Snapshots fail on structure chnages

[rafaelkrysciak]

Describe the bug

When the structure of an existing snapshot changes, the execution fails. There are two default macros involved that cause the failure. One is get_true_sql (v1.7.2 only), and the other one is create_columns.

The default implementation of get_true_sql delivers the keyword TRUE, which doesn't exist in Teradata.

The default implementation of create_columns performs the following alter table:

alter table {{ relation }} add column "{{ column.name }}" {{ column.data_type }}; 

Causing following error:

[Error 3707] Syntax error, expected something like '(' between the 'column' keyword and the word 'additional_column'.

In Teradata, the alter table should be performed without the column keyword.

To solve the problem, we overwriten the macros with the following code.

{% macro teradata__get_true_sql() %}
    {{ return('1 = 1') }}
{% endmacro %}

{% macro teradata__create_columns(relation, columns) %}
  {% for column in columns %}
    {% call statement() %}
      alter table {{ relation }} add "{{ column.name }}" {{ column.data_type }};
    {% endcall %}
  {% endfor %}
{% endmacro %}

Steps To Reproduce

Create a snapshot and add a new column to the snapshot.

Expected behavior

The new column is added without error.

Screenshots and log output

The output of dbt --version:

Core:
  - installed: 1.8.3
  - latest:    1.8.6 - Update available!

  Your version of dbt-core is out of date!
  You can find instructions for upgrading here:
  https://docs.getdbt.com/docs/installation

Plugins:
  - teradata: 1.8.0 - Up to date!

The operating system you're using:
Windows 11

The output of python --version:
Python 3.11.3