Read and write operations to the devspaces are buffered in order to save disk accesses. The pertinent main memory structures are called caches. They can be dimensioned appropriately. ADABAS defines the following caches:
Data Cache
This cache contains the last read- or write-accessed pages of the data devspaces. The data cache is shared by all simultaneously active users. The hit rate, i.e. the relation between successful and unsuccessful accesses to the data cache, is decisive for the performance. Successful access means that the required data was already available in the data cache.
Converter Cache
The converter cache and its hit rate are also decisive for performance. The converter cache contains the last read- or write-accessed pages of the system devspace. The converter cache is shared by all simultaneously active users. For the converter cache, you should strive for hit rates as close to 100% as possible.
Proc Code Cache
This structure contains the code of the last executed DB procedures, triggers, or DB functions. The proc code cache is shared by all simultaneously active users.
Proc Data Cache
This cache exists for each active user (or for each database session). It contains the parameters or variables belonging to the last executed DB procedures, triggers, and DB functions.
Catalog Cache
This cache exists for each active user (or for each database session). It contains the last catalog objects used by a database session and the internal representation (application plans) of the last executed commands. Displacements from the catalog cache first move the data into the data cache.
Temp Cache
This cache exists for each active user (or for each database session). It contains the last database objects (SELECT results, temporary tables) generated or temporarily used by a database session.
Applications that generate large join results or frequently work with temporary tables can improve their performance by configuring a temp cache with an appropriate size. Displacements from the temp cache first move the temporary data into the data cache.