Re: Out-of-memory errors

[Rick Hillegas]

The index key (time desc, username, name, facility, event, sector, item, 
details) could potentially be 32867 bytes long. However, an index key 
must be less than 1/2 the page size, according to the "Page size and key 
size" topic at 
https://db.apache.org/derby/docs/10.15/ref/rrefsqlj20937.html That is, 
your new index key is too big.

With the subquery-based approach, your covering index key would be only 
20 bytes long:

CREATE INDEX log_index ON system_log (time DESC, id);