Re: COPY FREEZE has no warning
От | Robert Haas |
---|---|
Тема | Re: COPY FREEZE has no warning |
Дата | |
Msg-id | CA+TgmobSWqv1HAjr81-QjnC78LWxauFnfT346q4ErntU=b2-GQ@mail.gmail.com обсуждение исходный текст |
Ответ на | COPY FREEZE has no warning (Bruce Momjian <bruce@momjian.us>) |
Список | pgsql-hackers |
On Wed, Jan 23, 2013 at 2:02 PM, Bruce Momjian <bruce@momjian.us> wrote: > As a reminder, COPY FREEZE still does not issue any warning/notice if > the freezing does not happen: > > Requests copying the data with rows already frozen, just as they > would be after running the <command>VACUUM FREEZE</> command. > This is intended as a performance option for initial data loading. > Rows will be frozen only if the table being loaded has been created > in the current subtransaction, there are no cursors open and there > are no older snapshots held by this transaction. If those conditions > are not met the command will continue without error though will not > freeze rows. It is also possible in rare cases that the request > cannot be honoured for internal reasons, hence <literal>FREEZE</literal> > is more of a guideline than a hard rule. > > Note that all other sessions will immediately be able to see the data > once it has been successfully loaded. This violates the normal rules > of MVCC visibility and by specifying this option the user acknowledges > explicitly that this is understood. > > Didn't we want to issue the user some kind of feedback? I believe that is what was agreed. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
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