Question: How to fetch Array(UInt64) values?

[gothug]

When trying to fetch the column of type Array(UInt64) via Java Http Client, the values in the client's response are of ClickHouseLongArrayValue type, but they do not represent unsigned long values correctly.

Example:

ClickHouseNode endpoint = ClickHouseNode.of("https://localhost");

try (ClickHouseClient client = ClickHouseClient.newInstance(ClickHouseProtocol.HTTP);
ClickHouseResponse response = client.connect(endpoint)
.format(ClickHouseFormat.RowBinaryWithNamesAndTypes)
.query("select array(toUInt64(9223372036854775808))").executeAndWait()) {

for (ClickHouseRecord r : response.records()) {
    String result = String.valueOf(r.getValue(0).asArray()[0]);
    System.out.println(result);
}

}

The result printed is -9223372036854775808, which is not the correct UInt64 number value that was inside the array (it becomes a negative number).

How could I parse the Array(UInt64) columns from CH to get correct results?

Thanks in advance.

[zhicwu]

Sorry for the inconvenience. UInt64 is mapped to long in Java mainly for performance reason. As of now, you'll have to convert negative value to BigInteger, for example: BigInteger.valueOf(longValue).abs().

I'll enhance ClickHouseLongArrayValue.asArray(Class) method to make it simpler, so that you only need to r.getValue(0).asArray(BigInteger.class).

[gothug]

Hi, thanks for a quick reply!

So, the current workaround that seems to work is something like this:

BigInteger bigInt = BigInteger.valueOf(longValue)
BigInteger twoPower64 = BigInteger.valueOf(2).pow(64)
if (bigInt.compareTo(BigInteger.ZERO) < 0) bigInt.add(twoPower64) else bigInt

Will wait for the fix in next releases. Thank you!

[ashishrajak]

please some one tell me how to connect to clickhouse using java client