FlexIndex: FlexQuery with OR is not using FTS index even though its sargable

Build: 7.0.0-1939

• Load dataset attached
• Create fts index with below:

  {

  "type": "fulltext-index",

  "name": "custom_index",

  "uuid": "15f8e556c0016faf",

  "sourceType": "gocbcore",

  "sourceName": "default",

  "sourceUUID": "0bb07ed3f6a8fe63615b7fa3b0d08d82",

  "planParams": {

  "maxPartitionsPerPIndex": 171

  },

  "params": {

  "doc_config": {

  "docid_prefix_delim": "",

  "docid_regexp": "",

  "mode": "type_field",

  "type_field": "type"

  },

  "mapping": {

  "analysis": {},

  "default_analyzer": "standard",

  "default_datetime_parser": "dateTimeOptional",

  "default_field": "_all",

  "default_mapping": {

  "dynamic": true,

  "enabled": false

  },

  "default_type": "_default",

  "docvalues_dynamic": true,

  "index_dynamic": true,

  "store_dynamic": false,

  "type_field": "type",

  "types": {

  "emp": {

  "dynamic": false,

  "enabled": true,

  "properties": {

  "is_manager": {

  "dynamic": false,

  "enabled": true,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "is_manager",

  "type": "boolean"

  }

  ]

  },

  "join_date": {

  "dynamic": false,

  "enabled": true,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "join_date",

  "type": "datetime"

  }

  ]

  },

  "manages": {

  "dynamic": false,

  "enabled": true,

  "properties": {

  "team_size": {

  "dynamic": false,

  "enabled": true,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "team_size",

  "type": "number"

  }

  ]

  }

  }

  },

  "mutated": {

  "dynamic": false,

  "enabled": true,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "mutated",

  "type": "number"

  }

  ]

  },

  "name": {

  "dynamic": false,

  "enabled": true,

  "fields": [

  {

  "analyzer": "keyword",

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "name",

  "type": "text"

  }

  ]

  }

  }

  }

  }

  },

  "store": {

  "indexType": "scorch",

  "mossStoreOptions": {}

  }

  },

  "sourceParams": {}

  }

• Create GSI primary index
• For the below flex query with OR, it uses GSI primary index even though FTS index has name, mutated and with type mapping emp

  select meta().id from default USE INDEX ( USING FTS) where type = "emp" and (name>= "Scott" and name <="Vala" ) or mutated = 0