[IMP] pg,orm,models: query ids server side

[cawo-odoo]

[ADD] pg.query_ids: query large numbers of ids memory-safely

This is mainly the code that has been recently added to orm.recompute_fields, here we're making it re-usasble.

[IMP] orm.recompute_fields: use new pg.query_ids

This code in recompute_fields has been made re-usable in a new util pg.query_ids. Use that.

[FIX] models.remove_model: MemoryError

Traceback (most recent call last):
[...]
  File "/tmp/tmpipxrg2eq/migrations/util/models.py", line 563, in merge_model
    remove_model(cr, source, drop_table=drop_table, ignore_m2m=ignore_m2m)
  File "/tmp/tmpipxrg2eq/migrations/util/models.py", line 138, in remove_model
    it = chunks([id for (id,) in cr.fetchall()], chunk_size, fmt=tuple)
MemoryError

[robodoo]

[KangOl]

upgradeci retry with always only crm hr

[cawo-odoo]

so, this avoids the memoryerror in upg-3307099 just fine

[aj-fuentes]

I think we could we follow the plan of "providing an object that would iterate ids and do the cleanup as early as possible". The cleanup would happen at iteration finished, __exit__, or __del__. Whatever happens first.

Technically:

• The class is primarily an iterator, once exhausted it will do all the cleanup.
• We guard against double iteration. (this pattern already exists in the utils)
• We double down the cleanup at __del__ just in case.
• We triple down the cleanup at __exit__ to leverage the context manager semantic. We don't need to __enter__ into _ncr. Current dummy __enter__ returning self is just fine.

Feel free to improve the stub suggestions below if you agree.

[cawo-odoo]

I pushed a version inspired by your suggestions, but I didn't use them verbatim. Please resolve conversations when you feel they have been addressed.

2 explanations up-front:

• It does not work to raise a real exception from __iter__ when the cursor is closed, because util.chunks works that way that it needs to catch StopIteration twice before it really stops iterating.
• afaik, returning a value from __del__ is useless, it is ignored always

[aj-fuentes]

I forgot to post this yesterday.

Some documentation nits.