#include <child-query.h>

Collaboration diagram for impala::ChildQuery:

Public Member Functions
	ChildQuery (const std::string &query, ImpalaServer::QueryExecState parent_exec_state, ImpalaServer parent_server)

	ChildQuery (const ChildQuery &other)

ChildQuery &	operator= (const ChildQuery &other)

Status	ExecAndFetch ()
	Executes this child query through HiveServer2 and fetches all its results. More...

void	Cancel ()

const apache::hive::service::cli::thrift::TTableSchema &	result_schema ()

const apache::hive::service::cli::thrift::TRowSet &	result_data ()

Static Public Attributes
static const string	PARENT_QUERY_OPT = "impala.parent_query_id"

Private Member Functions
void	SetQueryOptions (const TQueryOptions &parent_options, apache::hive::service::cli::thrift::TExecuteStatementReq *exec_stmt_req)

Status	IsCancelled ()

Private Attributes
std::string	query_
	SQL string to be executed. More...

ImpalaServer::QueryExecState *	parent_exec_state_

ImpalaServer *	parent_server_
	Parent Impala server used for executing this child query. Not owned. More...

apache::hive::service::cli::thrift::TGetResultSetMetadataResp	meta_resp_
	Result metadata and result rows of query. More...

apache::hive::service::cli::thrift::TFetchResultsResp	fetch_resp_

apache::hive::service::cli::thrift::TOperationHandle	hs2_handle_
	HS2 query handle. Set in ExecChildQuery(). More...

boost::mutex	lock_
	Protects is_running_ and is_cancelled_ to ensure idempotent cancellations. More...

bool	is_running_

bool	is_cancelled_
	Indicates whether this child query has been cancelled. Set in Cancel(). More...

Detailed Description

Child queries are used for implementing statements that consist of one or several query statements (e.g., compute stats) that require independent query handles for fetching results. Such queries are 'children' of a parent exec state in the sense that they are executed in the same session and that child queries are cancelled if the parent is cancelled (but not necessarily vice versa). For simplicity and consistency, child queries are always executed via HiveServer2, regardless of whether the parent session is Beeswax or HiveServer2. Parent queries are expected to call ExecAndWait() of a child query in a separate thread, and then join that thread to wait for child-query completion. The parent QueryExecState is independent of the child query's QueryExecState, with the exception that the child query selectively checks the parent's status for failure/cancellation detection. Child queries should never call into their parent's QueryExecState to avoid deadlock. TODO: Compute stats is the only stmt that requires child queries. Once the CatalogService performs background stats gathering the concept of child queries will likely become obsolete. Remove this class and all child-query related code.

Definition at line 47 of file child-query.h.

Constructor & Destructor Documentation

impala::ChildQuery::ChildQuery	(	const std::string &	query,
		ImpalaServer::QueryExecState *	parent_exec_state,
		ImpalaServer *	parent_server
	)

inline

Definition at line 49 of file child-query.h.

References parent_exec_state_, parent_server_, and query_.

impala::ChildQuery::ChildQuery ( const ChildQuery & other )

inline

Allow child queries to be added to std collections. (boost::mutex's operator= and copy c'tor are private)

Definition at line 63 of file child-query.h.

Member Function Documentation

void impala::ChildQuery::Cancel ( )

Cancels and closes the given child query if it is running. Sets is_cancelled_. Child queries can be cancelled by the parent query through QueryExecState::Cancel(). Child queries should never cancel their parent to avoid deadlock (but the parent query may decide to cancel itself based on a non-OK status from a child query). Note that child queries have a different QueryExecState than their parent query, so cancellation of a child query does not call into the parent's QueryExecState.

Definition at line 158 of file child-query.cc.

References impala::lock_, and VLOG_QUERY.

Referenced by impala::ImpalaServer::QueryExecState::Cancel().

Status impala::ChildQuery::ExecAndFetch ( )

Executes this child query through HiveServer2 and fetches all its results.

Definition at line 32 of file child-query.cc.

References impala::lock_, impala::Status::ok(), impala::PrintId(), RETURN_IF_ERROR, impala::ImpalaServer::TUniqueIdToTHandleIdentifier(), and VLOG_QUERY.

Status impala::ChildQuery::IsCancelled ( )

private

Returns Status::Cancelled if this child query has been cancelled, otherwise OK. Acquires lock_.

Definition at line 179 of file child-query.cc.

References impala::Status::CANCELLED, impala::lock_, and impala::Status::OK.

ChildQuery& impala::ChildQuery::operator= ( const ChildQuery & other )

inline

Allow child queries to be added to std collections. (boost::mutex's operator= and copy c'tor are private)

Definition at line 72 of file child-query.h.

References is_cancelled_, is_running_, parent_exec_state_, parent_server_, and query_.

const apache::hive::service::cli::thrift::TRowSet& impala::ChildQuery::result_data ( )

inline

Definition at line 96 of file child-query.h.

References fetch_resp_.

const apache::hive::service::cli::thrift::TTableSchema& impala::ChildQuery::result_schema ( )

inline

Definition at line 92 of file child-query.h.

References meta_resp_.

void impala::ChildQuery::SetQueryOptions	(	const TQueryOptions &	parent_options,
		apache::hive::service::cli::thrift::TExecuteStatementReq *	exec_stmt_req
	)

private

Sets the query options from the parent query in child's HS2 request. TODO: Consider moving this function into a more appropriate place.

Definition at line 119 of file child-query.cc.

References BATCH_SIZE, and SET_QUERY_OPTION.

Member Data Documentation

apache::hive::service::cli::thrift::TFetchResultsResp impala::ChildQuery::fetch_resp_

private

Definition at line 126 of file child-query.h.

Referenced by result_data().

apache::hive::service::cli::thrift::TOperationHandle impala::ChildQuery::hs2_handle_

private

HS2 query handle. Set in ExecChildQuery().

Definition at line 129 of file child-query.h.

bool impala::ChildQuery::is_cancelled_

private

Indicates whether this child query has been cancelled. Set in Cancel().

Definition at line 139 of file child-query.h.

Referenced by operator=().

bool impala::ChildQuery::is_running_

private

Indicates whether this query is running. False if the query has not started yet or if the query has finished either successfully or because of an error.

Definition at line 136 of file child-query.h.

Referenced by operator=().

boost::mutex impala::ChildQuery::lock_

private

Protects is_running_ and is_cancelled_ to ensure idempotent cancellations.

Definition at line 132 of file child-query.h.

apache::hive::service::cli::thrift::TGetResultSetMetadataResp impala::ChildQuery::meta_resp_

private

Result metadata and result rows of query.

Definition at line 125 of file child-query.h.

Referenced by result_schema().

ImpalaServer::QueryExecState* impala::ChildQuery::parent_exec_state_

private

Execution state of parent query. Used to synchronize and propagate parent cancellations/failures to this child query. Not owned.

Definition at line 119 of file child-query.h.

Referenced by ChildQuery(), and operator=().

const string impala::ChildQuery::PARENT_QUERY_OPT = "impala.parent_query_id"

static

The key in the HS2 conf overlay which indicates to the executing ImpalaServer that this query is a child query.

Definition at line 102 of file child-query.h.

ImpalaServer* impala::ChildQuery::parent_server_

private

Parent Impala server used for executing this child query. Not owned.

Definition at line 122 of file child-query.h.

Referenced by ChildQuery(), and operator=().

std::string impala::ChildQuery::query_

private

SQL string to be executed.

Definition at line 115 of file child-query.h.

Referenced by ChildQuery(), and operator=().

The documentation for this class was generated from the following files:

be/src/service/child-query.h
be/src/service/child-query.cc

Public Member Functions

Static Public Attributes

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation