2022年11月10日(木) 14:16 Adrian Klaver <adrian.klaver@xxxxxxxxxxx>: > > On 11/9/22 20:57, Ian Lawrence Barwick wrote: > > 2022年11月10日(木) 13:41 Igor Korot <ikorot01@xxxxxxxxx>: > >> > >> Hi, ALL, > >> According to https://chartio.com/resources/tutorials/how-to-list-databases-and-tables-in-postgresql-using-psql/, > >> there are generally 3 system DBs. > >> > >> However I'm confused with the word general. > >> How many system databases can be made on a PG server? > > > > template0 and template1 are the mandatory system databases which > > cannot be dropped. > > Actually that is not strictly true: > > https://www.postgresql.org/docs/current/manage-ag-templatedbs.html > > " > Note > > template1 and template0 do not have any special status beyond the fact > that the name template1 is the default source database name for CREATE > DATABASE. For example, one could drop template1 and recreate it from > template0 without any ill effects. This course of action might be > advisable if one has carelessly added a bunch of junk in template1. (To > delete template1, it must have pg_database.datistemplate = false.) OK, "cannot be dropped unless you manually convert them into non-template databases" :). Regards Ian Barwick
