Re: [sqlite] database file header: "schema layer file format" anomaly
On 27/05/2009 3:03 AM, D. Richard Hipp wrote: > John - what were you doing when you discovered this? > > On May 26, 2009, at 10:57 AM, John Machin wrote: > >> According to the file format document >> (http://www.sqlite.org/fileformat.html): "[H30120] The 4 byte block >> starting at byte offset 44 of a well-formed database file, the schema >> layer file format, contains a big-endian integer value between 1 and >> 4, >> inclusive." >> >> However it is possible to end up with this being zero, e.g. by >> dropping >> all tables/etc and then doing a VACUUM: Eyeballing the following output from my code: assert 1 <= self.schema_layer_file_format <= 4 AssertionError Cheers, John ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] database file header: "schema layer file format" anomaly
John - what were you doing when you discovered this? On May 26, 2009, at 10:57 AM, John Machin wrote: > According to the file format document > (http://www.sqlite.org/fileformat.html): "[H30120] The 4 byte block > starting at byte offset 44 of a well-formed database file, the schema > layer file format, contains a big-endian integer value between 1 and > 4, > inclusive." > > However it is possible to end up with this being zero, e.g. by > dropping > all tables/etc and then doing a VACUUM: > > # Assume vacked.db doesn't exist > DOS-prompt>sqlite3 vacked.db > SQLite version 3.6.14 > Enter ".help" for instructions > Enter SQL statements terminated with a ";" > sqlite> create table foo (x, y); > sqlite> insert into foo values(1, 2); > sqlite> drop table foo; > sqlite> vacuum; > sqlite> ^Z > > This seems very much a corner case and I don't imagine this is a > problem > in practice; any concern about this number being when it is too high > for > the software opening the file, and as far as I can guess there is no > "too low" problem -- however in my opinion differences between such > documents and reality should always be reported, so here it is. D. Richard Hipp d...@hwaci.com ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] database file header: "schema layer file format" anomaly
On May 26, 2009, at 9:57 PM, John Machin wrote: > According to the file format document > (http://www.sqlite.org/fileformat.html): "[H30120] The 4 byte block > starting at byte offset 44 of a well-formed database file, the schema > layer file format, contains a big-endian integer value between 1 and > 4, > inclusive." > > However it is possible to end up with this being zero, e.g. by > dropping > all tables/etc and then doing a VACUUM: > > # Assume vacked.db doesn't exist > DOS-prompt>sqlite3 vacked.db > SQLite version 3.6.14 > Enter ".help" for instructions > Enter SQL statements terminated with a ";" > sqlite> create table foo (x, y); > sqlite> insert into foo values(1, 2); > sqlite> drop table foo; > sqlite> vacuum; > sqlite> ^Z > > This seems very much a corner case and I don't imagine this is a > problem > in practice; any concern about this number being when it is too high > for > the software opening the file, and as far as I can guess there is no > "too low" problem -- however in my opinion differences between such > documents and reality should always be reported, so here it is. As you say, probably not important in practice but still worth getting right. Thanks for reporting this. Dan. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] database file header: "schema layer file format" anomaly
According to the file format document (http://www.sqlite.org/fileformat.html): "[H30120] The 4 byte block starting at byte offset 44 of a well-formed database file, the schema layer file format, contains a big-endian integer value between 1 and 4, inclusive." However it is possible to end up with this being zero, e.g. by dropping all tables/etc and then doing a VACUUM: # Assume vacked.db doesn't exist DOS-prompt>sqlite3 vacked.db SQLite version 3.6.14 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite> create table foo (x, y); sqlite> insert into foo values(1, 2); sqlite> drop table foo; sqlite> vacuum; sqlite> ^Z This seems very much a corner case and I don't imagine this is a problem in practice; any concern about this number being when it is too high for the software opening the file, and as far as I can guess there is no "too low" problem -- however in my opinion differences between such documents and reality should always be reported, so here it is. Cheers, John ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
