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 - on checkpoint_segments - 255 checkpoint_timeout - 25min postgres orginal: testname | wal_generated | duration -----------------------------------------+---------------+------------------ two short fields, no change | 1232914600 | 33.2914838790894 two short fields, one changed | 1232907632 | 34.2854881286621 two short fields, both changed | 1233407712 | 35.1660950183868 one short and one long field, no change | 1042332736 | 22.9023208618164 ten tiny fields, all changed | 1395194184 | 40.3592751026154 hundred tiny fields, first 10 changed | 633139480 | 20.936224937439 hundred tiny fields, all changed | 621895720 | 21.2956609725952 hundred tiny fields, half changed | 625431280 | 20.7431139945984 hundred tiny fields, half nulled | 560595680 | 18.4655048847198 (9 rows) postgres pglz micro optimization: testname | wal_generated | duration -----------------------------------------+---------------+------------------ two short fields, no change | 1237660232 | 33.8160381317139 two short fields, one changed | 1242485848 | 34.7965979576111 two short fields, both changed | 1232906856 | 35.3230299949646 one short and one long field, no change | 653320432 | 19.4206099510193 ten tiny fields, all changed | 1316414576 | 39.5244870185852 hundred tiny fields, first 10 changed | 461101960 | 20.2425429821014 hundred tiny fields, all changed | 634754640 | 23.9643130302429 hundred tiny fields, half changed | 623570968 | 23.4849381446838 hundred tiny fields, half nulled | 480426088 | 20.2109000682831 (9 rows) Approach-1: testname | wal_generated | duration -----------------------------------------+---------------+------------------ two short fields, no change | 1232915592 | 32.3785700798035 two short fields, one changed | 1232907368 | 34.0129780769348 two short fields, both changed | 1232904864 | 35.0703940391541 one short and one long field, no change | 664752848 | 18.4983038902283 ten tiny fields, all changed | 1314959760 | 38.9782929420471 hundred tiny fields, first 10 changed | 484085432 | 18.3570599555969 hundred tiny fields, all changed | 623688960 | 23.640851020813 hundred tiny fields, half changed | 626489960 | 23.6207790374756 hundred tiny fields, half nulled | 486715816 | 18.2742040157318 (9 rows) Approach-2: testname | wal_generated | duration -----------------------------------------+---------------+------------------ two short fields, no change | 1238692600 | 33.4670641422272 two short fields, one changed | 1237553432 | 33.2781448364258 two short fields, both changed | 1242385912 | 34.4291758537292 one short and one long field, no change | 728843440 | 24.6129009723663 ten tiny fields, all changed | 1314953336 | 38.9639298915863 hundred tiny fields, first 10 changed | 492468472 | 18.6584041118622 hundred tiny fields, all changed | 623053904 | 23.5239579677582 hundred tiny fields, half changed | 623678504 | 23.4059200286865 hundred tiny fields, half nulled | 483231808 | 18.4165120124817 (9 rows) Approach-3: testname | wal_generated | duration -----------------------------------------+---------------+------------------ two short fields, no change | 1237643976 | 33.7087278366089 two short fields, one changed | 1232906224 | 33.7791311740875 two short fields, both changed | 1232907472 | 33.6205348968506 one short and one long field, no change | 725165880 | 25.6599669456482 ten tiny fields, all changed | 1314959792 | 39.2160720825195 hundred tiny fields, first 10 changed | 489112776 | 18.3606278896332 hundred tiny fields, all changed | 622960672 | 23.4263441562653 hundred tiny fields, half changed | 623599392 | 23.6871449947357 hundred tiny fields, half nulled | 483190248 | 18.3869581222534 (9 rows)