SNOW-650150: Add some indication to DataFrame.show() that it isn't all the results

[mbkupfer]

What is the current behavior?

No indication that show is only printing top results, which could mislead users that aren't aware.

>>> df = session.range(1,12).to_df('col1') # create 11 element sequence
>>> df.show()
----------
|"COL1"  |
----------
|1       |
|2       |
|3       |
|4       |
|5       |
|6       |
|7       |
|8       |
|9       |
|10      |
----------
>>> df.show(n=11)
----------
|"COL1"  |
----------
|1       |
|2       |
|3       |
|4       |
|5       |
|6       |
|7       |
|8       |
|9       |
|10      |
|11      |
----------

What is the desired behavior?

Option 1:
Some indication that this is a paged result. Like 1/n, or 15 out of # rows (if that is efficient to do).

Option 2:
Create a DataFrame.head() function that replicates pandas behavior, making it more obvious that this is a preview.

How would this improve snowflake-snowpark-python?

Users will not accidentally realize that they are omitting results when results sets are right around the threshold of show

References, Other Background

[sfc-gh-jdu]

Hey @mbkupfer thanks for your suggestion. I think option 1 is better that we will add one line saying how many rows are displayed, but probably will not count the total rows in this dataframe since it needs another call to count(), which might not be efficient. Option 2 might make users confused because pandas' head is to return n rows, instead of print n rows.

[cpcloud]

We had to solve this in https://github.com/ibis-project/ibis and it's not particularly bad. You don't need two calls: you can execute a limit with N+1 rows where N is the number of rows to show and the check whether the number of returned rows is greater than N.

Ibis has great snowflake support, so if anyone is interested in a DataFrame API with a nice indicator of "more rows" check it out!

[mbkupfer]

@cpcloud I'll take a look at the project. Thanks for sharing.