Hi Jean-Marc,

> 2) However unserialization seems to perform awfully, or I do not know how to
> do it properly.

I haven't tried the query, but my guess is that the binary data is
streamed again and again. The stream:materialize function should help
you [1]:

  let $data := stream:materialize(file:read-binary($file))
  ...

Christian

[1] http://docs.basex.org/wiki/Streaming_Module

> declare function local:savebin($seq,$file as xs:string) {
>     file:write-binary($file,bin:join( (bin:pack-integer(count($seq),4) ,$seq
> ! bin:pack-integer(.,4))))
> };
> declare function local:loadbin($file as xs:string) {
>     let $data := file:read-binary($file)
>     let $size:= bin:unpack-integer($data,0,4)
>     let $seq := for $i in (1 to ($size)) return
> bin:unpack-integer($data,$i*4,4)
>     return  count($seq)
> };
>
> prof:time(local:savebin((1 to 100000),"Bin.dat"))
> ,prof:time(local:loadbin("Bin.dat"))
>
> output :
>
> 46.38 ms
> 10775.12 ms
> 100000
>
> To compare, unserializing a sequence (1 to 10 000 000) stored in a file as a
> big string using fn:tokenize takes about 10 sec (100 x faster). Did I
> mistake something ?
>
>
> 2015-01-08 16:44 GMT+01:00 Christian Grün <christian.gruen@gmail.com>:
>>
>> > This way of doing stores integers as string, then call a cast string /
>> > integer to unserialize it. For large integer list (I am dealing with
>> > lists
>> > of size 134 Mo), it is quite time and mem consuming.
>> >
>> > I was wondering if there exists a more efficient way to store and
>> > retrieve
>> > atomic list into BaseX ?
>>
>> One alternative is to store the integers in a binary file:
>>
>>   let $size := 4
>>   let $data := bin:join(
>>     for $n in 1 to 100
>>     return bin:pack-integer($n, $size)
>>   )
>>   return db:store('db', 'integers.bin', $data)
>>
>> This way, every integer will occupy the supplied number of bytes
>> (here: 4, allowing you to address 2^32 integers).
>
>