I have table with 350 rows - random text:
CREATE TABLE TAB1
(
  A1 Varchar(99),
  A2 Varchar(199)
);
ALTER TABLE TAB1 ADD A3 COMPUTED BY (coalesce(a1, '')||'-'||coalesce(a2, ''));
 and file try.sql:
 SELECT a3 FROM tab1;
 SELECT a3 FROM tab1;
... 5000 times
 SELECT a3 FROM tab1;
I run command:
"c:\Program Files\Firebird\Firebird_3_0\isql.exe" -u SYSDBA -p 1 -i c:\1\try.sql -o c:\1\result.txt "localhost/3051:c:\fdb\try.fdb"
Then, if I observe the firebird server in the task manager, it gradually consumes more and more memory.
However, if I select column a1 (ie uncounted) instead of a3, then the memory consumption does not increase. Also, if the computed would not use coalesce, the consumed memory does not increase (or the consumption increases much more slowly - I'm not sure).
If I use a 2.5.8 server, the memory consumption also does not increase.
commit and new transaction - no change
disconnect and connect - memory is freed