Alpha Video Training
Results 1 to 18 of 18

Thread: Network Slow

  1. #1
    David Little
    Guest

    Default Network Slow

    My problem is that my network performance is slowing down when we are adding records to my tables. When I initially set-up the network 6 weeks ago the Alpha performance was electric. No other utility programs are running on any machines. Can anybody give some advice?


    My network consists of 5 Pentium machines lowest spec 300 CPU and 64 Meg ram using Windows 98 second edition using Alpha 5v4.3 database files (only) networked

    Using files from a HP E60 Netserver with Pent500 and 256mem using Windows NT Server 4 operating system.

  2. #2
    "Certified" Alphaholic Stan Mathews's Avatar
    Real Name
    Stan Mathews
    Join Date
    Apr 2000
    Location
    Bowling Green, KY
    Posts
    25,119

    Default RE: Network Slow

    Indexing could be a slowdown source for record entry. As you add records, Alpha must keep the indexes updated.

    How many indexes do you have defined for the table accepting data entry, and how complex are they? Any full text search indexes?

  3. #3
    VAR csda1's Avatar
    Real Name
    Ira J Perlow
    Join Date
    Apr 2000
    Location
    Boston, Massachusetts, USA
    Posts
    3,530

    Default RE: Network Slow

    Stan,

    Adding indexes does NOT slow down Alpha significantly unless

    1. You are saving records (either adding or changing) faster than every 1 or 2 seconds
    2. You have a lot of indexes that need to be updated upon the save (like 100's of a set that has a lot of children where editing of children is possible)

    Assuming no changes were made to the application, adding records can cause queries and filters to be slower if you don't create queries that allow LQO (Lightning Query Optimization), but this is only during the query part that it get's proportionally slower. Since only one index is active for any one window of the data, the number of indexes and the number of records is irrelavant. To prove this to yourself, try doing a find (not a query) on a current index using 10 records, or 10 million records, whether there is 1 index or 24 indexes. It will be almost the same.

    The most likely case is that a Network Card or Network cable is bad (generally the connectors). This can cause numerous network retries and slow the whole network down. Disconnect each station at the network hub and see if it speeds up to try to isolate this problem.

    It's also possible that a workstation is running slower due to lack of RAM or virtual disk space. This would affect Alpha if that station were running the application.

    Regards,

    Ira J. Perlow
    Computer Systems Design & Associates
    csda@mediaone.net

  4. #4
    "Certified" Alphaholic Stan Mathews's Avatar
    Real Name
    Stan Mathews
    Join Date
    Apr 2000
    Location
    Bowling Green, KY
    Posts
    25,119

    Default RE: Network Slow

    Ira,

    Appreciate the response and information. With no more information given than was present, I was only suggesting

    "Indexing could be a slowdown source"

    a possible starting point.

    Have a good weekend.

    Stan

  5. #5
    "Certified" Alphaholic
    Real Name
    Raymond Lyons
    Join Date
    Apr 2000
    Location
    Carlsbad, CA
    Posts
    2,143

    Default RE: Network Slow

    Ira, I would like to think I am wrong and you are right, but as few as 6 people doing data entry on the same large table with 10 indexes most certainly can cause problems (slow downs and can't add key to tag errors, records locked that are not locked, etc.) that are clearly related to the indexes (i.e., removing the indexes removes the problems). Indexes on date fields seem to be the main culprit. I have been unable to get a fix for this because unless Selwyn gets 6 people to sit down and bang away for a while the problems never show up. And I am not the only one who has nad similar problems. A large primary table (500,000+ records) may also be part of the mix that produces the problems. I have reluctantly come to the conclusion that this is just one thing that A5 is not well suited to do.

    Ray

  6. #6
    Elliott Lester
    Guest

    Default RE: Network Slow

    Raymond:

    I agree with Ira on this one. We have found that
    indexes do not really slow the system down per se.
    Now, Filtered indexes can and do cause heap lock problems.

    We found that most of our unable to add key to tag problems
    resulted from a too slow network, a too slow server and
    a hub instead of a switch. Once we upgraded to 100 mhz,
    to a 100 switch instead of a hub, and to a very fast server
    with lots and lots of ram and lots of free fast harddrive space, we were only left with heap lock failures which by removing as many filtered indexes that we could have even reduced our twice a day heap failure.

    Now, we rebuild our indexes each night and after any major
    crash. We do not use queries however, because so far
    we have not found them to be quick enough for production.
    I have been following IRA's posts regarding his lighting
    queries and since I have found him on target for many years
    we are looking into how to utilize his method for our
    system.

    I believe that we would qualify as a system as complex and
    scaled as yours with many more indexes, tables and operations.

    What is your network, what speed, server and cards, do you
    have a switch, what OS?






  7. #7
    Jim Rowlen
    Guest

    Default RE: Network Slow

    2 cent time. (Did I hear a groan out there?)

    I would have to agree with Ira. Our app has about 14 databases and about 45 tables with large indexes, and over 360 layouts, @ 125 saved operations, and @ 55 global scripts (many running over 300 physical lines of code). Our primary database has been cut to 16 tables (2 @ 365 K records each, 2 others adding to 365 K, 2 @ 470 K each, one around 85 K, a few in the 50 K range, the rest under 5 K records). As has been indicated in previous posts, we are notorious for having what some consider to be an excessive number of indexes (including many with boolean filters). Our primary table had around 25 to 30 indexes. Depending on what specific task is being performed (such as development testing or troubleshooting), I myself have had 3 or more databases and individual table browses open on a Win 98 network station based on a 300 with 128 M RAM. This is with editing going on in more than 1 table (and more tahn 1 instance of a table), easily representing 3,000 K to 5,000 K records. No appreciable speed degradation. But the system has over 5 G of available drive space for swap files, etc, and has defrag run on it at least every month or so. (Home system based on a 600EB with over 35 G available on the 7200 RPM boot drive is actually faster than the 750 with a 12 G hard drive in the office which has more RAM.)

    Our progression of servers over the last year or so has been a 300, 550, and now a 750. At each upgrade we moved the replaced systems to the floor and bought a couple more, thereby upgrading all systems. Most systems are now 500 or 550's with 128 M RAM MINIMUM (256 on most). Each system has at least a 10 G hard drive.

    This progression has resulted in a network with almost no time lags for creating / updating records in a high-volume transaction processing operation. Each transaction can have up to about 2000 FIELDS of info associated with it. Almost every operation creating/editing/processing a transaction uses a fair number (at least 50 to 10) field rule based lookups and/or script based. Every operation does at least 2 lookups to create/edit non-attached tables.

    As everyone on the networks gets a faster more efficient system it also seems to speed up the network.


  8. #8
    VAR csda1's Avatar
    Real Name
    Ira J Perlow
    Join Date
    Apr 2000
    Location
    Boston, Massachusetts, USA
    Posts
    3,530

    Default RE: Network Slow

    Concerning the speed of the client (workstation) computers.

    The basic speed of the client is not really relevant to the speed of the system overall, EXCEPT

    That every time a record is accessed (or a group of records), a set of file lockings and unlockings, as well as record locking and unlockings must occur on the network. In a true client-server database, this is performed by the server.
    HOWEVER, Alpha 5 is not a true client-server program (currently anyway). (Neither is Access, FileMaker Pro and others too). This means that the client stations must perform this sequence of operations (at which time all other clients must wait). If the client is slow in doing this for any reason, it slows the whole system down. Multiply this by many clients accessing many records and it can add up to performance degradation.

    Thus, the speed of the Network, the quality (and latency) of the the Network Interface Card (NIC), the numbers of errors on the network all have some affect. A secondary issue is the speed of the client workstation, which adds a small (but not necessarily insignificant) contributing factor. Thus, clients that are way too slow (today that means

  9. #9
    "Certified" Alphaholic
    Real Name
    Raymond Lyons
    Join Date
    Apr 2000
    Location
    Carlsbad, CA
    Posts
    2,143

    Default RE: Network Slow

    The network I was referring to is not the fastest around but it is also not especially slow. I don't have the specs in my memory banks right now, but it is a farily recent Compaq NT server with what normally would be sufficient RAM, a very nice HP hub and all NICs are 3Com and all cabling is high quality. The workstations are a tad on the slow side (don't know specs right now).

    BUT, this setup runs other non client server database without such hitches. If I have to tell my client that to use Alpha Five he'll have to drastically upgrade his hardware along the lines some of you are suggesting, he'll boot my butt (and Alpha Five) right out the door. Some of you clearly have hardware budgets that most of my clients can only dream about.

    AND THE FACT REMAINS, if I remove just the date indexes, almost all of the problems go away. The problem is that doing away with those indexes weakens the app in other areas.

    Ray Lyons

  10. #10
    Jose de Leon
    Guest

    Default RE: Network Slow

    What do your SETS look like and what are the linking fields?

    If you have not created a well designed set, that can cause some problems and will be compounded if your linking fields are expressions.

    Addtionally, the problem will be compounded even further if you have not properly coded for a multiuser envirionment which can result in index corruption and the infamous "tag error".

    I suggest you review your sets (if any) and determine if they are properly linked and indexed. Also, review your multiuser envirionment and verify that it is safe and accurate. That means get down with paper and pencil (the old fashioned way) and prove it is correct. You'd be surprised how many people I tell them to prove their multiuser envirionment on paper who can't do it and find the reason for their error.

  11. #11
    Jose de Leon
    Guest

    Default RE: Network Slow

    I'd have to disagree. The "can't add key to tag errors" are more like to be related to incorrect multiuser handling on the part of the application programmer.

    I used to think this was an index problem too, but I discovered that the index corruption was only a symptom. The real culprit is multiuser handling.

    Sincerely,
    Jose

  12. #12
    "Certified" Alphaholic
    Real Name
    Tom Cone Jr
    Join Date
    Apr 2000
    Location
    Florida
    Posts
    23,310

    Default RE: Network Slow

    Jose, I'd be interested if you would good enough to outline what you mean by 'proving' a design is safe and accurate for multi-users. This is an area that I would like to improve in my own work.

    -- tom

  13. #13
    Jose de Leon
    Guest

    Default RE: Network Slow

    Multiuser programming is several courses in themselves. But I can get you started with a book reference. This book contains proofs and theorums for all the major concurrent algorithms and shows you how to proove a system.

    It is an old book called "Principles of Concurrent Programming". This got me through university. It discusses the principles and thus can be applied to any system. I've been in programming for so long that I use the principles intuitively when designing A5 applications so it is more difficult for me to explain than when I was in university.

    If you are interested to help yourself, the ISBN for the book is 0-13-701078-8. Author is M. Ben-Ari at Tel-Aviv University. Publisher Prentice-Hall International.

    Jose

  14. #14
    "Certified" Alphaholic
    Real Name
    Tom Cone Jr
    Join Date
    Apr 2000
    Location
    Florida
    Posts
    23,310

    Default RE: Network Slow

    Thanks, I'll check it out.

    If you were to write up an article outlining the key points, tips or pointers you regularly employ, I'm sure this would be of great assistance to many.

    Thanks.

    -- tom

  15. #15
    VAR csda1's Avatar
    Real Name
    Ira J Perlow
    Join Date
    Apr 2000
    Location
    Boston, Massachusetts, USA
    Posts
    3,530

    Default RE: Network Slow

    Ray,

    Based on what I'm saying and others, I think you should be convinced that Alpha 5 should not necessarily be slow. And assuming the network is in good condition, then you need to ascertain the difference in A5 technique used and change the method. This could mean an A5 bug or just a general limitation.

    Are you using an index based solely on a date field? (you can tell, because when you do a find, there will be slashes in the index key box) If so that creates a different type of index from, say a character field index. It's possible that A5 may be handling the "Date" type of index improperly. I never use this form of an index, and perhaps that is why I've never seen what you are describing.

    I suggest you change the index type by using an expression like

    CDATE(datefield)

    and then modifying your application accordingly to search for character values in the format of yyyymmdd.

    I never use "Date" type indexes because you can never add another field to the expression without converting it to character anyway. Most of my indexes would be similar to the form of

    CDATE(datefield)+ char_invoice_no

    or similar. There are probably a few places where just the date field alone would be absolutely required (although I can't think what it would be), but by adding a linking field or similar, the index can often do double duty. What I mean by this is rather than having several indexes like

    CDATE(datefield)
    CDATE(datefield)+ char_invoice_no
    CDATE(datefield)+ char_invoice_no+statuscode

    I would just have

    CDATE(datefield)+ char_invoice_no+statuscode

    The exception to this is if you are using KEY_EXISTS() or DBSUM() and similar that require an exact key match. In most cases you can use TABLE_COUNT() and similar (Sorry I can't remember the table function names- I'm on the road) and not require the use of an exact key match, but be sure to specify the equations in the TABLE() functions so that LQO (Lightning Query Optimization) can be used, otherwise it will be alot slower.


    Regards,

    Ira J. Perlow
    Computer Systems Design & Associates
    csda@mediaone.net

  16. #16
    ROBERT SULLIVAN
    Guest

    Default RE: Network Slow

    I agree with Tom. A brief list of tips might more adequately point out your previous comments in a more meaningful manner to me and other users on this site

    thank you for your comments

    BOB SULLIVAN

  17. #17
    Jose de Leon
    Guest

    Default RE: Network Slow

    I can write up a brief article. Give me some time though, as I need to:

    a) finish a DSL project (we are implementing DSL service for our area and I'm the network admin / alpha developer)

    b) I need to brush up on the proofs 8-)

  18. #18
    Oran Hamilton
    Guest

    Default RE: Network Slow

    Jose,

    I would like to add my 2 cents also.

    I have built my own small network to develop and test on. However, I often feel like I am re-inventing the wheel. Also, since it is essentially one user (me), I don't think that I can adequately insure my apps will run on larger networks. I use a laptop disconnected from the network for stand alone testing.

    Any and all help that you can give us in determinin whether or not we have built a goof multi-user app would be appreciated.

    Oran

Similar Threads

  1. 2 pc network-slow
    By bob buchman in forum Alpha Four Versions 7 and 8
    Replies: 0
    Last Post: 04-05-2004, 08:14 AM
  2. Network Slow
    By Richard Keith in forum Alpha Five Version 5
    Replies: 4
    Last Post: 06-06-2003, 02:05 PM
  3. Slow Network
    By W. Horton in forum Alpha Five Version 4
    Replies: 2
    Last Post: 01-01-2003, 10:15 AM
  4. Slow performance w/NT Network
    By Gail Smallwood in forum Alpha Five Version 4
    Replies: 4
    Last Post: 12-28-2001, 07:27 AM
  5. Slow Network File Saves
    By Wally Babbitt in forum Alpha Four Version 6 and Prior
    Replies: 0
    Last Post: 08-25-2000, 07:14 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •