2010YOUY01 commented on PR #13028:
URL: https://github.com/apache/datafusion/pull/13028#issuecomment-2428913421
Thank you. I have some suggestions for `LIMIT`'s behavior:
Before this PR, only int literals are accepted
```sh
DataFusion CLI v42.0.0
> create table t1(v1 int);
0 row(s) fetched.
Elapsed 0.052 seconds.
> insert into t1 values (1),(2),(3);
+-------+
| count |
+-------+
| 3 |
+-------+
1 row(s) fetched.
Elapsed 0.086 seconds.
> select * from t1 limit 1.5;
Error during planning: Unexpected expression in LIMIT clause
> select * from t1 limit true;
Error during planning: Unexpected expression in LIMIT clause
```
This PR:
```sh
> select * from t1 limit 1.5;
+----+
| v1 |
+----+
| 1 |
+----+
1 row(s) fetched.
Elapsed 0.006 seconds.
> select * from t1 offset 0.5 limit 10;
+----+
| v1 |
+----+
| 1 |
| 2 |
| 3 |
+----+
3 row(s) fetched.
Elapsed 0.004 seconds.
> select * from t1 limit false;
+----+
| v1 |
+----+
+----+
0 row(s) fetched.
Elapsed 0.009 seconds.
```
Postgres's behavior is: if `OFFSET` is not integer for example 0.5, 0th row
won't be included, if `LIMIT` is 0.5, then 0th row would be included:
```sh
postgres=# select * from t1 limit 1.5;
v1
----
1
2
(2 rows)
postgres=# select * from t1 offset 0.5 limit 10;
v1
----
2
3
(2 rows)
postgres=# select * from t1 limit false;
ERROR: argument of LIMIT must be type bigint, not type boolean
LINE 1: select * from t1 limit false;
```
1. I think it's good to follow Postgres' behavior for non-integer arguments
2. Don't support non-numeric arguments like bool, I think they are allowed
to cast to integer, but not meaningful in SQL query (maybe there are other
types that have a similar issue I'm not aware of)
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