feat(ts): Add label-based indexing support and TS.MGET command

[yezhizi]

Part of #3048
Add a new CF for label-based indexing. The key format is as following:

+-----------+--------------+----------------+------------+------------------+--------------+---------+
|     ns    |  index_type  | label_key_size |  label_key | label_value_size |  label_value |  key    | => null
| (1+Xbytes)|    (1byte)   |    (4byte)     |   (Ybyte)  |   (4byte)        |   (Zbyte)    | (Kbyte) |
+-----------+--------------+----------------+------------+------------------+--------------+---------+

enum	index_type
0	TS_LABEL

Now we can do:

127.0.0.1:6666> TS.CREATE temp:TLV LABELS type temp location TLV
127.0.0.1:6666> TS.CREATE temp:JLM LABELS type temp location JLM
127.0.0.1:6666> TS.MADD temp:TLV 1000 30 temp:TLV 1010 35 temp:TLV 1020 9999 temp:TLV 1030 40
127.0.0.1:6666> TS.MADD temp:JLM 1005 30 temp:JLM 1015 35 temp:JLM 1025 9999 temp:JLM 1035 40
127.0.0.1:6666> TS.MGET WITHLABELS FILTER type=temp
1) 1) "temp:JLM"
   2) 1) 1) "location"
         2) "JLM"
      2) 1) "type"
         2) "temp"
   3) 1) 1) (integer) 1035
         2) (double) 40
2) 1) "temp:TLV"
   2) 1) 1) "location"
         2) "TLV"
      2) 1) "type"
         2) "temp"
   3) 1) 1) (integer) 1030
         2) (double) 40
127.0.0.1:6666> TS.MGET SELECTED_LABELS location FILTER type=temp
1) 1) "temp:JLM"
   2) 1) 1) "location"
         2) "JLM"
   3) 1) 1) (integer) 1035
         2) (double) 40
2) 1) "temp:TLV"
   2) 1) 1) "location"
         2) "TLV"
   3) 1) 1) (integer) 1030
         2) (double) 40

[yezhizi]

@PragmaTwice Could you tell me how to fix this test error? I don't really understand why it failed.

/Users/runner/work/kvrocks/kvrocks/tests/cppunit/compact_test.cc:196: Failure
Value of: sg.IsNotFound()
  Actual: false
Expected: true

[  FAILED  ] 1 test, listed below:
[  FAILED  ] Compact.SearchFilter

[PragmaTwice]

@yezhizi Not necessary in this PR, but we need to consider:

• if a TS key is deleted, how to also delete related label index?
• if a TS key is expired, how to handle it in the compaction filter of the new CF?

Maybe when we are accessing the label index, we should check if the TS key is currently available (not expired or deleted), and in compaction we can recycle label index with expired/deleted TS keys.

[sonarqubecloud]

Quality Gate passed

Issues
55 New issues
0 Accepted issues

Measures
0 Security Hotspots
73.4% Coverage on New Code
0.5% Duplication on New Code

See analysis details on SonarQube Cloud

[yezhizi]

Okay, I’ll try to improve on this.