Subject Unusual memory consumption on Firebird
Author aiylam_s
I have set up a Firebird 1.5.2 classic database on Windows XP. It has
one table (CHUNK) with 3 columns:
- UUID VARCHAR(16) not-null unique indexed
- IndexedLocation VARCHAR(250) not-null indexed
- LocationPart1 VARCHAR(32700)
- LocationPart2 VARCHAR(32700)

I am using the C-API exposed by fbclient.dll. In my test program, I
created 100,000 records with UUID and IndexedLocation populated with
test values (LocationPart1 and Part2 are NULL) - this seemed to go
well; I got a reasonable number of insertions/sec. and memory usage
seems to be well under control.
The C function calls I make for a write are the following:
- isc_start_transaction
- isc_dsql_execute_immediate
- isc_commit_transaction

However, when I tried to read records (by indexedLocation), memory
consumed by fbserver seemed to keep increasing continuously at a
rapid rate with every call until I ran out of virtual memory on the

The C function calls I make for every access are the following:
- isc_start_transaction
- isc_dsql_allocate_statement
- isc_dsql_prepare
- isc_dsql_execute
- isc_dsql_fetch
- isc_commit_transaction
The SQL executed is:
SELECT uuid, locationPart1, locationPart2 from CHUNK where
indexedLocation = ?;

If I do an isc_attach_database() at the begining followed by an
isc_detach_database() at the end, memory does not keep increasing;
however the number of reads/sec. drops drastically (as expected). Am
I doing something wrong, in terms of the calls I am using? I would
think it is not necessary to keep attaching to and detaching from the
database every time I need to get a record. The increased memory
usage is not in my test application, but in the fbserver process

Any help would be greatly appreciated.