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NEAROFFPOSF and FAROFFPOSF are measures to gauge the organization of the data in the underlying table. It assumes that the index in question is the clustering index. The values indicate how many of the rows in the table are ill-placed given that assumption. If the index is not the clustering index, FAROFFPOSF and NEAROFFPOSF are not useful as indicators of data organization. The NEARINDREF and FARINDREF columns for a tablespace indicate the number of rows that have been relocated either near (2 to 15 pages) or far away (16 or more pages) from their original location. This relocation (also called indirection) can occur as the result of updates to variable length rows (that is, rows with VARCHAR columns, tables with EDITPROCs, or compressed rows). LEAFDIST helps determine the relative efficiency of each index. LEAFDIST indicates the average number of pages between successive index leaf pages. The more intervening pages, the less efficient the index will be. Finally, you can use CLUSTERRATIOF to determine the overall condition of the index as it corresponds to the physical order of the tablespace data. The more clustered an index is, the greater its conformance to the order of the rows as they are physically aligned in the tablespace. A cluster ratio of 100 percent indicates that the index and the tablespace ordering matches exactly. As the cluster ratio diminishes, access that uses the index becomes less efficient. Also, please note that CLUSTERRATIOF for partitioned indexes can be found in SYSIBM.SYSINDEXSTATS. This CLUSTERRATIOF is at the partition level and can help to determine if only a subset of the partitions needs to be reorganized. The following table can be used as guide to determine how frequently tablespaces and indexes should be reorganized. A + indicates that you should REORG more frequently as the value in that column gets larger. A - (subtract character) indicates that you should REORG more frequently as the value gets smaller. As the number of + or - characters increases, the need to REORG becomes more urgent. For example, as PERCDROP gets larger, the need to REORG is very urgent, as indicated by five plus signs. For CLUSTERRATIOF, as the value gets smaller, the need to REORG increases. Table Reorganization indicators. Column Object Impact ----------- ----------- ---------- PERCDROP Tablespace + + + + + NEAROFFPOSF Tablespace + FAROFFPOSF Tablespace + + + + NEARINDREF Index + FARINDREF Index + + + + LEAFDIST Index + + + CLUSTERRATIOF Index - - - - - (Note: the above information is culled from my book, DB2 Developer's Guide. It can be ordered online at the following link: http://www.amazon.com/exec/obidos/ASIN/0672318288/mullinassoci-20/002-578067
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