QueryResult and QuerySummary

QueryResult captures all information related to the execution of a query. Each returned tuple is wrapped into a FlatTuple where each entry is wrapped as a Value. You can also obtain a QuerySummary from a QueryResult, to learn profiling information, such as execution time, about the query you executed.

Example

unique_ptr<QueryResult> result = connection.query("MATCH (a:person) RETURN COUNT(*);");
if (!result->isSuccess()) {
    std::cout << result->getErrorMessage() << endl;
}
while (result->hasNext()) {
    auto row = result->getNext();
    std::cout << row->getResultValue(0)->getInt64Val() << std::endl;
}

Available APIs

class kuzu::main::QueryResult

QueryResult stores the result of a query execution.

getColumnDataTypes

std::vector<common::DataType> getColumnDataTypes ()

Returns:

• dataType of each column in query result.

getColumnNames

std::vector<std::string> getColumnNames ()

Returns:

• name of each column in query result.

getErrorMessage

std::string getErrorMessage ()

Returns:

• error message of the query execution if the query fails.

getNext

std::shared_ptr<processor::FlatTuple> getNext ()

Returns:

• next flat tuple in the query result.

getNumColumns

size_t getNumColumns ()

Returns:

• number of columns in query result.

getNumTuples

uint64_t getNumTuples ()

Returns:

• num of tuples in query result.

getQuerySummary

QuerySummary* getQuerySummary ()

Returns:

• query summary which stores the execution time, compiling time, plan and query options.

bool hasNext ()

Returns:

• whether there are more tuples to read.

isSuccess

bool isSuccess ()

Returns:

• query is executed successfully or not.

writeToCSV

void writeToCSV (const std::string & fileName, char delimiter = ',', char escapeCharacter = ''', char newline = 'n')

writes the query result to a csv file.

Parameters

• fileName name of the csv file.
• delimiter delimiter of the csv file.
• escapeCharacter escape character of the csv file.
• newline newline character of the csv file.

class kuzu::main::QuerySummary

QuerySummary stores the execution time, plan, compiling time and query options of a query.

getCompilingTime

double getCompilingTime ()

Returns:

• query compiling time.

getExecutionTime

double getExecutionTime ()

Returns:

• query execution time.

getPlan

std::string getPlan ()

Returns:

• physical plan for query in string format.