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* When WCOs are present, disable direct foreign table modification.Robert Haas2017-07-24
| | | | | | | | | | | | | | | If the user modifies a view that has CHECK OPTIONs and this gets translated into a modification to an underlying relation which happens to be a foreign table, the check options should be enforced. In the normal code path, that was happening properly, but it was not working properly for "direct" modification because the whole operation gets pushed to the remote side in that case and we never have an option to enforce the constraint against individual tuples. Fix by disabling direct modification when there is a need to enforce CHECK OPTIONs. Etsuro Fujita, reviewed by Kyotaro Horiguchi and by me. Discussion: http://postgr.es/m/f8a48f54-6f02-9c8a-5250-9791603171ee@lab.ntt.co.jp
* Stabilize postgres_fdw regression tests.Tom Lane2017-07-21
| | | | | | | | | | | | | The new test cases added in commit 8bf58c0d9 turn out to have output that can vary depending on the lc_messages setting prevailing on the test server. Hide the remote end's error messages to ensure stable output. This isn't a terribly desirable solution; we'd rather know that the connection failed for the expected reason and not some other one. But there seems little choice for the moment. Per buildfarm. Discussion: https://postgr.es/m/18419.1500658570@sss.pgh.pa.us
* Re-establish postgres_fdw connections after server or user mapping changes.Tom Lane2017-07-21
| | | | | | | | | | | | | | | | | Previously, postgres_fdw would keep on using an existing connection even if the user did ALTER SERVER or ALTER USER MAPPING commands that should affect connection parameters. Teach it to watch for catcache invals on these catalogs and re-establish connections when the relevant catalog entries change. Per bug #14738 from Michal Lis. In passing, clean up some rather crufty decisions in commit ae9bfc5d6 about where fields of ConnCacheEntry should be reset. We now reset all the fields whenever we open a new connection. Kyotaro Horiguchi, reviewed by Ashutosh Bapat and myself. Back-patch to 9.3 where postgres_fdw appeared. Discussion: https://postgr.es/m/20170710113917.7727.10247@wrigleys.postgresql.org
* Fix low-probability leaks of PGresult objects in the backend.Tom Lane2017-06-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We had three occurrences of essentially the same coding pattern wherein we tried to retrieve a query result from a libpq connection without blocking. In the case where PQconsumeInput failed (typically indicating a lost connection), all three loops simply gave up and returned, forgetting to clear any previously-collected PGresult object. Since those are malloc'd not palloc'd, the oversight results in a process-lifespan memory leak. One instance, in libpqwalreceiver, is of little significance because the walreceiver process would just quit anyway if its connection fails. But we might as well fix it. The other two instances, in postgres_fdw, are somewhat more worrisome because at least in principle the scenario could be repeated, allowing the amount of memory leaked to build up to something worth worrying about. Moreover, in these cases the loops contain CHECK_FOR_INTERRUPTS calls, as well as other calls that could potentially elog(ERROR), providing another way to exit without having cleared the PGresult. Here we need to add PG_TRY logic similar to what exists in quite a few other places in postgres_fdw. Coverity noted the libpqwalreceiver bug; I found the other two cases by checking all calls of PQconsumeInput. Back-patch to all supported versions as appropriate (9.2 lacks postgres_fdw, so this is really quite unexciting for that branch). Discussion: https://postgr.es/m/22620.1497486981@sss.pgh.pa.us
* postgres_fdw: Allow cancellation of transaction control commands.Robert Haas2017-06-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit f039eaac7131ef2a4cf63a10cf98486f8bcd09d2, later back-patched with commit 1b812afb0eafe125b820cc3b95e7ca03821aa675, allowed many of the queries issued by postgres_fdw to fetch remote data to respond to cancel interrupts in a timely fashion. However, it didn't do anything about the transaction control commands, which remained noninterruptible. Improve the situation by changing do_sql_command() to retrieve query results using pgfdw_get_result(), which uses the asynchronous interface to libpq so that it can check for interrupts every time libpq returns control. Since this might result in a situation where we can no longer be sure that the remote transaction state matches the local transaction state, add a facility to force all levels of the local transaction to abort if we've lost track of the remote state; without this, an apparently-successful commit of the local transaction might fail to commit changes made on the remote side. Also, add a 60-second timeout for queries issue during transaction abort; if that expires, give up and mark the state of the connection as unknown. Drop all such connections when we exit the local transaction. Together, these changes mean that if we're aborting the local toplevel transaction anyway, we can just drop the remote connection in lieu of waiting (possibly for a very long time) for it to complete an abort. This still leaves quite a bit of room for improvement. PQcancel() has no asynchronous interface, so if we get stuck sending the cancel request we'll still hang. Also, PQsetnonblocking() is not used, which means we could block uninterruptibly when sending a query. There might be some other optimizations possible as well. Nonetheless, this allows us to escape a wait for an unresponsive remote server quickly in many more cases than previously. Report by Suraj Kharage. Patch by me and Rafia Sabih. Review and testing by Amit Kapila and Tushar Ahuja. Discussion: http://postgr.es/m/CAF1DzPU8Kx+fMXEbFoP289xtm3bz3t+ZfxhmKavr98Bh-C0TqQ@mail.gmail.com
* postgres_fdw: Fix join push down with extensionsPeter Eisentraut2017-04-26
| | | | | | | | | | | | | | | | | | | Objects in an extension are shippable to a foreign server if the extension is part of the foreign server definition's shippable extensions list. But this was not properly considered in some cases when checking whether a join condition can be pushed to a foreign server and the join condition uses an object from a shippable extension. So the join would never be pushed down in those cases. So, the list of extensions needs to be made available in fpinfo of the relation being considered to be pushed down before any expressions are assessed for being shippable. Fix foreign_join_ok() to do that for a join relation. David Rowley and Ashutosh Bapat, per report from David Rowley reduced version of patch 332bec1e6096679b04ec9717beb44a858495260f for backpatch to 9.6, first release with join push down
* Fix typos in comments.Heikki Linnakangas2017-02-06
| | | | | | | | | Backpatch to all supported versions, where applicable, to make backpatching of future fixes go more smoothly. Josh Soref Discussion: https://www.postgresql.org/message-id/CACZqfqCf+5qRztLPgmmosr-B0Ye4srWzzw_mo4c_8_B_mtjmJQ@mail.gmail.com
* Invalidate cached plans on FDW option changes.Tom Lane2017-01-06
| | | | | | | | | | | | | | | | | | | | | | | | This fixes problems where a plan must change but fails to do so, as seen in a bug report from Rajkumar Raghuwanshi. For ALTER FOREIGN TABLE OPTIONS, do this through the standard method of forcing a relcache flush on the table. For ALTER FOREIGN DATA WRAPPER and ALTER SERVER, just flush the whole plan cache on any change in pg_foreign_data_wrapper or pg_foreign_server. That matches the way we handle some other low-probability cases such as opclass changes, and it's unclear that the case arises often enough to be worth working harder. Besides, that gives a patch that is simple enough to back-patch with confidence. Back-patch to 9.3. In principle we could apply the code change to 9.2 as well, but (a) we lack postgres_fdw to test it with, (b) it's doubtful that anyone is doing anything exciting enough with FDWs that far back to need this desperately, and (c) the patch doesn't apply cleanly. Patch originally by Amit Langote, reviewed by Etsuro Fujita and Ashutosh Bapat, who each contributed substantial changes as well. Discussion: https://postgr.es/m/CAKcux6m5cA6rRPTKkqVdJ-R=KKDfe35Q_ZuUqxDSV_4hwga=og@mail.gmail.com
* Improve dblink error message when remote does not provide itJoe Conway2016-12-21
| | | | | | | | | | | | | When dblink or postgres_fdw detects an error on the remote side of the connection, it will try to construct a local error message as best it can using libpq's PQresultErrorField(). When no primary message is available, it was bailing out with an unhelpful "unknown error". Make that message better and more style guide compliant. Per discussion on hackers. Backpatch to 9.2 except postgres_fdw which didn't exist before 9.3. Discussion: https://postgr.es/m/19872.1482338965%40sss.pgh.pa.us
* Add macros to make AllocSetContextCreate() calls simpler and safer.Tom Lane2016-08-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
* Fix assorted fallout from IS [NOT] NULL patch.Tom Lane2016-07-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commits 4452000f3 et al established semantics for NullTest.argisrow that are a bit different from its initial conception: rather than being merely a cache of whether we've determined the input to have composite type, the flag now has the further meaning that we should apply field-by-field testing as per the standard's definition of IS [NOT] NULL. If argisrow is false and yet the input has composite type, the construct instead has the semantics of IS [NOT] DISTINCT FROM NULL. Update the comments in primnodes.h to clarify this, and fix ruleutils.c and deparse.c to print such cases correctly. In the case of ruleutils.c, this merely results in cosmetic changes in EXPLAIN output, since the case can't currently arise in stored rules. However, it represents a live bug for deparse.c, which would formerly have sent a remote query that had semantics different from the local behavior. (From the user's standpoint, this means that testing a remote nested-composite column for null-ness could have had unexpected recursive behavior much like that fixed in 4452000f3.) In a related but somewhat independent fix, make plancat.c set argisrow to false in all NullTest expressions constructed to represent "attnotnull" constructs. Since attnotnull is actually enforced as a simple null-value check, this is a more accurate representation of the semantics; we were previously overpromising what it meant for composite columns, which might possibly lead to incorrect planner optimizations. (It seems that what the SQL spec expects a NOT NULL constraint to mean is an IS NOT NULL test, so arguably we are violating the spec and should fix attnotnull to do the other thing. If we ever do, this part should get reverted.) Back-patch, same as the previous commit. Discussion: <10682.1469566308@sss.pgh.pa.us>
* Fix typo in comment.Fujii Masao2016-07-25
| | | | Author: Masahiko Sawada
* Avoid invalidating all foreign-join cached plans when user mappings change.Tom Lane2016-07-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We must not push down a foreign join when the foreign tables involved should be accessed under different user mappings. Previously we tried to enforce that rule literally during planning, but that meant that the resulting plans were dependent on the current contents of the pg_user_mapping catalog, and we had to blow away all cached plans containing any remote join when anything at all changed in pg_user_mapping. This could have been improved somewhat, but the fact that a syscache inval callback has very limited info about what changed made it hard to do better within that design. Instead, let's change the planner to not consider user mappings per se, but to allow a foreign join if both RTEs have the same checkAsUser value. If they do, then they necessarily will use the same user mapping at runtime, and we don't need to know specifically which one that is. Post-plan-time changes in pg_user_mapping no longer require any plan invalidation. This rule does give up some optimization ability, to wit where two foreign table references come from views with different owners or one's from a view and one's directly in the query, but nonetheless the same user mapping would have applied. We'll sacrifice the first case, but to not regress more than we have to in the second case, allow a foreign join involving both zero and nonzero checkAsUser values if the nonzero one is the same as the prevailing effective userID. In that case, mark the plan as only runnable by that userID. The plancache code already had a notion of plans being userID-specific, in order to support RLS. It was a little confused though, in particular lacking clarity of thought as to whether it was the rewritten query or just the finished plan that's dependent on the userID. Rearrange that code so that it's clearer what depends on which, and so that the same logic applies to both RLS-injected role dependency and foreign-join-injected role dependency. Note that this patch doesn't remove the other issue mentioned in the original complaint, which is that while we'll reliably stop using a foreign join if it's disallowed in a new context, we might fail to start using a foreign join if it's now allowed, but we previously created a generic cached plan that didn't use one. It was agreed that the chance of winning that way was not high enough to justify the much larger number of plan invalidations that would have to occur if we tried to cause it to happen. In passing, clean up randomly-varying spelling of EXPLAIN commands in postgres_fdw.sql, and fix a COSTS ON example that had been allowed to leak into the committed tests. This reverts most of commits fbe5a3fb7 and 5d4171d1c, which were the previous attempt at ensuring we wouldn't push down foreign joins that span permissions contexts. Etsuro Fujita and Tom Lane Discussion: <d49c1e5b-f059-20f4-c132-e9752ee0113e@lab.ntt.co.jp>
* postgres_fdw: Fix cache lookup failure while creating error context.Robert Haas2016-07-01
| | | | | | | | This is fallout from join pushdown; get_relid_attribute_name can't handle an attribute number of 0, indicating a whole-row reference, and shouldn't be called in that case. Etsuro Fujita, reviewed by Ashutosh Bapat
* postgres_fdw: Remove schema-qualification from cast to text.Robert Haas2016-07-01
| | | | | | As pointed out by Ashutosh Bapat, the header comments for this file say that schema-qualification is needed for all and only those types outside pg_catalog. pg_catalog.text is not outside pg_catalog.
* postgres_fdw: Fix incorrect NULL handling in join pushdown.Robert Haas2016-06-24
| | | | | | | | | | something.* IS NOT NULL means that every attribute of the row is not NULL, not that the row itself is non-NULL (e.g. because it's coming from below an outer join. Use (somevar.*)::pg_catalog.text IS NOT NULL instead. Ashutosh Bapat, per a report by Rushabh Lathia. Reviewed by Amit Langote and Etsuro Fujita. Schema-qualification added by me.
* postgres_fdw: Remove useless return statement.Robert Haas2016-06-24
| | | | Etsuro Fujita
* postgres_fdw: Rephrase comment.Robert Haas2016-06-17
| | | | | Per gripe from Thomas Munro, who only complained about a more localized problem, but I couldn't resist a bit more wordsmithing.
* postgres_fdw: Check PlaceHolderVars before pushing down a join.Robert Haas2016-06-14
| | | | | | | | | | | | | | | | | | | As discovered by Andreas Seltenreich via sqlsmith, it's possible for a remote join to need to generate a target list which contains a PlaceHolderVar which would need to be evaluated on the remote server. This happens when we try to push down a join tree which contains outer joins and the nullable side of the join contains a subquery which evauates some expression which can go to NULL above the level of the join. Since the deparsing logic can't build a remote query that involves subqueries, it fails while trying to produce an SQL query that can be sent to the remote side. Detect such cases and don't try to push down the join at all. It's actually fine to push down the join if the PlaceHolderVar needs to be evaluated at the current join level. This patch makes a small change to build_tlist_to_deparse so that this case will work. Amit Langote, Ashutosh Bapat, and me.
* postgres_fdw: Promote an Assert() to elog().Robert Haas2016-06-14
| | | | | | | | | | Andreas Seltenreich reports that it is possible for a PlaceHolderVar to creep into this tlist, and I fear that even after that's fixed we might have other, similar bugs in this area either now or in the future. There's a lot of action-at-a-distance here, because the validity of this assertion depends on core planner behavior; so, let's use elog() to make sure we catch this even in non-assert builds, rather than just crashing.
* pgindent run for 9.6Robert Haas2016-06-09
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* postgres_fdw: Fix the fix for crash when pushing down multiple joins.Robert Haas2016-05-16
| | | | | | | | | | | | | | Commit 3151f16e1874db82ed85a005dac15368903ca9fb was intended to be a commit of a patch from Ashutosh Bapat, but instead I mistakenly committed an earlier version from Michael Paquier (because both patches were submitted with the same filename, and I confused them). Michael's patch fixes the crash but doesn't actually implement the correct test. Repair the incorrect logic, and also expand the comments considerably so that this is all more clear. Ashutosh Bapat and Robert Haas
* Fix multiple problems in postgres_fdw query cancellation logic.Robert Haas2016-05-16
| | | | | | | | | | | First, even if we cancel a query, we still have to roll back the containing transaction; otherwise, the session will be left in a failed transaction state. Second, we need to support canceling queries whe aborting a subtransaction as well as when aborting a toplevel transaction. Etsuro Fujita, reviewed by Michael Paquier
* Allow queries submitted by postgres_fdw to be canceled.Robert Haas2016-04-21
| | | | | | | | | | This fixes a problem which is not new, but with the advent of direct foreign table modification in 0bf3ae88af330496517722e391e7c975e6bad219, it's somewhat more likely to be annoying than previously. So, arrange for a local query cancelation to propagate to the remote side. Michael Paquier, reviewed by Etsuro Fujita. Original report by Thom Brown.
* postgres_fdw: Don't push down certain full joins.Robert Haas2016-04-20
| | | | | | | | | | | | | | | | If there's a filter condition on either side of a full outer join, it is neither correct to attach it to the join's ON clause nor to throw it into the toplevel WHERE clause. Just don't push down the join in that case. To maximize the number of cases where we can still push down full joins, push inner join conditions into the ON clause at the first opportunity rather than postponing them to the top-level WHERE clause. This produces nicer SQL, anyway. This bug was introduced in e4106b2528727c4b48639c0e12bf2f70a766b910. Ashutosh Bapat, per report from Rajkumar Raghuwanshi.
* postgres_fdw: Clean up handling of system columns.Robert Haas2016-04-15
| | | | | | | | | | | | | | | | Previously, querying the xmin column of a single postgres_fdw foreign table fetched the tuple length, xmax the typmod, and cmin or cmax the composite type OID of the tuple. However, when you queried several such tables and the join got shipped to the remote side, these columns ended up containing the remote values of the corresponding columns. Both behaviors are rather unprincipled, the former for obvious reasons and the latter because the remote values of these columns don't have any local significance; our transaction IDs are in a different space than those of the remote machine. Clean this up by setting all of these fields to 0 in both cases. Also fix the handling of tableoid to be sane. Robert Haas and Ashutosh Bapat, reviewed by Etsuro Fujita.
* Run pgindent on a batch of (mostly-planner-related) source files.Tom Lane2016-04-06
| | | | | Getting annoyed at the amount of unrelated chatter I get from pgindent'ing Rowley's unique-joins patch. Re-indent all the files it touches.
* Don't require a user mapping for FDWs to work.Robert Haas2016-03-28
| | | | | | | | | Commit fbe5a3fb73102c2cfec11aaaa4a67943f4474383 accidentally changed this behavior; put things back the way they were, and add some regression tests. Report by Andres Freund; patch by Ashutosh Bapat, with a bit of kibitzing by me.
* postgres_fdw: Fix crash when pushing down multiple joins.Robert Haas2016-03-23
| | | | | | | | | A join clause might mention multiple relations on either side, so it need not be the case that a given joinrel's constituent relations are all on one side of the join clause or all on the other. Report by Rajkumar Raghuwanshi. Analysis and fix by Michael Paquier and Ashutosh Bapat.
* Clean up some Coverity complaints about commit 0bf3ae88af330496.Tom Lane2016-03-21
| | | | | | | | | The two get_tle_by_resno() calls introduced by this commit lacked any check for a NULL return, unlike any other calls of that function anywhere in our tree. Coverity quite properly complained about it. Also fix a misindented line in process_query_params(), which Coverity also complained about on the grounds that the bad indentation suggested possible programmer misinterpretation.
* Directly modify foreign tables.Robert Haas2016-03-18
| | | | | | | | | postgres_fdw can now sent an UPDATE or DELETE statement directly to the foreign server in simple cases, rather than sending a SELECT FOR UPDATE statement and then updating or deleting rows one-by-one. Etsuro Fujita, reviewed by Rushabh Lathia, Shigeru Hanada, Kyotaro Horiguchi, Albe Laurenz, Thom Brown, and me.
* postgres_fdw: make_tuple_from_result_row should set cur_attno for ctid.Robert Haas2016-03-15
| | | | | | | | | There's no reason for this function to do this for every other attribute number and omit it for CTID, especially since conversion_error_callback has code to handle that case. This seems to be an oversight in commit e690b9515072fd7767fdeca5c54166f6a77733bc. Etsuro Fujita
* Allow callers of create_foreignscan_path to specify nondefault PathTarget.Tom Lane2016-03-14
| | | | | | | | | Although the default choice of rel->reltarget should typically be sufficient for scan or join paths, it's not at all sufficient for the purposes PathTargets were invented for; in particular not for upper-relation Paths. So break API compatibility by adding a PathTarget argument to create_foreignscan_path(). To ease updating of existing code, accept a NULL value of the argument as selecting rel->reltarget.
* Rethink representation of PathTargets.Tom Lane2016-03-14
| | | | | | | | | | | | | | In commit 19a541143a09c067 I did not make PathTarget a subtype of Node, and embedded a RelOptInfo's reltarget directly into it rather than having a separately-allocated Node. In hindsight that was misguided micro-optimization, enabled by the fact that at that point we didn't have any Paths with custom PathTargets. Now that PathTarget processing has been fleshed out some more, it's easier to see that it's better to have PathTarget as an indepedent Node type, even if it does cost us one more palloc to create a RelOptInfo. So change it while we still can. This commit just changes the representation, without doing anything more interesting than that.
* Update more comments for 96198d94cb7adc664bda341842dc8db671d8be72.Robert Haas2016-03-14
| | | | | Etsuro Fujita, reviewed (though not completely endorsed) by Ashutosh Bapat, and slightly expanded by me.
* Refactor pull_var_clause's API to make it less tedious to extend.Tom Lane2016-03-10
| | | | | | | | | | | | | | | | | | | | In commit 1d97c19a0f748e94 and later c1d9579dd8bf3c92, we extended pull_var_clause's API by adding enum-type arguments. That's sort of a pain to maintain, though, because it means every time we add a new behavior we must touch every last one of the call sites, even if there's a reasonable default behavior that most of them could use. Let's switch over to using a bitmask of flags, instead; that seems more maintainable and might save a nanosecond or two as well. This commit changes no behavior in itself, though I'm going to follow it up with one that does add a new behavior. In passing, remove flatten_tlist(), which has not been used since 9.1 and would otherwise need the same API changes. Removing these enums means that optimizer/tlist.h no longer needs to depend on optimizer/var.h. Changing that caused a number of C files to need addition of #include "optimizer/var.h" (probably we can thank old runs of pgrminclude for that); but on balance it seems like a good change anyway.
* postgres_fdw: Consider foreign joining and foreign sorting together.Robert Haas2016-03-09
| | | | | | | | | | | | Commit ccd8f97922944566d26c7d90eb67ab7848ee9905 gave us the ability to request that the remote side sort the data, and, later, commit e4106b2528727c4b48639c0e12bf2f70a766b910 gave us the ability to request that the remote side perform the join for us rather than doing it locally. But we could not do both things at the same time: a remote SQL query that had an ORDER BY clause would never be a join. This commit adds that capability. Ashutosh Bapat, reviewed by me.
* Fix reversed argument to bms_is_subset.Robert Haas2016-03-08
| | | | Ashutosh Bapat
* postgres_fdw: When sending ORDER BY, always include NULLS FIRST/LAST.Robert Haas2016-03-04
| | | | | | | | | Previously, we included NULLS FIRST when appropriate but relied on the default behavior to be NULLS LAST. This is, however, not true for a sort in descending order and seems like a fragile assumption anyway. Report by Rajkumar Raghuwanshi. Patch by Ashutosh Bapat. Review comments from Michael Paquier and Tom Lane.
* postgres_fdw: Avoid sharing list substructure.Robert Haas2016-02-21
| | | | | | | | list_concat(list_concat(a, b), c) destructively changes both a and b; to avoid such perils, copy lists of remote_conds before incorporating them into larger lists via list_concat(). Ashutosh Bapat, per a report from Etsuro Fujita
* Add an explicit representation of the output targetlist to Paths.Tom Lane2016-02-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Up to now, there's been an assumption that all Paths for a given relation compute the same output column set (targetlist). However, there are good reasons to remove that assumption. For example, an indexscan on an expression index might be able to return the value of an expensive function "for free". While we have the ability to generate such a plan today in simple cases, we don't have a way to model that it's cheaper than a plan that computes the function from scratch, nor a way to create such a plan in join cases (where the function computation would normally happen at the topmost join node). Also, we need this so that we can have Paths representing post-scan/join steps, where the targetlist may well change from one step to the next. Therefore, invent a "struct PathTarget" representing the columns we expect a plan step to emit. It's convenient to include the output tuple width and tlist evaluation cost in this struct, and there will likely be additional fields in future. While Path nodes that actually do have custom outputs will need their own PathTargets, it will still be true that most Paths for a given relation will compute the same tlist. To reduce the overhead added by this patch, keep a "default PathTarget" in RelOptInfo, and allow Paths that compute that column set to just point to their parent RelOptInfo's reltarget. (In the patch as committed, actually every Path is like that, since we do not yet have any cases of custom PathTargets.) I took this opportunity to provide some more-honest costing of PlaceHolderVar evaluation. Up to now, the assumption that "scan/join reltargetlists have cost zero" was applied not only to Vars, where it's reasonable, but also PlaceHolderVars where it isn't. Now, we add the eval cost of a PlaceHolderVar's expression to the first plan level where it can be computed, by including it in the PathTarget cost field and adding that to the cost estimates for Paths. This isn't perfect yet but it's much better than before, and there is a way forward to improve it more. This costing change affects the join order chosen for a couple of the regression tests, changing expected row ordering.
* Add missing "static" qualifier.Tom Lane2016-02-12
| | | | Per buildfarm member pademelon.
* postgres_fdw: Remove unnecessary variable.Robert Haas2016-02-10
| | | | | | It causes warnings in non-Assert-enabled builds. Per report from Jeff Janes.
* postgres_fdw: Remove unstable regression test.Robert Haas2016-02-09
| | | | Per Tom Lane and the buildfarm.
* postgres_fdw: Push down joins to remote servers.Robert Haas2016-02-09
| | | | | | | | | | | | | | | If we've got a relatively straightforward join between two tables, this pushes that join down to the remote server instead of fetching the rows for each table and performing the join locally. Some cases are not handled yet, such as SEMI and ANTI joins. Also, we don't yet attempt to create presorted join paths or parameterized join paths even though these options do get tried for a base relation scan. Nevertheless, this seems likely to be a very significant win in many practical cases. Shigeru Hanada and Ashutosh Bapat, reviewed by Robert Haas, with additional review at various points by Tom Lane, Etsuro Fujita, KaiGai Kohei, and Jeevan Chalke.
* Use %u not %d to print OIDs.Tom Lane2016-02-08
| | | | | | Oversight in commit 96198d94c. Etsuro Fujita
* Add missing "static" qualifier.Tom Lane2016-02-06
| | | | Per buildfarm member pademelon.
* postgres_fdw: pgindent run.Robert Haas2016-02-04
| | | | In preparation for upcoming commits.
* postgres_fdw: Avoid possible misbehavior when RETURNING tableoid column only.Robert Haas2016-02-04
| | | | | | | | deparseReturningList ended up adding up RETURNING NULL to the code, but code elsewhere saw an empty list of attributes and concluded that it should not expect tuples from the remote side. Etsuro Fujita and Robert Haas, reviewed by Thom Brown
* Code review for commit dc203dc3ac40a4b02b92fb827848a547d2957153.Robert Haas2016-02-03
| | | | | | | | | Remove duplicate assignment. This part by Ashutosh Bapat. Remove now-obsolete comment. This part by me, although the pending join pushdown patch does something similar, and for the same reason: there's no reason to keep two lists of the things in the fdw_private structure that have to be kept in sync with each other.