Title
c
cl
09/01/2022, 3:03 PMHi, I am running 6.5.1 jdk8 ILP java client. For Sender class, I need to have a better way to handle null. Some fields in the same object could be null for int, short, or long column. I am looking for a better way dynamically to skip some columns which contain null value.
a
Andrey Pechkurov
09/01/2022, 3:19 PMHello
You could simply skip those columns. The inserted row would get null values for the skipped columns then
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cl
09/01/2022, 3:21 PMright, but I need to handle all cases. So, I don't want to rebuild all column call every time.
a
Andrey Pechkurov
09/01/2022, 3:23 PMif (objectLongValue != null) {
sender.longColumn("my_long_col", objectLongValue);
}c
cl
09/01/2022, 3:24 PMwill it create multiple row if I check for each column.
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Andrey Pechkurov
09/01/2022, 3:25 PMNo, it'll be the same row. The row gets "finalized" only when you call at/atNow
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cl
09/01/2022, 3:26 PMgreat. Let me give it a try. Thanks a lot.
sender.table("connections")
.timestampColumn("ts", Os.currentTimeNanos())
.stringColumn("tenantid", "localhost-08312022")
.longColumn("id", conn.getId())
if (conn.getMachine() != null)
sender.table("connections").stringColumn("machine", conn.getMachine());
if (conn.getPort() != null)
sender.table("connections").longColumn("port", conn.getPort());
sender.table("connections").atNow();The second null check is trying to append more columns, but it failed with error
io.questdb.cutlass.line.LineSenderException: duplicated table. call <http://sender.at|sender.at>() or sender.atNow() to finish the current row firsta
Andrey Pechkurov
09/01/2022, 4:16 PMYou should remove extra .table() calls
sender.table("connections")
.timestampColumn("ts", Os.currentTimeNanos())
.stringColumn("tenantid", "localhost-08312022")
.longColumn("id", conn.getId())
if (conn.getMachine() != null)
sender.stringColumn("machine", conn.getMachine());
if (conn.getPort() != null)
sender.longColumn("port", conn.getPort());
sender.atNow();c
cl
09/01/2022, 4:23 PMI am able to by-pass exception, but no row in db. I do use sender.flush() right away.
a
Andrey Pechkurov
09/01/2022, 4:24 PMYou should call .flush() for a batch of rows, ideally. This would bring the best performance. But for local testing it's fine to call it on each row individually
As for the inserted rows becoming visible with a delay, we have a concept of "commit lag". Please check this doc page:
https://questdb.io/docs/guides/out-of-order-commit-lag
c
cl
09/01/2022, 4:26 PMok, but row does not create in questdb.
a
Andrey Pechkurov
09/01/2022, 4:27 PMThat's because you need to call .flush().
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cl
09/01/2022, 4:30 PMyes, I did after I set atNow().
Thanks Andrey. I have a bug in my code. It works now.