Hi, I'm new here, I'm trying to use knime for my master thesis (twitter data analisys) in particular I need to perform some basic k-means clustering over tweet features that a parser daemon measures.
Now, I don't need to parse all the data for that, but just a sample.
I considered using a row sampling node, but I wander if there is a way to just use a LIMIT clause in the sql query. I tried to just add "LIMIT 0,1000" to the sql query both in database connector and database reader, but if I click "apply" it gets a red dot.
Is there a way to avoid downloading everything (best if with slq LIMIT clause)?
Thank you for your time and attention!
The read dot should also show you the reason in its tooltip. In your case I believe the SQL syntax is wrong, limit only take one argument (the number of rows) instead of two.
Dear thor, thanks a lot for your reply,
I tried to use only one argument in the query, but the result is the same error, althrought I find that the error is quite illuminating:
while my query is now
SELECT tweet.metadata FROM tweet LIMIT '1';
the error I get is:
WARN Database Reader com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''1'; LIMIT 0' at line 1
which makes me think that there is a limit clause that the program itself adds to the query. Now I have to find where to edit that value to fit my task.
Anyone knows how?
This is an error in the node. It adds a "LIMIT 0" at the end of the query in order to determine the table structure. If you have a LIMIT already in the original query, the resulting SQL is invalid. This will be fixed in 2.9.
Ok, thank you!
That's quite a problem to my project, I'll build a dummy table to host just the sample and use the data from that instead than the original one, but now I know what's the problem ;)
thanks again and goodbye!