[0.9.4.1] Drop Measurement for 1 DB drops all measurements of same name

[simcap]

Hi,

I have a measurement called p2p in my db viewers. It happens that I also have a testviewers db with also a measurement p2p.

I wanted to clean my testviewers db and drop the p2p measurement. I did the following steps:

> use testviewers
Using database testviewers
> drop measurement p2p
> select count(value) from p2p
> 

So it is empty. The issue is that it also cleaned the db viewers!! Beforehand this db viewers had a lot of data:

> select count(value) from p2p
name: p2p
---------
time      count
1970-01-01T00:00:00Z  1.042289e+06

Now it is empty:

> use viewers
> select count(value) from p2p
name: p2p
---------
time            count
1970-01-01T00:00:00Z    

or 

> select * from p2p
> 

Is there a from clause where we should specify the db from which to drop the measurement. Or it is that it just wipe a measurement across all dbs?

[simcap]

Actually the measurement p2p from the viewers db came back!! (a bit more data since we have live customers pushing data)

> select count(value) from p2p
name: p2p
---------
time      count
1970-01-01T00:00:00Z  1.042318e+06

I guess it might be a sync or display issue in the CLI.

[rkuchan]

@simcap, thank you for pointing this out. That is definitely unexpected behavior. Interestingly, I'm able to repro the first part with version 0.9.4.1:

> create database first
> use first
Using database first
> insert pumpkin orange=1
> insert pumpkin orange=2
> insert pumpkin orange=3
> create database second
> use second
Using database second
> insert pumpkin orange=11
> insert pumpkin orange=12
> insert pumpkin orange=13
> select * from first."default".pumpkin
name: pumpkin
-------------
time                orange
2015-10-02T19:18:22.026149413Z  1
2015-10-02T19:18:23.487714562Z  2
2015-10-02T19:18:24.668921664Z  3

> select * from second."default".pumpkin
name: pumpkin
-------------
time                orange
2015-10-02T19:18:42.130289879Z  11
2015-10-02T19:18:43.805793895Z  12
2015-10-02T19:18:45.448094234Z  13

> use second
Using database second
> drop measurement pumpkin
> select * from second."default".pumpkin
> select * from first."default".pumpkin
>

but I can't seem to repro the second part:

> use first
Using database first
> select * from pumpkin
> insert pumpkin orange=4
> select * from pumpkin
name: pumpkin
-------------
time                orange
2015-10-02T19:28:18.147674321Z  4

[otoolep]

This is bad.

If a measurement name is shard across two databases, drop them from 1 drops them from the other.

[otoolep]

Thanks for the report @simcap -- we definitely need to fix this ASAP.

[otoolep]

The bz1, and presumably b1, engines suffer from this. However the tsm1 engine does not!

[otoolep]

This may actually be fixed by moving to the tsm1 engine when it is released.

[simcap]

@rkuchan The second part I added (see my second comment) was to say that when I logged out of the shell and logged back in the measurement came back (so the drop only wipe one db as expected). So I was thinking more of a display sync issue in the shell.

But as @otoolep points out some engines seems to suffer from this issue.

Anyway thanks for the promptness, and before doing a lot of work let's ensure it is not just a shell issue.

[markusr]

Any updates on this?

[dgnorton]

@markusr fix coming soon