Hello Nicolas, What version of MonetDB are you using? It seems to work for me in Mar2018: Welcome to mclient, the MonetDB/SQL interactive terminal (Mar2018) Database: MonetDB v11.29.1 (Mar2018), 'foo' Type \q to quit, \? for a list of available commands auto commit mode: on sql>create table foo (i real); operation successful sql>insert into foo values (NULL), (1); 2 affected rows sql>select count(1) from foo; +------+ | L3 | +======+ | 2 | +------+ 1 tuple sql>select count(1) from foo where i is null; +------+ | L3 | +======+ | 1 | +------+ 1 tuple sql>create table lala (i int, j real); operation successful sql>insert into lala values (1, NULL), (2, NULL), (3, 1.0), (4, 1.0); 4 affected rows sql>select count(1), j from lala group by j; +------+-----------------+ | L2 | j | +======+=================+ | 2 | null | | 2 | 1 | +------+-----------------+ 2 tuples sql>select count(1) from lala where j is null; +------+ | L3 | +======+ | 2 | +------+ 1 tuple sql> Best regards, Panos. On 04/15/2018 03:21 PM, Nicolas Paris wrote:

Hello

I have those DOUBLE PRECISION fields, sometimes containing null values:

sql>select count(1), range_low from omop.measurement group by range_low; +-----------+--------------------------+ | L2 | range_low | +===========+==========================+ | 304875924 | null | | 9448250 | 50 | | 16519843 | 0 | | 13198932 | 10 | | 14364002 | 20 | | 3964808 | 30 | | 2998528 | 3 | | 855829 | 2 | +-----------+--------------------------+ 8 tuples

However, I am not able to filter based on is null:

sql>select count(1) from omop.measurement where range_low is null; +------+ | L3 | +======+ | 0 | +------+ 1 tuple

I am not able to understand if this behavior is normal regarding the documentation:

"The types REAL, FLOAT and DOUBLE map to the underlying implementation system. No special attention is given to the value NaN."

Thanks

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