On 2018-02-13 16:06:43 -0700, David G. Johnston wrote: > On Tue, Feb 13, 2018 at 3:57 PM, Peter J. Holzer <hjp-pg...@hjp.at> wrote: > > (That said, it looks like both PostgreSQL and MariaDB include additional > columns beyond those mandated by the standard - you can't rely on those, > of course. And some databases like Oracle don't even have an information > schema.) > > > Given the documented charter of information_schema I'd present your conclusion > and evidence to pgsql-bugs...while I suppose extra columns are not inherently > harmful at minimum they would need to be documented if kept.
I don't have evidence, as I don't have access to a recent SQL standard. But I noticed that for example information_schema.tables have only a few columns in common between PostgreSQL and MariaDB: hjp=> select * from information_schema.tables where table_type='BASE TABLE' limit 1; ─[ RECORD 1 ]────────────────┬─────────── table_catalog │ hjp table_schema │ public table_name │ hjpnet table_type │ BASE TABLE self_referencing_column_name │ (∅) reference_generation │ (∅) user_defined_type_catalog │ (∅) user_defined_type_schema │ (∅) user_defined_type_name │ (∅) is_insertable_into │ YES is_typed │ NO commit_action │ (∅) MariaDB [simba]> select * from information_schema.tables where table_type='BASE TABLE' limit 1\G *************************** 1. row *************************** TABLE_CATALOG: def TABLE_SCHEMA: simba TABLE_NAME: archived_versions TABLE_TYPE: BASE TABLE ENGINE: MyISAM VERSION: 10 ROW_FORMAT: Fixed TABLE_ROWS: 0 AVG_ROW_LENGTH: 0 DATA_LENGTH: 0 MAX_DATA_LENGTH: 7036874417766399 INDEX_LENGTH: 1024 DATA_FREE: 0 AUTO_INCREMENT: 1 CREATE_TIME: 2008-01-28 01:24:48 UPDATE_TIME: 2008-01-28 01:24:48 CHECK_TIME: NULL TABLE_COLLATION: utf8_general_ci CHECKSUM: NULL CREATE_OPTIONS: TABLE_COMMENT: 1 row in set (0.01 sec) The first 4 are the same, all others are different. It is possible that all the columns that PostgreSQL has are required by the standard and that MariaDB is non-conforming by omitting them, but at least some of the names look quite PostgreSQL-specific to me. So my guess is that the standard only requires the first 4 and the rest are RDBMS-specific. hp -- _ | Peter J. Holzer | we build much bigger, better disasters now |_|_) | | because we have much more sophisticated | | | h...@hjp.at | management tools. __/ | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
Description: PGP signature