Re: NexusDB Memory Manager version 2 released

From: Alex Zencovich (zencovich_at_pivotcube.com)
Date: 07/31/04 

Date: Sat, 31 Jul 2004 14:20:16 +0300

> act). Aligning record fields is something that is used in most languages
to get
> best performance. It's not used in Delphi *because* it is useless with the
> Borland MM.
In same test application, when I change record from

testrec = record // 13 bytes length
a : integer;
b : double;
c : boolean;
end;

to

testrec = record // 16 bytes length
a : integer;
b : double;
c : boolean;
d: integer;
k : boolean;
end;

I get pefomance better in 1 sec (from 44 sec to 43 sec for Delphi MM and
from 48 to 46 sec for NexusDB MM). I think (check me if I wrong) it is
result of record array allocation and value of compiler <Record field
alignment> value.

While changing RFA value from 8 to 1 I get preformance increasing from 46
sec to 40.5 for same code and same record type.
Same test for NexusDB MM show me difference from 47 sec with RFA=8 and 45
sec with RFA = 1

When RFA=8 Sizeof(testrec) = 24 and records aligned by 8-byte boundaries,
moreover record fields aligned too. So all needed conditions performed.

But performance better when records is not aligned even inside same MM.

Could you say, where I wrong? Yes, I understand memory occupation larger
when RFA=8 but it is RAM (random access memory) and number of memory
allocation units must be the same? 

--
Alex Zencovich
PivotWare Lab
------------------------
OLAP solutions for Delphi,C++ Builder and ActiveX environment