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* Expand virtual generated columns in the plannerRichard Guo2025-02-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 83ea6c540 added support for virtual generated columns that are computed on read. All Var nodes in the query that reference virtual generated columns must be replaced with the corresponding generation expressions. Currently, this replacement occurs in the rewriter. However, this approach has several issues. If a Var referencing a virtual generated column has any varnullingrels, those varnullingrels need to be propagated into the generation expression. Failing to do so can lead to "wrong varnullingrels" errors and improper outer-join removal. Additionally, if such a Var comes from the nullable side of an outer join, we may need to wrap the generation expression in a PlaceHolderVar to ensure that it is evaluated at the right place and hence is forced to null when the outer join should do so. In certain cases, such as when the query uses grouping sets, we also need a PlaceHolderVar for anything that is not a simple Var to isolate subexpressions. Failure to do so can result in incorrect results. To fix these issues, this patch expands the virtual generated columns in the planner rather than in the rewriter, and leverages the pullup_replace_vars architecture to avoid code duplication. The generation expressions will be correctly marked with nullingrel bits and wrapped in PlaceHolderVars when needed by the pullup_replace_vars callback function. This requires handling the OLD/NEW RETURNING list Vars in pullup_replace_vars_callback, as it may now deal with Vars referencing the result relation instead of a subquery. The "wrong varnullingrels" error was reported by Alexander Lakhin. The incorrect result issue and the improper outer-join removal issue were reported by Richard Guo. Author: Richard Guo <guofenglinux@gmail.com> Author: Dean Rasheed <dean.a.rasheed@gmail.com> Reviewed-by: Jian He <jian.universality@gmail.com> Discussion: https://postgr.es/m/75eb1a6f-d59f-42e6-8a78-124ee808cda7@gmail.com
* Virtual generated columnsPeter Eisentraut2025-02-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a new variant of generated columns that are computed on read (like a view, unlike the existing stored generated columns, which are computed on write, like a materialized view). The syntax for the column definition is ... GENERATED ALWAYS AS (...) VIRTUAL and VIRTUAL is also optional. VIRTUAL is the default rather than STORED to match various other SQL products. (The SQL standard makes no specification about this, but it also doesn't know about VIRTUAL or STORED.) (Also, virtual views are the default, rather than materialized views.) Virtual generated columns are stored in tuples as null values. (A very early version of this patch had the ambition to not store them at all. But so much stuff breaks or gets confused if you have tuples where a column in the middle is completely missing. This is a compromise, and it still saves space over being forced to use stored generated columns. If we ever find a way to improve this, a bit of pg_upgrade cleverness could allow for upgrades to a newer scheme.) The capabilities and restrictions of virtual generated columns are mostly the same as for stored generated columns. In some cases, this patch keeps virtual generated columns more restricted than they might technically need to be, to keep the two kinds consistent. Some of that could maybe be relaxed later after separate careful considerations. Some functionality that is currently not supported, but could possibly be added as incremental features, some easier than others: - index on or using a virtual column - hence also no unique constraints on virtual columns - extended statistics on virtual columns - foreign-key constraints on virtual columns - not-null constraints on virtual columns (check constraints are supported) - ALTER TABLE / DROP EXPRESSION - virtual column cannot have domain type - virtual columns are not supported in logical replication The tests in generated_virtual.sql have been copied over from generated_stored.sql with the keyword replaced. This way we can make sure the behavior is mostly aligned, and the differences can be visible. Some tests for currently not supported features are currently commented out. Reviewed-by: Jian He <jian.universality@gmail.com> Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com> Tested-by: Shlok Kyal <shlok.kyal.oss@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/a368248e-69e4-40be-9c07-6c3b5880b0a6@eisentraut.org
* Handle default NULL insertion a little better.Tom Lane2025-01-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a column is omitted in an INSERT, and there's no column default, the code in preptlist.c generates a NULL Const to be inserted. Furthermore, if the column is of a domain type, we wrap the Const in CoerceToDomain, so as to throw a run-time error if the domain has a NOT NULL constraint. That's fine as far as it goes, but there are two problems: 1. We're being sloppy about the type/typmod that the Const is labeled with. It really should have the domain's base type/typmod, since it's the input to CoerceToDomain not the output. This can result in coerce_to_domain inserting a useless length-coercion function (useless because it's being applied to a null). The coercion would typically get const-folded away later, but it'd be better not to create it in the first place. 2. We're not applying expression preprocessing (specifically, eval_const_expressions) to the resulting expression tree. The planner's primary expression-preprocessing pass already happened, so that means the length coercion step and CoerceToDomain node miss preprocessing altogether. This is at the least inefficient, since it means the length coercion and CoerceToDomain will actually be executed for each inserted row, though they could be const-folded away in most cases. Worse, it seems possible that missing preprocessing for the length coercion could result in an invalid plan (for example, due to failing to perform default-function-argument insertion). I'm not aware of any live bug of that sort with core datatypes, and it might be unreachable for extension types as well because of restrictions of CREATE CAST, but I'm not entirely convinced that it's unreachable. Hence, it seems worth back-patching the fix (although I only went back to v14, as the patch doesn't apply cleanly at all in v13). There are several places in the rewriter that are building null domain constants the same way as preptlist.c. While those are before the planner and hence don't have any reachable bug, they're still applying a length coercion that will be const-folded away later, uselessly wasting cycles. Hence, make a utility routine that all of these places can call to do it right. Making this code more careful about the typmod assigned to the generated NULL constant has visible but cosmetic effects on some of the plans shown in contrib/postgres_fdw's regression tests. Discussion: https://postgr.es/m/1865579.1738113656@sss.pgh.pa.us Backpatch-through: 14
* Add OLD/NEW support to RETURNING in DML queries.Dean Rasheed2025-01-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This allows the RETURNING list of INSERT/UPDATE/DELETE/MERGE queries to explicitly return old and new values by using the special aliases "old" and "new", which are automatically added to the query (if not already defined) while parsing its RETURNING list, allowing things like: RETURNING old.colname, new.colname, ... RETURNING old.*, new.* Additionally, a new syntax is supported, allowing the names "old" and "new" to be changed to user-supplied alias names, e.g.: RETURNING WITH (OLD AS o, NEW AS n) o.colname, n.colname, ... This is useful when the names "old" and "new" are already defined, such as inside trigger functions, allowing backwards compatibility to be maintained -- the interpretation of any existing queries that happen to already refer to relations called "old" or "new", or use those as aliases for other relations, is not changed. For an INSERT, old values will generally be NULL, and for a DELETE, new values will generally be NULL, but that may change for an INSERT with an ON CONFLICT ... DO UPDATE clause, or if a query rewrite rule changes the command type. Therefore, we put no restrictions on the use of old and new in any DML queries. Dean Rasheed, reviewed by Jian He and Jeff Davis. Discussion: https://postgr.es/m/CAEZATCWx0J0-v=Qjc6gXzR=KtsdvAE7Ow=D=mu50AgOe+pvisQ@mail.gmail.com
* Update copyright for 2025Bruce Momjian2025-01-01
| | | | Backpatch-through: 13
* Remove useless casts to (void *)Peter Eisentraut2024-11-28
| | | | | | | | Many of them just seem to have been copied around for no real reason. Their presence causes (small) risks of hiding actual type mismatches or silently discarding qualifiers Discussion: https://www.postgresql.org/message-id/flat/461ea37c-8b58-43b4-9736-52884e862820@eisentraut.org
* Ensure cached plans are correctly marked as dependent on role.Nathan Bossart2024-11-11
| | | | | | | | | | | | | | If a CTE, subquery, sublink, security invoker view, or coercion projection references a table with row-level security policies, we neglected to mark the plan as potentially dependent on which role is executing it. This could lead to later executions in the same session returning or hiding rows that should have been hidden or returned instead. Reported-by: Wolfgang Walther Reviewed-by: Noah Misch Security: CVE-2024-10976 Backpatch-through: 12
* Message style improvementsPeter Eisentraut2024-08-29
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* Restrict accesses to non-system views and foreign tables during pg_dump.Masahiko Sawada2024-08-05
| | | | | | | | | | | | | | | | | | | | | | | | When pg_dump retrieves the list of database objects and performs the data dump, there was possibility that objects are replaced with others of the same name, such as views, and access them. This vulnerability could result in code execution with superuser privileges during the pg_dump process. This issue can arise when dumping data of sequences, foreign tables (only 13 or later), or tables registered with a WHERE clause in the extension configuration table. To address this, pg_dump now utilizes the newly introduced restrict_nonsystem_relation_kind GUC parameter to restrict the accesses to non-system views and foreign tables during the dump process. This new GUC parameter is added to back branches too, but these changes do not require cluster recreation. Back-patch to all supported branches. Reviewed-by: Noah Misch Security: CVE-2024-7348 Backpatch-through: 12
* Correctly check updatability of columns targeted by INSERT...DEFAULT.Tom Lane2024-07-20
| | | | | | | | | | | | | | | If a view has some updatable and some non-updatable columns, we failed to verify updatability of any columns for which an INSERT or UPDATE on the view explicitly specifies a DEFAULT item (unless the view has a declared default for that column, which is rare anyway, and one would almost certainly not write one for a non-updatable column). This would lead to an unexpected "attribute number N not found in view targetlist" error rather than the intended error. Per bug #18546 from Alexander Lakhin. This bug is old, so back-patch to all supported branches. Discussion: https://postgr.es/m/18546-84a292e759a9361d@postgresql.org
* Fix assorted bugs related to identity column in partitioned tablesPeter Eisentraut2024-05-07
| | | | | | | | | | | | | | | | | When changing the data type of a column of a partitioned table, craft the ALTER SEQUENCE command only once. Partitions do not have identity sequences of their own and thus do not need a ALTER SEQUENCE command for each partition. Fix getIdentitySequence() to fetch the identity sequence associated with the top-level partitioned table when a Relation of a partition is passed to it. While doing so, translate the attribute number of the partition into the attribute number of the partitioned table. Author: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> Reported-by: Alexander Lakhin <exclusion@gmail.com> Reviewed-by: Dmitry Dolgov <9erthalion6@gmail.com> Discussion: https://www.postgresql.org/message-id/3b8a9dc1-bbc7-0ef5-6863-c432afac7d59@gmail.com
* Add RETURNING support to MERGE.Dean Rasheed2024-03-17
| | | | | | | | | | | | | | | | | | | | | | | | | | This allows a RETURNING clause to be appended to a MERGE query, to return values based on each row inserted, updated, or deleted. As with plain INSERT, UPDATE, and DELETE commands, the returned values are based on the new contents of the target table for INSERT and UPDATE actions, and on its old contents for DELETE actions. Values from the source relation may also be returned. As with INSERT/UPDATE/DELETE, the output of MERGE ... RETURNING may be used as the source relation for other operations such as WITH queries and COPY commands. Additionally, a special function merge_action() is provided, which returns 'INSERT', 'UPDATE', or 'DELETE', depending on the action executed for each row. The merge_action() function can be used anywhere in the RETURNING list, including in arbitrary expressions and subqueries, but it is an error to use it anywhere outside of a MERGE query's RETURNING list. Dean Rasheed, reviewed by Isaac Morland, Vik Fearing, Alvaro Herrera, Gurjeet Singh, Jian He, Jeff Davis, Merlin Moncure, Peter Eisentraut, and Wolfgang Walther. Discussion: http://postgr.es/m/CAEZATCWePEGQR5LBn-vD6SfeLZafzEm2Qy_L_Oky2=qw2w3Pzg@mail.gmail.com
* Make INSERT-from-multiple-VALUES-rows handle domain target columns.Tom Lane2024-03-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | Commit a3c7a993d fixed some cases involving target columns that are arrays or composites by applying transformAssignedExpr to the VALUES entries, and then stripping off any assignment ArrayRefs or FieldStores that the transformation added. But I forgot about domains over arrays or composites :-(. Such cases would either fail with surprising complaints about mismatched datatypes, or insert unexpected coercions that could lead to odd results. To fix, extend the stripping logic to get rid of CoerceToDomain if it's atop an ArrayRef or FieldStore. While poking at this, I realized that there's a poorly documented and not-at-all-tested behavior nearby: we coerce each VALUES column to the domain type separately, and rely on the rewriter to merge those operations so that the domain constraints are checked only once. If that merging did not happen, it's entirely possible that we'd get unexpected domain constraint failures due to checking a partially-updated container value. There's no bug there, but while we're here let's improve the commentary about it and add some test cases that explicitly exercise that behavior. Per bug #18393 from Pablo Kharo. Back-patch to all supported branches. Discussion: https://postgr.es/m/18393-65fedb1a0de9260d@postgresql.org
* Remove unused #include's from backend .c filesPeter Eisentraut2024-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | as determined by include-what-you-use (IWYU) While IWYU also suggests to *add* a bunch of #include's (which is its main purpose), this patch does not do that. In some cases, a more specific #include replaces another less specific one. Some manual adjustments of the automatic result: - IWYU currently doesn't know about includes that provide global variable declarations (like -Wmissing-variable-declarations), so those includes are being kept manually. - All includes for port(ability) headers are being kept for now, to play it safe. - No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the patch from exploding in size. Note that this patch touches just *.c files, so nothing declared in header files changes in hidden ways. As a small example, in src/backend/access/transam/rmgr.c, some IWYU pragma annotations are added to handle a special case there. Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org
* Support MERGE into updatable views.Dean Rasheed2024-02-29
| | | | | | | | | | | | | | | | | | | This allows the target relation of MERGE to be an auto-updatable or trigger-updatable view, and includes support for WITH CHECK OPTION, security barrier views, and security invoker views. A trigger-updatable view must have INSTEAD OF triggers for every type of action (INSERT, UPDATE, and DELETE) mentioned in the MERGE command. An auto-updatable view must not have any INSTEAD OF triggers. Mixing auto-update and trigger-update actions (i.e., having a partial set of INSTEAD OF triggers) is not supported. Rule-updatable views are also not supported, since there is no rewriter support for non-SELECT rules with MERGE operations. Dean Rasheed, reviewed by Jian He and Alvaro Herrera. Discussion: https://postgr.es/m/CAEZATCVcB1g0nmxuEc-A+gGB0HnfcGQNGYH7gS=7rq0u0zOBXA@mail.gmail.com
* Support identity columns in partitioned tablesPeter Eisentraut2024-01-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, identity columns were disallowed on partitioned tables. (The reason was mainly that no one had gotten around to working through all the details to make it work.) This makes it work now. Some details on the behavior: * A newly created partition inherits identity property The partitions of a partitioned table are integral part of the partitioned table. A partition inherits identity columns from the partitioned table. An identity column of a partition shares the identity space with the corresponding column of the partitioned table. In other words, the same identity column across all partitions of a partitioned table share the same identity space. This is effected by sharing the same underlying sequence. When INSERTing directly into a partition, the sequence associated with the topmost partitioned table is used to calculate the value of the corresponding identity column. In regular inheritance, identity columns and their properties in a child table are independent of those in its parent tables. A child table does not inherit identity columns or their properties automatically from the parent. (This is unchanged.) * Attached partition inherits identity column A table being attached as a partition inherits the identity property from the partitioned table. This should be fine since we expect that the partition table's column has the same type as the partitioned table's corresponding column. If the table being attached is a partitioned table, the identity properties are propagated down its partition hierarchy. An identity column in the partitioned table is also marked as NOT NULL. The corresponding column in the partition needs to be marked as NOT NULL for the attach to succeed. * Drop identity property when detaching partition A partition's identity column shares the identity space (i.e. underlying sequence) as the corresponding column of the partitioned table. If a partition is detached it can longer share the identity space as before. Hence the identity columns of the partition being detached loose their identity property. When identity of a column of a regular table is dropped it retains the NOT NULL constraint that came with the identity property. Similarly the columns of the partition being detached retain the NOT NULL constraints that came with identity property, even though the identity property itself is lost. The sequence associated with the identity property is linked to the partitioned table (and not the partition being detached). That sequence is not dropped as part of detach operation. * Partitions with their own identity columns are not allowed. * The usual ALTER operations (add identity column, add identity property to existing column, alter properties of an indentity column, drop identity property) are supported for partitioned tables. Changing a column only in a partitioned table or a partition is not allowed; the change needs to be applied to the whole partition hierarchy. Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Peter Eisentraut <peter@eisentraut.org> Discussion: https://www.postgresql.org/message-id/flat/CAExHW5uOykuTC+C6R1yDSp=o8Q83jr8xJdZxgPkxfZ1Ue5RRGg@mail.gmail.com
* Update copyright for 2024Bruce Momjian2024-01-03
| | | | | | | | Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
* Add TupleDescGetDefault()Peter Eisentraut2023-09-27
| | | | | | | | | | | | | | | This unifies some repetitive code. Note: I didn't push the "not found" error message into the new function, even though all existing callers would be able to make use of it. Using the existing error handling as-is would probably require exposing the Relation type via tupdesc.h, which doesn't seem desirable. (Or even if we changed it to just report the OID, it would inject the concept of a relation containing the tuple descriptor into tupdesc.h, which might be a layering violation. Perhaps some further improvements could be considered here separately.) Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da%40eisentraut.org
* Fix typo in comment.Amit Langote2023-06-16
| | | | | | | Back-patch down to 11. Author: Sho Kato (<kato-sho@fujitsu.com>) Discussion: https://postgr.es/m/TYCPR01MB68499042A33BC32241193AAF9F5BA%40TYCPR01MB6849.jpnprd01.prod.outlook.com
* Retain relkind too in RTE_SUBQUERY entries for views.Amit Langote2023-06-14
| | | | | | | | | | | | | | | | | | 47bb9db75 modified the ApplyRetrieveRule()'s conversion of a view's original RTE_RELATION entry into an RTE_SUBQUERY one to retain relid, rellockmode, and perminfoindex so that the executor can lock the view and check its permissions. It seems better to also retain relkind for cross-checking that the exception of an RTE_SUBQUERY entry being allowed to carry relation details only applies to views, so do so. Bump catversion because this changes the output format of RTE_SUBQUERY RTEs. Suggested-by: David Steele <david@pgmasters.net> Reviewed-by: David Steele <david@pgmasters.net> Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/3953179e-9540-e5d1-a743-4bef368785b0%40pgmasters.net
* Correctly update hasSubLinks while mutating a rule action.Tom Lane2023-06-13
| | | | | | | | | | | | | | | | | | | | | rewriteRuleAction neglected to check for SubLink nodes in the securityQuals of range table entries. This could lead to failing to convert such a SubLink to a SubPlan, resulting in assertion crashes or weird errors later in planning. In passing, fix some poor coding in rewriteTargetView: we should not pass the source parsetree's hasSubLinks field to ReplaceVarsFromTargetList's outer_hasSubLinks. ReplaceVarsFromTargetList knows enough to ignore that when a Query node is passed, but it's still confusing and bad precedent: if we did try to update that flag we'd be updating a stale copy of the parsetree. Per bug #17972 from Alexander Lakhin. This has been broken since we added RangeTblEntry.securityQuals (although the presented test case only fails back to 215b43cdc), so back-patch all the way. Discussion: https://postgr.es/m/17972-f422c094237847d0@postgresql.org
* Pre-beta mechanical code beautification.Tom Lane2023-05-19
| | | | | | | | | | | | | | | Run pgindent, pgperltidy, and reformat-dat-files. This set of diffs is a bit larger than typical. We've updated to pg_bsd_indent 2.1.2, which properly indents variable declarations that have multi-line initialization expressions (the continuation lines are now indented one tab stop). We've also updated to perltidy version 20230309 and changed some of its settings, which reduces its desire to add whitespace to lines to make assignments etc. line up. Going forward, that should make for fewer random-seeming changes to existing code. Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
* Fix more bugs caused by adding columns to the end of a view.Tom Lane2023-03-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If a view is defined atop another view, and then CREATE OR REPLACE VIEW is used to add columns to the lower view, then when the upper view's referencing RTE is expanded by ApplyRetrieveRule we will have a subquery RTE with fewer eref->colnames than output columns. This confuses various code that assumes those lists are always in sync, as they are in plain parser output. We have seen such problems before (cf commit d5b760ecb), and now I think the time has come to do what was speculated about in that commit: let's make ApplyRetrieveRule synthesize some column names to preserve the invariant that holds in parser output. Otherwise we'll be chasing this class of bugs indefinitely. Moreover, it appears from testing that this actually gives us better results in the test case d5b760ecb added, and likely in other corner cases that we lack coverage for. In HEAD, I replaced d5b760ecb's hack to make expandRTE exit early with an elog(ERROR) call, since the case is now presumably unreachable. But it seems like changing that in back branches would bring more risk than benefit, so there I just updated the comment. Per bug #17811 from Alexander Lakhin. Back-patch to all supported branches. Discussion: https://postgr.es/m/17811-d31686b78f0dffc9@postgresql.org
* Fix mishandling of OLD/NEW references in subqueries in rule actions.Dean Rasheed2023-02-25
| | | | | | | | | | | | | | | | | If a rule action contains a subquery that refers to columns from OLD or NEW, then those are really lateral references, and the planner will complain if it sees such things in a subquery that isn't marked as lateral. However, at rule-definition time, the user isn't required to mark the subquery with LATERAL, and so it can fail when the rule is used. Fix this by marking such subqueries as lateral in the rewriter, at the point where they're used. Dean Rasheed and Tom Lane, per report from Alexander Lakhin. Back-patch to all supported branches. Discussion: https://postgr.es/m/5e09da43-aaba-7ea7-0a51-a2eb981b058b%40gmail.com
* Fix multi-row DEFAULT handling for INSERT ... SELECT rules.Dean Rasheed2023-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Given an updatable view with a DO ALSO INSERT ... SELECT rule, a multi-row INSERT ... VALUES query on the view fails if the VALUES list contains any DEFAULTs that are not replaced by view defaults. This manifests as an "unrecognized node type" error, or an Assert failure, in an assert-enabled build. The reason is that when RewriteQuery() attempts to replace the remaining DEFAULT items with NULLs in any product queries, using rewriteValuesRTEToNulls(), it assumes that the VALUES RTE is located at the same rangetable index in each product query. However, if the product query is an INSERT ... SELECT, then the VALUES RTE is actually in the SELECT part of that query (at the same index), rather than the top-level product query itself. Fix, by descending to the SELECT in such cases. Note that we can't simply use getInsertSelectQuery() for this, since that expects to be given a raw rule action with OLD and NEW placeholder entries, so we duplicate its logic instead. While at it, beef up the checks in getInsertSelectQuery() by checking that the jointree->fromlist node is indeed a RangeTblRef, and that the RTE it points to has rtekind == RTE_SUBQUERY. Per bug #17803, from Alexander Lakhin. Back-patch to all supported branches. Dean Rasheed, reviewed by Tom Lane. Discussion: https://postgr.es/m/17803-53c63ed4ecb4eac6%40postgresql.org
* Get rid of the "new" and "old" entries in a view's rangetable.Tom Lane2023-01-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rule system needs "old" and/or "new" pseudo-RTEs in rule actions that are ON INSERT/UPDATE/DELETE. Historically it's put such entries into the ON SELECT rules of views as well, but those are really quite vestigial. The only thing we've used them for is to carry the view's relid forward to AcquireExecutorLocks (so that we can re-lock the view to verify it hasn't changed before re-using a plan) and to carry its relid and permissions data forward to execution-time permissions checks. What we can do instead of that is to retain these fields of the RTE_RELATION RTE for the view even after we convert it to an RTE_SUBQUERY RTE. This requires a tiny amount of extra complication in the planner and AcquireExecutorLocks, but on the other hand we can get rid of the logic that moves that data from one place to another. The principal immediate benefit of doing this, aside from a small saving in the pg_rewrite data for views, is that these pseudo-RTEs no longer trigger ruleutils.c's heuristic about qualifying variable names when the rangetable's length is more than 1. That results in quite a number of small simplifications in regression test outputs, which are all to the good IMO. Bump catversion because we need to dump a few more fields of RTE_SUBQUERY RTEs. While those will always be zeroes anyway in stored rules (because we'd never populate them until query rewrite) they are useful for debugging, and it seems like we'd better make sure to transmit such RTEs accurately in plans sent to parallel workers. I don't think the executor actually examines these fields after startup, but someday it might. This is a second attempt at committing 1b4d280ea. The difference from the first time is that now we can add some filtering rules to AdjustUpgrade.pm to allow cross-version upgrade testing to pass despite all the cosmetic changes in CREATE VIEW outputs. Amit Langote (filtering rules by me) Discussion: https://postgr.es/m/CA+HiwqEf7gPN4Hn+LoZ4tP2q_Qt7n3vw7-6fJKOf92tSEnX6Gg@mail.gmail.com Discussion: https://postgr.es/m/891521.1673657296@sss.pgh.pa.us
* Revert "Get rid of the "new" and "old" entries in a view's rangetable."Tom Lane2023-01-11
| | | | | | | | | | | This reverts commit 1b4d280ea1eb7ddb2e16654d5fa16960bb959566. It's broken the buildfarm members that run cross-version-upgrade tests, because they're not prepared to deal with cosmetic differences between CREATE VIEW commands emitted by older servers and HEAD. Even if we had a solution to that, which we don't, it'd take some time to roll it out to the affected animals. This improvement isn't valuable enough to justify addressing that problem on an emergency basis, so revert it for now.
* Get rid of the "new" and "old" entries in a view's rangetable.Tom Lane2023-01-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rule system needs "old" and/or "new" pseudo-RTEs in rule actions that are ON INSERT/UPDATE/DELETE. Historically it's put such entries into the ON SELECT rules of views as well, but those are really quite vestigial. The only thing we've used them for is to carry the view's relid forward to AcquireExecutorLocks (so that we can re-lock the view to verify it hasn't changed before re-using a plan) and to carry its relid and permissions data forward to execution-time permissions checks. What we can do instead of that is to retain these fields of the RTE_RELATION RTE for the view even after we convert it to an RTE_SUBQUERY RTE. This requires a tiny amount of extra complication in the planner and AcquireExecutorLocks, but on the other hand we can get rid of the logic that moves that data from one place to another. The principal immediate benefit of doing this, aside from a small saving in the pg_rewrite data for views, is that these pseudo-RTEs no longer trigger ruleutils.c's heuristic about qualifying variable names when the rangetable's length is more than 1. That results in quite a number of small simplifications in regression test outputs, which are all to the good IMO. Bump catversion because we need to dump a few more fields of RTE_SUBQUERY RTEs. While those will always be zeroes anyway in stored rules (because we'd never populate them until query rewrite) they are useful for debugging, and it seems like we'd better make sure to transmit such RTEs accurately in plans sent to parallel workers. I don't think the executor actually examines these fields after startup, but someday it might. Amit Langote Discussion: https://postgr.es/m/CA+HiwqEf7gPN4Hn+LoZ4tP2q_Qt7n3vw7-6fJKOf92tSEnX6Gg@mail.gmail.com
* Fix calculation of which GENERATED columns need to be updated.Tom Lane2023-01-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We were identifying the updatable generated columns of inheritance children by transposing the calculation made for their parent. However, there's nothing that says a traditional-inheritance child can't have generated columns that aren't there in its parent, or that have different dependencies than are in the parent's expression. (At present it seems that we don't enforce that for partitioning either, which is likely wrong to some degree or other; but the case clearly needs to be handled with traditional inheritance.) Hence, drop the very-klugy-anyway "extraUpdatedCols" RTE field in favor of identifying which generated columns depend on updated columns during executor startup. In HEAD we can remove extraUpdatedCols altogether; in back branches, it's still there but always empty. Another difference between the HEAD and back-branch versions of this patch is that in HEAD we can add the new bitmap field to ResultRelInfo, but that would cause an ABI break in back branches. Like 4b3e37993, add a List field at the end of struct EState instead. Back-patch to v13. The bogus calculation is also being made in v12, but it doesn't have the same visible effect because we don't use it to decide which generated columns to recalculate; as a consequence of which the patch doesn't apply easily. I think that there might still be a demonstrable bug associated with trigger firing conditions, but that's such a weird corner-case usage that I'm content to leave it unfixed in v12. Amit Langote and Tom Lane Discussion: https://postgr.es/m/CA+HiwqFshLKNvQUd1DgwJ-7tsTp=dwv7KZqXC4j2wYBV1aCDUA@mail.gmail.com Discussion: https://postgr.es/m/2793383.1672944799@sss.pgh.pa.us
* Update copyright for 2023Bruce Momjian2023-01-02
| | | | Backpatch-through: 11
* Update outdated comment in ApplyRetrieveRuleAlvaro Herrera2022-12-07
| | | | | | | After a61b1f74823c. Author: Amit Langote <amitlangote09@gmail.com> Discussion: https://postgr.es/m/CA+HiwqGZm7hb2VAy8HGM22-fTDaQzqE6T=5GbAk=GkT9H0hJEg@mail.gmail.com
* Rework query relation permission checkingAlvaro Herrera2022-12-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, information about the permissions to be checked on relations mentioned in a query is stored in their range table entries. So the executor must scan the entire range table looking for relations that need to have permissions checked. This can make the permission checking part of the executor initialization needlessly expensive when many inheritance children are present in the range range. While the permissions need not be checked on the individual child relations, the executor still must visit every range table entry to filter them out. This commit moves the permission checking information out of the range table entries into a new plan node called RTEPermissionInfo. Every top-level (inheritance "root") RTE_RELATION entry in the range table gets one and a list of those is maintained alongside the range table. This new list is initialized by the parser when initializing the range table. The rewriter can add more entries to it as rules/views are expanded. Finally, the planner combines the lists of the individual subqueries into one flat list that is passed to the executor for checking. To make it quick to find the RTEPermissionInfo entry belonging to a given relation, RangeTblEntry gets a new Index field 'perminfoindex' that stores the corresponding RTEPermissionInfo's index in the query's list of the latter. ExecutorCheckPerms_hook has gained another List * argument; the signature is now: typedef bool (*ExecutorCheckPerms_hook_type) (List *rangeTable, List *rtePermInfos, bool ereport_on_violation); The first argument is no longer used by any in-core uses of the hook, but we leave it in place because there may be other implementations that do. Implementations should likely scan the rtePermInfos list to determine which operations to allow or deny. Author: Amit Langote <amitlangote09@gmail.com> Discussion: https://postgr.es/m/CA+HiwqGjJDmUhDSfv-U2qhKJjt9ST7Xh9JXC_irsAQ1TAUsJYg@mail.gmail.com
* Fix DEFAULT handling for multi-row INSERT rules.Dean Rasheed2022-12-03
| | | | | | | | | | | | | | | | | | | | | | | | | | When updating a relation with a rule whose action performed an INSERT from a multi-row VALUES list, the rewriter might skip processing the VALUES list, and therefore fail to replace any DEFAULTs in it. This would lead to an "unrecognized node type" error. The reason was that RewriteQuery() assumed that a query doing an INSERT from a multi-row VALUES list would necessarily only have one item in its fromlist, pointing to the VALUES RTE to read from. That assumption is correct for the original query, but not for product queries produced for rule actions. In such cases, there may be multiple items in the fromlist, possibly including multiple VALUES RTEs. What is required instead is for RewriteQuery() to skip any RTEs from the product query's originating query, which might include one or more already-processed VALUES RTEs. What's left should then include at most one VALUES RTE (from the rule action) to be processed. Patch by me. Thanks to Tom Lane for reviewing. Back-patch to all supported branches. Discussion: https://postgr.es/m/CAEZATCV39OOW7LAR_Xq4i%2BLc1Byux%3DeK3Q%3DHD_pF1o9LBt%3DphA%40mail.gmail.com
* Yet further fixes for multi-row VALUES lists for updatable views.Tom Lane2022-10-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | DEFAULT markers appearing in an INSERT on an updatable view could be mis-processed if they were in a multi-row VALUES clause. This would lead to strange errors such as "cache lookup failed for type NNNN", or in older branches even to crashes. The cause is that commit 41531e42d tried to re-use rewriteValuesRTE() to remove any SetToDefault nodes (that hadn't previously been replaced by the view's own default values) appearing in "product" queries, that is DO ALSO queries. That's fundamentally wrong because the DO ALSO queries might not even be INSERTs; and even if they are, their targetlists don't necessarily match the view's column list, so that almost all the logic in rewriteValuesRTE() is inapplicable. What we want is a narrow focus on replacing any such nodes with NULL constants. (That is, in this context we are interpreting the defaults as being strictly those of the view itself; and we already replaced any that aren't NULL.) We could add still more !force_nulls tests to further lobotomize rewriteValuesRTE(); but it seems cleaner to split out this case to a new function, restoring rewriteValuesRTE() to the charter it had before. Per bug #17633 from jiye_sw. Patch by me, but thanks to Richard Guo and Japin Li for initial investigation. Back-patch to all supported branches, as the previous fix was. Discussion: https://postgr.es/m/17633-98cc85e1fa91e905@postgresql.org
* Fix grammar in error messageJohn Naylor2022-09-15
| | | | | | | | | | While at it, make ellipses formatting consistent when describing SQL statements. Ekaterina Kiryanova and Alexander Lakhin Reviewed by myself and Álvaro Herrera Discussion: https://www.postgresql.org/message-id/eed5cec0-a542-53da-6a5e-7789c6ed9817%40postgrespro.ru Backpatch only the grammar fix to v15
* Add support for MERGE SQL commandAlvaro Herrera2022-03-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MERGE performs actions that modify rows in the target table using a source table or query. MERGE provides a single SQL statement that can conditionally INSERT/UPDATE/DELETE rows -- a task that would otherwise require multiple PL statements. For example, MERGE INTO target AS t USING source AS s ON t.tid = s.sid WHEN MATCHED AND t.balance > s.delta THEN UPDATE SET balance = t.balance - s.delta WHEN MATCHED THEN DELETE WHEN NOT MATCHED AND s.delta > 0 THEN INSERT VALUES (s.sid, s.delta) WHEN NOT MATCHED THEN DO NOTHING; MERGE works with regular tables, partitioned tables and inheritance hierarchies, including column and row security enforcement, as well as support for row and statement triggers and transition tables therein. MERGE is optimized for OLTP and is parameterizable, though also useful for large scale ETL/ELT. MERGE is not intended to be used in preference to existing single SQL commands for INSERT, UPDATE or DELETE since there is some overhead. MERGE can be used from PL/pgSQL. MERGE does not support targetting updatable views or foreign tables, and RETURNING clauses are not allowed either. These limitations are likely fixable with sufficient effort. Rewrite rules are also not supported, but it's not clear that we'd want to support them. Author: Pavan Deolasee <pavan.deolasee@gmail.com> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Author: Amit Langote <amitlangote09@gmail.com> Author: Simon Riggs <simon.riggs@enterprisedb.com> Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com> Reviewed-by: Andres Freund <andres@anarazel.de> (earlier versions) Reviewed-by: Peter Geoghegan <pg@bowt.ie> (earlier versions) Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier versions) Reviewed-by: Japin Li <japinli@hotmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com> Reviewed-by: Zhihong Yu <zyu@yugabyte.com> Discussion: https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.com Discussion: https://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com Discussion: https://postgr.es/m/20201231134736.GA25392@alvherre.pgsql
* Add support for security invoker views.Dean Rasheed2022-03-22
| | | | | | | | | | | | | | | | | | | | A security invoker view checks permissions for accessing its underlying base relations using the privileges of the user of the view, rather than the privileges of the view owner. Additionally, if any of the base relations are tables with RLS enabled, the policies of the user of the view are applied, rather than those of the view owner. This allows views to be defined without giving away additional privileges on the underlying base relations, and matches a similar feature available in other database systems. It also allows views to operate more naturally with RLS, without affecting the assignments of policies to users. Christoph Heiss, with some additional hacking by me. Reviewed by Laurenz Albe and Wolfgang Walther. Discussion: https://postgr.es/m/b66dd6d6-ad3e-c6f2-8b90-47be773da240%40cybertec.at
* Update copyright for 2022Bruce Momjian2022-01-07
| | | | Backpatch-through: 10
* Fix rewriter to set hasModifyingCTE correctly on rewritten queries.Tom Lane2021-09-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we copy data-modifying CTEs from the original query to a replacement query (from a DO INSTEAD rule), we must set hasModifyingCTE properly in the replacement query. Failure to do this can cause various unpleasantness, such as unsafe usage of parallel plans. The code also neglected to propagate hasRecursive, though that's only cosmetic at the moment. A difficulty arises if the rule action is an INSERT...SELECT. We attach the original query's RTEs and CTEs to the sub-SELECT Query, but data-modifying CTEs are only allowed to appear in the topmost Query. For the moment, throw an error in such cases. It would probably be possible to avoid this error by attaching the CTEs to the top INSERT Query instead; but that would require a bunch of new code to adjust ctelevelsup references. Given the narrowness of the use-case, and the need to back-patch this fix, it does not seem worth the trouble for now. We can revisit this if we get field complaints. Per report from Greg Nancarrow. Back-patch to all supported branches. (The test case added here does not fail before v10, but there are plenty of places checking top-level hasModifyingCTE in 9.6, so I have no doubt that this code change is necessary there too.) Greg Nancarrow and Tom Lane Discussion: https://postgr.es/m/CAJcOf-f68DT=26YAMz_i0+Au3TcLO5oiHY5=fL6Sfuits6r+_w@mail.gmail.com Discussion: https://postgr.es/m/CAJcOf-fAdj=nDKMsRhQzndm-O13NY4dL6xGcEvdX5Xvbbi0V7g@mail.gmail.com
* Reject cases where a query in WITH rewrites to just NOTIFY.Tom Lane2021-07-09
| | | | | | | | | | | | | | | | | Since the executor can't cope with a utility statement appearing as a node of a plan tree, we can't support cases where a rewrite rule inserts a NOTIFY into an INSERT/UPDATE/DELETE command appearing in a WITH clause of a larger query. (One can imagine ways around that, but it'd be a new feature not a bug fix, and so far there's been no demand for it.) RewriteQuery checked for this, but it missed the case where the DML command rewrites to *only* a NOTIFY. That'd lead to crashes later on in planning. Add the missed check, and improve the level of testing of this area. Per bug #17094 from Yaoguang Chen. It's been busted since WITH was introduced, so back-patch to all supported branches. Discussion: https://postgr.es/m/17094-bf15dff55eaf2e28@postgresql.org
* Remove unused function argumentPeter Eisentraut2021-05-03
| | | | became unused by 04942bffd0aa9bd0d143d99b473342eb9ecee88b
* Remove rewriteTargetListIU's expansion of view targetlists in UPDATE.Tom Lane2021-04-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 2ec993a7c, which added triggers on views, modified the rewriter to add dummy entries like "SET x = x" for all columns that weren't actually being updated by the user in any UPDATE directed at a view. That was needed at the time to produce a complete "NEW" row to pass to the trigger. Later it was found to cause problems for ordinary updatable views, so commit cab5dc5da restricted it to happen only for trigger-updatable views. But in the wake of commit 86dc90056, we really don't need it at all. nodeModifyTable.c populates the trigger "OLD" row from the whole-row variable that is generated for the view, and then it computes the "NEW" row using that old row and the UPDATE targetlist. So there is no need for the UPDATE tlist to have dummy entries, any more than it needs them for regular tables or other types of views. (The comments for rewriteTargetListIU suggest that we must do this for correct expansion of NEW references in rules, but I now think that that was just lazy comment editing in 2ec993a7c. If we didn't need it for rules on views before there were triggers, we don't need it after that.) This essentially propagates 86dc90056's decision that we don't need dummy column updates into the view case. Aside from making the different cases more uniform and hence possibly forestalling future bugs, it ought to save a little bit of rewriter/planner effort. Discussion: https://postgr.es/m/2181213.1619397634@sss.pgh.pa.us
* Update comments for rewriteTargetListIU().Tom Lane2021-04-25
| | | | | | | | | This function's behavior for UPDATE on a trigger-updatable view was justified by analogy to what preptlist.c used to do for UPDATE on regular tables. Since preptlist.c hasn't done that since 86dc90056, that argument is no longer sensible, let alone convincing. I think we do still need it to act that way, so update the comment to explain why.
* doc: Improve hyphenation consistencyPeter Eisentraut2021-04-21
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* Clean up treatment of missing default and CHECK-constraint records.Tom Lane2021-04-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andrew Gierth reported that it's possible to crash the backend if no pg_attrdef record is found to match an attribute that has atthasdef set. AttrDefaultFetch warns about this situation, but then leaves behind a relation tupdesc that has null "adbin" pointer(s), which most places don't guard against. We considered promoting the warning to an error, but throwing errors during relcache load is pretty drastic: it effectively locks one out of using the relation at all. What seems better is to leave the load-time behavior as a warning, but then throw an error in any code path that wants to use a default and can't find it. This confines the error to a subset of INSERT/UPDATE operations on the table, and in particular will at least allow a pg_dump to succeed. Also, we should fix AttrDefaultFetch to not leave any null pointers in the tupdesc, because that just creates an untested bug hazard. While at it, apply the same philosophy of "warn at load, throw error only upon use of the known-missing info" to CHECK constraints. CheckConstraintFetch is very nearly the same logic as AttrDefaultFetch, but for reasons lost in the mists of time, it was throwing ERROR for the same cases that AttrDefaultFetch treats as WARNING. Make the two functions more nearly alike. In passing, get rid of potentially-O(N^2) loops in equalTupleDesc by making AttrDefaultFetch sort the entries after fetching them, so that equalTupleDesc can assume that entries in two equal tupdescs must be in matching order. (CheckConstraintFetch already was sorting CHECK constraints, but equalTupleDesc hadn't been told about it.) There's some argument for back-patching this, but with such a small number of field reports, I'm content to fix it in HEAD. Discussion: https://postgr.es/m/87pmzaq4gx.fsf@news-spur.riddles.org.uk
* Rework planning and execution of UPDATE and DELETE.Tom Lane2021-03-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes two closely related sets of changes: 1. For UPDATE, the subplan of the ModifyTable node now only delivers the new values of the changed columns (i.e., the expressions computed in the query's SET clause) plus row identity information such as CTID. ModifyTable must re-fetch the original tuple to merge in the old values of any unchanged columns. The core advantage of this is that the changed columns are uniform across all tables of an inherited or partitioned target relation, whereas the other columns might not be. A secondary advantage, when the UPDATE involves joins, is that less data needs to pass through the plan tree. The disadvantage of course is an extra fetch of each tuple to be updated. However, that seems to be very nearly free in context; even worst-case tests don't show it to add more than a couple percent to the total query cost. At some point it might be interesting to combine the re-fetch with the tuple access that ModifyTable must do anyway to mark the old tuple dead; but that would require a good deal of refactoring and it seems it wouldn't buy all that much, so this patch doesn't attempt it. 2. For inherited UPDATE/DELETE, instead of generating a separate subplan for each target relation, we now generate a single subplan that is just exactly like a SELECT's plan, then stick ModifyTable on top of that. To let ModifyTable know which target relation a given incoming row refers to, a tableoid junk column is added to the row identity information. This gets rid of the horrid hack that was inheritance_planner(), eliminating O(N^2) planning cost and memory consumption in cases where there were many unprunable target relations. Point 2 of course requires point 1, so that there is a uniform definition of the non-junk columns to be returned by the subplan. We can't insist on uniform definition of the row identity junk columns however, if we want to keep the ability to have both plain and foreign tables in a partitioning hierarchy. Since it wouldn't scale very far to have every child table have its own row identity column, this patch includes provisions to merge similar row identity columns into one column of the subplan result. In particular, we can merge the whole-row Vars typically used as row identity by FDWs into one column by pretending they are type RECORD. (It's still okay for the actual composite Datums to be labeled with the table's rowtype OID, though.) There is more that can be done to file down residual inefficiencies in this patch, but it seems to be committable now. FDW authors should note several API changes: * The argument list for AddForeignUpdateTargets() has changed, and so has the method it must use for adding junk columns to the query. Call add_row_identity_var() instead of manipulating the parse tree directly. You might want to reconsider exactly what you're adding, too. * PlanDirectModify() must now work a little harder to find the ForeignScan plan node; if the foreign table is part of a partitioning hierarchy then the ForeignScan might not be the direct child of ModifyTable. See postgres_fdw for sample code. * To check whether a relation is a target relation, it's no longer sufficient to compare its relid to root->parse->resultRelation. Instead, check it against all_result_relids or leaf_result_relids, as appropriate. Amit Langote and Tom Lane Discussion: https://postgr.es/m/CA+HiwqHpHdqdDn48yCEhynnniahH78rwcrv1rEX65-fsZGBOLQ@mail.gmail.com
* Revert "Propagate CTE property flags when copying a CTE list into a rule."Tom Lane2021-02-07
| | | | | | | | | | This reverts commit ed290896335414c6c069b9ccae1f3dcdd2fac6ba and equivalent back-branch commits. The issue is subtler than I thought, and it's far from new, so just before a release deadline is no time to be fooling with it. We'll consider what to do at a bit more leisure. Discussion: https://postgr.es/m/CAJcOf-fAdj=nDKMsRhQzndm-O13NY4dL6xGcEvdX5Xvbbi0V7g@mail.gmail.com
* Propagate CTE property flags when copying a CTE list into a rule.Tom Lane2021-02-06
| | | | | | | | | | | | | | | | | | rewriteRuleAction() neglected this step, although it was careful to propagate other similar flags such as hasSubLinks or hasRowSecurity. Omitting to transfer hasRecursive is just cosmetic at the moment, but omitting hasModifyingCTE is a live bug, since the executor certainly looks at that. The proposed test case only fails back to v10, but since the executor examines hasModifyingCTE in 9.x as well, I suspect that a test case could be devised that fails in older branches. Given the nearness of the release deadline, though, I'm not going to spend time looking for a better test. Report and patch by Greg Nancarrow, cosmetic changes by me Discussion: https://postgr.es/m/CAJcOf-fAdj=nDKMsRhQzndm-O13NY4dL6xGcEvdX5Xvbbi0V7g@mail.gmail.com
* SEARCH and CYCLE clausesPeter Eisentraut2021-02-01
| | | | | | | | | | | | This adds the SQL standard feature that adds the SEARCH and CYCLE clauses to recursive queries to be able to do produce breadth- or depth-first search orders and detect cycles. These clauses can be rewritten into queries using existing syntax, and that is what this patch does in the rewriter. Reviewed-by: Vik Fearing <vik@postgresfriends.org> Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/db80ceee-6f97-9b4a-8ee8-3ba0c58e5be2@2ndquadrant.com
* Update copyright for 2021Bruce Momjian2021-01-02
| | | | Backpatch-through: 9.5