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pg_dump supposed that a stats object necessarily shares the same schema as its underlying table, and that it doesn't have a separate owner. These things may have been true during early development of the feature, but they are not true as of v10 release. Failure to track the object's schema separately turns out to have only limited consequences, because pg_get_statisticsobjdef() always schema- qualifies the target object name in the generated CREATE STATISTICS command (a decision out of step with the rest of ruleutils.c, but I digress). Therefore the restored object would be in the right schema, so that the only problem is that the TOC entry would be mislabeled as to schema. That could lead to wrong decisions for schema-selective restores, for example. The ownership issue is a bit more serious: not only was the TOC entry potentially mislabeled as to owner, but pg_dump didn't bother to issue an ALTER OWNER command at all, so that after restore the stats object would continue to be owned by the restoring superuser. A final point is that decisions as to whether to dump a stats object or not were driven by whether the underlying table was dumped or not. While that's not wrong on its face, it won't scale nicely to the planned future extension to cross-table statistics. Moreover, that design decision comes out of the view of stats objects as being auxiliary to a particular table, like a rule or trigger, which is exactly where the above problems came from. Since we're now treating stats objects more like independent objects in their own right, they ought to behave like standalone objects for this purpose too. So change to using the generic selectDumpableObject() logic for them (which presently amounts to "dump if containing schema is to be dumped"). Along the way to fixing this, restructure so that getExtendedStatistics collects the identity info (only) for all extended stats objects in one query, and then for each object actually being dumped, we retrieve the definition in dumpStatisticsExt. This is necessary to ensure that schema-qualification in the generated CREATE STATISTICS command happens with respect to the search path that pg_dump will now be using at restore time (ie, the schema the stats object is in, not that of the underlying table). It's probably also significantly faster in the typical scenario where only a minority of tables have extended stats. Back-patch to v10 where extended stats were introduced. Discussion: https://postgr.es/m/18272.1518328606@sss.pgh.pa.us |
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PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.