Add optimizer rule for pushing limit into the fulltext index scan

[yixinglu]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

Description:

Support the optimization for pushing the limit into the fulltext index scan, such as:

      LOOKUP ON tag2 WHERE prefix(tag2.prop2,"nebula")
      YIELD id(vertex) as id, tag2.prop1 as prop1, tag2.prop2 as prop2 |
      LIMIT 1,1

Execution Plan (optimize time 2609 us)

-----+-------------------+--------------+----------------+--------------------------------------------------
| id | name              | dependencies | profiling data | operator info                                   |
-----+-------------------+--------------+----------------+--------------------------------------------------
|  8 | Project           | 9            |                | outputVar: {                                    |
|    |                   |              |                |   "colNames": [                                 |
|    |                   |              |                |     "id",                                       |
|    |                   |              |                |     "prop1",                                    |
|    |                   |              |                |     "prop2"                                     |
|    |                   |              |                |   ],                                            |
|    |                   |              |                |   "name": "__Limit_4",                          |
|    |                   |              |                |   "type": "DATASET"                             |
|    |                   |              |                | }                                               |
|    |                   |              |                | inputVar: __Limit_7                             |
|    |                   |              |                | columns: [                                      |
|    |                   |              |                |   "id(VERTEX) AS id",                           |
|    |                   |              |                |   "tag2.prop1 AS prop1",                        |
|    |                   |              |                |   "tag2.prop2 AS prop2"                         |
|    |                   |              |                | ]                                               |
-----+-------------------+--------------+----------------+--------------------------------------------------
|  9 | Limit             | 11           |                | outputVar: {                                    |
|    |                   |              |                |   "colNames": [],                               |
|    |                   |              |                |   "name": "__Limit_7",                          |
|    |                   |              |                |   "type": "DATASET"                             |
|    |                   |              |                | }                                               |
|    |                   |              |                | inputVar: __GetVertices_10                      |
|    |                   |              |                | offset: 1                                       |
|    |                   |              |                | count: 1                                        |
-----+-------------------+--------------+----------------+--------------------------------------------------
| 11 | GetVertices       | 12           |                | outputVar: {                                    |
|    |                   |              |                |   "colNames": [],                               |
|    |                   |              |                |   "type": "DATASET",                            |
|    |                   |              |                |   "name": "__GetVertices_10"                    |
|    |                   |              |                | }                                               |
|    |                   |              |                | inputVar: __FulltextIndexScan_12                |
|    |                   |              |                | space: 6                                        |
|    |                   |              |                | dedup: 0                                        |
|    |                   |              |                | limit: 2                                        |
|    |                   |              |                | filter:                                         |
|    |                   |              |                | orderBy: []                                     |
|    |                   |              |                | src: COLUMN[0]                                  |
|    |                   |              |                | props: [                                        |
|    |                   |              |                |   {                                             |
|    |                   |              |                |     "tagId": 7,                                 |
|    |                   |              |                |     "props": [                                  |
|    |                   |              |                |       "_vid",                                   |
|    |                   |              |                |       "_tag",                                   |
|    |                   |              |                |       "prop1",                                  |
|    |                   |              |                |       "prop2"                                   |
|    |                   |              |                |     ]                                           |
|    |                   |              |                |   }                                             |
|    |                   |              |                | ]                                               |
|    |                   |              |                | exprs:                                          |
-----+-------------------+--------------+----------------+--------------------------------------------------
| 12 | FulltextIndexScan | 0            |                | outputVar: {                                    |
|    |                   |              |                |   "colNames": [],                               |
|    |                   |              |                |   "name": "__FulltextIndexScan_12",             |
|    |                   |              |                |   "type": "DATASET"                             |
|    |                   |              |                | }                                               |
|    |                   |              |                | inputVar:                                       |
|    |                   |              |                | space: 0                                        |
|    |                   |              |                | dedup: 0                                        |
|    |                   |              |                | limit: 2                                        |
|    |                   |              |                | filter:                                         |
|    |                   |              |                | orderBy: []                                     |
|    |                   |              |                | isEdge: 0                                       |
|    |                   |              |                | searchExpr: PREFIX(tag2.prop2, "nebula", 10000) |
|    |                   |              |                | index: nebula_index_tag2_prop2                  |
-----+-------------------+--------------+----------------+--------------------------------------------------
|  0 | Start             |              |                | outputVar: {                                    |
|    |                   |              |                |   "colNames": [],                               |
|    |                   |              |                |   "name": "__Start_0",                          |
|    |                   |              |                |   "type": "DATASET"                             |
|    |                   |              |                | }                                               |
-----+-------------------+--------------+----------------+--------------------------------------------------

How do you solve it?

Special notes for your reviewer, ex. impact of this fix, design document, etc:

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• N/A

Affects:

• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

Please confirm whether to be reflected in release notes and how to describe:

ex. Fixed the bug .....

[cangfengzhs]

How to support offset? I don't find it in operator info

[yixinglu]

offset has been supported in LIMIT sentence, such as LIMIT 1, 2, FulltextIndexScan only has limit field and need not to keep the offset which is in Limit plan node.

[yixinglu]

pls hold on this PR, i need to add more rules to support offset in fulltextIndexScan