DatabaseOperations.bulk_batch_size() should consider more database limits on SQLite and Oracle

[Sarah Boyce]

DatabaseOperations.bulk_batch_size() is used to calculate the maximum batch size when doing operations such as bulk_update and bulk_create

When investigating the impact of composite primary keys on the maximum batch size calculation for bulk_update(), it became clear that there are more database limits that need to be considered when calculating the maximum batch size in order to have a bullet proof solution.

One possible limit in play on SQLite is SQLITE_MAX_EXPR_DEPTH which is 1000 (see ​https://www.sqlite.org/limits.html#max_expr_depth).
On Oracle, we found that a query could error with the ambiguous message: ORA-00907: missing right parenthesis, which may be due to hitting some limit (possibly documented here: ​https://docs.oracle.com/en/database/oracle/oracle-database/23/lnpls/plsql-program-limits.html)

We may need to revisit the API design.

PR discussion: ​https://github.com/django/django/pull/19088#discussion_r1929940327
Ticket which sparked the discussion/discovery: #36118

[Natalia Bidart]

Thank you Sarah, I read the conversation and it makes sense.