[Info-vax] 64-bit file sizes, was: Re: scp or sftp: file is "raw", needs to be parsed - possible to work around that?

[Arne Vajhøj]

On 5/20/2021 8:58 PM, David Jones wrote:
> On Thursday, May 20, 2021 at 7:59:30 PM UTC-4, Arne Vajhøj wrote:
>> On 5/20/2021 4:35 PM, Stephen Hoffman wrote:
>>> SQLite is 64-bit. 🤷🏼 🦆🦆
>> It may compile with 64 bit pointers,
> 
> I'm not sure what the emoji sequence is supposed to convey. SQLite does indeed compile
> and run with 64-bi pointers.
>>
>> But https://www.sqlite.org/limits.html says:
>>
>> <quote>
>> 14. Maximum Database Size
>>
>> Every database consists of one or more "pages". Within a single
>> database, every page is the same size, but different database can have
>> page sizes that are powers of two between 512 and 65536, inclusive. The
>> maximum size of a database file is 4294967294 pages. At the maximum page
>> size of 65536 bytes, this translates into a maximum database size of
>> approximately 1.4e+14 bytes (281 terabytes, or 256 tebibytes, or 281474
>> gigabytes or 256,000 gibibytes).
>> </quote>
>>
>> 4294967294 smells very 32bitish.
>>
> 
> The file format (https://www.sqlite.org/fileformat2.html) has a fixed header with
> 2 byte and 4 byte cells for the page size and total page count, respectively.

So SQLite has the same fundamental 32 bit problem as ODS-5, but because
the page size 64 KB is bigger than 512 byte blocks it is not
currently a real limitation.

Arne