[FIX] account: index account codes

Account codes are very commonly searched by prefix. This field used to
be implicitly indexed thanks to a unique constraint on `(code,
company_id)`, however the constraint was removed in #125642 rather
than converted to an index.

For the issue at hand `code` has a much higher discrimination power
than `company_id`, however it might make sense to also index
`company_id`, or to add compound indexes for `code, company_id` and /
or `company_id, code` for other work loads.

X-original-commit: 45c579908d90f6275b7d255d59c6555e8a57b959
Part-of: odoo/odoo#133530

addons/account/models/account_account.py

@@ -38,7 +38,7 @@ class AccountAccount(models.Model):
     name = fields.Char(string="Account Name", required=True, index='trigram', tracking=True, translate=True)
     currency_id = fields.Many2one('res.currency', string='Account Currency', tracking=True,
         help="Forces all journal items in this account to have a specific currency (i.e. bank journals). If no currency is set, entries can use any currency.")
-    code = fields.Char(size=64, required=True, tracking=True)
+    code = fields.Char(size=64, required=True, tracking=True, index=True)
     deprecated = fields.Boolean(default=False, tracking=True)
     used = fields.Boolean(compute='_compute_used', search='_search_used')
     account_type = fields.Selection(