show series, show measurements, select commands return no results

__Steps to reproduce:__

I get no results for almost any commands like show series, show measurements, etc.

I have a 44gb database with records from the last year on a default autogen retention policy. This is the first time in maybe 8 months that I've tried to do much with this so its been running un-monitored.

Running `show measurements`, `show series`, etc returns no results.

The only data I can get out is about the shards which I'll share here:
```
> show shards

name: _internal
id database retention_policy shard_group start_time end_time expiry_time owners
-- -------- ---------------- ----------- ---------- -------- ----------- ------
65 _internal monitor 65 2019-10-11T00:00:00Z 2019-10-12T00:00:00Z 2019-10-19T00:00:00Z
66 _internal monitor 66 2019-10-12T00:00:00Z 2019-10-13T00:00:00Z 2019-10-20T00:00:00Z
67 _internal monitor 67 2019-10-14T00:00:00Z 2019-10-15T00:00:00Z 2019-10-22T00:00:00Z
68 _internal monitor 68 2019-10-15T00:00:00Z 2019-10-16T00:00:00Z 2019-10-23T00:00:00Z

name: recordsdb
id database retention_policy shard_group start_time end_time expiry_time owners
-- -------- ---------------- ----------- ---------- -------- ----------- ------
7 recordsdb autogen 7 2015-06-08T00:00:00Z 2015-06-15T00:00:00Z 2015-06-15T00:00:00Z
6 recordsdb autogen 6 2018-10-22T00:00:00Z 2018-10-29T00:00:00Z 2018-10-29T00:00:00Z
9 recordsdb autogen 9 2018-10-29T00:00:00Z 2018-11-05T00:00:00Z 2018-11-05T00:00:00Z
17 recordsdb autogen 17 2018-11-05T00:00:00Z 2018-11-12T00:00:00Z 2018-11-12T00:00:00Z
25 recordsdb autogen 25 2018-11-12T00:00:00Z 2018-11-19T00:00:00Z 2018-11-19T00:00:00Z
31 recordsdb autogen 31 2018-11-19T00:00:00Z 2018-11-26T00:00:00Z 2018-11-26T00:00:00Z
37 recordsdb autogen 37 2018-11-26T00:00:00Z 2018-12-03T00:00:00Z 2018-12-03T00:00:00Z
38 recordsdb autogen 38 2018-12-03T00:00:00Z 2018-12-10T00:00:00Z 2018-12-10T00:00:00Z
42 recordsdb autogen 42 2018-12-10T00:00:00Z 2018-12-17T00:00:00Z 2018-12-17T00:00:00Z
43 recordsdb autogen 43 2018-12-31T00:00:00Z 2019-01-07T00:00:00Z 2019-01-07T00:00:00Z
44 recordsdb autogen 44 2019-01-07T00:00:00Z 2019-01-14T00:00:00Z 2019-01-14T00:00:00Z
46 recordsdb autogen 46 2019-01-28T00:00:00Z 2019-02-04T00:00:00Z 2019-02-04T00:00:00Z
47 recordsdb autogen 47 2019-02-04T00:00:00Z 2019-02-11T00:00:00Z 2019-02-11T00:00:00Z
49 recordsdb autogen 49 2019-02-11T00:00:00Z 2019-02-18T00:00:00Z 2019-02-18T00:00:00Z
50 recordsdb autogen 50 2019-02-18T00:00:00Z 2019-02-25T00:00:00Z 2019-02-25T00:00:00Z
51 recordsdb autogen 51 2019-02-25T00:00:00Z 2019-03-04T00:00:00Z 2019-03-04T00:00:00Z
52 recordsdb autogen 52 2019-04-01T00:00:00Z 2019-04-08T00:00:00Z 2019-04-08T00:00:00Z
53 recordsdb autogen 53 2019-04-08T00:00:00Z 2019-04-15T00:00:00Z 2019-04-15T00:00:00Z
54 recordsdb autogen 54 2019-04-29T00:00:00Z 2019-05-06T00:00:00Z 2019-05-06T00:00:00Z
55 recordsdb autogen 55 2019-07-01T00:00:00Z 2019-07-08T00:00:00Z 2019-07-08T00:00:00Z
56 recordsdb autogen 56 2019-07-08T00:00:00Z 2019-07-15T00:00:00Z 2019-07-15T00:00:00Z
57 recordsdb autogen 57 2019-07-15T00:00:00Z 2019-07-22T00:00:00Z 2019-07-22T00:00:00Z
59 recordsdb autogen 59 2019-07-29T00:00:00Z 2019-08-05T00:00:00Z 2019-08-05T00:00:00Z
61 recordsdb autogen 61 2019-08-05T00:00:00Z 2019-08-12T00:00:00Z 2019-08-12T00:00:00Z
63 recordsdb autogen 63 2019-08-12T00:00:00Z 2019-08-19T00:00:00Z 2019-08-19T00:00:00Z
64 recordsdb autogen 64 2019-10-07T00:00:00Z 2019-10-14T00:00:00Z 2019-10-14T00:00:00Z
```

__Expected behavior:__
Expecting to see saved data

__Actual behavior:__
An empty new line.

__Environment info:__

* System info: Linux 4.15.0-38-generic x86_64
* InfluxDB version: InfluxDB v1.6.4 (git: 1.6 c75cdfdfa6f71a08473fefcec71f6cbcbdef1ff4)

__Config:__
Using default

__Logs:__
Log file doesn't exist
```
ls -la /var/log/influxdb
total 8
drwxr-xr-x 2 influxdb influxdb 4096 Oct 16 2018 .
drwxrwxr-x 13 root syslog 4096 Oct 15 06:25 ..
```

__Performance:__
Generate profiles with the following commands for bugs related to performance, locking, out of memory (OOM), etc.

```sh
# Commands should be run when the bug is actively.
# Note: This command will run for at least 30 seconds.
curl -o profiles.tar.gz "http://localhost:8086/debug/pprof/all?cpu=true"
curl -o vars.txt "http://localhost:8086/debug/vars"
iostat -xd 1 30 > iostat.txt
# Attach the `profiles.tar.gz`, `vars.txt`, and `iostat.txt` output files.
```

Start by reproducing `show measurements`, `show series`, and related commands against InfluxDB v1.6.4, then compare the empty results with the listed `recordsdb` shard data. Done means identifying why saved data is not returned and verifying that these commands show the expected measurements and series.

Written by the indexing model from the issue text.