Dot/period at start of index name fails to parse

[aetter]

POST _opendistro/_sql
{
  "query": "SELECT * FROM .kibana LIMIT 50"
}

This query fails with the following error:

{
  "error": {
    "reason": "Invalid SQL query",
    "details": "ERROR. token : DOT, pos : 15",
    "type": "ParserException"
  },
  "status": 400
}

Indices starting with . is perfectly valid in Elasticsearch, so unless there's a good reason, I think we should support this operation.

[abbashus]

Thanks @aetter , looks like a valid case. Even wrapping .kibana in back-ticks and single quotes is not working. We will look into it and come with a fix.

[dai-chen]

Thanks @aetter , looks like a valid case. Even wrapping .kibana in back-ticks and single quotes is not working. We will look into it and come with a fix.

I remember we ran into the similar issue for identifiers in back-ticks when evaluating support for Tableau. @qreshi may have more context.

[dai-chen]

New issue related: #212