google::cloud::spanner::QueryPartition Class Reference

The QueryPartition class is a regular type that represents a single slice of a parallel SQL read. More...

#include <google/cloud/spanner/query_partition.h>

Public Member Functions
	QueryPartition ()=default
	Constructs an instance of QueryPartition that is not associated with any SqlStatement. More...
SqlStatement const &	sql_statement () const
	Accessor for the SqlStatement associated with this QueryPartition. More...
Copy and move
	QueryPartition (QueryPartition const &)=default
	QueryPartition (QueryPartition &&)=default
QueryPartition &	operator= (QueryPartition const &)=default
QueryPartition &	operator= (QueryPartition &&)=default

Friends
StatusOr< std::string >	SerializeQueryPartition (QueryPartition const &query_partition)
	Serializes an instance of QueryPartition to a string of bytes. More...
StatusOr< QueryPartition >	DeserializeQueryPartition (std::string const &serialized_query_partition)
	Deserializes the provided string into a QueryPartition. More...
Equality
bool	operator== (QueryPartition const &a, QueryPartition const &b)
bool	operator!= (QueryPartition const &a, QueryPartition const &b)

Detailed Description

The QueryPartition class is a regular type that represents a single slice of a parallel SQL read.

Instances of QueryPartition are created by Client::PartitionQuery. Once created, QueryPartition objects can be serialized, transmitted to separate processes, and used to read data in parallel using Client::ExecuteQuery. If data_boost is set, those requests will be executed using the independent compute resources of Cloud Spanner Data Boost.

Constructor & Destructor Documentation

QueryPartition() [1/3]

google::cloud::spanner::QueryPartition::QueryPartition ( )

default

Constructs an instance of QueryPartition that is not associated with any SqlStatement.

QueryPartition() [2/3]

google::cloud::spanner::QueryPartition::QueryPartition ( QueryPartition const &  )

default

QueryPartition() [3/3]

google::cloud::spanner::QueryPartition::QueryPartition ( QueryPartition &&  )

default

Member Function Documentation

operator=() [1/2]

QueryPartition & google::cloud::spanner::QueryPartition::operator= ( QueryPartition &&  )

default

operator=() [2/2]

QueryPartition & google::cloud::spanner::QueryPartition::operator= ( QueryPartition const &  )

default

sql_statement()

SqlStatement const & google::cloud::spanner::QueryPartition::sql_statement ( ) const

inline

Accessor for the SqlStatement associated with this QueryPartition.

Friends And Related Function Documentation

DeserializeQueryPartition

StatusOr< QueryPartition > DeserializeQueryPartition ( std::string const &  serialized_query_partition )

friend

Deserializes the provided string into a QueryPartition.

The serialized_query_partition argument must be a string that was previously returned by a call to SerializeQueryPartition().

Note

The serialized string may contain NUL and other non-printable characters. Therefore, callers should avoid formatted IO functions that may incorrectly reformat the string data.

Parameters

serialized_query_partition

Example

  google::cloud::StatusOr<google::cloud::spanner::QueryPartition>
  ReceiveQueryPartitionFromRemoteMachine() {
    std::string serialized_partition = Receive();
    return google::cloud::spanner::DeserializeQueryPartition(
        serialized_partition);
  }

operator!=

bool operator!= ( QueryPartition const &  a, QueryPartition const &  b  )

friend

operator==

bool operator== ( QueryPartition const &  a, QueryPartition const &  b  )

friend

SerializeQueryPartition

StatusOr< std::string > SerializeQueryPartition ( QueryPartition const &  query_partition )

friend

Serializes an instance of QueryPartition to a string of bytes.

The serialized string of bytes is suitable for writing to disk or transmission to another process.

Note

The serialized string may contain NUL and other non-printable characters. Therefore, callers should avoid formatted IO functions that may incorrectly reformat the string data.

Parameters

query_partition

- instance to be serialized.

Example

    namespace spanner = ::google::cloud::spanner;
    google::cloud::StatusOr<std::string> serialized_partition =
        spanner::SerializeQueryPartition(partition);
    if (!serialized_partition) throw std::move(serialized_partition).status();
    std::string const& bytes = *serialized_partition;
    // `bytes` contains the serialized data, which may contain NULs and other
    // non-printable characters.
    SendBinaryStringData(bytes);