David, this is surely the pain of caching mechanism a this is the almost 100% right way. (It could give some wrong cached key for two statements on the same line.)

The question is:

• what means better cache performance
• what is it the average number of this cached keys - filesystems are becoming unusable if there is more than 1000 files in a directory

IMO: If we would accept the forbidding "two statements on the same line", we could do some other optimizations for getting caching key.

By „better performance“ I mean really previously accessed columns are fetched from database, not previously accessed columns by similar query. (Yes, I was talking about DB performance, not cache performance.)

Number of cached keys is very low, it nearly corresponds with number of {foreach $query} and fetch() in code. Because there is only few writes and a tons of reading, maybe we can use some smarter one-file storage for accessed columns (SQLiteStorage? Or solution based on FileJournal?)

The question was more like "Is it really more effective to call debug_backtrace than fetching 'two more' columns?".

FileJournal is still buggy... #76. SQLiteStorage... I would like to avoid that.

Moved to nette/database#6