N1QL-FTS Integration phase 2: FTSClient not selecting index with custom mapping in some cases

Build: 6.5.0 build 2832 

Cluster configuration:

• standard `default` bucket
• no GSI indexes
• FTS index:

  {

  "name": "custom_index",

  "type": "fulltext-index",

  "params": \{

  "doc_config": {

  "docid_prefix_delim": "",

  "docid_regexp": "",

  "mode": "type_field",

  "type_field": "type"

  },

  "mapping": \{

  "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": {

  "manages": {

  "dynamic": false,

  "enabled": true,

  "properties": {

  "reports": {

  "enabled": true,

  "dynamic": false,

  "fields": [

  {

  "analyzer": "standard",

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "reports",

  "type": "text"

  }

  ]

  }

  }

  },

  "email": \{

  "enabled": true,

  "dynamic": false,

  "fields": [

  {

  "analyzer": "en",

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "email",

  "type": "text"

  }

  ]

  },

  "join_date": \{

  "enabled": true,

  "dynamic": false,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "join_date",

  "type": "datetime"

  }

  ]

  },

  "mutated": \{

  "enabled": true,

  "dynamic": false,

  "fields": [

  {

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "mutated",

  "type": "number"

  }

  ]

  },

  "name": \{

  "enabled": true,

  "dynamic": false,

  "fields": [

  {

  "analyzer": "keyword",

  "include_in_all": true,

  "include_term_vectors": true,

  "index": true,

  "name": "name",

  "type": "text"

  }

  ]

  }

  }

  }

  }

  },

  "store": \{

  "indexType": "scorch",

  "kvStoreName": "mossStore",

  "mossStoreOptions": {}

  }

  },

  "sourceType": "couchbase",

  "sourceName": "default",

  "sourceUUID": "f424775c2182aa574ef2965ae19ccf37",

  "sourceParams": null,

  "planParams": \{

  "maxPartitionsPerPIndex": 171,

  "numReplicas": 0

  },

  "uuid": "295531dfb94aeb05"

  }

Trying to run the following query:

select meta().id from default where type='emp' and search(default, {"disjuncts": [{"field": "manages.reports", "match": "Beryl"}, {"field": "name", "match": "Nicol\u00e1s"}]})

Getting the following error as a response:

[

 {

 "code": 4000,

 "msg": "No index available on keyspace default that matches your query. Use CREATE INDEX or CREATE PRIMARY INDEX to create an index, or check that your expected index is online.",

 "query": "select meta().id from default where type='emp' and search(default, {\"disjuncts\": [{\"field\": \"manages.reports\", \"match\": \"Beryl\"}, {\"field\": \"name\", \"match\": \"Nicol\\u00e1s\"}]})"

 }

]

Investigations gave the following results:

query

select meta().id from default where search(default, {"field": "manages.reports", "match": "Beryl"}) and type='emp'

runs successfully, I can find this in explain plan:

"~children": [

 {

 "#operator": "IndexFtsSearch",

 "index": "custom_index",

 "index_id": "295531dfb94aeb05",

 "keyspace": "default",

 "namespace": "default",

 "search_info": {

 "field": "\"\"",

 "outname": "out",

 "query": "{\"field\": \"manages.reports\", \"match\": \"Beryl\"}"

 },

 "using": "fts"

 },

...

But if I'm trying to run this:

select meta().id from default where search(default, {"field": "name", "match": "Nicol\u00e1s"}) and type='emp'

I'm getting an error - 

[

  {

    "code": 4000,

    "msg": "No index available on keyspace default that matches your query. Use CREATE INDEX or CREATE PRIMARY INDEX to create an index, or check that your expected index is online.",

    "query": "/*select meta().id from default where type='emp' and search(default, {\"disjuncts\": [{\"field\": \"manages.reports\", \"match\": \"Beryl\"}, {\"field\": \"name\", \"match\": \"Nicol\\u00e1s\"}]})*/\nselect meta().id from default where search(default, {\"field\": \"name\", \"match\": \"Nicol\\u00e1s\"}) and type='emp'"

  }

]