- When renaming a column concurrently, drop any existing trigger before
attempting to create a new one.
When running migration specs multiple times (as it happens during
local development), the down method of previous migrations are called.
If any of the called methods contains a call to
rename_column_concurrently, a trigger will be created and not removed.
So, the next time a migration spec is run, if the same down method is
executed again, it will cause an error when attempting to create the
trigger (since it already exists). Dropping the trigger if it already
exists will prevent this problem.
This improves the `add_timestamps_with_timezone` helper by allowing the
column names to be configured. This has the advantage that unnecessary
columns can be avoided, saving space.
A helper for removing the columns is also provided, to be used in the
`down` method of migrations.
In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21497, we
migrated all project import data into a separate table,
`project_import_data`. In addition, we also added:
```
ignore_column :import_status, :import_jid, :import_error
```
In https://gitlab.com/gitlab-com/gl-infra/production/issues/908, we
observed some of these `import_error` columns consumed megabytes of
error backtraces and caused slow loading of projects whenever a `SELECT
* from projects` query loaded the row into memory.
Since we have long migrated away from these columns, we can now drop
these columns entirely.
1. Ignore tables that use STI in reltuples count strategy.
Models that use Rails' single-type inheritance, such as `Group` and
`CiService`, need an additional WHERE clause to count the total
properly, which isn't supported by the reltuples strategy. For now,
we just omit these from the statistics sampling and rely on the other
strategies to get this data.
2. Fix tablesample count strategy not counting groups properly.
Models such as `Group` needs a WHERE clause to distinguish it from
namespaces. We now add in the WHERE clause if STI is in use.
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/7435
A tablesample count executes in two phases:
* Estimate table sizes based on reltuples.
* Based on the estimate:
* If the table is considered 'small', execute an exact relation count.
* Otherwise, count on a sample of the table using TABLESAMPLE.
The size of the sample is chosen in a way that we always roughly scan
the same amount of rows (see TABLESAMPLE_ROW_TARGET).
GitLab Bot
Peter Leitzen
Ash McKenzie
Reuben Pereira
Andreas Brandl
Stan Hu
Thong Kuah
Heinrich Lee Yu
Nick Thomas
Alex Kalderimis
Jason Goodman
Yorick Peterse
Takuya Noguchi
Jasper Maes
Jan Provaznik