Re: [pyspark 2.3+] CountDistinct
I can't exactly reproduce this. Here is what I tried quickly:
import uuid
import findspark
findspark.init() # noqa
import pyspark
from pyspark.sql import functions as F # noqa: N812
spark = pyspark.sql.SparkSession.builder.getOrCreate()
df = spark.createDataFrame([
[str(uuid.uuid4()) for i in range(45)],
], ['col1'])
print(' Spark version:', spark.sparkContext.version)
print(' Null count:', df.filter(F.col('col1').isNull()).count())
print(' Value count:', df.filter(F.col('col1').isNotNull()).count())
print(' Distinct Count 1:',
df.agg(F.countDistinct(F.col('col1'))).collect()[0][0])
print(' Distinct Count 2:',
df.agg(F.countDistinct(F.col('col1'))).collect()[0][0])
This always returns:
Spark version: 2.4.0
Null count: 0
Value count: 45
Distinct Count 1: 45
Distinct Count 2: 45
On Sat, Jun 29, 2019 at 6:51 PM Rishi Shah wrote:
> Thanks Abdeali! Please find details below:
>
> df.agg(countDistinct(col('col1'))).show() --> 450089
> df.agg(countDistinct(col('col1'))).show() --> 450076
> df.filter(col('col1').isNull()).count() --> 0
> df.filter(col('col1').isNotNull()).count() --> 450063
>
> col1 is a string
> Spark version 2.4.0
> datasize: ~ 500GB
>
>
> On Sat, Jun 29, 2019 at 5:33 AM Abdeali Kothari
> wrote:
>
>> How large is the data frame and what data type are you counting distinct
>> for?
>> I use count distinct quite a bit and haven't noticed any thing peculiar.
>>
>> Also, which exact version in 2.3.x?
>> And, are performing any operations on the DF before the countDistinct?
>>
>> I recall there was a bug when I did countDistinct(PythonUDF(x)) in the
>> same query which was resolved in one of the minor versions in 2.3.x
>>
>> On Sat, Jun 29, 2019, 10:32 Rishi Shah wrote:
>>
>>> Hi All,
>>>
>>> Just wanted to check in to see if anyone has any insight about this
>>> behavior. Any pointers would help.
>>>
>>> Thanks,
>>> Rishi
>>>
>>> On Fri, Jun 14, 2019 at 7:05 AM Rishi Shah
>>> wrote:
>>>
Hi All,
Recently we noticed that countDistinct on a larger dataframe doesn't
always return the same value. Any idea? If this is the case then what is
the difference between countDistinct & approx_count_distinct?
--
Regards,
Rishi Shah
>>>
>>>
>>> --
>>> Regards,
>>>
>>> Rishi Shah
>>>
>>
>
> --
> Regards,
>
> Rishi Shah
>
Re: [pyspark 2.3+] CountDistinct
Thanks Abdeali! Please find details below:
df.agg(countDistinct(col('col1'))).show() --> 450089
df.agg(countDistinct(col('col1'))).show() --> 450076
df.filter(col('col1').isNull()).count() --> 0
df.filter(col('col1').isNotNull()).count() --> 450063
col1 is a string
Spark version 2.4.0
datasize: ~ 500GB
On Sat, Jun 29, 2019 at 5:33 AM Abdeali Kothari
wrote:
> How large is the data frame and what data type are you counting distinct
> for?
> I use count distinct quite a bit and haven't noticed any thing peculiar.
>
> Also, which exact version in 2.3.x?
> And, are performing any operations on the DF before the countDistinct?
>
> I recall there was a bug when I did countDistinct(PythonUDF(x)) in the
> same query which was resolved in one of the minor versions in 2.3.x
>
> On Sat, Jun 29, 2019, 10:32 Rishi Shah wrote:
>
>> Hi All,
>>
>> Just wanted to check in to see if anyone has any insight about this
>> behavior. Any pointers would help.
>>
>> Thanks,
>> Rishi
>>
>> On Fri, Jun 14, 2019 at 7:05 AM Rishi Shah
>> wrote:
>>
>>> Hi All,
>>>
>>> Recently we noticed that countDistinct on a larger dataframe doesn't
>>> always return the same value. Any idea? If this is the case then what is
>>> the difference between countDistinct & approx_count_distinct?
>>>
>>> --
>>> Regards,
>>>
>>> Rishi Shah
>>>
>>
>>
>> --
>> Regards,
>>
>> Rishi Shah
>>
>
--
Regards,
Rishi Shah
Re: [pyspark 2.3+] CountDistinct
How large is the data frame and what data type are you counting distinct for? I use count distinct quite a bit and haven't noticed any thing peculiar. Also, which exact version in 2.3.x? And, are performing any operations on the DF before the countDistinct? I recall there was a bug when I did countDistinct(PythonUDF(x)) in the same query which was resolved in one of the minor versions in 2.3.x On Sat, Jun 29, 2019, 10:32 Rishi Shah wrote: > Hi All, > > Just wanted to check in to see if anyone has any insight about this > behavior. Any pointers would help. > > Thanks, > Rishi > > On Fri, Jun 14, 2019 at 7:05 AM Rishi Shah > wrote: > >> Hi All, >> >> Recently we noticed that countDistinct on a larger dataframe doesn't >> always return the same value. Any idea? If this is the case then what is >> the difference between countDistinct & approx_count_distinct? >> >> -- >> Regards, >> >> Rishi Shah >> > > > -- > Regards, > > Rishi Shah >
Re: [pyspark 2.3+] CountDistinct
Hi All, Just wanted to check in to see if anyone has any insight about this behavior. Any pointers would help. Thanks, Rishi On Fri, Jun 14, 2019 at 7:05 AM Rishi Shah wrote: > Hi All, > > Recently we noticed that countDistinct on a larger dataframe doesn't > always return the same value. Any idea? If this is the case then what is > the difference between countDistinct & approx_count_distinct? > > -- > Regards, > > Rishi Shah > -- Regards, Rishi Shah
[pyspark 2.3+] CountDistinct
Hi All, Recently we noticed that countDistinct on a larger dataframe doesn't always return the same value. Any idea? If this is the case then what is the difference between countDistinct & approx_count_distinct? -- Regards, Rishi Shah
