Index alias queries not returning cumulative (duplicate) results from its targets.

7.6.0-2090

Steps to reproduce:

• Create a bucket: default
• Load 1000000 docs with "000*" on all docs
• Create fts index: fts_idx_slow like below:

{

  "type": "fulltext-index",

  "name": "fts_idx_slow",

  "uuid": "4f286836597c2e49",

  "sourceType": "gocbcore",

  "sourceName": "default",

  "sourceUUID": "0708cec5df052130e9bc05e398dd0475",

  "planParams": {

    "maxPartitionsPerPIndex": 1024,

    "indexPartitions": 1

  },

  "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": true

      },

      "default_type": "_default",

      "docvalues_dynamic": true,

      "index_dynamic": true,

      "store_dynamic": false,

      "type_field": "_type"

    },

    "store": {

      "indexType": "scorch",

      "mossStoreOptions": {},

      "segmentVersion": 15

    }

  },

  "sourceParams": {}

}

• Create alias: fts_component_alias

  {

  "type": "fulltext-alias",

  "name": "fts_component_alias",

  "uuid": "5fc9e443b01832ed",

  "sourceType": "nil",

  "planParams": {},

  "params": {

  "store": {

  "indexType": "scorch",

  "kvStoreName": "mossStore",

  "mossStoreOptions": {}

  },

  "targets": {

  "fts_idx_slow": {}

  }

  },

  "sourceParams": {}

  }

• Create another alias with both alias above and index above:

  {

  "type": "fulltext-alias",

  "name": "fts_idx_alias",

  "uuid": "10dedff71e8ad4c7",

  "sourceType": "nil",

  "planParams": {},

  "params": {

  "store": {

  "indexType": "scorch",

  "kvStoreName": "mossStore",

  "mossStoreOptions": {}

  },

  "targets": {

  "fts_component_alias": {},

  "fts_idx_slow": {}

  }

  },

  "sourceParams": {}

  }

• Querying index: fts_idx_slow with wildcard : 000*, which returns 1000000 docs
• Querying on fts_idx_alias with wildcard : 000*, also returns 1000000 docs, expected is 2000000 docs

This was working in 7.2.5 build 7532