Disabling Cache for Table Mapper Tables

Service Builder creates relational mappings between entities. It uses mapping tables to associate the entities. In your service.xml file, both entities have a mapping-table column attribute of the format mapping-table="table1_table2". For example, a service.xml that maps AssetEntrys to AssetCategorys has an AssetCategory entity with this column:

<column entity="AssetEntry" 
mapping-table="AssetEntries_AssetCategories" 
name="entries" type="Collection" />

and an AssetEntry entity element with this column:

<column entity="AssetCategory" 
mapping-table="AssetEntries_AssetCategories" 
name="categories" type="Collection" />

By default, a table mapper cache is associated with each mapping table. The cache optimizes object retrieval. In some cases, however, it’s best to disable a table mapper cache.

Why would I want to disable cache on a table mapper?

Super-large entity tables can result in a memory-hogging table mapper cache. For this reason, consider disabling cache on a table mapper.

The table.mapper.cacheless.mapping.table.names Portal property disables cache for table mappers associated with the specified mapping tables. Here’s the default property setting:

##
## Table Mapper
##

  #
  # Set a list of comma delimited mapping table names that will not be using
  # cache in their table mappers.
  #
  table.mapper.cacheless.mapping.table.names=\
    Users_Groups,\
    Users_Orgs,\
    Users_Roles,\
    Users_Teams,\
    Users_UserGroups

All of the disabled caches above pertain to the User object because the table mappers tend to be much too large to have a useful cache—each User can have several entries in each related table.

Potential race conditions retrieving objects from the cache is another reason to disable a table mapper.

For example, LPS-84374 describes a race condition in which a custom entity’s table mapper cache can be cleared while in use, causing transactional rollbacks. Publishing AssetEntrys clears all associated table mapper caches. If they’re published at the same time getter methods are retrieving objects from the AssetEntries_AssetCategories mapping table, transaction rollbacks occur.

Disabling a Table Mapper Cache

Adding a mapping table name to the table.mapper.cacheless.mapping.table.names Portal property disables the associated table mapper cache.

1. In your [Liferay_Home]/portal-ext.properties file, add the current table.mapper.cacheless.mapping.table.names property setting. The setting is in your Liferay DXP installation’s portal-impl.jar/portal.properties file.

2. Append your mapping table name to the list. For example, to disable the cache associated with a mapping table named AssetEntries_AssetCategories, add that name to the list.

   table.mapper.cacheless.mapping.table.names=\
       Users_Groups,\
       Users_Orgs,\
       Users_Roles,\
       Users_Teams,\
       Users_UserGroups,\
       AssetEntries_AssetCategories
   

3. Restart the Liferay DXP instance to delete the table mapper cache.

You’ve disabled an unwanted table mapper cache.