Currently, our workforce has about 15 users who all view the same file geodatabases. Typically, when viewing the data only, a schema lock (sr.lock) is created for whichever feature class is being viewed inside of the geodatabase. Here lately, one of the users has been creating both a schema lock and a read lock (rd.lock) on the same feature classes. However, it does not do this for all feature classes being viewed. I can start an editing session on the geodatabase in which the read lock is created, and it will create my editing locks (ed.lock) and allow me to edit just fine like normal. It's only when I go to save my work that "a lock cannot be acquired". It at this point will not allow me to save my edits like normal. What would be causing just a few feature layers to be creating the random read locks on top of the schema locks?
I hope you have found your answer. In case you have not, we encountered the same problem. Turns out that if any one of the users on a mutually used Feature Class OPENS the TABLE it creates the rd.lock file. This is what prevents others' from SAVING their edits. Our solution has been to ask neighbors if they have that particular table open, if so, Close JUST the table, then the editor can save his/her edits. I hope this helps; I know it is a massive headache, but this solution has worked for us thus far.
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I am using Bohemian Coding Sketch to design websites. All my files are in Dropbox, shared with a team (another designer). Most of the time we are working together with same files — one is editing, another is watching and discussing. I think this is a pretty common scenario these days.
When files are changed by the other, they get changed on my disk by Dropbox. And after that things go worse. Sketch gives this warning:
Any choice I make is bad, because:
Revert changes. It does not mean "revert to a file on disk". It actually means "revert to a file state, that was when you last opened the file".
Save. Means "overwrite with your changes work from other designer".
Cancel. Means "Do nothing"
Since this dialog opens when I close the Sketch, I have no option, but to shoot myself in a foot.
Does someone have a solution? One proposed is to copy files from shared folders to view them, which works but smells funky...
Ok. So this is a workflow issue. Sketch doesn't have or offer the ability of multiple user versioning. So it's a highly bad idea for more than one person to be working on the same file.
You're two choices are...
Have the other artist create a duplicate file. Not only does this insure proper versioning (something you guys should be keeping track of), but it also allows for the lead to then take the best ideas from each and combine them into a new versioned file.
Purchase an asset management system like AlienBrain. It handles a lot of the tedious processes of versioning for multiple artists in a studio. However I'm not aware of its integration with DropBox.
In one of the lotus notes db, too frequent replication/save conflicts are caused reason being a scheduled agent and any user working on the document at the same time.
is there any way to avoid this.
Thanks,
H.P.
Several options in addition to merging conflicts:
Change the schedule The best way to avoid it is to have your scheduled agents running at times when users are not likely to be accessing the system. If the LastContact field on a Client document is updated by an agent every hour as it checks all Contact documents, maybe the agent should run overnight instead.
Run the agent on user action It may also be the case that the agent shouldn't be running on a schedule, but should be running when the user takes some action. For example, run the agent to update the Client document when the user saves the supporting Contact document.
Break the form into smaller bits A third thing to consider is redesigning your form so that not every piece of data is on a main form. For example, if comments on recent contacts with a client are currently held in a field on the Client document, you might change the design to have a separate ClientMeeting form from which the comments on the meeting are displayed in an embedded view or computed text (or designed using Xpages).
Despite the fact that I am a developer, I think rep/saves are far more often the result of design decisions than anything else.
You can use the Conflict Handling option on the form(s) in question and select either Merge Conflicts or Merge/No Conflicts in order to have Notes handle merging of edit conflicts.
From the Help database:
At the "Conflict Handling" section of the Form Info tab, choose one of the following options for the form:
Create Conflicts -- Creates conflicts so that a replication conflict appears as a response document to the main document. The main document is selected based on the time and date of the changes and an internal document sequence number.
Merge Conflicts -- If a replication conflict occurs, saves the edits to each field in a single document. However, if two users edit the same field in the same document, Notes saves one document as a main document and the other document as a response document marked as a replication conflict. The main document is selected based on the criteria listed in the bullet above.
Merge/No Conflicts -- If replication occurs, saves the edits to each field in a single document. If two users edit the same field in the same document, Notes selects the field from the main document, based on time and date, and an internal document sequence number. No conflict document is generated, instead conflicting documents are merged into a single document at the field level.
Do Not Create Conflicts -- No merge occurs. IBM® Lotus® Domino(TM) simply chooses one document over another. The other document is lost.
In later versions of Notes there is the concept of document locking, and used properly that can prevent conflicts (but also add complexity).
Usually most conflicts can be avoided by planning to run the agents late at night when users aren't on the system. If that's not an option, then locking may be the best solution. If the conflicts aren't too many, you might benefit from adding a view filtered to show only conflicts, which would make findind and resolving them easier.
IMHO, the best answer to conflicts between users and agents is to make sure that they are operating on different documents. I.e., there are two documents with a common key. They can be parent and child if it would be convenient to show them that way in a view, but they don't have to be. Just call them DocA and DocB for the purposes of this discussion.
DocA is read and updated by users. When a user is viewing DocA, computed field formulas can pull information from DocB via DbLookup or GetDocField. Users never update DocB.
DocB, on the other hand, is read and updated by agents, but agents only read DocA. They never update them.
If you design your application any other way, then you either have to use locking -- which can create the possibility of not being able to update something when you need to, or accepting the fact that conflicts can happen occasionally and will need to be resolved.
Note that even with this strategy, you can still have conflicts if you have multiple replicas of the database. You can use the 'Conflict Handling' section of the Form properties to help minimize replication conflicts, as per #Per Henrik Lausten's answer, but since you are talking about an existing please also see my comment to his answer for additional info about what you would have to do in order to use this feature.
If this is a mission critical application, consider creating a database with lock-documents. That means, every time a user opens a document, a separate lock-document is created.
Then code the agent to see if lock-documents exist for every document that the agent wants to modify. If it does, skip that document.
Document-close should remove the doc-lock.
The lock-doc should be created on document open, not just read. This way, when a user has the document open in read mode, the agent will not be able to modify as well. This is to prohibit, that the user might change to editmode afterwards and make changes.
If the agent has a long modification time, it should create lock-docs as well.
I'm doing a db in access 2002 and I've had some problems with the locking shared mode. I have an app that has a lot of programs and almost 10 users logged on. And one of things that the app do is open a report, that user choose the program and the number (usually has 4 numbers for each program), and before the report open, I open it in hidden mode and I edit the report for current program/number, with this rotine I just have one report that may turn in hundreds... saving memory and optimizing it. Then I save it and open it again in view mode.
But the problem is when has other person using the app, so the access can't edit and save report... just in exclusive mode!
Has a cmd in vba to allow momentarily changes in shared mode? I don't know, like freeze all user, save and then unfreeze them?
Or any other suggestion?
About create a Front-End/Back-End I think that is impracticable, cause is a beta version and I have to update it often and I already tried to do this also, but it's became too slow... I splitted then in a database(just tables) into network and front-end with all querys, forms, reports and linked tables in local PC, but it really became tooo slow. If someone can help me let it faster would solve my problems too
I splitted the db and I'm trying optimize it. I read a lot about it on the web and I changed all Access setting that I saw that need to be changed and now I get a faster program. But slower than with a single app.
But now there are just fell Forms that making my app slow.
For example I have some Forms that always when I close it I spends a long time waiting it to close ;(
So I realised that this Forms are always saving before close. And always that a form need to save(with linked tables taht are in the network) waste a lot of time, so I need to avoid this.
But I didn't get it so far...
I realise that this forms are saving because in form_open I hidde some columns(that are different for each program) and edit it caption. And then if I need to close form, it saves and waste this such time!
How could I hidde/edit this columns withou need to save form? Or how could I close form without save structure changes?
I know how to do that with just a button, but these forms are datasheets and I can close it only in "X" Form button. And unfortunattely Access dont have BeforeClose event, and in a OnClose event it save before go to this sub!
See if you can make use of a WhereCondition with the DoCmd.OpenReport Method to avoid the need to modify your report's design at run time.
The WhereCondition is applied to your report's existing record source query as if it where written into that query's WHERE clause.
So if the record source for YourReport is ...
SELECT program_id, some_number, another_field
FROM YourTable;
... then this ...
DoCmd.OpenReport "YourReport", _
WhereCondition:="program_id = 7 AND some_number = 22"
would give you the same set of rows as would revising the record source to this ...
SELECT program_id, some_number, another_field
FROM YourTable
WHERE
program_id = 7
AND some_number = 22;
This advantage of this approach, if you can make it work for your situation, is that you would no longer need exclusive access to the db since you're not actually changing the report's design.
The related issue about beta status making it impractical to split the application is something you should re-consider carefully. Splitting ensures you can easily preserve the data in the BE when you roll out changes to the FE application. Even if you've come up with another method to avoid losing data when you change versions, that method can not be simpler than segregating the data into a BE file.
And when you split the application, each user should get their own copy of the FE file which is stored locally on their machine's hard drive; those FE files will contain links to the tables in the BE file which is stored on a file share.
Keeping the users' FE applications updated as you release new versions is a problem which has been solved. For example, see Tony Toews' Auto FE Updater. And you can find other approaches by searching the web.
If your concern is performance with a split application, check Tony's Microsoft Access Performance FAQ.
What I'm trying to do is seperate my existing MS Access application into a front-end (which will run locally on a user's machine) and backend (which will be hosted on a networked file server) and allow users to choose between "read-only" and "write" modes. The idea is that only one user can use the "write" mode at a time, thus preventing the same piece of inventory being allocated to mutliple customers. My problem is that the application currently handles concurrency by requiring users to open a .bat file which only allows them to enter application if a .ldb file does not already exist (there is no read-only mode currently), so I need to prevent users accessing the production data in "read-only" mode from creating a .ldb file and unessarily blocking out other users.
The biggest challenge to implemnting this is that users must have write access to the temporary tables in the MS Access (.mdb) file installed locally. I have tried to implement this using a linked table, but I'm not sure how I can control when records become locked using linked tables (which creates a .ldb file).
You could change the sharing setting back to Exclusive Mode. Then only one person can access the file at a time. Check out this link and the other sharing options you have.
http://office.microsoft.com/en-us/access-help/set-options-for-a-shared-access-database-mdb-HP005188297.aspx
Side note: Yikes. Using Access in a shared network environment is not fun. I hope nothing important/time sensitive/secure is in this file. The .ldb file not being deleted and blocking other users is something that I use to see happen regularly in this situation. I believe splitting the Access file into a front-end and back-end like you've done is the first step. Then using linked tables to a SQL Server database can help resolve these issues. But if you're going to this level of effort you may want to consider dumping Access and get a COTS product or create a new application.
Depending on which version of Access you are using, theres alot of flexibility in the UI developement. In other words, this sounds more like an "interface" issue as apposed to a "database" issue. Given everybody is able write to a table, you should be able to check in somewhat real time (performance can be an issue with larger datasets), whether a particular has been added to inventory or not.
They I handled this problem is have two tables, an incomming and outgoing log, and set up a query that did the math against the inventory list on the amount of products. And like a general ledger, select set amount of time to "close the log" (monthly, quarterly) so that the query is not taking into account stuff that happened two years ago.
If you need more help with Access related stuff, Access Monster is a good forum site that deal with nothing but access.
My problem is that the application currently handles concurrency by requiring users to open a .bat file which only allows them to enter application if a .ldb file does not already exist (there is no read-only mode currently), so I need to prevent users accessing the production data in "read-only" mode from creating a .ldb file and unessarily blocking out other users.
--> If every user has his own copy of the front-end on his own machine, you'd have to check the .ldb file of the back-end.
I guess it would be easier to give everyone write access to the backend and manage the actual writing programmatically with a "locked by User X" field in the backend:
You said:
preventing the same piece of inventory being allocated to mutliple customers
If this is the only reason for putting all users but one in read-only mode, you could put a "locked by User X" field on the inventory table. If someone starts to modify (or even opens) a piece of inventory, update the record with his user name, and delete the user name again when he's done.
If another user tries to open the same piece of inventory as well, the name of the first user will already be in the "locked by User X" field, so you can put the second user in read-only mode.
If the inventory pieces are not the only problem and all the other users really are not allowed to change anything as soon as someone else already is editing, you can create a new table with only one column and one row and use this as the "locked by User X" field. As soon as there is a user name inside, you can put everyone else in readonly mode.
No matter how you do it, you will have to provide some kind of admin menu, so if someone's front-end crashes while editing, someone else needs to be able to unlock this user's locked data (=delete his username from the "locked by User X" field).
I am using NHibernate and really new to that. My dilemna is when
I open a web browser, it shows the table data. Meantime another person opens another web browser and hence read the existing data from the database.
Meantime, I make changes in the my pages and save. And the user save his changes afterwards. When I reload the page, I no more find my data, but that of the user, i.e his was the latest and mine were replaced.
How can I avoid this issue?
You need to implement optimistic concurrency control: http://nhibernate.info/doc/nhibernate-reference/transactions.html#transactions-optimistic
The most performant way is adding a <version> to your entities (see http://nhibernate.info/doc/nhibernate-reference/mapping.html#mapping-declaration-version)