zclllyybb commented on issue #3883:
URL: https://github.com/apache/doris-website/issues/3883#issuecomment-4601434847
Breakwater-GitHub-Analysis-Slot: slot_fdfc1ed06e14
Initial analysis from current upstream Doris master (`7ec8f7d0d61`):
This looks like an expected display/metadata compatibility behavior, not a
loss of the actual column type.
The relevant code paths are different:
- Parser/type mapping: `text` and `string` are both mapped to the same Doris
string type. In `DataType.convertPrimitiveFromStrings(...)`, both `text` and
`string` return `StringType.INSTANCE`; `StringType.toCatalogDataType()` returns
`Type.STRING`.
- SQL display for table DDL: `ScalarType.toSql()` and
`ScalarType.toString()` render `PrimitiveType.STRING` as `text`. `SHOW CREATE
TABLE` goes through `Env.getDdlStmt(...)` -> `Column.toSql(...)` ->
`type.toSql()`, so it prints `text`.
- `DESC` / unfiltered `SHOW COLUMNS`: `ShowColumnsCommand` reads the column
type from the catalog type display path, so it also prints `text`.
- `information_schema.columns`: this is populated by the BE schema scanner.
`schema_columns_scanner.cpp` explicitly says `DATA_TYPE` is converted for MySQL
compatibility, and maps both `TPrimitiveType::VARCHAR` and
`TPrimitiveType::STRING` to `varchar`. In the same scanner, `COLUMN_TYPE` for
`TPrimitiveType::STRING` returns `string`.
So on current master I would expect:
- DDL input `STRING` and `TEXT` are accepted as the same Doris
variable-length string type.
- `SHOW CREATE TABLE` and `DESC` display that type as `text`.
- `information_schema.columns.DATA_TYPE` displays `varchar` for
MySQL-compatible metadata.
- `information_schema.columns.COLUMN_TYPE` should display `string` for this
type. If `COLUMN_TYPE` is also `varchar` in the reporter's environment, that
would need a version-specific check because it does not match the current
master code path.
Recommended next step for this website issue: treat it as a documentation
gap. The `STRING` data type page currently describes length and usage
restrictions, but it does not explain the display aliases. A useful doc note
would be:
> `STRING` and `TEXT` are accepted spellings for the same Doris
variable-length string type. Doris may canonicalize this type as `TEXT` in
`SHOW CREATE TABLE` and `DESC`. In `information_schema.columns`, `DATA_TYPE`
follows MySQL-compatible metadata and may show `varchar`; use `COLUMN_TYPE`
when checking the Doris-specific column type.
Missing information only if we want to validate a version-specific
inconsistency:
- Doris version/build.
- Minimal `CREATE TABLE` statement.
- Exact selected output for `DATA_TYPE` and `COLUMN_TYPE`, for example:
`select column_name, data_type, column_type from
information_schema.columns where table_name = '...';`
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