morningman opened a new pull request, #14382:
URL: https://github.com/apache/doris/pull/14382
# Proposed changes
Issue Number: close #xxx
## Problem summary
When executing `create table as select` stmt,
the varchar/char/string type of column in created table will be unified to
`string` type.
Because when select from external table (mysql/pg, etc), the length of
varchar in external database
is calculated by "char" length, not "byte" length.
So if there is a column with `varchar(10)` in external table, then there
will be a same `varchar(10)`
in created table. But the byte length of data in external table may be
larger than 10, causing failure of CTAS.
Change to string will not impact performance of the capacity of disk storage.
And notice that if a string type column is the first column, it will be
changed to `varchar(65535)`,
because we do not allow string type column as sort key column.
## Checklist(Required)
1. Does it affect the original behavior:
- [ ] Yes
- [ ] No
- [ ] I don't know
2. Has unit tests been added:
- [ ] Yes
- [ ] No
- [ ] No Need
3. Has document been added or modified:
- [ ] Yes
- [ ] No
- [ ] No Need
4. Does it need to update dependencies:
- [ ] Yes
- [ ] No
5. Are there any changes that cannot be rolled back:
- [ ] Yes (If Yes, please explain WHY)
- [ ] No
## Further comments
If this is a relatively large or complex change, kick off the discussion at
[[email protected]](mailto:[email protected]) by explaining why you
chose the solution you did and what alternatives you considered, etc...
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