revert: feat(dtypes): fall back to dt.unknown for unknown types (#9569

)

ibis/backends/sql/datatypes.py

@@ -170,9 +170,7 @@ def to_ibis(cls, typ: sge.DataType, nullable: bool | None = None) -> dt.DataType
         if method := getattr(cls, f"_from_sqlglot_{typecode.name}", None):
             dtype = method(*typ.expressions)
         else:
-            dtype = _from_sqlglot_types.get(typecode, dt.unknown)(
-                nullable=cls.default_nullable
-            )
+            dtype = _from_sqlglot_types[typecode](nullable=cls.default_nullable)
 
         if nullable is not None:
             return dtype.copy(nullable=nullable)
@@ -419,6 +417,8 @@ class PostgresType(SqlglotType):
 
     unknown_type_strings = FrozenDict(
         {
+            "vector": dt.unknown,
+            "tsvector": dt.unknown,
             "line": dt.linestring,
             "line[]": dt.Array(dt.linestring),
             "polygon": dt.polygon,
@@ -454,6 +454,16 @@ def _from_ibis_Map(cls, dtype: dt.Map) -> sge.DataType:
             raise com.IbisTypeError("Postgres only supports string values in maps")
         return sge.DataType(this=typecode.HSTORE)
 
+    @classmethod
+    def from_string(cls, text: str, nullable: bool | None = None) -> dt.DataType:
+        if text.lower().startswith("vector"):
+            text = "vector"
+        if dtype := cls.unknown_type_strings.get(text.lower()):
+            return dtype
+
+        sgtype = sg.parse_one(text, into=sge.DataType, read=cls.dialect)
+        return cls.to_ibis(sgtype, nullable=nullable)
+
 
 class RisingWaveType(PostgresType):
     dialect = "risingwave"