Обсуждение: Dropping a database that does not exist
Hi, I've been getting duplicate databases within my server. Dropping one of them works, but when I try to drop the other, psql will say that the database does not exist. For example: db1 db1 db2 db3 db4 db4 db5 Running DROP DATABASE db1 for the first time works and I'm left with: db1 db2 db3 db4 db4 db5 Attempting to run DROP DATABASE db1 again will just give me "FATAL: database "db1" does not exist" Same scenario for db4. I could ignore the error, but because of the duplicate database, I cannot make a dump of the server. Any one has any ideas why this is happening and how I can solve it? A similar thing happened previously, but it was with tables within a database. The only way we solved that was by dropping the database and recreating the structure, which wasn't the ideal way I wanted to use. I've got PostgreSQL 8.0.4 running on SuSE 9.3. Regards, Shiming
Tham Shiming <shiming@misatravel.com> writes:
> I've been getting duplicate databases within my server.
What exactly makes you think you have that?
regards, tom lane
I don't think you have duplicate databases - that would be the first time I heard that postgreSQL supports that. Are you sure you didn't create the database with a name that just doesn't print? I.e. a simple createdb test works. do another createdb "test " (note the space) works too, but when you list the db's you'll see test twice, although the one of them is created with a space at the end, so you can't connect to it or drop it unless you use quotes. Did you use some kind of tool that may have a done this? Most tools use quotes when creating sql statements, so if you accidentially added a space in the dialog you end up with a scenario like you describe. On Friday 10 February 2006 01:42, Tham Shiming wrote: > Hi, > > I've been getting duplicate databases within my server. Dropping one of > them works, but when I try to drop the other, psql will say that the > database does not exist. > > For example: > > db1 > db1 > db2 > db3 > db4 > db4 > db5 > > Running DROP DATABASE db1 for the first time works and I'm left with: > > db1 > db2 > db3 > db4 > db4 > db5 > > Attempting to run DROP DATABASE db1 again will just give me "FATAL: > database "db1" does not exist" > > Same scenario for db4. > > I could ignore the error, but because of the duplicate database, I > cannot make a dump of the server. > > Any one has any ideas why this is happening and how I can solve it? A > similar thing happened previously, but it was with tables within a > database. The only way we solved that was by dropping the database and > recreating the structure, which wasn't the ideal way I wanted to use. > I've got PostgreSQL 8.0.4 running on SuSE 9.3. > > Regards, > Shiming > > > > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq -- UC -- Open Source Solutions 4U, LLC 1618 Kelly St Phone: +1 707 568 3056 Santa Rosa, CA 95401 Cell: +1 650 302 2405 United States Fax: +1 707 568 6416
"Uwe C. Schroeder" <uwe@oss4u.com> writes:
> I don't think you have duplicate databases - that would be the first time I
> heard that postgreSQL supports that.
> Are you sure you didn't create the database with a name that just doesn't
> print?
That's one possibility that I was wondering about; another was there
somehow being two entries in pg_shadow for the same usesysid, which'd
result in apparent "duplicate" output from queries that involve joining
pg_database and pg_shadow. That's why I wanted to know exactly what
was leading to the conclusion that there were duplicate databases.
regards, tom lane
Well, not exactly support. We didn't create the duplicate databases, it just appear suddenly out of nowhere, which was also odd. OK, checking pg_shadow, the usesysid for each entry is unique. pg_database, however, showed the duplicate databases. A short sample output from pgAdmin. datname datdba db1 101 db1 101 db2 102 db3 103 db3 103 Whether there is a significance, I am not really sure. Hopefully, one of you can help us. None of our code will create a database, and we will not manually create one unless requirements forces us to do it. Regards, Shiming Tom Lane wrote: > "Uwe C. Schroeder" <uwe@oss4u.com> writes: > >> I don't think you have duplicate databases - that would be the first time I >> heard that postgreSQL supports that. >> Are you sure you didn't create the database with a name that just doesn't >> print? >> > > That's one possibility that I was wondering about; another was there > somehow being two entries in pg_shadow for the same usesysid, which'd > result in apparent "duplicate" output from queries that involve joining > pg_database and pg_shadow. That's why I wanted to know exactly what > was leading to the conclusion that there were duplicate databases. > > regards, tom lane > > >
Tham Shiming <shiming@misatravel.com> writes:
> OK, checking pg_shadow, the usesysid for each entry is unique.
> pg_database, however, showed the duplicate databases. A short sample
> output from pgAdmin.
> datname datdba
> db1 101
> db1 101
> db2 102
> db3 103
> db3 103
Does anyone know what the underlying query is that pgadmin uses for
this display?
regards, tom lane
> -----Original Message----- > From: pgsql-general-owner@postgresql.org > [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Tom Lane > Sent: 13 February 2006 14:36 > To: Tham Shiming > Cc: Uwe C. Schroeder; pgsql-general@postgresql.org > Subject: Re: [GENERAL] Dropping a database that does not exist > > Tham Shiming <shiming@misatravel.com> writes: > > OK, checking pg_shadow, the usesysid for each entry is unique. > > pg_database, however, showed the duplicate databases. A > short sample > > output from pgAdmin. > > > datname datdba > > db1 101 > > db1 101 > > db2 102 > > db3 103 > > db3 103 > > Does anyone know what the underlying query is that pgadmin uses for > this display? pgAdmin wouldn't display anything like that unless the user entered the query themselves, or did a 'view data' on pg_database (in which case it would just be a select *, possibly with a user entered WHERE restriction or an ORDER BY). Regards, Dave
"Dave Page" <dpage@vale-housing.co.uk> writes:
>> Tham Shiming <shiming@misatravel.com> writes:
>>> OK, checking pg_shadow, the usesysid for each entry is unique.
>>> pg_database, however, showed the duplicate databases. A
>>> short sample output from pgAdmin.
>>>
>>> datname datdba
>>> db1 101
>>> db1 101
>>> db2 102
>>> db3 103
>>> db3 103
>>
>> Does anyone know what the underlying query is that pgadmin uses for
>> this display?
> pgAdmin wouldn't display anything like that unless the user entered the
> query themselves, or did a 'view data' on pg_database (in which case it
> would just be a select *, possibly with a user entered WHERE restriction
> or an ORDER BY).
Hmm. If it's not a join, the only explanation that comes to mind for
phantom rows is transaction ID wraparound. Could we see the output of
select ctid, xmin, xmax, datname from pg_database;
regards, tom lane
Sorry, I wasn't being clear. For the sample output from pgAdmin below, I just did a select * from pg_database, then just typed out the 2 columns that I thought would be relevant. OK, here's the output for select ctid, xmin, xmax, datname from pg_database; ctid(tid) xmin(xid) xmax(xid) datname(name) (0,1) 2 0 postgres (0,2) 2 0 postgres8 (0,4) 746707934 0 db1 (0,5) 2 2213800494 db2 (pgAdmin says this DB does not exist) (0,6) 2 0 template1 (0,7) 2 0 template0 (0,8) 2 2214815770 db3 (pgAdmin says this DB does not exist) (0,9) 746707976 0 db4 (0,10) 2 2213853192 db5 (repeat) (0,11) 746867758 0 db6 (0,13) 2 0 db5 (repeat) (0,14) 2 0 db7 (0,16) 144476800 0 db8 (0,17) 144476893 0 db9 (0,19) 730724276 0 db10 (0,20) 741565079 0 db11 (actual output, i just changed the names of the databases) As a form of clarification, for db2 and db3, we saw the duplicate databases and tried to drop the duplicate by simply executing DROP DATABASE db2 and DROP DATABASE db3. The command executed without errors, but there is still one copy of db2 and db3 left. We tried to drop this copy as well, but PostgreSQL then told us both databases did not exist. Regards, Shiming Tom Lane wrote: > "Dave Page" <dpage@vale-housing.co.uk> writes: > >>> Tham Shiming <shiming@misatravel.com> writes: >>> >>>> OK, checking pg_shadow, the usesysid for each entry is unique. >>>> pg_database, however, showed the duplicate databases. A >>>> short sample output from pgAdmin. >>>> >>>> datname datdba >>>> db1 101 >>>> db1 101 >>>> db2 102 >>>> db3 103 >>>> db3 103 >>>> >>> Does anyone know what the underlying query is that pgadmin uses for >>> this display? >>> > > >> pgAdmin wouldn't display anything like that unless the user entered the >> query themselves, or did a 'view data' on pg_database (in which case it >> would just be a select *, possibly with a user entered WHERE restriction >> or an ORDER BY). >> > > Hmm. If it's not a join, the only explanation that comes to mind for > phantom rows is transaction ID wraparound. Could we see the output of > > select ctid, xmin, xmax, datname from pg_database; > > > regards, tom lane > > >
Tham Shiming <shiming@misatravel.com> writes:
> ctid(tid) xmin(xid) xmax(xid) datname(name)
> (0,5) 2 2213800494 db2 (pgAdmin says this DB does not
> exist)
> (0,8) 2 2214815770 db3 (pgAdmin says this DB does not
> exist)
> (0,10) 2 2213853192 db5 (repeat)
> (0,13) 2 0 db5 (repeat)
This does start to look like an XID wraparound problem. What is your
current XID counter? (The "NextXID" line from pg_controldata output
is close enough.) What *exactly* do you mean by "pgAdmin says this
DB does not exist"?
regards, tom lane
From pg_controldata Latest checkpoint NextXID: 746940488 Under the database tree that is displayed in pgAdmin, when I click on the database, an error dialog pops up with this message "An error has occured: FATAL: database "db2" does not exist". Even if I disconnect and reconnect, the database tree still shows db2 but if I just click on it, the same error dialog will appear. Regards, Shiming Tom Lane wrote: > Tham Shiming <shiming@misatravel.com> writes: > >> ctid(tid) xmin(xid) xmax(xid) datname(name) >> (0,5) 2 2213800494 db2 (pgAdmin says this DB does not >> exist) >> (0,8) 2 2214815770 db3 (pgAdmin says this DB does not >> exist) >> (0,10) 2 2213853192 db5 (repeat) >> (0,13) 2 0 db5 (repeat) >> > > This does start to look like an XID wraparound problem. What is your > current XID counter? (The "NextXID" line from pg_controldata output > is close enough.) What *exactly* do you mean by "pgAdmin says this > DB does not exist"? > > regards, tom lane > > >