Hi,
And more info from "SAM.pdf" ("old" System Administrator Manual):
"HASHMETHOD
The hash method defines how the records are allocated into the
file buckets or groups. The hash methods can make slight
differences to performance dependent upon the values of the
record keys, however the methods can also improve the performance
of the Account Restore dependent upon source of file. The numeric
parameter can be one of the following:
1 - Uniform hash algorithm
2 - General hashing algorithm
3 - Pick/Reality hash emulation
4 - Sequoia hash emulation
TYPE
The tname parameter is used to specify the type of file to be
created. The following file types are provided as standard.
HASH1 or j1
The HASH1 file format was an early portable file format, which
uses read() and write() system calls to perform file I/O. This
file type will use jRLA locking when enabled. This file type has
been succeeded by later file types, but is kept for backward
compatibility. The bucket size of a HASH1 file is 512 bytes.
HASH2 or j2
The HASH2 file type is a memory mapped file type offering 5 times
the throughput of the HASH1 file type. This file type will use
jRLA locking when enabled. This file type is only available on
systems with memory mapping and has since been succeeded by a
later type, but is kept for backward compatibility. This file
type is not portable across platforms. The bucket size of a HASH2
file is 4096 bytes.
HASH3 or j3
The HASH3 file type is an improved HASH1 file type, which is
portable across platforms and is network friendly in that if a
network connection is disconnected during the update procedure
then file integrity can still be guaranteed. The HASH3 file type
does not use the jRLA locking even when enabled but uses the
default system locking capability, thus allowing record or item
locking with networked applications. The default bucket size of a
HASH3 file is 1024 bytes.
HASH4 or j4
The HASH4 file type is an improved HASH2 file type. It uses
memory mapping when available, otherwise defaults to reads and
writes and is portable across platforms. The HASH4 file type will
use jRLA locking when enabled but can also be configured to use
the default system locking method for networking. The default
bucket size of a HASH4 file is 4096 bytes.
UD
The UD file type specifies NT or UNIX directories and NT or UNIX
files are to be used to represent file and records respectively.
TJLOG
Creates a stub file in the current directory that points to the
current transaction log set. An additional parameter, SET can be
used to specify the log set. For more information see jlogdup.
DISTRIB
Creates a stub file in the current directory that references a
distributed file. See distributed files for further information."
They do not mentiond XMLTYPE, etc. It is a pity that this kind of
information is distributed between different documents.
Another one interesting discussion - hashing discussed:
http://groups.google.com/group/jBASE/browse_thread/thread/f46274e4eac432b3
Now I am closing my mouth and waiting for Jim's feedback ;-)
Kind regards
Pawel
Dnia 16-06-2009 o godz. 21:47 Pawel napisał(a):
> Hi Pawel,
>
> Short summary from Jim:
> "If this is a fairly static file then using J4/JP files with a decent
> modulo and the HASHMETHOD of 2 is what you want. 3 and 4 are basically
> "Pick" compatible and are not very good compared to 2.
>
> If the file is very dynamic or needs to be bigger than 2GB, you can
> now
> use J5 files on jBASE 5. These do not need to be resized. However, the
> performance of these files is terrible and there are all sorts of
> response times issues on writes and so on. I would not use them
> myself :-("
>
> From "jBASE Files.pdf":
> "HASHMETHOD
> Used when a hash file is to be created. The numeric parameter nnn
> specifies the hashing method to be used when accessing the file.
> The default method of 2 works very well with all sorts of key types.
> However if the record keys will be perfectly uniform numeric keys
> then there may be a slight advantage to using method 1 on the file.
>
> TYPE
> J3 � files with configurable levels of flushing
> J4 � standard hash files (the default)
> JP � jPLUS files
> UD � Directory files used to access files in the OS"
>
> Yet another useful link:
> http://groups.google.pl/group/jBASE/browse_thread/thread/fc4a61d0a5777b50/f2950c5f918cb52a?hl=pl&lnk=gst&q=hash+jbase#f2950c5f918cb52a
>
> Hope that some group member will give some more details, eg. about J3
> flushing levels.
>
> Kind regards
> Pawel
>
> On 16 Cze, 20:50, pawel <[email protected]> wrote:
> > Hi All
> >
> > Could anybody explain me differences between diferent hash file
> > format?
> > I mean HASH3(j3), HASH4(j4) and JP.
> >
> > jsh test ~ -->jstat -v ../bnk.data/pd/FBNK.PD.B001
> > File ../bnk.data/pd/FBNK.PD.B001
> > Type=J3 , Hash method = 5 , Created Mon Jun 15 18:16:07 2009
> > Groups = 280011 , Frame size = 1024 bytes , Secondary Record Size =
> > 2048 bytes
> > Restore re-size parameters : (none)
> > File size = 1532420096 bytes , Inode = 5221128 , Device = Id 2949122
> > Last Accessed Mon Jun 15 18:30:02 2009 , Last Modified Mon Jun 15
> > 18:30:02 2009
> > Backup = YES , Log = YES , Rollback = YES , Secure updates = NO
> >
> > Record Count = 2430591 , Record Bytes = 1321644218
> > Bytes/Record = 543 , Bytes/Group = 4719
> > Primary file space: Total Frames = 1238769 , Total Bytes =
> > 1100816016
> > Secondary file space: Total Frames = 257734 , Total Bytes =
> > 220828202
> >
> > jsh test ~ -->jstat -v FBNK.PD.BALANCES.HIST
> > File ../bnk.data/pd/FBNK.PD.B001
> > Type=J3 , Hash method = 5 , Created Tue Jun 16 18:41:28 2009
> > Groups = 280001 , Frame size = 4096 bytes , Secondary Record Size =
> > 8192 bytes
> > Restore re-size parameters : (none)
> > File size = 1878487040 bytes , Inode = 4887491 , Device = Id 2949122
> > Last Accessed Tue Jun 16 18:47:08 2009 , Last Modified Tue Jun 16
> > 18:47:08 2009
> > Backup = YES , Log = YES , Rollback = YES , Secure updates = NO
> >
> > Record Count = 2432713 , Record Bytes = 1322414964
> > Bytes/Record = 543 , Bytes/Group = 4722
> > Primary file space: Total Frames = 458547 , Total Bytes =
> > 1322201998
> > Secondary file space: Total Frames = 67 , Total Bytes = 212966
> >
> > jsh test ~ -->jstat -v ../bnk.data/pd/FBNK.PD.B001
> > File ../bnk.data/pd/FBNK.PD.B001
> > Type=J4 , Hash method = 3
> > Created at Mon Jun 15 17:38:02 2009
> > Groups = 280005 , Frame size = 4096 bytes , Secondary Record Size =
> > 8192 bytes
> > Restore re-size parameters : (none)
> > File size = 1897713664 bytes , Inode = 5221129 , Device = Id 2949122
> > Last Accessed Mon Jun 15 18:03:20 2009 , Last Modified Mon Jun 15
> > 18:03:20 2009
> > Backup = YES , Log = YES , Rollback = YES , Network = AUTO
> >
> > Record Count = 2430591 , Record Bytes = 1331151885
> > Bytes/Record = 547 , Bytes/Group = 4754
> > Primary file space: Total Frames = 463238 , Total Bytes =
> > 1330938919
> > Secondary file space: Total Frames = 70 , Total Bytes = 212966
> >
> > jsh test ~ -->jstat -v ../bnk.data/pd/FBNK.PD.B001
> > File ../bnk.data/pd/FBNK.PD.B001
> > Type=JP , Hash method = 5 , Created Tue Jun 16 18:32:33 2009
> > Groups = 280005 , Frame size = 4096 bytes , Secondary Record Size =
> > 8192 bytes
> > Restore re-size parameters : (none)
> > File size = 1881387008 bytes , Inode = 4917579 , Device = Id 2949122
> > Last Accessed Tue Jun 16 18:39:51 2009 , Last Modified Tue Jun 16
> > 18:39:51 2009
> > Backup = YES , Log = YES , Rollback = YES , Network = NO, Secure
> > updates = NO
> >
> > Record Count = 2432713 , Record Bytes = 1322414964
> > Bytes/Record = 543 , Bytes/Group = 4722
> > Primary file space: Total Frames = 459255 , Total Bytes =
> > 1322201998
> > Secondary file space: Total Frames = 67 , Total Bytes = 212966
> >
> > RELEASE Information: Major 4.1 , Minor 5.17 , Patch 5690 (Change
> > 52756)
> > AIX 5.3
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