Selecting elements of nested array #43
Description
Given table:
CREATE TABLE IF NOT EXISTS maps.multiarray
(
`arr` Array(Array(UInt64))
)
ENGINE = Memory;with single row:
INSERT INTO maps.multiarray VALUES ([[0,1,2,3,4,5], [100, 200], [10,20, 50, 70]]);I am trying to run select, using code similar to what is written at test:
string SELECT_QUERY = "SELECT arr FROM maps.multiarray";
client.Select(SELECT_QUERY, [](const Block& block)
{
if (block.GetRowCount() == 0) {
return;
}
for (size_t c = 0; c < block.GetRowCount(); ++c) {
auto col = block[0]->As<ColumnArray>()->GetAsColumn(c);
cout << col->Size() << endl;
cout << "[";
for (size_t i = 0; i < col->Size(); ++i) {
auto col2 = col->As<ColumnArray>()->GetAsColumn(i);
for (size_t j = 0; j < col2->Size(); ++j) {
cout << (int)(*col2->As<ColumnUInt64>())[j];
if (j + 1 != col2->Size()) {
cout << " ";
}
}
}
std::cout << "]" << std::endl;
}
});And as a result got only this kind of output:
1
[0]While I was expecting to have something like that:
5
[0 1 2 3 4 5]
2
[100 200]
4
[10 20 50 70]I've tried to access exact same table using client in other languages and it seems to work as expected:
from clickhouse_driver import connect
conn = connect('clickhouse://localhost')
cursor = conn.cursor()
cursor.execute('SELECT * FROM maps.multiarray')
cursor.fetchall()
[([[0, 1, 2, 3, 4, 5], [100, 200], [10, 20, 50, 70]],)]I've also saw similar issue within alternative(?) implementation - here.
I can sort of work-around it by issuing first SELECT length(arr) FROM maps.multiarray with subsequent series of calls select arrayElement(arr, idx) from maps.multiarray;
But it is not clear is it limitation of existing client or I just miss something important in my implementation?