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          |    1396691368 | 42.6557660102844
 hundred tiny fields, first 10 changed |     624956184 | 20.7321319580078
 hundred tiny fields, all changed      |     627513704 | 20.4518117904663
 hundred tiny fields, half changed     |     634719488 | 20.1086249351501
 hundred tiny fields, half nulled      |     568837664 | 19.2674238681793
(5 rows)

pglz-with-micro-optimization-compress-using-newdata-5:

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1319577672 | 41.927258014679
 hundred tiny fields, first 10 changed |     451450776 | 19.5925290584564
 hundred tiny fields, all changed      |     457981512 | 17.7323400974274
 hundred tiny fields, half changed     |     462757976 | 18.209489107132
 hundred tiny fields, half nulled      |     486234720 | 18.5473780632019
(5 rows)

pglz-with-micro-optimization-compress-using-newdata_snappy_hash-1:

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1324971032 | 41.6224391460419
 hundred tiny fields, first 10 changed |     453388104 | 17.6829369068146
 hundred tiny fields, all changed      |     457076440 | 18.0532441139221
 hundred tiny fields, half changed     |     452937088 | 17.8225939273834
 hundred tiny fields, half nulled      |     474202416 | 18.8006780147552
(5 rows)


TEMPFS:

Head code: 

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1401354568 | 25.6572861671448
 hundred tiny fields, first 10 changed |     633699368 | 13.5204498767853
 hundred tiny fields, all changed      |     632917632 | 13.5536248683929
 hundred tiny fields, half changed     |     624010728 | 13.5120921134949
 hundred tiny fields, half nulled      |     572948704 | 12.1847529411316
(5 rows)

pglz-with-micro-optimization-compress-using-newdata-5:

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1331402424 | 23.7896168231964
 hundred tiny fields, first 10 changed |     456955584 | 15.5029740333557
 hundred tiny fields, all changed      |     463473224 | 15.1785190105438
 hundred tiny fields, half changed     |     463465584 | 15.2339129447937
 hundred tiny fields, half nulled      |     490292096 | 17.0547699928284
(5 rows)

pglz-with-micro-optimization-compress-using-newdata_snappy_hash-1:

               testname                | wal_generated |     duration
---------------------------------------+---------------+------------------
 ten tiny fields, all changed          |    1326931160 | 24.2566108703613
 hundred tiny fields, first 10 changed |     462023880 | 14.5646378993988
 hundred tiny fields, all changed      |     459025744 | 14.321811914444
 hundred tiny fields, half changed     |     461399096 | 14.2813529968262
 hundred tiny fields, half nulled      |     472081992 | 13.5119450092316
(5 rows)