Microsoft Dynamics AX Support

This blog contains posts by the Microsoft Dynamics AX Support Teams Worldwide

Dynamics AX Table Caching: Basic Rules

This post provides some basic general guidance to get you started on setting table caching for custom tables, bearing in mind there will be exceptions. This should generally be defined at design time to avoid costly round trips to the database. As explained by Bertrand Caillet from our PFE (Premier Field Engineering) team:

“This is one of the most fundamental feature of the product today. The three tiers architecture of Dynamics AX allows you to define caching on AOS and client. Not using caching properly is the first root cause for performance.”
http://blogs.msdn.com/b/axinthefield/archive/2014/02/18/top-10-issues-discovered-in-the-dynamics-ax-code-review.aspx

Essentially there are two types of table caching as explained on msdn:
Set based caching (AX 2012)
Single record caching (AX 2012)

In AX 2012, table caching is more advanced than in previous versions, including support for joins, unique indexes (as opposed to primary indexes only), cross company queries, etc. (under certain constraints as explained in the above links). So for AX 2009, please see the following links (which generally cover previous versions too):
Set Based Caching (AX 2009)
Single Record Caching (AX 2009)

Cache settings for a table can be found in the following location in the application:
AOT > Data Dictionary > Tables > [TableName] > Properties > CacheLookup

Changes like this should be made by a developer in accordance with best practice guidance.

You can use the script at the bottom of this post to check cache lookup settings for all tables using the “Performance Analyser 1.20 for Microsoft Dynamics” (DynamicsPerf) tool (partly based on the analysis scripts that come with this tool).

Set the appropriate table group depending on how the table is used; see the following article for further details for AX 2012 (for previous versions it is basically the same but with fewer table groups):

Table and table group reference [AX 2012]
http://technet.microsoft.com/en-us/library/gg731855.aspx

Following that, you can generally set table caching according to the table below, again bearing in mind there can be exceptions. Please refer back to the above links for an explanation of each cache lookup type.

Table Group Cache Lookup
Miscellaneous*  See notes below
 Parameter  EntireTable
 Group  Found
 Main  Found
 Transaction  NotInTTS
 WorksheetHeader  NotInTTS
 WorksheetLine  NotInTTS
 Framework  N/A
 Reference  Found
 Worksheet  NotInTTS
 TransactionHeader  NotInTTS
 TransactionLine  NotInTTS

 * All newly created tables default to a table group of Miscellaneous. Ideally don’t use this table group for custom tables.

Finally, bear in mind that in AX 2012, the cache limit is configurable for every table group in the server performance settings:

System Administration > Setup > System > Server Configuration > Performance optimisation tab

Entire table cache size determines in kilobytes how much data is cached in memory before spilling to disk. The defaults are 32KB for AX 2012 RTM and 96KB for AX 2012 R2/R3.

The record cache limits define (per table group) the number of records stored in the server side cache and the client record cache factor defines based on that the number records stored in client cache, e.g. server side cache of 2000 (default) and client record cache factor of 20 (default) means 100 records are stored in client cache. Each AOS server can have its own cache settings. The basic rule here it is to keep the defaults unless performance testing proves it addresses a specific issue.

The “Inside Microsoft Dynamics AX” book series provides more in depth information.

TableCaching.sql