Here are the different cases in which you can easily make adjustments in the setting of virtual memory. In such cases, you can make your Access database faster just by allotting a different drive for the virtual memory. You have also the option to specify some fixed space on the disk drive for the virtual memory. You can only allot 1. The compacting database actually does not compact the database but it deletes the unwanted and unused objects and records, thereby reduce the size of the database files.
Work with your Access database by opening it up in exclusive mode. This will ultimately boost up slow running Access database speed. Alternatively, you can make use of the Look in list to browse for the database file.
By default, MS Access display sub datasheets between related tables. Unluckily, they reduce performance. View and seeing related data is absolutely a great feature and if you work a lot in Datasheet then you like to use this feature.
However, there are users who do not want to see the data presented in this way. Hence, suggest users turn off this feature. Here how to disable it:. If your Access database running slow over network then try this method. Try to make adjustments in the Update retry interval msec , ODBC refresh interval sec , Refresh interval sec , Number of updates retry settings if applicable.
In order to specify the number of times, the MS Access tries for saving up the record mainly when it gets locked by any other user. Opt for Refresh interval and ODBC refresh interval options for time interval settings after which Access refreshes its data automatically.
You can then display a message and close the report. This is easier than running a separate process to see if data exists for the report.
If a sub report is based on the same query as its parent report, or the query is similar, consider removing the sub report and placing its data in the main report.
While this is not always feasible, such changes can speed up the overall report. Minimize the number of controls on your report. Loading controls is the biggest performance hit when loading a report. Convert macros to Visual Basic code.
In almost all cases, Visual Basic code runs faster than macros. This obviously doesn't apply if you are using macros for a SharePoint deployment of your Access forms. If possible, make an MDE file out of your database. Additionally, since no source code is stored in the MDE file, the database loads faster and uses less memory. Module code is saved in two states in your Access database: the source state, and the compiled state. The source state consists of the contents of your actual modules, with full text including white space, procedure and variable names, and comments.
The compiled state is the executable version of your code. All comments and white space have been removed, and a stream of executable instructions has been produced-the code is ready to be run. The difference between these two states can cause your application to run slower than molasses in January if you don't understand them.
When you run a procedure, VBA checks to see if the module containing the procedure is compiled. If it is, VBA simply runs the code. If it is not compiled, VBA compiles it by loading the code into memory, performing a syntax check, and compiling it into an executable format. If all these operations succeed, it can then run the code. You probably surmised that this process of compiling is not a free lunch-it does take some time. And herein lies the crux of the matter: compiling code takes time, and compiling lots of code takes lots of time.
So if you want your database to run as fast as possible, your task is obviously to reduce the amount of time Access spends compiling your code to a bare minimum.
In fact, in an ideal application, all your code should be compiled and saved in the compiled state. So how do you go about this? Your Access database or project in VBA parlance is said to be in a compiled state when all modules, including form and report modules, are saved in both states in the database. This means that the original source code is stored, as is the compiled version. In such a state, Access runs much faster, because it can completely bypass the compilation process.
Your database is now in the compiled state. This includes form and report modules called class modules using Access terminology and standard modules.
All VBA code that is called by your application is immediately ready for execution. There is no need for compilation. This is all fine and well, but is just as easy for your database to become decompiled.
When you make certain changes to your database, it automatically becomes decompiled, which means that the compiled state that you created using the previous steps no longer exists. So how do you avoid decompilation, or loss of the compiled state? Any of the following actions can decompile your database:.
So the bottom line is: to avoid decompilation, don't do the above. It's not as bad as it seems. After all, your database does not need to be in a compiled state while you are doing development work on it-it only really requires the performance benefits of the compiled state when it is actually running on your user's workstations. Therefore, if you follow these guidelines, you can enjoy peak performance from your module code:.
The Compact feature only compacts the data, but not the code portion of an Access database. Read this reference for more information on the Microsoft Access decompile feature.
This allows you to use early binding to bind variables to the control's objects, making it load and run faster. In most cases, this is handled for you: when you insert an ActiveX control into a form or report, Access automatically creates a Reference for that control. Always explicitly declare variables. Ensure this happens in every module in your application by using the Option Explicit phrase at the top of each module.
Use the most efficient variable type possible when declaring variables. For example, don't use a Long Integer when an Integer will do.
Avoid Variant types because the can be inefficient and slow. Avoid using the Object data type. Instead use the specific data type for the object you are working with. This allows Visual Basic to employ "early binding" which can be substantially faster in many cases. If you are going to refer to a property, control, object or data access object DAO more than once, assign it to an object variable. Use the IIf immediate if statement sparingly.
IIf does not employ "short-circuit" evaluation. This means that both sides of the expression are always evaluated, which may not be what you want since intuitively it looks like only the criteria satisfying side would run.
Instead of fixed arrays, use dynamic arrays with the Erase and ReDim statements to make better use of memory. Organize and structure you modules to take advantage of Visual Basic's demand loading architecture. When a procedure is loaded from a module, the entire module is loaded into memory. By placing related procedures in the same module, you can reduce the number of loads the Visual Basic has to make.
Eliminate unused procedures and unused variables. These elements use memory unnecessarily, and slow program load and execution. Our Total Access Analyzer program finds unused classes, procedures, variables, constants, enums, user defined types, and variables assigned but not used. If you are using data that is not going to change, put it in a constant instead of a variable. This allows Visual Basic to compile the value into the constant when the module is compiled, making the execution of that code faster.
Avoid Infinite Recursion. Don't have code that can call itself without having some type of short-circuit mechanism. This can lead to "Out of Stack Space" errors. Visual Basic allocates stack and heap memory differently according to the type of strings you create. By understanding how this works, you can write more efficient string code. String variables in procedures that are non-static use space on the computer's stack.
Use the following information to write code that minimizes stack memory usage. Every time you reference a Visual Basic object, method or property, you are initiating one or more calls the OLE's Idispatch interface. Each one of these calls takes time. Minimizing the number of such calls is one of the best ways to make you code run faster.
You can minimize OLE references by doing the following:. Turn off screen painting during repetitive operations that update the screen. Consider using the Application. Echo property to turn off screen painting. Depending on the type of video card in your computer, this can have moderate to dramatic effects of performance. We've seen pages of VBA code written using various recordset operations when one or a few queries would do the trick.
Queries are not only faster and optimizable, they're easier to understand and maintain. VBA dynamically loads code into memory as needed on a module level. If a function is called or a variable is used, the entire module containing that function or variable is loaded into memory. As you are developing your application, you keep loading code into memory.
Visual Basic for Applications does not support dynamic unloading of these modules. Because of this, RAM will begin to fill up. To boost development performance i. Note that you do not have to close Access itself, just the database itself. However, if you have library database code loaded, you should exit Access also. It is especially important to close your database after a Compile All Modules command.
The Compile All Modules command pulls all of your code into memory. Closing and reopening the application will unload the code and enable you to develop faster because of the additional free memory. If you are developing your application in a single-user environment, you can improve your development performance by opening the application exclusively.
This allows Visual Basic for Applications to save and compile faster by eliminating multiple-user save situations. If use loop constructs in your VBA code, such as For Next, Do While, etc.
For example, instead of saying:. In the second example, VBA only has to determine the value of Forms. Count once. In the first example, the value needs to be determined for each iteration of the loop. Use Seek instead of Find It uses indexes more efficiently and is the fastest data access method.
Whenever possible, use bookmarks to move among records instead of using the FindNext method. The Jet engine can navigate to bookmark values quicker than doing the sequential reads required by FindNext. If you can't use the Seek method, and must use the FindRecord or FindNext methods, use them on indexed fields.
These methods are much more efficient when used on a field that is indexed. Microsoft Access lets you wrap table update code in transactions so you can rollback incomplete attempts to save data. Any code operation that adds, modifies, or deletes data can be enclosed in a transaction using the BeginTrans CommitTrans pair.
If you do not need to rollback your updates, you can avoid using transactions and the overhead of maintaining a rollback log. Microsoft Jet implements a cost-based query optimizer in its query engine. During the compilation process of the query, Jet determines the most effective way to execute the query.
You can view this plan using the ShowPlan registry setting. To turn ShowPlan on, set the value of this new entry to "ON". To turn the feature off, set the value to "OFF". OUT is created or appended to if it already exists in the current directory. This file contains the query plans. Microsoft Jet lets you tune many parameters to tweak the engine for the best possible performance. These registry keys are located in:.
Using SetOption causes Jet to apply the changes immediately-the changes are not stored permanently in the registry, and you do not have to restart Access.
If you want to get the maximum performance out of your data operations, experiment with these settings. Experiment with the Threads setting in the registry. With this setting you can increase or decrease the number of operating system threads available to the Jet database engine. Use the FlushTransactionTimeout registry setting to tune the performance of asynchronous write operations. Use the ExclusiveAsyncDelay registry setting to tune the performance of asynchronous mode writes to exclusively opened databases.
Use the SharedAsyncDelay registry setting to tune the performance of asynchronous mode writes to databases opened for shared access. Use the PageTimeout registry setting to change the delay for checking other user's changes to the database.
Use the LockDelay registry setting to change how long Microsoft Jet waits between retries on locked pages in a shared database. Use the MaxLocksPerFile registry setting to tune performance by setting the maximum number of locks can be placed on a database MDB file. The syntax of the function is:. If you use a Startup form instead on an Autoexec macro, place the Visual Basic code needed for that form in the form's module instead of a standard module. Since Access has to load your Startup form, it will automatically load that form's module, which is generally faster than loading a standard module.
This technique gives your application the appearance that it is loading faster. Minimize the amount of code in your Startup form. You may want to defer certain operations, such as opening data access objects in code, or checking objects to a later time. Don't use ActiveX controls on your Startup Form. These controls can take long to load than other controls and will subsequently slow down the load time of your application.
Centrally manage and simplify the automatic deployment of your Access application to each desktop. When you update your application, you want to distribute it quickly and easily. It's also important to make sure each user is using the right version of Access.
Our Total Access Startup program makes it easy to manage your database version and Access version by letting you distribute a simple shortcut to launch your program. Split your database into an application and data database. Place only the data database on the server, keeping the application objects such as forms, reports and queries locally, where they can load and execute faster.
Keep static data, such as lookup tables, on the local machine. Update the local tables as necessary from the server. For example, a lookup table containing the two-letter abbreviations for American states is not likely to change anytime soon.
When such a table is used in a data entry application, it is a performance bottleneck to retrieve that data from the server every time it is needed. For example, the secondary index OrderDate will be heavily used in an order database. Go ahead and add it and any more of them that you need. Use the Access Database splitter and split that bad boy already.
Performance stayed the same. I would recommend taking the splitting the DB one step further. I then maintain an MDB on my development box and lots of backups! I have done this many times on some larger dbs large for MS Access and had no performance issues. As always, make backupS before you start.
Theoretical transfer times you mean. Everything about a PC is a bottleneck. Bring up your networking stats for both NICs and watch them as you open the database on the other machine, what's your throughput? After purging about 13, records the database seems to be running significantly faster. This must be a problem with the number of records in access and the number of machines hitting the database. Now I am seeing different problems. Tables within the database losing their "primary keys" duplication of records which is what causes the primary key to become broken.
An app written in a very broken manner. I hope you have a good backup prior to this. A repair and compact is, ideally, all an MDB file will need, on a regular basis. Access allows cascade updates and deletes at the JET engine level, and the counter field datatype is there to make it brain-damage easy to have a clean relational structure completely independent of the data.
Sorry to hear that. I have been running a compact and repair and i will randomly see instances where their are in the fields in a table or 2. To continue this discussion, please ask a new question.
0コメント