til function problem

[skuvvv]

Hello all,

I am curious about usage simple functions such as til.

1)type til 10

returns 7h instead 6h

I run at win x64

2)using `int$ till 10 requires 3x times more memory than simple filling by integer values 

(4 byte for int instead 8byte for long + 4 byte for conversion)

3)I got wsfull with 

aa: til 150000000

ps I just want fast fill big array by integer values(not by longs) and reach 300-400mil of values

[skuvvv]

Additional thing that can be a reason of wsfull,

when I fill array, kdb allots memory by steps and not by necessary amount, 

for example additional 10mil of integers will allocate 500Mb of memory, and next step with 270mil+ will get wsfull:

q)\ts aa: 130000000?1000i
634 536871120
q)aa: null
q).Q.gc[]
536870912
q)\ts aa: 140000000?1000i
682 1073742032

[LamHinYan]

buddy memory system

http://www.timestored.com/kdb-guides/memory-management

[LamHinYan]

[LamHinYan]

The default integer type is 64 bit long on both kdb32bit and kdb64bit. http://code.kx.com/wiki/Releases/ChangesIn3.0

[LamHinYan]

http://kx.com/q/d/kdb+.htm

22 Limits

Each database runs in memory and/or disk map-on-demand -- possibly partitioned. There is no limit on the size of a partitioned database but on 32-bit systems the main memory OLTP portion of a database is limited to about 1GB of raw data, i.e. 1/4 of the address space. The raw data of a main memory 64bit process should be limited to about 1/2 of available RAM.

260 million int32 takes 991 MB

300 million int32 gives a wsfull

list1m:`int$til 1000*1000;

bigList:();

a:0i;

do[260;

  bigList,:list1m+a*1000000i;

  a+:1i];