[CT-242] Release notes for v0.21.0 misleading

[dorachan2000]

Hello.

I noticed that the "Breaking changes" section of the v0.21.0 release notes mentioned the following

Turn off transactions and turn on autocommit by default. Explicitly specify begin and commit for DML statements in incremental and snapshot materializations.

This is misleading because it suggests that dbt users need to modify their dbt code even though dbt still wraps DML statements in incremental materialization in "begin" and "commit". The expected behavior is verified with the debug output of dbt running an incremental materialization.

$ pip freeze | grep dbt
dbt-core==1.0.1
dbt-extractor==0.4.0
dbt-snowflake==1.0.0

------------------------------------------------

23:43:29.508174 [debug] [Thread-1  ]: On model.dataeng.sellside_conversion_events: begin;
23:43:29.738323 [debug] [Thread-1  ]: SQL status: SUCCESS 1 in 0.23 seconds
23:43:29.739150 [debug] [Thread-1  ]: Using snowflake connection "model.dataeng.sellside_conversion_events"
23:43:29.739755 [debug] [Thread-1  ]: On model.dataeng.sellside_conversion_events: delete from dataeng_stage.reviews.sellside_conversion_events
    where (network || '_' || conversion_date) in (
        select (network || '_' || conversion_date)
        from dataeng_stage.reviews.sellside_conversion_events__dbt_tmp
    );
23:43:31.396181 [debug] [Thread-1  ]: SQL status: SUCCESS 10 in 1.66 seconds
23:43:31.397025 [debug] [Thread-1  ]: Using snowflake connection "model.dataeng.sellside_conversion_events"
23:43:31.397649 [debug] [Thread-1  ]: On model.dataeng.sellside_conversion_events: insert into dataeng_stage.reviews.sellside_conversion_events ("NETWORK", "CONVERSION_DATE", "DATA_TZ", "SESSION_ID", "VERTICAL", "ADVERTISER", "EVENT", "REVENUE", "BUYSIDE_DIMENSIONS", "ROAS_TRACKING", "SOURCE_INFO", "LINEAGE")
    (
        select "NETWORK", "CONVERSION_DATE", "DATA_TZ", "SESSION_ID", "VERTICAL", "ADVERTISER", "EVENT", "REVENUE", "BUYSIDE_DIMENSIONS", "ROAS_TRACKING", "SOURCE_INFO", "LINEAGE"
        from dataeng_stage.reviews.sellside_conversion_events__dbt_tmp
    );
23:43:32.622635 [debug] [Thread-1  ]: SQL status: SUCCESS 10 in 1.22 seconds
23:43:32.623389 [debug] [Thread-1  ]: Using snowflake connection "model.dataeng.sellside_conversion_events"
23:43:32.624332 [debug] [Thread-1  ]: On model.dataeng.sellside_conversion_events: commit

I believe the release notes came directly from the pr comments but it should be modified to be something like the following

Turn off transactions and turn on autocommit by default for non-DML statements.
DML statements running outside of dbt materializations should be explicitly wraped in `begin` and `commit`.
Note that this may affect user-space code that depends on transactions.

[jtcohen6]

@dorachan2000 Thanks for this! I agree with your suggested language. I think we'll want to update:

• docs migration guide - Update v0.21 migration guide: confusing note about breaking change to Snowflake transactions docs.getdbt.com#1265
• v0.21 release notes
• changelog: Update v0.21 changelog: confusing note about breaking change to Snowflake transactions #4937

I do believe we should keep this under Breaking Changes. This came up just the other day, where a user upgrading from v0.20 needed to adjust user-space code to account for this change: #4721

[jtcohen6]

Language I settled on:

• Breaking: Turn off transactions and turn on autocommit by default. Within dbt materializations, wrap DML statements in explicit begin and commit. Note that it is not recommended to run DML statements outside of dbt materialization logic. If you do this, despite our recommendation, you will need to wrap those statements in explicit begin and commit. Note also that this may affect user-space code that depends on transactions, such as pre-hooks and post-hooks that specify transaction: true or transaction: false. We recommend removing those references to transactions. (#2748, #3480, #3510)