Oracle AWR wri$, wrh$ and wrm$

AWR Performance Tables

The Oracle10g dynamic performance tables constitute the foundation of sophisticated automations such as Automatic Memory Management  (AMM ) as well as intelligent advisory tools such as ADDM and the SQL Tuning   Advisor. 

Remember, the AWR is a core feature of the 10g database kernel and automatically collects and stores important run-time performance information for our historical analysis.

The tables that store this information are prefixed with wrh$ and are very similar in function to the STATSPACK tables.  This could make STATSPACK appear somewhat obsolete, although it is still available in the $ORACLE_HOME/rdbms/admin directory.

Unlike the more cumbersome STATSPACK utility, which requires knowledge of the table structure and creation of complex query scripts, the 10g Enterprise Manager (OEM) automatically displays and interprets this valuable time-series performance data.

The wrh$ AWR tables store important historical statistical information about the database in the form of periodic snapshots. Each snapshot is a capture of the in–memory x$ fixed view and other control structures at a certain point in time. Each of the AWR table names is prefixed with wrm$ (Metadata tables), wrh$ (History tables), or wri$ (Advisory tables).

§       The wrm$ tables store metadata information for the Workload Repository.

§       The wrh$ tables store historical data or snapshots.

§       The wri$ tables: These 49 tables store data related to advisory functions.

The next section provides a closer look at the underlying data structures so that how the AWR tables store important time-series performance data becomes more evident.

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