REORG PLUS architecture
The architecture of REORG PLUS differs from that of the IBM Db2 REORG utility.
The Db2 REORG utility performs reorganization processing in several phases (UNLOAD, RELOAD, SORT, and BUILD), which run serially. However, REORG PLUS combines these phases into either a two-phase architecture or a single-phase architecture.
Two-phase architectureWhen you specify UNLOAD CONTINUE or UNLOAD PAUSE, REORG PLUS uses two phases: UNLOAD and RELOAD. When you specify UNLOAD RELOAD, REORG PLUS combines the UNLOAD and RELOAD phases into a single processing phase named REORG. All functions of the Db2 REORG utility are performed in these phases of REORG PLUS.
The UNLOAD installation option determines the phase processing that REORG PLUS uses at a global level. You can override this value for a particular reorganization job by specifying the UNLOAD command option. You can only specify UNLOAD PAUSE on the command option.
The two-phase architecture allows REORG PLUS to perform several tasks concurrently, reducing the elapsed time for a table space reorganization. For example, REORG PLUS sorts the index keys and builds the indexes while it reloads the table space rows.
Single-phase architectureThe REORG PLUS single-phase architecture builds on the advantages of the two-phase processing and allows for even greater reductions in CPU usage and elapsed time. Single-phase processing eliminates some read and write processes by combining the UNLOAD and RELOAD phases.
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