Background documentation Number of physical reads Locate the document in its SAP Library structure

Number of physical reads: <count>

Explanation

A large number of physical reads are being made on the Structure linkvolumes of the database instance, since the data requested by the applications was not found in the Structure linkdata cache.

User Response

If a table is accessed for the first time, or if it has not been used for a long time, and was therefore displaced from the data cache, then this situation is not a problem.

However, if this does not explain the read activity, check the hit rate for the data cache, and increase the size of the data cache, if necessary.

Also make sure that the SQL statements specified by the application do not read significantly more data than needed for processing, because of poor Structure linksearch strategies, for example.

If the database parameter Structure linkLRU_FOR_SCAN has the value yes, then Structure linktable scans use only 10% of the data cache for caching the table. This means that the table cannot be held completely in the data cache, and the next scan has to read it physically again.