不明白INFORMIX为什么不对表的最大扩展个数给出个固定值。所以今天就按照《性能指南》第6章即P163页来测试了一下不同页大小的表各自的默认初始扩展、下一个扩展数据块以及一个表允许的最大扩展数。以下是测试结果和测试过程。
页大小 extent_size frcnt 最大扩展个数
2k 8,8 1844 1844/8=230
4k 4,4 3982 3982/8=497
8k 4,4 7988 7988/8=998
结论：较大的页有更好的扩容性。
[13] % oncheck -pt edudb:lilei_2
TBLspace Report for edudb:informix.lilei_2
Physical Address 30:5 Creation date 07/08/2010 10:22:02
TBLspace Flags 801 Page Locking
TBLspace use 4 bit bit-maps
Maximum row size 4
Number of special columns 0
Number of keys 0
Number of extents 1
Current serial value 1
Current SERIAL8 value 1
Current BIGSERIAL value 1
Current REFID value 1
Pagesize (k) 2
First extent size 8
Next extent size 8 Number of pages allocated 8
Number of pages used 1
Number of data pages 0
Number of rows 0
Partition partnum 31457282
Partition lockid 31457282
Extents
Logical Page Physical Page Size Physical Pages
0 30:53 8 8
[15] % oncheck -pP 30 5
addr stamp chksum nslots flag type frptr frcnt next prev
30:5 14568307 4bb6 5 2 PARTN 180 1844 0 0
slot ptr len flg
1 24 104 0
2 128 36 0
3 164 0 0
4 164 0 0
5 164 16 0
slot 1:
0: 1 e0 0 2 0 0 8 1 0 0 0 4 0 0 0 0 .`..............
16: 0 1 8 0 4c 35 36 4a 0 0 0 1 0 0 0 8 ....L56J........
32: 0 0 0 8 0 0 0 8 0 0 0 1 0 0 0 0 ................
48: ff ff ff ff 1 e0 0 2 0 0 0 0 0 0 0 1 .....`..........
64: 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 ................
80: 0 1 0 0 0 0 0 24 8 b 22 28 0 0 0 0 .......$.."(....
96: 0 0 0 0 0 0 0 1 ................
slot 2:
0: 6e 6d 6f 73 64 62 0 69 6e 66 6f 72 6d 69 78 0 edudb.informix.
16: 6c 69 6c 65 69 5f 32 0 65 6e 5f 55 53 2e 38 31 lilei_2.en_US.81
32: 39 0 0 18 9...............
slot 3:
slot 4:
slot 5:
0: 0 0 0 0 0 0 0 35 0 0 0 8 0 0 0 0 .......5........
[16] % oncheck -pt edudb:lilei_4
TBLspace Report for edudb:informix.lilei_4
Physical Address 8:626 Creation date 07/08/2010 10:21:37
TBLspace Flags 801 Page Locking
TBLspace use 4 bit bit-maps
Maximum row size 4
Number of special columns 0
Number of keys 0
Number of extents 1
Current serial value 1
Current SERIAL8 value 1
Current BIGSERIAL value 1
Current REFID value 1
Pagesize (k) 4
First extent size 4
Next extent size 4 Number of pages allocated 4
Number of pages used 1
Number of data pages 0
Number of rows 0
Partition partnum 8388674
Partition lockid 8388674
Extents
Logical Page Physical Page Size Physical Pages
0 8:12522 4 8
[17] % oncheck -pP 8 626
addr stamp chksum nslots flag type frptr frcnt next prev
8:626 14568257 49e5 5 2 PARTN 180 3892 0 0
slot ptr len flg
1 24 104 0
2 128 36 0
3 164 0 0
4 164 0 0
5 164 16 0
slot 1:
0: 0 80 0 42 0 0 8 1 0 0 0 4 0 0 0 0 ...B............
16: 0 1 10 0 4c 35 36 31 0 0 0 1 0 0 0 8 ....L561........
32: 0 0 0 8 0 0 0 4 0 0 0 1 0 0 0 0 ................
48: ff ff ff ff 0 80 0 42 0 0 0 0 0 0 0 1 .......B........
64: 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 ................
80: 0 1 0 0 0 0 0 24 8 b 5 64 0 0 0 0 .......$...d....
96: 0 0 0 0 0 0 0 1 ................
slot 2:
0: 6e 6d 6f 73 64 62 0 69 6e 66 6f 72 6d 69 78 0 edudb.informix.
16: 6c 69 6c 65 69 5f 34 0 65 6e 5f 55 53 2e 38 31 lilei_4.en_US.81
32: 39 0 0 0 9...............
slot 3:
slot 4:
slot 5:
0: 0 0 0 0 0 0 30 ea 0 0 0 4 0 0 0 0 ......0j........
[18] % oncheck -pt edudb:lilei_8
TBLspace Report for edudb:informix.lilei_8
Physical Address 28:40
Creation date 07/08/2010 10:21:52
TBLspace Flags 801 Page Locking
TBLspace use 4 bit bit-maps
Maximum row size 4
Number of special columns 0
Number of keys 0
Number of extents 1
Current serial value 1
Current SERIAL8 value 1
Current BIGSERIAL value 1
Current REFID value 1
Pagesize (k) 8
First extent size 4
Next extent size 4 Number of pages allocated 4
Number of pages used 1
Number of data pages 0
Number of rows 0
Partition partnum 29360135
Partition lockid 29360135
Extents
Logical Page Physical Page Size Physical Pages
0 28:5364 4 16
[19] % oncheck -pP 28 40
addr stamp chksum nslots flag type frptr frcnt next prev
28:40 14568279 4bbd 5 2 PARTN 180 7988 0 0
slot ptr len flg
1 24 104 0
2 128 36 0
3 164 0 0
4 164 0 0
5 164 16 0
slot 1:
0: 1 c0 0 7 0 0 8 1 0 0 0 4 0 0 0 0 .@..............
16: 0 1 20 0 4c 35 36 40 0 0 0 1 0 0 0 10 .. .L56@........
32: 0 0 0 10 0 0 0 4 0 0 0 1 0 0 0 0 ................
48: ff ff ff ff 1 c0 0 7 0 0 0 0 0 0 0 1 .....@..........
64: 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 ................
80: 0 1 0 0 0 0 0 24 8 b 13 c8 0 0 0 0 .......$...H....
96: 0 0 0 0 0 0 0 1 ................
slot 2:
0: 6e 6d 6f 73 64 62 0 69 6e 66 6f 72 6d 69 78 0 edudb.informix.
16: 6c 69 6c 65 69 5f 38 0 65 6e 5f 55 53 2e 38 31 lilei_8.en_US.81
32: 39 0 0 18 9...............
slot 3:
slot 4:
slot 5:
0: 0 0 0 0 0 0 14 f4 0 0 0 4 0 0 0 0 .......t........
[20] %