Subject Re: Maximum Capacity
Author Frank Emser <>
--- In, Marco Bommeljé <mbommelj@x> wrote:
> Read this list carefully. The topic is discussed frequently.
Looks like a good idea to put this question (or even better: the
answer) into an easily reachable faq.
At least I did not find such one.

> Yesterday, Sean Leyne mentioned in one of his postings that the
> (current) theoretical limit is 32TB.
Well, to be precise:
He only said that he *believes* the (current) theoretical limit is
32 TB.
This is exactly the amount mentioned in the IB6 techspecs quoted
But then, this was before the 64-bit version of firebird.

It would be a nice if anyone could provide some *reliable*
information about the actual firebird limits.
I just intended to send a note to the author of a comparison of
several open-source-databases (mysql, postgresql, firebird, sap db)
which was just recently published in a German computer magazine (c't
5/2003, p.142).
He stated
=> a. that firebird can handle 2^64 colums per table
(this simply makes no sense if the maximum row size is still 64
Kbytes as with IB6)

=> b. that firebird can handle 16 columns / index
(if the 256-bytes limit still applies, then these 16 columns might
be too much as well as too few ... depending of the (size of) the
datatypes of the columns.

=> c. that the maximum database size with firebird is "only" 980
I consider a *real* existing database of 980 GBytes to be huge (
especially compared for example to the maximum "real" size of about
60 GB
for Postgresql-databases (

but compared to the theoretical limits given for the other databases
(SAP DB: 32 TByte, Postgresql: 64 TByte and MySQL's: "unlimited")
this 980 GB-limit just sounds like a child's toy.

I just intended to reply to him that Firebird maximum database size
calculates as the maximum number of files per database times the
maximum file size.
According to the Firebird 1.0 release notes, p.5&6, this would mean
for Windows NT a maximum of about 2040 files per database times
a maximum of about 16384 GBytes per file and therefore result in
about 32000 TBytes per database; => a quite impressive number !
(Well, to be true, not quite as impressive as MySQL's "unlimited",
but "good enough" anyway ? ).

Now I read that you assume Firebirds theoretical limit to be about
a factor of thousand below that so I am quite lucky that I have not
yet mentioned my numbers.

Any idea what went wrong with my calculation or what else is the
reason for this theoretical limit of 32 TB (if it really still
exists with 64-bit-firebird) ?

=> d. that firebird's maximum table size is only limited by the
database size.
Of course, this statement of that author sounds good.
But is it really valid ?
In case the maximum database indeed goes to the thousands of
terabytes, the maximum number of rows (if this is still 2^32 like in
IB6) would quite probably become very fast the limiting factor for a
maximum table size (for example when inserting small samples of
measuring data every few milliseconds)

By the way, just in case that someone of you really happen to read
this twice: I have posted a very similar reply in the max-table-size
thread but even after many hours, it has not yet appeared there , so
I assume that it got lost.