feat: simple limit impl in PartSort

[waynexia]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

This patch

• implement a simple limit to PartSort
• fixes a old semantic bug

This simple limit mechanism can bring an obvious improvement even though it's not the optimal impl

Before:

+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| stage | node | plan                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|     0 |    0 |  MergeScanExec: peers=[7967164334080(1855, 0), ] metrics=[output_rows: 1, greptime_exec_read_cost: 0, first_consume_time: 4422746177, finish_time: 4423509695, ready_time: 2067118, ]
                                                                                                                                                                                                                                                                                                                                                                                                 |
|     1 |    0 |  GlobalLimitExec: skip=0, fetch=1 metrics=[output_rows: 1, elapsed_compute: 19264562, ]
  SortPreservingMergeExec: [ts@20 DESC] metrics=[output_rows: 32, elapsed_compute: 343122, ]
    WindowedSortExec metrics=[output_rows: 84, elapsed_compute: 2184785, ]
      PartSortExec ts@20 DESC metrics=[output_rows: 20896000, elapsed_compute: 32, ]
        UnorderedScan: region=7967164334080(1855, 0), partition_count=1000 (1 memtable ranges, 6 file 999 ranges) metrics=[output_rows: 20896000, mem_used: 8192401024, elapsed_poll: 10590199207, elapsed_await: 17958644936, ]
 |
|  NULL | NULL | Total rows: 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+-------+------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
3 rows in set (4.435 sec)

After:

+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| stage | node | plan                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|     0 |    0 |  MergeScanExec: peers=[7967164334080(1855, 0), ] metrics=[output_rows: 1, greptime_exec_read_cost: 0, first_consume_time: 2913701812, finish_time: 2914868211, ready_time: 1752908, ]
                                                                                                                                                                                                                                                                                                                                                                                   |
|     1 |    0 |  GlobalLimitExec: skip=0, fetch=1 metrics=[output_rows: 1, elapsed_compute: 1176240, ]
  SortPreservingMergeExec: [ts@20 DESC] metrics=[output_rows: 32, elapsed_compute: 88515, ]
    WindowedSortExec metrics=[output_rows: 32, elapsed_compute: 32, ]
      PartSortExec ts@20 DESC metrics=[output_rows: 138, elapsed_compute: 32, ]
        UnorderedScan: region=7967164334080(1855, 0), partition_count=1000 (1 memtable ranges, 6 file 999 ranges) metrics=[output_rows: 15732800, mem_used: 6000557824, elapsed_await: 5066264562, elapsed_poll: 3775656192, ]
 |
|  NULL | NULL | Total rows: 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
3 rows in set (2.919 sec)

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.

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[fengjiachun]

LGTM

[codecov]

Codecov Report

Attention: Patch coverage is 63.88889% with 13 lines in your changes missing coverage. Please review.

Project coverage is 83.91%. Comparing base (39ab1a6) to head (880e599).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4922      +/-   ##
==========================================
- Coverage   84.17%   83.91%   -0.27%     
==========================================
  Files        1137     1137              
  Lines      210022   210050      +28     
==========================================
- Hits       176792   176269     -523     
- Misses      33230    33781     +551     

[discord9]

How about add more info in DisplayAs for PartSortExec ? Like limit and sort expr?