On Tue, 2007-07-24 at 18:45 +0900, Tatsuo Ishii wrote: > > > I noticed in 8.3 there are chances where we can avoid WAL logging. For > > > example, 8.3's pgbench was modified to use TRUNCATE right before > > > COPY. Is there any documentation which describes that kind of > > > techniques? If there's none, I would volunteer the work to create such > > > a documentation since I think this is valuable information for DBAs > > > who wish to migrate to 8.3. > > > > The Performance Tips section has been modified to describe this. Would > > you like me to add something elsewhere also? Multiple entry points to > > information helps everybody, so I'll happily add more. > > Thanks for pointing out. I found following: > > "COPY is fastest when used within the same transaction as an earlier > CREATE TABLE or TRUNCATE command. In such cases no WAL needs to be > written, because in case of an error, the files containing the newly > loaded data will be removed anyway." > > Sounds great! > > BTW, I noticed that "COPY, CLUSTER, B-Tree split logging improvements" > in Josh's presentation in Tokyo. Are they just internal changes and > are nothing to do with DBA's job?
Cluster is also mentioned lower down http://developer.postgresql.org/pgdocs/postgres/populate.html#POPULATE-PITR The b-tree split logging is an algorithmic reduction in WAL, so isn't user visible or optional in any way. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org