correct & update example to add/drop constraint #21542
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rmloveland
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rmloveland
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LGTM modulo the multi DDL inside one transaction thing which we explicitly recommend against in https://www.cockroachlabs.com/docs/v25.4/online-schema-changes#schema-changes-within-transactions
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i think this should be a separate docs-infra type PR
| #### Demo | ||
| {% include_cached youtube.html video_id="MPx-LXY2D-c" %} |
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oh man -1000 points to slytherin for adding YT links and then making private during a "cleanup"
| #### Drop and add a primary key constraint | ||
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| Suppose that you want to add `name` to the composite primary key of the `users` table, [without creating a secondary index of the existing primary key](#changing-primary-keys-with-add-constraint-primary-key). | ||
| Suppose that you want to add `creation_time` to the composite primary key of the `promo_codes` table, [without creating a secondary index of the existing primary key](#changing-primary-keys-with-add-constraint-primary-key). |
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not needed due to https://www.cockroachlabs.com/docs/releases/release-support-policy.html#supported-versions but now that it's here 🆗
| ALTER TABLE promo_codes ALTER COLUMN creation_time SET NOT NULL; | ||
| ~~~ | ||
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| 1. Turn off autocommit for DDL for the current session, so that multiple DDL statements can execute within one explicit transaction: |
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we should not recommend this, running multiple DDLs in one transaction is not recommended: https://www.cockroachlabs.com/docs/v24.3/online-schema-changes#schema-changes-within-transactions
recommend doing this in two separate implicit transactions one after the other (unless there is a reason i'm missing here why they need to be in the same transaction? if it's just to keep the example neater i'd argue that's not a good reason)
| #### Demo | ||
| {% include_cached youtube.html video_id="MPx-LXY2D-c" %} |
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-1000 points to ravenclaw
| #### Demo | ||
| {% include_cached youtube.html video_id="MPx-LXY2D-c" %} |
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-1000 points to slytherin
| ALTER TABLE promo_codes ALTER COLUMN creation_time SET NOT NULL; | ||
| ~~~ | ||
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| 1. Turn off autocommit for DDL for the current session, so that multiple DDL statements can execute within one explicit transaction: |
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please revise to not do multi DDLs in one transaction per the holy book
| #### Demo | ||
| {% include_cached youtube.html video_id="MPx-LXY2D-c" %} |
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-1000 points to gryffindor (i was hoping to avoid dinging gryffindor here but have to be fair)
| ALTER TABLE promo_codes ALTER COLUMN creation_time SET NOT NULL; | ||
| ~~~ | ||
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| 1. Turn off autocommit for DDL for the current session, so that multiple DDL statements can execute within one explicit transaction: |
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same as above re: please revise to not do multi-ddl in one transaction, i think these can just be two implicit transactions in a row
| #### Demo | ||
| {% include_cached youtube.html video_id="MPx-LXY2D-c" %} |
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i shall look askance at YT links from now on i must admit
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DOC-14789
Update the
ALTER TABLEexample to drop & add constraint atomically. For the following reasons, this example did not work (and may have never worked):primary, nottablename_pkeyas per convention).users) is referenced by several FKs in the MovR dataset, so the txn actually rolls back.autocommit_before_ddlwas introduced, which causes the txn to commit before issuing the DDL, which causes the statements to fail.create_table_with_schema_lockedwas enabled by default, and the MovR tables were adjusted accordingly. This means the tables disallow schema changes unless theschema_lockedstorage param is disabled on the table.The examples are updated (appropriately for each version) to use a different MovR table (
promo_codes), use the correct PK name, disableautocommit_before_ddl, and disable/re-enableschema_lockedto allow the example to work.