Relation name '*__dbt_tmp' is longer than 63 characters

Describe the bug

My view name is pretty long, but it is less than 63 characters.

When dbt adds the __dbt_tmp suffix, it goes over the limit of 63 chars.

The following error is thrown by PostgreSQL:

Relation name ‘foo__dbt_tmp’ is longer than 63 characters

Steps To Reproduce

1. Use a view name that is 63 characters long.
2. dbt run

Expected behavior

To work anyways.

Screenshots and log output

See above.

System information

Which database are you using dbt with?

• postgres
• redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

Using Docker image fishtownanalytics/dbt:0.18.1.

The operating system you’re using:

Using Docker image fishtownanalytics/dbt:0.18.1.

The output of python --version:

Using Docker image fishtownanalytics/dbt:0.18.1.

Additional context

Perhaps the temporary name can be truncated by the length of the suffix to make sure it fits within the limits?

[danielefrigo]

Thanks for opening, @moltar! I agree, this is peskier than it could be.

Following the discussion about this over in #2850, the real max character length of a model name on Postgres is currently 51, because of the appended suffix __dbt_backup in the table and view materializations.

I think we could do as you recommend, and truncate the model name (if >51 characters) to accommodate the suffix. I view that as a reasonable next step on top of the work in #2850, which handles the truncation of uniquely suffixed identifiers in the incremental materialization.

Regarding the proposal of truncating the model name, I see a potential overlapping issue: you could have 2 models running in parallel, with a long common prefix in the name. If we truncate the model name, the tmp tables created by dbt could end up having exactly the same name. An alternative could be to completely loose the name link between the model name and the temp table name, using some kind of unique short identifier (e.g. an hash of the model name).

[jtcohen6]

@danielefrigo A hash of the model name makes a lot of sense to me! I’d still like to keep the conventional suffixes (__dbt_backup, __dbt_tmp) as well, for clarity of ownership.