Minor: add test + docs for 2 argument trunc with columns #7042
Conversation
github-actions
bot
added
core
|
@Syleechan would you have time to review this PR? |
| # trunc with columns and precision | ||
| query RRR rowsort | ||
| select trunc(a, 3) as a3, trunc(a, 1) as a1, trunc(arrow_cast(a, 'Float64'), 3) as a3_f64 from small_floats; | ||
| ---- | ||
| -0.7 -0.7 -0.7 | ||
| -1 -1 -1 | ||
| 0.2 0.2 0.2 | ||
| 0.5 0.5 0.5 |
There was a problem hiding this comment.
Hmm, as a has at most 1 decimal point, trunc(a, 3) or trunc(a, 1) basically cannot show the difference. I think it doesn't actually test what we want?
There was a problem hiding this comment.
maybe add some long decimal point float number
| trunc(numeric_expression[, decimal_places]) | ||
| ``` | ||
|
|
||
| #### Arguments | ||
|
|
||
| - **numeric_expression**: Numeric expression to operate on. | ||
| Can be a constant, column, or function, and any combination of arithmetic operators. | ||
|
|
||
| - **decimal_places**: Optional. The number of decimal places to truncate to. | ||
| Defaults to 0. |
There was a problem hiding this comment.
Doc looks good to me. Just one question. Can decimal_places be negative?
There was a problem hiding this comment.
can not be negative, modify the trunc function just meet the self-defined precision of decimal to '.'
There was a problem hiding this comment.
TIL turns out that negative precision means "truncate to the left of the decimal place": https://www.postgresqltutorial.com/postgresql-math-functions/postgresql-trunc/#:~:text=If%20the%20precision%20argument%20is,The%20precision%20argument%20is%20optional.
postgres=# select trunc(12345.6789, -2);
trunc
-------
12300
(1 row)
This is actually what the current datafusion implementation does too so I have added a test and updated the docs
| # trunc with columns and precision | ||
| query RRR rowsort | ||
| select trunc(a, 3) as a3, trunc(a, 1) as a1, trunc(arrow_cast(a, 'Float64'), 3) as a3_f64 from small_floats; | ||
| ---- | ||
| -0.7 -0.7 -0.7 | ||
| -1 -1 -1 | ||
| 0.2 0.2 0.2 | ||
| 0.5 0.5 0.5 |
There was a problem hiding this comment.
maybe add some long decimal point float number
| trunc(numeric_expression[, decimal_places]) | ||
| ``` | ||
|
|
||
| #### Arguments | ||
|
|
||
| - **numeric_expression**: Numeric expression to operate on. | ||
| Can be a constant, column, or function, and any combination of arithmetic operators. | ||
|
|
||
| - **decimal_places**: Optional. The number of decimal places to truncate to. | ||
| Defaults to 0. |
There was a problem hiding this comment.
can not be negative, modify the trunc function just meet the self-defined precision of decimal to '.'
|
Thanks @viirya and @Syleechan - I have addressed your comments. |
Which issue does this PR close?
Related to #6942 from @Syleechan
Rationale for this change
While reviewing #6942 I noticed the two argument version of
truncwasn't tested via sql and it wasn't documentedWhat changes are included in this PR?
add test + docs for 2 argument trunc with columns
Are these changes tested?
Yes
Are there any user-facing changes?