fix: adjust fill behavior of range query

[Taylor-lagrange]

I hereby agree to the terms of the GreptimeDB CLA.

What's changed and what's your intention?

Adjust fill behavior on range query

• When user not use fill, the null result calculate by range expr, or the missing datapoint will not be fill.
• If user use fill NULL, the missing datapoint will be fill.
• If user use fill LINEAR/PREV/Const, all null value and missing datapoint will be fill.

Case like

CREATE TABLE host (
  ts timestamp(3) time index,
  host STRING PRIMARY KEY,
  val BIGINT,
);

INSERT INTO TABLE host VALUES
    (0,     'host1', 0),
    -- missing data for 5000, 10000
    (15000, 'host1', 6),
    (0,     'host2', 6),
    -- missing data for 5000, 10000
    (15000, 'host2', 12);

SELECT ts, host, min(val) RANGE '5s' FROM host ALIGN '5s' ORDER BY host, ts;

+---------------------+-------+------------------------+
| ts                  | host  | MIN(host.val) RANGE 5s |
+---------------------+-------+------------------------+
| 1970-01-01T00:00:00 | host1 | 0                      |
| 1970-01-01T00:00:15 | host1 | 6                      |
| 1970-01-01T00:00:00 | host2 | 6                      |
| 1970-01-01T00:00:15 | host2 | 12                     |
+---------------------+-------+------------------------+

SELECT ts, host, min(val) RANGE '5s' FILL NULL FROM host ALIGN '5s' ORDER BY host, ts;

+---------------------+-------+----------------------------------+
| ts                  | host  | MIN(host.val) RANGE 5s FILL NULL |
+---------------------+-------+----------------------------------+
| 1970-01-01T00:00:00 | host1 | 0                                |
| 1970-01-01T00:00:05 | host1 |                                  |
| 1970-01-01T00:00:10 | host1 |                                  |
| 1970-01-01T00:00:15 | host1 | 6                                |
| 1970-01-01T00:00:00 | host2 | 6                                |
| 1970-01-01T00:00:05 | host2 |                                  |
| 1970-01-01T00:00:10 | host2 |                                  |
| 1970-01-01T00:00:15 | host2 | 12                               |
+---------------------+-------+----------------------------------+

SELECT ts, host, min(val) RANGE '5s' FILL PREV FROM host ALIGN '5s' ORDER BY host, ts;

+---------------------+-------+----------------------------------+
| ts                  | host  | MIN(host.val) RANGE 5s FILL PREV |
+---------------------+-------+----------------------------------+
| 1970-01-01T00:00:00 | host1 | 0                                |
| 1970-01-01T00:00:05 | host1 | 0                                |
| 1970-01-01T00:00:10 | host1 | 0                                |
| 1970-01-01T00:00:15 | host1 | 6                                |
| 1970-01-01T00:00:00 | host2 | 6                                |
| 1970-01-01T00:00:05 | host2 | 6                                |
| 1970-01-01T00:00:10 | host2 | 6                                |
| 1970-01-01T00:00:15 | host2 | 12                               |
+---------------------+-------+----------------------------------+

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

Attention: Patch coverage is 93.85246% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 85.03%. Comparing base (aa125a5) to head (3eecb3e).
Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3489      +/-   ##
==========================================
- Coverage   85.40%   85.03%   -0.37%     
==========================================
  Files         897      898       +1     
  Lines      148106   148658     +552     
==========================================
- Hits       126495   126417      -78     
- Misses      21611    22241     +630     

[killme2008]

@tisonkun Is this behavior you expected?

[killme2008]

LGTM

[tisonkun]

+1

Update PR description we need docs update for this.

cc @nicecui