what are the x & y values of your the last of your 200000 tuples, i.e., the one omitted if you only load the first 199999 tuples? ----- Original Message -----
Hi all,
I am trying to evaluate the performance of MonetDB for an analytical workload.
I am using MonetDB-11.15.17 built from source on Ubuntu 13.04.
I have encountered a problem with user using defined functions in SQL which I have reduced to this test case. I appears that whenever I have over 200,000 rows in the table, the UDF returns null.
First create a test data set with the following python:
import random with open("test_data.csv","w") as f: for i in range(0,1000000): f.write("%s,%s\n" % (random.random(),random.random()))
Then I use the following to load the data, and try using a simple UDF in SQL.
CREATE TABLE TEST ( x float, y float );
COPY 200000 RECORDS INTO TEST from '/home/alastair/test_data.csv' USING DELIMITERS ',','\n','"' NULL AS '';
CREATE FUNCTION MY_UDF (x float, y float) RETURNS float BEGIN DECLARE ret float; set ret = LOG(x/y); RETURN ret; END;
SELECT 'udf alone',MY_UDF(0.1,0.2);
SELECT 'udf from table',MY_UDF(t.x,t.y) FROM TEST as t limit 1; -- this returns NULL with 200000 records
DROP FUNCTION MY_UDF; DROP TABLE TEST;
The value returned my MY_UDF is null with 200,000 records, changing to 199,999 records in COPY INTO produces the correct result.
If I use a UDF built in C, the problem does not exist at all.
I feel like I might have missed something silly but I can't think of anything.
Best regards,
Alastair
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