Thread: How to check is the table system
Hello!
In what way can I determine is the table system? ODBC driver does it
by checking table name's prefix: if it begins with 'pg_' - driver
desides that the table is system, but that's a bad idea. I can create
table and call it 'pg_mytable', but it won't become system!
Big Thanks,
Andrei
On Thu, Sep 15, 2005 at 09:12:44PM +0300, ???????????? wrote: > In what way can I determine is the table system? ODBC driver does it > by checking table name's prefix: if it begins with 'pg_' - driver > desides that the table is system, but that's a bad idea. I can create > table and call it 'pg_mytable', but it won't become system! If a table is in the pg_catalog schema, it's a system table. The pg_ prefix was used as a convention before the introduction of schemas in 7.3 -- users were not supposed to create tables with names beggining with pg_. I guess it's still a bad idea to create tables with such names. -- Alvaro Herrera -- Valdivia, Chile Architect, www.EnterpriseDB.com "La gente vulgar solo piensa en pasar el tiempo; el que tiene talento, en aprovecharlo"
=?UTF-8?B?0JDQvdC00YDQtdC5?= <andyk@softwarium.net> writes:
> In what way can I determine is the table system? ODBC driver does it
> by checking table name's prefix: if it begins with 'pg_' - driver
> desides that the table is system, but that's a bad idea.
Yup, that's been incorrect since PG 7.3. The proper test is whether the
table is in the pg_catalog schema.
Depending on your purposes you might also want to exclude pg_toast.
regards, tom lane
On Thu, Sep 15, 2005 at 09:12:44PM +0300, ???????????? wrote: > Hello! > > In what way can I determine is the table system? ODBC driver does it > by checking table name's prefix: if it begins with 'pg_' - driver > desides that the table is system, but that's a bad idea. I can create > table and call it 'pg_mytable', but it won't become system! Check it is in the pg_catalog schema... -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a > tool for doing 5% of the work and then sitting around waiting for someone > else to do the other 95% so you can sue them.
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On Thu, Sep 15, 2005 at 09:12:44PM +0300, ???????????? wrote: > Hello! > > In what way can I determine is the table system? ODBC driver does it > by checking table name's prefix: if it begins with 'pg_' - driver > desides that the table is system, but that's a bad idea. I can create > table and call it 'pg_mytable', but it won't become system! From http://lnk.nu/cvs.pgfoundry.org/3yb.sql: -- Note that generic case would be "select $1 like ''pg!_%'' escape ''!'' create or replace function _pg_sv_system_schema(name) returns boolean as 'select $1 in (name ''pg_catalog'', name ''pg_toast'', name ''pg_sysviews'', name ''information_schema'')' language sql immutable strict; create or replace function _pg_sv_temp_schema(name) returns boolean as 'select $1 like ''pg!_temp!_%'' escape ''!'' ' language sql immutable strict; Of course, as others have mentioned, that won't work if you're pre-schemas. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461