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DDL Generation

DDL generation is handled by TiberoDDLCompiler and TiberoTypeCompiler.

CREATE TABLE column specification

TiberoDDLCompiler.get_column_specification() builds each column as:

  1. Formatted column name
  2. Compiled Tibero type
  3. NOT NULL when applicable
  4. Identity or default clause

Identity behavior:

  • If column is the table autoincrement column and has no server default, emit:
GENERATED ALWAYS AS IDENTITY
  • Otherwise, emit explicit DEFAULT <expr> if present.

Table comments

Supported comment methods:

  • post_create_table(table) appends COMMENT ON TABLE ...
  • visit_set_table_comment(create, **kw)
  • visit_drop_table_comment(drop, **kw)

Example emitted SQL:

COMMENT ON TABLE users IS 'Application users'

Column comments

visit_set_column_comment(create, **kw) emits:

COMMENT ON COLUMN users.name IS 'Display name'

Sequences

The dialect advertises supports_sequences = True and sequences_optional = True, so SQLAlchemy sequence constructs are supported.

DDL compilation flow

mermaid flowchart LR model[Table/Column metadata] --> ddl[TiberoDDLCompiler] ddl --> typec[TiberoTypeCompiler] typec --> sql[CREATE/ALTER/COMMENT SQL] sql --> exec[DB-API execution via engine]

Comments are emitted separately

inline_comments = False, so comments are produced as standalone COMMENT ON statements.

Identity condition is strict

Identity SQL is only emitted for SQLAlchemy's detected autoincrement column with no explicit server default.

Alembic Migration Support

This dialect ships with an Alembic DDLImpl registered via alembic.ddl entry point. After installing sqlalchemy-pytibero, Alembic migrations work automatically.

Key behavior: transactional_ddl = False — Tibero auto-commits DDL statements, so Alembic will not wrap migrations in a transaction.

# alembic.ini
sqlalchemy.url = tibero://tibero:password@localhost:8629/TESTDB

alembic upgrade head

Install Alembic extra

pip install "sqlalchemy-pytibero[alembic]" to pull in Alembic as a dependency.