Performance Data
-----------------
Machine:

CPU - 4 core
RAM - 24GB
OS  - SUSE 11 SP2

Configurations:

Encoding - SQL_ASCII
lc-collate - C
lc-ctype   - C

Sharedbuffers - 4GB
walbuffers    - 16MB
synchronous_commit - off
checkpoint_segments - 255
checkpoint_timeout - 25min
autovacuum - off


NORMAL DISK:
 
Head code: 

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1408441624 | 42.9247660636902
 hundred tiny fields, first 10 changed |     623904568 | 19.5896420478821
 hundred tiny fields, all changed      |     626929520 | 20.4015860557556
 hundred tiny fields, half changed     |     632949424 | 20.4108989238739
 hundred tiny fields, half nulled      |     568672600 | 16.9662220478058
(5 rows)


lz snappy hash delta encoding

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1314962968 | 39.8615770339966
 hundred tiny fields, first 10 changed |     452513816 | 16.8626310825348
 hundred tiny fields, all changed      |     458503728 | 18.5805869102478
 hundred tiny fields, half changed     |     463203696 | 17.7005319595337
 hundred tiny fields, half nulled      |     472732888 | 17.7074511051178
(5 rows)


robin delta encoding

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1321761080 | 40.9638168811798
 hundred tiny fields, first 10 changed |     501064768 | 18.8991298675537
 hundred tiny fields, all changed      |     631711040 | 22.2287940979004
 hundred tiny fields, half changed     |     628356072 | 21.4988770484924
 hundred tiny fields, half nulled      |     506637272 | 18.4065499305725
(5 rows)


TEMPFS:

Head code: 

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1395199584 | 23.9126200675964
 hundred tiny fields, first 10 changed |     636436752 | 13.5280549526215
 hundred tiny fields, all changed      |     635591368 | 13.5622470378876
 hundred tiny fields, half changed     |     628001440 | 13.5341370105743
 hundred tiny fields, half nulled      |     564033176 | 12.3501629829407
(5 rows)


lz snappy hash delta encoding

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1314964400 | 23.2445130348206
 hundred tiny fields, first 10 changed |     456703104 | 14.2320129871368
 hundred tiny fields, all changed      |     463224736 | 14.0170950889587
 hundred tiny fields, half changed     |     462589768 | 14.032851934433
 hundred tiny fields, half nulled      |     473361760 | 13.3050961494446
(5 rows)


robin delta encoding

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1319550032 | 23.7516498565674
 hundred tiny fields, first 10 changed |     512198256 | 15.0410940647125
 hundred tiny fields, all changed      |     638134296 | 15.143513917923
 hundred tiny fields, half changed     |     635378360 | 15.1855199337006
 hundred tiny fields, half nulled      |     508630832 | 13.4496691226959
(5 rows)