hqbhoho opened a new issue, #12518:
URL: https://github.com/apache/gravitino/issues/12518
### Version
main branch
### Describe what's wrong
For a MySQL catalog, the metadata path and the projection-pushdown path
report different Trino types for the same column: `getTableMetadata` maps MySQL
`tinytext` / `text` / `mediumtext` / `enum` / `set` to an unbounded `varchar`,
while `applyProjection` forwards the internal connector's assignment types
as-is, which are derived from the JDBC column size (e.g. `varchar(255)` for
tinytext).
Since Trino 444 the planner verifies that both sides of an assignment have
the same type (trinodb/trino#21286), so pushing a projection down over such a
column now fails the query at planning time. Trino 443 and earlier silently
tolerated the same divergence (verified on both versions against the same MySQL
server). A plain `mysql` catalog is not affected, because there both types come
from the same column handle.
### Error message and/or stacktrace
```
GENERIC_INTERNAL_ERROR: Types don't match: varchar vs varchar(255),
for col_tinytext::[varchar] and col_tinytext_7::varchar(255)
```
### How to reproduce
`jdbc-mysql` catalog on Trino 478:
```sql
CREATE TABLE gt_mysql.db.t (id int, name varchar); -- unbounded varchar
becomes MySQL TEXT
SELECT *, if(name is null, '', name) FROM gt_mysql.db.t;
```
Triggering it takes referencing every column of the table, a projection
expression the internal connector cannot push down, and a bare text / enum /
set column in the output — the typical `SELECT *, <computed column>` query.
### Additional context
The fix is to restore the engine-assigned types (available from the
`Variable`s in the `projections` argument) when
`GravitinoMetadata#applyProjection` returns the assignments, the same way
`DefaultJdbcMetadata` types them in its own expression-pushdown branch.
Session-level mitigation: `SET SESSION allow_pushdown_into_connectors =
false` (disables all pushdown for the session).
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