Limitations on project totals imposed by databases:
1000. (See JRA-19317 - Ofbiz generates queries with large IN clauses that result in ORA-01795 errors Resolved for more details.)
No hard limit as a query can have any number of parameters, as long as it remains within the maximum batch size — which defaults to 65,536 * Network Packet Size (256MB). In practice, however, 2100 is the limit as this is the maximum number of parameters allowed by SQL Server.
No hard limit; maximum query size has to be less than max_allowed_packet, which defaults to 1GB, but can be any value in the range 1024-1073741824 Bytes.
No hard limits; SQL query size is limited to the OS maximum file size.
No limits specified, but in practice limited by heap memory.