InfluxQL query to restore data to another database should preserve all data types

[afausti]

I was following the procedure to restore data to an existing database more specifically the InfluxQL query:

SELECT *
INTO "example-db".autogen.:MEASUREMENT
FROM "example-tmp-db".autogen./.*/ GROUP BY *

and found that this query is not preserving all data types in the destination database.

I'm reporting it here after discussing it with @Anaisdg on this community post.

Steps to reproduce:

I've tried to come up with a minimal example to reproduce this bug:

> CREATE DATABASE mydb

Load these two measurements into mydb:

measurement1 field1=1i
measurement1 field2=1i
measurement2 field1=1.0

> show field keys on mydb
name: measurement1
fieldKey fieldType
-------- ---------
field1   integer
field2   integer

name: measurement2
fieldKey fieldType
-------- ---------
field1   float

Copy data to another database

> CREATE DATABASE "mydb-copy"
> SELECT * INTO "mydb-copy".autogen.:MEASUREMENT FROM "mydb".autogen./.*/ GROUP BY *
name: result
time written
---- -------
0    2

Expected behavior:

I would expect data types to be preserved inmydb-copy.

Actual behavior:

We can see that field1 in measurement1 was created with the wrong data type.

> show field keys on "mydb-copy"
name: measurement1
fieldKey fieldType
-------- ---------
field1   float
field2   integer

name: measurement2
fieldKey fieldType
-------- ---------
field1   float

which probably happens because field1 also exists in measurement2 with a different data type.

This bug leads to the ERR: partial write: field type conflict error if we write data back to the original database:

> SELECT * INTO "mydb".autogen.:MEASUREMENT FROM "mydb-copy".autogen./.*/ GROUP BY *
ERR: partial write: field type conflict: input field "field1" on measurement "measurement1" is type float, already exists as type integer dropped=1

Environment info:

• System info:

# uname -r
3.10.0-1160.62.1.el7.x86_64 

• InfluxDB version:

# influxd version
InfluxDB v1.8.10 (git: 1.8 688e697c51fd)