Update Table.union

[jdunkerley]

Allow more relaxed type coercion.

• If there is a mixed column, then the result will be mixed. Only way to get a Mixed column.
• Widen including text (so everything can be widened enough). If binary columns then should error.
• By default we warn if we take a non-text type to text.
• Warn if potential loss of accuracy (e.g. Int64 merging to a Float64).
  • Int32 and Float32 can merge to Float64 (no warn).
• Warn if attaching a TZ to a non-TZ column.
  • Date ==> Date_Time with 00:00:00 and attach a TZ (hence warning).

Changes to the API:

• allow_type_widening is removed.
• keep_unmatched_columns is removed.
• New keep_columns arguments with new Atom type:
  (feel free to name better!)

type Columns_To_Keep
    ## All columns are kept, 
    In_Any

    ## On columns present in all are kept.
    In_All

    ## Specific list of column names
    In_List (column_names:Vector Text)

• If ..By_Position and ..List throw an error.
• tables should have a vector editor as default widget.

[enso-bot]

Radosław Waśko reports a new STANDUP for yesterday (2024-05-15):

Progress: Some additional fixes in the DataLink PR. Got merged a PR preparing for Cloud endpoint move. Prepared a PR reverting a temporary fallback. Started work on Table.union improvement - clarifications, documenting new behaviour to deeper understand what we need. It should be finished by 2024-05-21.

Next Day: Next day I will be working on the same task. Update tests. Update implementation.

[enso-bot]

Radosław Waśko reports a new STANDUP for yesterday (2024-05-16):

Progress: Updated Union tests to reflect the new semantics. Some minor docs clarifications. Last minute improvements to Datalink PR, finally merged. It should be finished by 2024-05-21.

Next Day: Next day I will be working on the same task. Update implementation.

[enso-bot]

Radosław Waśko reports a new STANDUP for the provided date (2024-05-17):

Progress: Implemented the new column matching logic, incl. In_List and error handling. Updating the column type unification logic - WIP. It should be finished by 2024-05-21.

Next Day: Next day I will be working on the same task. Continue implementation of new type merging logic for Union.

[enso-bot]

Radosław Waśko reports a new STANDUP for today (2024-05-20):

Progress: Got the unification mostly working on in-memory. Also aligned the DB backend - SQLite tests are passing. Postgres crashing. It should be finished by 2024-05-21.

Next Day: Next day I will be working on the same task. Fix Postgres problem. Add missing warning on Date->Date_Time. Try cleanup as there's some repetitiveness in current implementation between DB and in-mem.

[enso-bot]

Radosław Waśko reports a new STANDUP for yesterday (2024-05-21):

Progress: Finished DB implementation. Code cleanup, implemented warnings for Date->Date_Time, fixed failing tests and separated type logic changes to only affect Union. PR ready and reviewed. One seemingly unrelated test is failing so blocked from merge :( It should be finished by 2024-05-21.

Next Day: Next day I will be working on the #9849 task. Fix that one test and get the PR in. Work on next task (UTF BOM).