The adapter supports the complete join syntax in Google Spanner. Google Spanner supports inner joins, outer joins, and cross joins. The default is inner. Multiple join operations are supported.
SELECT field_1 [..., field_n] FROM table_1 [[AS] alias_1] [[INNER|[FULL|RIGHT|LEFT] OUTER|CROSS] JOIN [EACH] table_2 [[AS] alias_2] [ON join_condition_1 [... AND join_condition_n]] ]+
Note that the default join is an inner join. The following limitations exist on joins in Google Spanner:
- Cross joins must not contain an ON clause.
- Normal joins require that the right-side table must contain less than 8 MB of compressed data. If you are working with tables larger than 8 MB, use the EACH modifier. Note that EACH cannot be used in cross joins.