postgres

Commit Graph

Author	SHA1	Message	Date
Tom Lane	5b86fedfb5	Document cross-version compatibility issues for contrib/postgres_fdw. One of the use-cases for postgres_fdw is extracting data from older PG servers, so cross-version compatibility is important. Document what we can do here, and further annotate some of the coding choices that create compatibility constraints. In passing, remove one unnecessary incompatibility with old servers, namely assuming that we didn't need to quote the timezone name 'UTC'.	13 years ago
Tom Lane	e690b95150	Avoid retrieving dummy NULL columns in postgres_fdw. This should provide some marginal overall savings, since it surely takes many more cycles for the remote server to deal with the NULL columns than it takes for postgres_fdw not to emit them. But really the reason is to keep the emitted queries from looking quite so silly ...	13 years ago
Tom Lane	9cbc4b80dd	Redo postgres_fdw's planner code so it can handle parameterized paths. I wasn't going to ship this without having at least some example of how to do that. This version isn't terribly bright; in particular it won't consider any combinations of multiple join clauses. Given the cost of executing a remote EXPLAIN, I'm not sure we want to be very aggressive about doing that, anyway. In support of this, refactor generate_implied_equalities_for_indexcol so that it can be used to extract equivalence clauses that aren't necessarily tied to an index.	13 years ago
Tom Lane	ed3ddf918b	Introduce less-bogus handling of collations in contrib/postgres_fdw. Treat expressions as being remotely executable only if all collations used in them are determined by Vars of the foreign table. This means that, if the foreign server gets different answers than we do, it's the user's fault for not having marked the foreign table columns with collations equivalent to the remote table's. This rule allows most simple expressions such as "var < 'constant'" to be sent to the remote side, because the constant isn't determining the collation (the Var's collation would win). There's still room for improvement, but it's hard to see how to do it without a lot more knowledge and/or assumptions about what the remote side will do.	13 years ago
Tom Lane	50c19fc76f	Fix contrib/postgres_fdw's handling of column defaults. Adopt the position that only locally-defined defaults matter. Any defaults defined in the remote database do not affect insertions performed through a foreign table (unless they are for columns not known to the foreign table). While it'd arguably be more useful to permit remote defaults to be used, making that work in a consistent fashion requires far more work than seems possible for 9.3.	13 years ago
Tom Lane	0247d43dd9	Avoid row-processing-order dependency in postgres_fdw regression test. A test intended to provoke an error on the remote side was coded in such a way that multiple rows should be updated, so the output would vary depending on which one was processed first. Per buildfarm.	13 years ago
Tom Lane	cc3f281ffb	Fix postgres_fdw's issues with inconsistent interpretation of data values. For datatypes whose output formatting depends on one or more GUC settings, we have to worry about whether the other server will interpret the value the same way it was meant. pg_dump has been aware of this hazard for a long time, but postgres_fdw needs to deal with it too. To fix data retrieval from the remote server, set the necessary remote GUC settings at connection startup. (We were already assuming that settings made then would persist throughout the remote session.) To fix data transmission to the remote server, temporarily force the relevant GUCs to the right values when we're about to convert any data values to text for transmission. This is all pretty grotty, and not very cheap either. It's tempting to think of defining one uber-GUC that would override any settings that might render printed data values unportable. But of course, older remote servers wouldn't know any such thing and would still need this logic. While at it, revert commit `f7951eef89`, since this provides a real fix. (The timestamptz given in the error message returned from the "remote" server will now reliably be shown in UTC.)	13 years ago
Tom Lane	8f9cc41daf	Avoid generating bad remote SQL for INSERT ... DEFAULT VALUES. "INSERT INTO foo() VALUES ()" is invalid syntax, so don't do that.	13 years ago
Tom Lane	f7951eef89	Band-aid for regression test expected-results problem with timestamptz. We probably need to tell the remote server to use specific timezone and datestyle settings, and maybe other things. But for now let's just hack the postgres_fdw regression test to not provoke failures when run in non-EST5EDT environments. Per buildfarm.	13 years ago
Tom Lane	21734d2fb8	Support writable foreign tables. This patch adds the core-system infrastructure needed to support updates on foreign tables, and extends contrib/postgres_fdw to allow updates against remote Postgres servers. There's still a great deal of room for improvement in optimization of remote updates, but at least there's basic functionality there now. KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather heavily revised by Tom Lane.	13 years ago
Tom Lane	09a7cd409e	Rename postgres_fdw's use_remote_explain option to use_remote_estimate. The new name was originally my typo, but per discussion it seems like a better name anyway. So make the code match the docs, not vice versa.	13 years ago
Tom Lane	c0c6acdfa0	Fix some planning oversights in postgres_fdw. Include eval costs of local conditions in remote-estimate mode, and don't assume the remote eval cost is zero in local-estimate mode. (The best we can do with that at the moment is to assume a seqscan, which may well be wildly pessimistic ... but zero won't do at all.) To get a reasonable local estimate, we need to know the relpages count for the remote rel, so improve the ANALYZE code to fetch that rather than just setting the foreign table's relpages field to zero.	13 years ago
Tom Lane	6da378dbc9	Fix whole-row references in postgres_fdw. The optimization to not retrieve unnecessary columns wasn't smart enough. Noted by Thom Brown.	13 years ago
Tom Lane	211e157a51	Change postgres_fdw to show casts as casts, not underlying function calls. On reflection this method seems to be exposing an unreasonable amount of implementation detail. It wouldn't matter when talking to a remote server of the identical Postgres version, but it seems likely to make things worse not better if the remote is a different version with different casting infrastructure. Instead adopt ruleutils.c's policy of regurgitating the cast as it was originally specified; including not showing it at all, if it was implicit to start with. (We must do that because for some datatypes explicit and implicit casts have different semantics.)	13 years ago
Tom Lane	5fd386bb31	Get rid of postgres_fdw's assumption that remote type OIDs match ours. The only place we depended on that was in sending numeric type OIDs in PQexecParams; but we can replace that usage with explicitly casting each Param symbol in the query string, so that the types are specified to the remote by name not OID. This makes no immediate difference but will be essential if we ever hope to support use of non-builtin types.	13 years ago
Tom Lane	6d06049493	Adjust postgres_fdw's search path handling. Set the remote session's search path to exactly "pg_catalog" at session start, then schema-qualify only names that aren't in that schema. This greatly reduces clutter in the generated SQL commands, as seen in the regression test changes. Per discussion. Also, rethink use of FirstNormalObjectId as the "built-in object" cutoff --- FirstBootstrapObjectId is safer, since the former will accept objects in information_schema for instance.	13 years ago
Tom Lane	54a2786835	Need to decorate XactIsoLevel as PGDLLIMPORT for postgres_fdw. Per buildfarm.	13 years ago
Tom Lane	d0d75c4022	Add postgres_fdw contrib module. There's still a lot of room for improvement, but it basically works, and we need this to be present before we can do anything much with the writable-foreign-tables patch. So let's commit it and get on with testing. Shigeru Hanada, reviewed by KaiGai Kohei and Tom Lane	13 years ago

18 Commits (ae7f1c3ef2eef9584e3c9a42c395eb0c0e59a5ed)