New Features¶ ↑

• Database#freeze has now been implemented. It is now recommended to use it in production and during testing, after loading extensions and making other changes to Database state. Once frozen, the Database settings cannot be modified, but the Database can execute queries and return results. By freezing the Database, you gain greater thread-safety assurance and will be alerted via an exception if runtime code attempts to modify Database state.

Other Improvements¶ ↑

• Model#refresh now uses the same optimization that Model.with_pk uses, resulting in faster refreshing for most models.

• The prepared_statements plugin no longer automatically uses prepared statements in cases where it is likely to be slower. Now, prepared statements are only used by default for INSERT and UPDATE statements (and DELETE on Oracle and DB2). This change was made after benchmarking showed that using prepared statements for primary key lookups, refreshes, and deletes is significantly slower than non-prepared statements across almost all adapters.

• Database#extension no longer attempts to load the same extension more than once.

• The timestamp migrator now handles key length limitations when using MySQL with InnoDB engine and utf8mb4 charset default.

• The jdbc/sqlite adapter will now use SQLite result codes for more accurate exception types, if the jdbc-sqlite driver supports them.

• dataset_module is now inherited correctly if using the single_table_inheritance plugin. This was broken in 4.42.0, and fixed in 4.42.1.

• The prepared_statements plugin now respects a server specified for the model instance, instead of always using the default server.

• The prepared_statements_associations plugin now respects a server specified for the model instance if using the sharding plugin, instead of always using the default server.

• The prepared_statements_associations plugin now works correctly when using some instance-specific associations, such as many_to_one associations using a nil :key option.

• The prepared_statements_with_pk plugin now respects a server specified for the dataset, instead of always using the default server.

• Model#freeze now freezes the associations hash after validating the model instance, instead of before, fixing cases where validation calls association methods.

• Sequel no longer continually tries to determine the server version on HSQLDB, if the first attempt fails.

• The mock adapter now uses a thread-safe incrementor for autoid.

• Mysql2 native prepared statement support now better handles sharding where connection options differ per shard.

• On Oracle, Database#sequence_for_table is now thread-safe.

• On PostgreSQL, Database#type_supported? is now thread-safe.

• On MySQL, Database#supports_timestamp_usecs? now correctly memoizes false values.

• The jdbc/postgresql adapter now works correctly if the pg_hstore extension is loaded first.

Backwards Compatibility¶ ↑

• Maintainers of external adapters and Database extensions should update their code to support Database#freeze.

• Code that relies on Database extensions being loaded multiple times if called multiple times needs to be updated, because now the extension only gets loaded the first time Database#extension is called.

• @enum_labels in the pg_enum extension is now frozen by default.