表格空间压缩计算中的可用空间
DSN1COMP 实用程序在进行压缩估算时会考虑PCTFREE和FREEPAGE值，除非输入数据集是LOB表空间或LOB表空间的图像复制数据集。 PCTFREE和FREEPAGE值不适用于LOB。
DSN1COMP 报告所使用的 PCTFREE 和 FREEPAGE 值以及未压缩的数据量，如下例所示。 请注意，如果您为 DSN1COMP 指定的PCTFREE或FREEPAGE值与创建或更改表空间SQL中指定的值不同，则 DSN1COMP 输出中包含未压缩页面的不同值。
以下示例显示了压缩数据的 DSN1COMP 输出：
DSN1998I INPUT DSNAME = DB2SMS.DSNDBC.DSN03686.ZZINSRZY.I0001.A001 , VSAM
DSN1944I DSN1COMP INPUT PARAMETERS
INPUT DATA SET CONTAINS COMPRESSED DATA
USING HUFFMAN COMPRESSION TYPE
INPUT DICTIONARY WAS BUILT BY INSERT
4,096 DICTIONARY SIZE USED
0 FREEPAGE VALUE USED
5 PCTFREE VALUE USED
COMPTYPE(ALL) REQUESTED
NO ROWLIMIT WAS REQUESTED
ESTIMATE BASED ON DB2 LOAD METHOD
255 MAXROWS VALUE USED
DSN1940I DSN1COMP COMPRESSION REPORT
HARDWARE SUPPORT FOR HUFFMAN COMPRESSION IS AVAILABLE
+-----------------------------------+------------------+------------------+------------------+------------------+
| | | Estimated state | Estimated state | Calculated |
| | UNCOMPRESSED | Compressed | Compressed | Compressed from |
| | | FIXED | HUFFMAN | INPUT DICTIONARY |
+-----------------------------------+------------------+------------------+------------------+------------------+
| DATA (IN KB) | 1,659,179 | 434,603 | 222,697 | 436,780 |
| PERCENT SAVINGS | | 73%| 86%| 73%|
| | | | | |
| AVERAGE BYTES PER ROW | 1,701 | 448 | 231 | 450 |
| PERCENT SAVINGS | | 73%| 86%| 73%|
| | | | | |
| DATA PAGES NEEDED | 500,000 | 125,000 | 62,500 | 125,000 |
| PERCENT DATA PAGES SAVED | | 75%| 87%| 75%|
| | | | | |
| DICTIONARY PAGES REQUIRED | 0 | 64 | 64 | 64 |
| ROWS SCANNED TO BUILD DICTIONARY | | 81 | 81 | N/A |
| ROWS SCANNED TO PROVIDE ESTIMATE | | 1,000,000 | 1,000,000 | N/A |
| DICTIONARY ENTRIES | | 4,096 | 4,080 | 4,096 |
| | | | | |
| TOTAL PAGES (DICTIONARY + DATA) | 500,000 | 125,064 | 62,564 | 125,064 |
| PERCENT SAVINGS | | 74%| 87%| 74%|
+-----------------------------------+------------------+------------------+------------------+------------------+
DSN1994I DSN1COMP COMPLETED SUCCESSFULLY, 118,475 PAGES PROCESSED 以下示例显示了未压缩数据的 DSN1COMP 输出：
DSN1999I START OF DSN1COMP FOR JOB DSN1CMP COMPTS1
DSN1998I INPUT DSNAME = DSNC000.DSNDBC.EMPDB.EMPSPACE.I0001.A001 , VSAM
DSN1944I DSN1COMP INPUT PARAMETERS
INPUT DATA SET CONTAINS NON-COMPRESSED DATA
4,096 DICTIONARY SIZE USED
30 FREEPAGE VALUE USED
45 PCTFREE VALUE USED
COMPTYPE(FIXED) REQUESTED
NO ROWLIMIT WAS REQUESTED
ESTIMATE BASED ON DB2 REORG METHOD
255 MAXROWS VALUE USED
DSN1940I DSN1COMP COMPRESSION REPORT
HARDWARE SUPPORT FOR HUFFMAN COMPRESSION IS NOT AVAILABLE
+-----------------------------------+------------------+------------------+
| | | Estimated state |
| | UNCOMPRESSED | Compressed |
| | | FIXED |
+-----------------------------------+------------------+------------------+
| DATA (IN KB) | 224 | 142 |
| PERCENT SAVINGS | | 36%|
| | | |
| AVERAGE BYTES PER ROW | 48 | 32 |
| PERCENT SAVINGS | | 33%|
| | | |
| DATA PAGES NEEDED | 145 | 113 |
| PERCENT DATA PAGES SAVED | | 22%|
| | | |
| DICTIONARY PAGES REQUIRED | 0 | 16 |
| ROWS SCANNED TO BUILD DICTIONARY | | 1,969 |
| ROWS SCANNED TO PROVIDE ESTIMATE | | 5,000 |
| DICTIONARY ENTRIES | | 4,096 |
| | | |
| TOTAL PAGES (DICTIONARY + DATA) | 145 | 129 |
| PERCENT SAVINGS | | 11%|
+-----------------------------------+------------------+------------------+
DSN1994I DSN1COMP COMPLETED SUCCESSFULLY, 63 PAGES PROCESSED