Oracle Tablespace Reorganization

TS_NAME         ID OWNER      SEGMENT_NA   BEGIN  BLOCKS     END       KB F

-------------- --- ---------- ---------- ------- ------- ------- -------- -

DONALD3_DETAILS  15 DON        ZIP_UPS          2       5       6       20

DONALD3_DETAILS  15 DON        ACCC_TY          7       2       8        8

DONALD3_DETAILS  15 DON        BUS_UNIT         9      35      43      140

DONALD3_DETAILS                                44       2      45        8 F

DONALD3_DETAILS  15 DON        PLANT           46       3      48       12

DONALD3_DETAILS                                49      10      58       40 F

DONALD3_DETAILS  15 DON        DON_TABLES      59       4      62       16

DONALD3_DETAILS  15 DON        ZONE            63       2      64        8

                                                                 -------- *

                                                                      252 s

DONALD3_DETAILS  15                            65    1216    1282     4869 F

                                                                 -------- *

                                                                     4869 s

In the tablespace fragmentation report we see two discontiguous chunks of free space, as indicated by the “F” column on the far right-hand side of the report. Here, we see that blocks 46-48 are free, as are blocks 49-58.  There are other tools that will provide this information in a graphical format such as Oracle’s Performance Pack’s Tablespace Manager, and the Eventus AdHawk Spacer product.

Oracle version 7.3 will automatically detect and coalesce tablespaces--provided that all affected tablespaces default storage clause has PCTINCREASE set to 1. The coalesce mechanism for tablespace coalescing is the SMON process, which periodically wakes up to coalesce free space. Between SMON coalesces, any transaction that requires an extent that is larger than any available free extent, will trigger a coalesce on the tablespace to move all free space into a single chunk--hopefully making room for the required extent.
 

This is an excerpt from "High Performance Data Warehousing", copyright 1997.

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