, then default is used.

Overrides:

setPageSize in class Query<List<?>>

Parameters:

pageSize - Optional page size.

Returns:

this for chaining.

setLocal

public SqlFieldsQuery setLocal(boolean loc)

Sets whether this query should be executed on local node only.

Overrides:

setLocal in class Query<List<?>>

Parameters:

loc - Local flag.

Returns:

this for chaining.

setReplicatedOnly

@Deprecated
public SqlFieldsQuery setReplicatedOnly(boolean replicatedOnly)

Deprecated. No longer used as of Apache Ignite 2.8.

Specify if the query contains only replicated tables. This is a hint for potentially more effective execution.

Parameters:

replicatedOnly - The query contains only replicated tables.

Returns:

this For chaining.

isReplicatedOnly

@Deprecated
public boolean isReplicatedOnly()

Deprecated. No longer used as of Apache Ignite 2.8.

Check is the query contains only replicated tables.

Returns:

true If the query contains only replicated tables.

setLazy

public SqlFieldsQuery setLazy(boolean lazy)

Sets lazy query execution flag.

By default Ignite attempts to fetch the whole query result set to memory and send it to the client. For small and medium result sets this provides optimal performance and minimize duration of internal database locks, thus increasing concurrency.

If result set is too big to fit in available memory this could lead to excessive GC pauses and even OutOfMemoryError. Use this flag as a hint for Ignite to fetch result set lazily, thus minimizing memory consumption at the cost of moderate performance hit.

Defaults to false, meaning that the whole result set is fetched to memory eagerly.

Parameters:

lazy - Lazy query execution flag.

Returns:

this For chaining.

isLazy

public boolean isLazy()

Gets lazy query execution flag.

See setLazy(boolean) for more information.

Returns:

Lazy flag.

getPartitions

@Nullable
public @Nullable int[] getPartitions()

Gets partitions for query, in ascending order.

setPartitions

public SqlFieldsQuery setPartitions(@Nullable
                                    int... parts)

Sets partitions for a query. The query will be executed only on nodes which are primary for specified partitions.

Note what passed array'll be sorted in place for performance reasons, if it wasn't sorted yet.

Parameters:

parts - Partitions.

Returns:

this for chaining.

getSchema

@Nullable
public @Nullable String getSchema()

Get schema for the query. If not set, current cache name is used, which means you can omit schema name for tables within the current cache.

Returns:

Schema. Null if schema is not set.

setSchema

public SqlFieldsQuery setSchema(@Nullable
                                @Nullable String schema)

Set schema for the query. If not set, current cache name is used, which means you can omit schema name for tables within the current cache.

Parameters:

schema - Schema. Null to unset schema.

Returns:

this for chaining.

copy

public SqlFieldsQuery copy()

Returns:

Copy of this query.

toString

public String toString()

Overrides:

toString in class Query<List<?>>