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* Support all SQL:2011 options for window frame clauses.Tom Lane2018-02-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds the ability to use "RANGE offset PRECEDING/FOLLOWING" frame boundaries in window functions. We'd punted on that back in the original patch to add window functions, because it was not clear how to do it in a reasonably data-type-extensible fashion. That problem is resolved here by adding the ability for btree operator classes to provide an "in_range" support function that defines how to add or subtract the RANGE offset value. Factoring it this way also allows the operator class to avoid overflow problems near the ends of the datatype's range, if it wishes to expend effort on that. (In the committed patch, the integer opclasses handle that issue, but it did not seem worth the trouble to avoid overflow failures for datetime types.) The patch includes in_range support for the integer_ops opfamily (int2/int4/int8) as well as the standard datetime types. Support for other numeric types has been requested, but that seems like suitable material for a follow-on patch. In addition, the patch adds GROUPS mode which counts the offset in ORDER-BY peer groups rather than rows, and it adds the frame_exclusion options specified by SQL:2011. As far as I can see, we are now fully up to spec on window framing options. Existing behaviors remain unchanged, except that I changed the errcode for a couple of existing error reports to meet the SQL spec's expectation that negative "offset" values should be reported as SQLSTATE 22013. Internally and in relevant parts of the documentation, we now consistently use the terminology "offset PRECEDING/FOLLOWING" rather than "value PRECEDING/FOLLOWING", since the term "value" is confusingly vague. Oliver Ford, reviewed and whacked around some by me Discussion: https://postgr.es/m/CAGMVOdu9sivPAxbNN0X+q19Sfv9edEPv=HibOJhB14TJv_RCQg@mail.gmail.com
* Fix incorrect grammar.Robert Haas2018-02-06
| | | | | | Etsuro Fujita Discussion: http://postgr.es/m/5A7981EA.8020201@lab.ntt.co.jp
* Avoid valgrind complaint about write() of uninitalized bytes.Robert Haas2018-02-06
| | | | | | | | | | | | | | | | | | | | LogicalTapeFreeze() may write out its first block when it is dirty but not full, and then immediately read the first block back in from its BufFile as a BLCKSZ-width block. This can only occur in rare cases where very few tuples were written out, which is currently only possible with parallel external tuplesorts. To avoid valgrind complaints, tell it to treat the tail of logtape.c's buffer as defined. Commit 9da0cc35284bdbe8d442d732963303ff0e0a40bc exposed this problem but did not create it. LogicalTapeFreeze() has always tended to write out some amount of garbage bytes, but previously never wrote less than one block of data in total, so the problem was masked. Per buildfarm members lousyjack and skink. Peter Geoghegan, based on a suggestion from Tom Lane and me. Some comment revisions by me.
* Doc: move info for btree opclass implementors into main documentation.Tom Lane2018-02-06
| | | | | | | | | | | | | | | Up to now, useful info for writing a new btree opclass has been buried in the backend's nbtree/README file. Let's move it into the SGML docs, in preparation for extending it with info about "in_range" functions in the upcoming window RANGE patch. To do this, I chose to create a new chapter for btree indexes in Part VII (Internals), parallel to the chapters that exist for the newer index AMs. This is a pretty short chapter as-is. At some point somebody might care to flesh it out with more detail about btree internals, but that is beyond the scope of my ambition for today. Discussion: https://postgr.es/m/23141.1517874668@sss.pgh.pa.us
* Fix possible crash in partition-wise join.Robert Haas2018-02-05
| | | | | | | | | | | The previous code assumed that we'd always succeed in creating child-joins for a joinrel for which partition-wise join was considered, but that's not guaranteed, at least in the case where dummy rels are involved. Ashutosh Bapat, with some wordsmithing by me. Discussion: http://postgr.es/m/CAFjFpRf8=uyMYYfeTBjWDMs1tR5t--FgOe2vKZPULxxdYQ4RNw@mail.gmail.com
* Last-minute updates for release notes.Tom Lane2018-02-05
| | | | Security: CVE-2018-1052, CVE-2018-1053
* Ensure that all temp files made during pg_upgrade are non-world-readable.Tom Lane2018-02-05
| | | | | | | | | | | | | | | | | | | | | | | pg_upgrade has always attempted to ensure that the transient dump files it creates are inaccessible except to the owner. However, refactoring in commit 76a7650c4 broke that for the file containing "pg_dumpall -g" output; since then, that file was protected according to the process's default umask. Since that file may contain role passwords (hopefully encrypted, but passwords nonetheless), this is a particularly unfortunate oversight. Prudent users of pg_upgrade on multiuser systems would probably run it under a umask tight enough that the issue is moot, but perhaps some users are depending only on pg_upgrade's umask changes to protect their data. To fix this in a future-proof way, let's just tighten the umask at process start. There are no files pg_upgrade needs to write at a weaker security level; and if there were, transiently relaxing the umask around where they're created would be a safer approach. Report and patch by Tom Lane; the idea for the fix is due to Noah Misch. Back-patch to all supported branches. Security: CVE-2018-1053
* Fix RelationBuildPartitionKey's processing of partition key expressions.Tom Lane2018-02-05
| | | | | | | | | | | | | Failure to advance the list pointer while reading partition expressions from a list results in invoking an input function with inappropriate data, possibly leading to crashes or, with carefully crafted input, disclosure of arbitrary backend memory. Bug discovered independently by Álvaro Herrera and David Rowley. This patch is by Álvaro but owes something to David's proposed fix. Back-patch to v10 where the issue was introduced. Security: CVE-2018-1052
* Skip setting up shared instrumentation for Hash node if not needed.Tom Lane2018-02-04
| | | | | | | | | | | | | | We don't need to set up the shared space for hash join instrumentation data if instrumentation hasn't been requested. Let's follow the example of the similar Sort node code and save a few cycles by skipping that when we can. This reverts commit d59ff4ab3 and instead allows us to use the safer choice of passing noError = false to shm_toc_lookup in ExecHashInitializeWorker, since if we reach that call there should be a TOC entry to be found. Thomas Munro Discussion: https://postgr.es/m/E1ehkoZ-0005uW-43%40gemulon.postgresql.org
* doc: Update mentions of MD5 in the documentationPeter Eisentraut2018-02-04
| | | | Reported-by: Shay Rojansky <roji@roji.org>
* Release notes for 10.2, 9.6.7, 9.5.11, 9.4.16, 9.3.21.Tom Lane2018-02-04
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* Doc: minor clarifications in xindex.sgml.Tom Lane2018-02-04
| | | | | | I noticed some slightly confusing or out-of-date verbiage here while working on the window RANGE patch. Seems worth committing separately.
* doc: Fix name in release notesPeter Eisentraut2018-02-03
| | | | Author: Alexander Lakhin <exclusion@gmail.com>
* doc: Clarify psql --list documentation a bit morePeter Eisentraut2018-02-03
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* Minor copy-editing for 10.2 release notes.Tom Lane2018-02-02
| | | | Second pass after taking a break ...
* doc: Fix index linkPeter Eisentraut2018-02-02
| | | | The index entry was pointing to a slightly wrong location.
* Fix another instance of unsafe coding for shm_toc_lookup failure.Tom Lane2018-02-02
| | | | | | | | One or another author of commit 5bcf389ec seems to have thought that computing an offset from a NULL pointer would yield another NULL pointer. There may possibly be architectures where that works, but common machines don't work like that. Per a quick code review of places calling shm_toc_lookup and not using noError = false.
* Be more wary about shm_toc_lookup failure.Tom Lane2018-02-02
| | | | | | | | | | | | | | | | Commit 445dbd82a basically missed the point of commit d46633506, which was that we shouldn't allow shm_toc_lookup() failure to lead to a core dump or assertion crash, because the odds of such a failure should never be considered negligible. It's correct that we can't expect the PARALLEL_KEY_ERROR_QUEUE TOC entry to be there if we have no workers. But if we have no workers, we're not going to do anything in this function with the lookup result anyway, so let's just skip it. That lets the code use the easy-to-prove-safe noError=false case, rather than anything requiring effort to review. Back-patch to v10, like the previous commit. Discussion: https://postgr.es/m/3647.1517601675@sss.pgh.pa.us
* First-draft release notes for 10.2.Tom Lane2018-02-02
| | | | | As usual, the release notes for other branches will be made by cutting these down, but put them up for community review first.
* Fix application of identity values in some casesPeter Eisentraut2018-02-02
| | | | | | | | | | | | | | | | | | | | Investigation of 2d2d06b7e27e3177d5bef0061801c75946871db3 revealed that identity values were not applied in some further cases, including logical replication subscribers, VALUES RTEs, and ALTER TABLE ... ADD COLUMN. To fix all that, apply the identity column expression in build_column_default() instead of repeating the same logic at each call site. For ALTER TABLE ... ADD COLUMN ... IDENTITY, the previous coding completely ignored that existing rows for the new column should have values filled in from the identity sequence. The coding using build_column_default() fails for this because the sequence ownership isn't registered until after ALTER TABLE, and we can't do it before because we don't have the column in the catalog yet. So we specially remember in ColumnDef the sequence name that we decided on and build a custom NextValueExpr using that. Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
* Support parallel btree index builds.Robert Haas2018-02-02
| | | | | | | | | | | | | | | | | | | | | | To make this work, tuplesort.c and logtape.c must also support parallelism, so this patch adds that infrastructure and then applies it to the particular case of parallel btree index builds. Testing to date shows that this can often be 2-3x faster than a serial index build. The model for deciding how many workers to use is fairly primitive at present, but it's better than not having the feature. We can refine it as we get more experience. Peter Geoghegan with some help from Rushabh Lathia. While Heikki Linnakangas is not an author of this patch, he wrote other patches without which this feature would not have been possible, and therefore the release notes should possibly credit him as an author of this feature. Reviewed by Claudio Freire, Heikki Linnakangas, Thomas Munro, Tels, Amit Kapila, me. Discussion: http://postgr.es/m/CAM3SWZQKM=Pzc=CAHzRixKjp2eO5Q0Jg1SoFQqeXFQ647JiwqQ@mail.gmail.com Discussion: http://postgr.es/m/CAH2-Wz=AxWqDoVvGU7dq856S4r6sJAj6DBn7VMtigkB33N5eyg@mail.gmail.com
* Refactor code for partition bound searchingRobert Haas2018-02-02
| | | | | | | | | | | | | | | | | | | | | | | | Remove partition_bound_cmp() and partition_bound_bsearch(), whose void * argument could be, depending on the situation, of any of three different types: PartitionBoundSpec *, PartitionRangeBound *, Datum *. Instead, introduce separate bound-searching functions for each situation: partition_list_bsearch, partition_range_bsearch, partition_range_datum_bsearch, and partition_hash_bsearch. This requires duplicating the code for binary search, but it makes the code much more type safe, involves fewer branches at runtime, and at least in my opinion, is much easier to understand. Along the way, add an option to partition_range_datum_bsearch allowing the number of keys to be specified, so that we can search for partitions based on a prefix of the full list of partition keys. This is important for pending work to improve partition pruning. Amit Langote, per a suggestion from me. Discussion: http://postgr.es/m/CA+TgmoaVLDLc8=YESRwD32gPhodU_ELmXyKs77gveiYp+JE4vQ@mail.gmail.com
* Add new function WaitForParallelWorkersToAttach.Robert Haas2018-02-02
| | | | | | | | | | | | | | | | Once this function has been called, we know that all workers have started and attached to their error queues -- so if any of them subsequently exit uncleanly, we'll be sure to throw an ERROR promptly. Otherwise, users of the ParallelContext machinery must be careful not to wait forever for a worker that has failed to start. Parallel query manages to work without needing this for reasons explained in new comments added by this patch, but it's a useful primitive for other parallel operations, such as the pending patch to make creating a btree index run in parallel. Amit Kapila, revised by me. Additional review by Peter Geoghegan. Discussion: http://postgr.es/m/CAA4eK1+e2MzyouF5bg=OtyhDSX+=Ao=3htN=T-r_6s3gCtKFiw@mail.gmail.com
* Improve ALTER TABLE synopsisStephen Frost2018-02-02
| | | | | | | | | | | Add into the ALTER TABLE synopsis the definition of partition_bound_spec, column_constraint, index_parameters and exclude_element. Initial patch by Lætitia Avrot, with further improvements by Amit Langote and Thomas Munro. Discussion: https://postgr.es/m/flat/27ec4df3-d1ab-3411-f87f-647f944897e1%40lab.ntt.co.jp
* Fix possible failure to mark hash metapage dirty.Robert Haas2018-02-01
| | | | | | | Report and suggested fix by Lixian Zou. Amit Kapila put it in the form of a patch and reviewed. Discussion: http://postgr.es/m/151739848647.1239.12528851873396651946@wrigleys.postgresql.org
* psql: Add quit/help behavior/hint, for other tool portabilityBruce Momjian2018-02-01
| | | | | | | | | | | | | | Issuing 'quit'/'exit' in an empty psql buffer exits psql. Issuing 'quit'/'exit' in a non-empty psql buffer alone on a line with no prefix whitespace issues a hint on how to exit. Also add similar 'help' hints for 'help' in a non-empty psql buffer. Reported-by: Everaldo Canuto Discussion: https://postgr.es/m/flat/CALVFHFb-C_5_94hueWg6Dd0zu7TfbpT7hzsh9Zf0DEDOSaAnfA%40mail.gmail.com Author: original author Robert Haas, modified by me
* doc: fix trigger inheritance wordingBruce Momjian2018-01-31
| | | | | | | | Fix wording from commit 1cf1112990cff432b53a74a0ac9ca897ce8a7688 Reported-by: Robert Haas Backpatch-through: 10
* doc: clarify major/minor pg_upgrade versions with examplesBruce Momjian2018-01-31
| | | | | | | | | | | | The previous docs added in PG 10 were not clear enough for someone who didn't understand the PG 10 version change, so give more specific examples. Reported-by: jim@room118solutions.com Discussion: https://postgr.es/m/20171218213041.25744.8414@wrigleys.postgresql.org Backpatch-through: 10
* doc: clearify trigger behavior for inheritanceBruce Momjian2018-01-31
| | | | | | | | | | | The previous wording added in PG 10 wasn't specific enough about the behavior of statement and row triggers when using inheritance. Reported-by: ian@thepathcentral.com Discussion: https://postgr.es/m/20171129193934.27108.30796@wrigleys.postgresql.org Backpatch-through: 10
* doc: in contrib-spi, mention and link to the meaning of SPIBruce Momjian2018-01-31
| | | | | | | | | | Also remove outdated comment about SPI subtransactions. Reported-by: gregory@arenius.com Discussion: https://postgr.es/m/151726276676.1240.10501743959198501067@wrigleys.postgresql.org Backpatch-through: 9.3
* Fix typo: colums -> columns.Robert Haas2018-01-31
| | | | | | | | Along the way, also fix code indentation. Alexander Lakhin, reviewed by Michael Paquier Discussion: http://postgr.es/m/45c44aa7-7cfa-7f3b-83fd-d8300677fdda@gmail.com
* doc: Improve pg_upgrade rsync examples to use clusterdirBruce Momjian2018-01-31
| | | | | | | | | | | | | Commit 9521ce4a7a1125385fb4de9689f345db594c516a from Sep 13, 2017 and backpatched through 9.5 used rsync examples with datadir. The reporter has pointed out, and testing has verified, that clusterdir must be used, so update the docs accordingly. Reported-by: Don Seiler Discussion: https://postgr.es/m/CAHJZqBD0u9dCERpYzK6BkRv=663AmH==DFJpVC=M4Xg_rq2=CQ@mail.gmail.com Backpatch-through: 9.5
* pgcrypto's encrypt() supports AES-128, AES-192, and AES-256Robert Haas2018-01-31
| | | | | | | | Previously, only 128 was mentioned, but the others are also supported. Thomas Munro, reviewed by Michael Paquier and extended a bit by me. Discussion: http://postgr.es/m/CAEepm=1XbBHXYJKofGjnM2Qfz-ZBVqhGU4AqvtgR+Hegy4fdKg@mail.gmail.com
* doc: mention datadir locations are actually config locationsBruce Momjian2018-01-31
| | | | | | | | | | | | | | Technically, pg_upgrade's --old-datadir and --new-datadir are configuration directories, not necessarily data directories. This is reflected in the 'postgres' manual page, so do the same for pg_upgrade. Reported-by: Yves Goergen Bug: 14898 Discussion: https://postgr.es/m/20171110220912.31513.13322@wrigleys.postgresql.org Backpatch-through: 10
* Fix list partition constraints for partition keys of array type.Robert Haas2018-01-31
| | | | | | | | | | | | | | | | | The old code generated always generated a constraint of the form col = ANY(ARRAY[val1, val2, ...]), but that's invalid when col is an array type. Instead, generate col = val when there's only one value, col = val1 OR col = val2 OR ... when there are multiple values and col is of array type, and the old form when there are multiple values and col is not of an array type. As a side benefit, this makes constraint exclusion able to prune a list partition declared to accept a single Boolean value, which didn't work before. Amit Langote, reviewed by Etsuro Fujita Discussion: http://postgr.es/m/97267195-e235-89d1-a41a-c110198dfce9@lab.ntt.co.jp
* pg_prewarm: Add missing LWLockRegisterTranche call.Robert Haas2018-01-31
| | | | | | | | | Commit 79ccd7cbd5ca44bee0191d12e9e65abf702899e7, which added automatic prewarming, neglected this. Kyotaro Horiguchi, reviewed by me. Discussion: http://postgr.es/m/20171215.173219.38055760.horiguchi.kyotaro@lab.ntt.co.jp
* Refactor client-side SSL certificate checking codePeter Eisentraut2018-01-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | Separate the parts specific to the SSL library from the general logic. The previous code structure was open_client_SSL() calls verify_peer_name_matches_certificate() calls verify_peer_name_matches_certificate_name() calls wildcard_certificate_match() and was completely in fe-secure-openssl.c. The new structure is open_client_SSL() [openssl] calls pq_verify_peer_name_matches_certificate() [generic] calls pgtls_verify_peer_name_matches_certificate_guts() [openssl] calls openssl_verify_peer_name_matches_certificate_name() [openssl] calls pq_verify_peer_name_matches_certificate_name() [generic] calls wildcard_certificate_match() [generic] Move the generic functions into a new file fe-secure-common.c, so the calls generally go fe-connect.c -> fe-secure.c -> fe-secure-${impl}.c -> fe-secure-common.c, although there is a bit of back-and-forth between the last two. Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
* Fix up references to scram-sha-256Peter Eisentraut2018-01-30
| | | | | | | | | | pg_hba_file_rules erroneously reported this as scram-sha256. Fix that. To avoid future errors and confusion, also adjust documentation links and internal symbols to have a separator between "sha" and "256". Reported-by: Christophe Courtois <christophe.courtois@dalibo.com> Author: Michael Paquier <michael.paquier@gmail.com>
* Fix test case for 'outer pathkeys do not match mergeclauses' fix.Robert Haas2018-01-30
| | | | | | | | | | | | Commit 4bbf6edfbd5d03743ff82dda2f00c738fb3208f5 added a test case, but it turns out that the test case doesn't reliably test for the bug, and in the context of the regression test suite did not because ANALYZE had not been run. Report and patch by Etsuro Fujita. I added a comment along lines previously suggested by Tom Lane. Discussion: http://postgr.es/m/5A6195D8.8060206@lab.ntt.co.jp
* Add some noreturn attributes to help static analyzersPeter Eisentraut2018-01-29
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* Silence complaint about dead assignmentPeter Eisentraut2018-01-29
| | | | | | The preferred place for "placate compiler" assignments is after elog(ERROR), not before it. Otherwise, scan-build complains about a dead assignment.
* Remove dead assignmentPeter Eisentraut2018-01-29
| | | | per scan-build
* Introduce ExecQualAndReset() helper.Andres Freund2018-01-29
| | | | | | | | | | | | | | | | It's a common task to evaluate a qual and reset the corresponding expression context. Currently that requires storing the result of the qual eval, resetting the context, and then reacting on the result. As that's awkward several places only reset the context next time through a node. That's not great, so introduce a helper that evaluates and resets. It's a bit ugly that it currently uses MemoryContextReset() instead of ResetExprContext(), but that seems easier than reordering all of executor.h. Author: Andres Freund Discussion: https://postgr.es/m/20180109222544.f7loxrunqh3xjl5f@alap3.anarazel.de
* Save a few bytes by removing useless last argument to SearchCatCacheList.Tom Lane2018-01-29
| | | | | | | | | | | | | | | | | | | | | | There's never any value in giving a fully specified cache key to SearchCatCacheList: you might as well call SearchCatCache instead, since there could be only one match. So the maximum useful number of key arguments is one less than the supported number of key columns. We might as well remove the useless extra argument and save some few bytes per call site, as well as a cycle or so per call. I believe the reason it was coded like this is that originally, callers had to write out all the dummy arguments in each call, and so it seemed less confusing if SearchCatCache and SearchCatCacheList took the same number of key arguments. But since commit e26c539e9, callers only write their live arguments explicitly, making that a non-factor; and there's surely been enough time for third-party modules to adapt to that coding style. So this is only an ABI break not an API break for callers. Per discussion with Oliver Ford, this might also make it less confusing how to use SearchCatCacheList correctly. Discussion: https://postgr.es/m/27788.1517069693@sss.pgh.pa.us
* Initialize unused ExprEvalStep fields.Andres Freund2018-01-29
| | | | | | | | | | ExecPushExprSlots didn't initialize ExprEvalStep's resvalue/resnull steps as it didn't use them. That caused wrong valgrind warnings for an upcoming patch, so zero-intialize. Also zero-initialize all scratch ExprEvalStep's allocated on the stack, to avoid issues with similar future omissions of non-critial data.
* doc: Clarify pg_upgrade documentationPeter Eisentraut2018-01-29
| | | | | | Clarify that the restriction against reg* types only applies to table columns using these types, not to the type appearing in any other way, for example as a function argument.
* Prevent growth of simplehash tables when they're "too empty".Andres Freund2018-01-29
| | | | | | | | | | | | | | | | | | | | In cases where simplehash tables where filled with either a lot of conflicting hash-values, or values that hash to consecutive values (i.e. build "chains") the growth heuristics in d4c62a6b623d6eef88218158e9fa3cf974c6c7e5 could trigger rather explosively. To fix that, address some of the reasons (see previous commit) of why the growth heuristics where needed, and only allow growth when the table isn't too empty. While that means there's a few cases of bad input that can be slower, that seems a lot better than running very quickly out of memory. Author: Tomas Vondra and Andres Freund, with additional input by Thomas Munro, Tom Lane Todd A. Cook Reported-By: Todd A. Cook, Tomas Vondra, Thomas Munro Discussion: https://postgr.es/m/20171127185700.1470.20362@wrigleys.postgresql.org Backpatch: 10, where simplehash was introduced
* Improve bit perturbation in TupleHashTableHash.Andres Freund2018-01-29
| | | | | | | | | | | | | | | | The changes in b81b5a96f424531b97cdd1dba97d9d1b9c9d372e did not fully address the issue, because the bit-mixing of the IV into the final hash-key didn't prevent clustering in the input-data survive in the output data. This didn't cause a lot of problems because of the additional growth conditions added d4c62a6b623d6eef88218158e9fa3cf974c6c7e5. But as we want to rein those in due to explosive growth in some edges, this needs to be fixed. Author: Andres Freund Discussion: https://postgr.es/m/20171127185700.1470.20362@wrigleys.postgresql.org Backpatch: 10, where simplehash was introduced
* Avoid misleading psql password prompt when username is multiply specified.Tom Lane2018-01-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a password is needed, cases such as psql -d "postgresql://alice@localhost/testdb" -U bob would incorrectly prompt for "Password for user bob: ", when actually the connection will be attempted with username alice. The priority order of which name to use isn't that important here, but the misleading prompt is. When we are prompting for a password after initial connection failure, we can fix this reliably by looking at PQuser(conn) to see how libpq interpreted the connection arguments. But when we're doing a forced password prompt because of a -W switch, we can't use that solution. Fortunately, because the main use of -W is for noninteractive situations, it's less critical to produce a helpful prompt in such cases. I made the startup prompt for -W just say "Password: " all the time, rather than expending extra code on trying to identify which username to use. In the case of a \c command (after -W has been given), there's already logic in do_connect that determines whether the "dbname" is a connstring or URI, so we can avoid lobotomizing the prompt except in cases that are actually dubious. (We could do similarly in startup.c if anyone complains, but for now it seems not worthwhile, especially since that would still be only a partial solution.) Per bug #15025 from Akos Vandra. Although this is arguably a bug fix, it doesn't seem worth back-patching. The case where it matters seems like a very corner-case usage, and someone might complain that we'd changed the behavior of -W in a minor release. Discussion: https://postgr.es/m/20180123130013.7407.24749@wrigleys.postgresql.org
* Add stack-overflow guards in set-operation planning.Tom Lane2018-01-28
| | | | | | | | | | | | | | | | | | | | | | | create_plan_recurse lacked any stack depth check. This is not per our normal coding rules, but I'd supposed it was safe because earlier planner processing is more complex and presumably should eat more stack. But bug #15033 from Andrew Grossman shows this isn't true, at least not for queries having the form of a many-thousand-way INTERSECT stack. Further testing showed that recurse_set_operations is also capable of being crashed in this way, since it likewise will recurse to the bottom of a parsetree before calling any support functions that might themselves contain any stack checks. However, its stack consumption is only perhaps a third of create_plan_recurse's. It's possible that this particular problem with create_plan_recurse can only manifest in 9.6 and later, since before that we didn't build a Path tree for set operations. But having seen this example, I now have no faith in the proposition that create_plan_recurse doesn't need a stack check, so back-patch to all supported branches. Discussion: https://postgr.es/m/20180127050845.28812.58244@wrigleys.postgresql.org
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