v0.1.0-alpha.2

Adds schema management: creating and altering tables, columns, indexes, foreign
keys and views from Tabularis's dialogs. Tested against CockroachDB v24.3 and
the latest release.

Added

• Schema management: get_create_table_sql, get_add_column_sql,
  get_alter_column_sql, get_create_index_sql, get_create_foreign_key_sql,
  drop_index, drop_foreign_key, create_view, alter_view and drop_view.
  • Primary keys are named <table>_pkey, composite keys work, and SERIAL
    columns keep their width (SMALLSERIAL, SERIAL4, SERIAL).
  • A new primary key column is added and then extends the table's key through
    ALTER PRIMARY KEY (CockroachDB rejects ADD COLUMN .. PRIMARY KEY on a
    table that already has a key). A table with no key still generates, with a
    warning comment.
  • Altering a column emits one statement per change (rename, type, nullability,
    default, description). A change that converts data gets USING and a note
    about the session setting CockroachDB v24.3 needs.
  • Indexes are dropped as schema.table@index, so an index name shared by two
    tables is never ambiguous.
  • A view whose columns change is replaced by dropping and creating it in one
    transaction, so a failure in between restores the old view. A view's query
    resolves unqualified table names in the view's own schema.
  • Types, default expressions and view queries are validated before they are
    used in SQL (no ;, no comment, nothing left open), names are always quoted,
    foreign key actions are limited to the five SQL actions, and drops never
    cascade.

Changed

• docs/architecture/04-ddl.md records the host's real request and reply shapes
  and what was verified on v24.3 and v26.3.

Known limitations

Tracked in #16:

• EXPLAIN is not implemented; the explain button returns "Method not found".
• Materialized views, sequences, routines, triggers, multi-region metadata and
  the schema snapshot (ER diagram) are not provided yet.
• Schema management follows what the host's dialogs send. Options they do not
  offer are not generated: STORING, hash-sharded, inverted and partial indexes,
  NOT VALID foreign keys, comments on tables and schemas, and LOCALITY.
• On v24.3, a type change that converts data needs
  SET enable_experimental_alter_column_type_general = true in the same session.
  The host runs each generated statement separately, so the setting is explained
  in a comment and not emitted; v26.3 needs nothing.
• Replacing a view whose columns change makes it invisible for about 70 ms. A
  view other views depend on cannot be replaced, and an index behind a referenced
  UNIQUE constraint is not dropped (the error gives the CASCADE statement).
• Not exercised against a real CockroachDB Cloud cluster, nor query cancellation
  behind a load balancer; a real 40001 retry of an implicit statement could not
  be provoked on the tested releases.