Ignore primary key, foreign key and unique constraints for DDL generation #541
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willmostly
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damian3031
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Apr 11, 2025
trino/sqlalchemy/compiler.py
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| def visit_foreign_key_constraint(self, constraint, **kw): | ||
| return None |
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Rather than silently ignoring constraints, maybe we should raise an explicit error indicating that these constraints are not supported in Trino:
Suggested change
| def visit_foreign_key_constraint(self, constraint, **kw): | |
| return None | |
| from sqlalchemy.exc import CompileError | |
| ... | |
| def visit_foreign_key_constraint(self, constraint, **kw): | |
| raise CompileError("Trino does not support FOREIGN KEY constraints.") |
Or at least we could add a warning to make it clearer that the constraint is being ignored:
Suggested change
| def visit_foreign_key_constraint(self, constraint, **kw): | |
| return None | |
| import warnings | |
| from sqlalchemy.exc import SAWarning | |
| ... | |
| def visit_foreign_key_constraint(self, constraint, **kw): | |
| warnings.warn("Trino does not support FOREIGN KEY constraints. Constraint will be ignored.", SAWarning) | |
| return None |
@willmostly @hashhar WDYT?
|
this would enable using sqlalchemy ORM-like features, being aware that PK and FK are not enforced. Right now it's not otherwise possible. |
|
@hashhar @willmostly I added warnings about unsupported constraints, PTAL |
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Description
Define custom visitors in
TrinoDDLCompilerto ignore constraints.Non-technical explanation
By default, SQLAlchemy adds
PRIMARY KEYand other constraint keywords to table creation DDL when these constraints are defined on aTableor class derived from declarative base. Since Trino does not support constraints, this results in invalid SQL. With this change the trino sqlalchemy extension now ignores primary key, foreign key and unique constraints when generating table DDL.Release notes
( ) This is not user-visible or docs only and no release notes are required.
( ) Release notes are required, please propose a release note for me.
(x) Release notes are required, with the following suggested text:
* ignore constraints for table DDL generation