2018-05-28 16:41 GMT-03:00 Pavel Stehule <pavel.steh...@gmail.com>: > I am writing a article about PostgreSQL 11 features. Now I am looking on new > option --create-slot option of pg_basebackup command. > > I don't understand to use case for this option, because It fails when > requested slot already exists. I cannot to imagine use case for this. If I > write some scripts, then I prefer the behave like "create if doesn't exist > or do nothing". > In prior versions, you should create a slot (via SQL function or streaming replication protocol) *before* run pg_basebackup. In 11, use --create-slot option and you don't need an extra step (of course, you should drop that slot after the end of backup -- if that is not a new standby. It also does not make sense to use _persistent_ replication slots for backup because you are probably archiving WAL). IMHO the use case is new standbys that will use replication slots.
> Any repeated running of script with this option should to fail. Is it > required? Why? > As I said, you should have an extra step to drop that slot (even before 11). There is no "create replication slots if not exists". If you are repeatedly running a script, why don't you let pg_basebackup use temporary replication slots? -- Euler Taveira Timbira - http://www.timbira.com.br/ PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento
