I have a line of pyspark that I am running in databricks:
df = df.toDF(*[format_column(c) for c in df.columns])
where format_column is a python function that upper cases, strips and removes the characters full stop . and backtick ` from the column names.
Before and after this line of code, the dataframe randomly loses a bunch of rows. If I do a count before and after the line, then the number of rows drops. I did some more digging with this and found the same behaviour if I tried the following:
import pyspark.sql.functions as F
df = df.toDF(*[F.col(column_name).alias(column_name) for column_name in df.columns])
although the following is ok without the aliasing:
import pyspark.sql.functions as F
df = df.toDF(*[F.col(column_name) for column_name in df.columns])
and it is also ok if I don't rename all columns such as:
import pyspark.sql.functions as F
df = df.toDF(*[F.col(column_name).alias(column_name) for column_name in df.columns[:-1]])
And finally, there were some pipe (|) characters in the column names, which when removed manually beforehand then resulted in no issue. As far as I know, pipe is not actually a special character in spark sql column names (unlike full stop and backtick).
Has anyone seen this kind of behaviour before and know of a solution aside from removing the pipe character manually beforehand?
Running on Databricks Runtime 10.4LTS.