I've run some tests with 7.1 + WAL & 7.0.2
Setup: 5 tables (i int, t text), 100000 records in each table,
sizeof(t column) is rand(256), indices on i column for all tables.
-B 16384 -A 0 (+ --wal_buffers=256 in 7.1)
System: SUN Ultra 10, 512M RAM, 1 (fast) IDE disk
Test: 5 clients simultaneously performed
UPDATE tableN SET t = '...rand(256) chars...' WHERE i = ...rand(100000)...;
Each UPDATE was in separate transaction, client N changed tableN only,
each client made 1000 transactions.
Results: 5000 transactions took ~60 sec in 7.1, ~550 sec in 7.0.2 with fsync
and ~60 sec without fsync.
So, seems that WAL added not just complexity to system -:)
I'm going to commit redo for sequences tomorrow evening and
#define XLOG by default after this (initdb will be required).
Vadim