452 Commits (e2cda3c20a61c76e497fb2ebb6d2b2ae8c43c014)

Author	SHA1	Message	Date
Amit Kapila	e2cda3c20a	Fix use of relcache TriggerDesc field introduced by commit 05c8482f7f. ... The commit added code which used a relcache TriggerDesc field across another cache access, which it shouldn't because the relcache doesn't guarantee it won't get moved. Diagnosed-by: Tom Lane Author: Greg Nancarrow Reviewed-by: Hou Zhijie, Amit Kapila Discussion: https://postgr.es/m/2309260.1615485644@sss.pgh.pa.us	5 years ago
Amit Kapila	e4e87a32cc	Fix valgrind issue in commit 05c8482f7f. ... Initialize other newly added variables in max_parallel_hazard_context via is_parallel_safe() because we don't check the parallel-safety of target relations in that function. Reported-by: Tom Lane as per buildfarm Author: Amit Kapila Discussion: https://postgr.es/m/2060179.1615347455@sss.pgh.pa.us	5 years ago
Amit Kapila	05c8482f7f	Enable parallel SELECT for "INSERT INTO ... SELECT ...". ... Parallel SELECT can't be utilized for INSERT in the following cases: - INSERT statement uses the ON CONFLICT DO UPDATE clause - Target table has a parallel-unsafe: trigger, index expression or predicate, column default expression or check constraint - Target table has a parallel-unsafe domain constraint on any column - Target table is a partitioned table with a parallel-unsafe partition key expression or support function The planner is updated to perform additional parallel-safety checks for the cases listed above, for determining whether it is safe to run INSERT in parallel-mode with an underlying parallel SELECT. The planner will consider using parallel SELECT for "INSERT INTO ... SELECT ...", provided nothing unsafe is found from the additional parallel-safety checks, or from the existing parallel-safety checks for SELECT. While checking parallel-safety, we need to check it for all the partitions on the table which can be costly especially when we decide not to use a parallel plan. So, in a separate patch, we will introduce a GUC and or a reloption to enable/disable parallelism for Insert statements. Prior to entering parallel-mode for the execution of INSERT with parallel SELECT, a TransactionId is acquired and assigned to the current transaction state. This is necessary to prevent the INSERT from attempting to assign the TransactionId whilst in parallel-mode, which is not allowed. This approach has a disadvantage in that if the underlying SELECT does not return any rows, then the TransactionId is not used, however that shouldn't happen in practice in many cases. Author: Greg Nancarrow, Amit Langote, Amit Kapila Reviewed-by: Amit Langote, Hou Zhijie, Takayuki Tsunakawa, Antonin Houska, Bharath Rupireddy, Dilip Kumar, Vignesh C, Zhihong Yu, Amit Kapila Tested-by: Tang, Haiying Discussion: https://postgr.es/m/CAJcOf-cXnB5cnMKqWEp2E2z7Mvcd04iLVmV=qpFJrR3AcrTS3g@mail.gmail.com Discussion: https://postgr.es/m/CAJcOf-fAdj=nDKMsRhQzndm-O13NY4dL6xGcEvdX5Xvbbi0V7g@mail.gmail.com	5 years ago
Tom Lane	1046dbedde	Silence another gcc 11 warning. ... Per buildfarm and local experimentation, bleeding-edge gcc isn't convinced that the MemSet in reorder_function_arguments() is safe. Shut it up by adding an explicit check that pronargs isn't negative, and by changing MemSet to memset. (It appears that either change is enough to quiet the warning at -O2, but let's do both to be sure.)	5 years ago
Tom Lane	55dc86eca7	Fix pull_varnos' miscomputation of relids set for a PlaceHolderVar. ... Previously, pull_varnos() took the relids of a PlaceHolderVar as being equal to the relids in its contents, but that fails to account for the possibility that we have to postpone evaluation of the PHV due to outer joins. This could result in a malformed plan. The known cases end up triggering the "failed to assign all NestLoopParams to plan nodes" sanity check in createplan.c, but other symptoms may be possible. The right value to use is the join level we actually intend to evaluate the PHV at. We can get that from the ph_eval_at field of the associated PlaceHolderInfo. However, there are some places that call pull_varnos() before the PlaceHolderInfos have been created; in that case, fall back to the conservative assumption that the PHV will be evaluated at its syntactic level. (In principle this might result in missing some legal optimization, but I'm not aware of any cases where it's an issue in practice.) Things are also a bit ticklish for calls occurring during deconstruct_jointree(), but AFAICS the ph_eval_at fields should have reached their final values by the time we need them. The main problem in making this work is that pull_varnos() has no way to get at the PlaceHolderInfos. We can fix that easily, if a bit tediously, in HEAD by passing it the planner "root" pointer. In the back branches that'd cause an unacceptable API/ABI break for extensions, so leave the existing entry points alone and add new ones with the additional parameter. (If an old entry point is called and encounters a PHV, it'll fall back to using the syntactic level, again possibly missing some valid optimization.) Back-patch to v12. The computation is surely also wrong before that, but it appears that we cannot reach a bad plan thanks to join order restrictions imposed on the subquery that the PlaceHolderVar came from. The error only became reachable when commit 4be058fe9 allowed trivial subqueries to be collapsed out completely, eliminating their join order restrictions. Per report from Stephan Springl. Discussion: https://postgr.es/m/171041.1610849523@sss.pgh.pa.us	5 years ago
Bruce Momjian	ca3b37487b	Update copyright for 2021 ... Backpatch-through: 9.5	5 years ago
Tom Lane	653aa603f5	Provide an error cursor for "can't subscript" error messages. ... Commit c7aba7c14 didn't add this, but after more fooling with the feature I feel that it'd be useful. To make this possible, refactor getSubscriptingRoutines() so that the caller is responsible for throwing any error. (In clauses.c, I just chose to make the most conservative assumption rather than throwing an error. We don't expect failures there anyway really, so the code space for an error message would be a poor investment.)	5 years ago
Tom Lane	c7aba7c14e	Support subscripting of arbitrary types, not only arrays. ... This patch generalizes the subscripting infrastructure so that any data type can be subscripted, if it provides a handler function to define what that means. Traditional variable-length (varlena) arrays all use array_subscript_handler(), while the existing fixed-length types that support subscripting use raw_array_subscript_handler(). It's expected that other types that want to use subscripting notation will define their own handlers. (This patch provides no such new features, though; it only lays the foundation for them.) To do this, move the parser's semantic processing of subscripts (including coercion to whatever data type is required) into a method callback supplied by the handler. On the execution side, replace the ExecEvalSubscriptingRef* layer of functions with direct calls to callback-supplied execution routines. (Thus, essentially no new run-time overhead should be caused by this patch. Indeed, there is room to remove some overhead by supplying specialized execution routines. This patch does a little bit in that line, but more could be done.) Additional work is required here and there to remove formerly hard-wired assumptions about the result type, collation, etc of a SubscriptingRef expression node; and to remove assumptions that the subscript values must be integers. One useful side-effect of this is that we now have a less squishy mechanism for identifying whether a data type is a "true" array: instead of wiring in weird rules about typlen, we can look to see if pg_type.typsubscript == F_ARRAY_SUBSCRIPT_HANDLER. For this to be bulletproof, we have to forbid user-defined types from using that handler directly; but there seems no good reason for them to do so. This patch also removes assumptions that the number of subscripts is limited to MAXDIM (6), or indeed has any hard-wired limit. That limit still applies to types handled by array_subscript_handler or raw_array_subscript_handler, but to discourage other dependencies on this constant, I've moved it from c.h to utils/array.h. Dmitry Dolgov, reviewed at various times by Tom Lane, Arthur Zakirov, Peter Eisentraut, Pavel Stehule Discussion: https://postgr.es/m/CA+q6zcVDuGBv=M0FqBYX8DPebS3F_0KQ6OVFobGJPM507_SZ_w@mail.gmail.com Discussion: https://postgr.es/m/CA+q6zcVovR+XY4mfk-7oNk-rF91gH0PebnNfuUjuuDsyHjOcVA@mail.gmail.com	5 years ago
Tom Lane	62ee703313	Teach contain_leaked_vars that assignment SubscriptingRefs are leaky. ... array_get_element and array_get_slice qualify as leakproof, since they will silently return NULL for bogus subscripts. But array_set_element and array_set_slice throw errors for such cases, making them clearly not leakproof. contain_leaked_vars was evidently written with only the former case in mind, as it gave the wrong answer for assignment SubscriptingRefs (nee ArrayRefs). This would be a live security bug, were it not that assignment SubscriptingRefs can only occur in INSERT and UPDATE target lists, while we only care about leakproofness for qual expressions; so the wrong answer can't occur in practice. Still, that's a rather shaky answer for a security-related question; and maybe in future somebody will want to ask about leakproofness of a tlist. So it seems wise to fix and even back-patch this correction. (We would need some change here anyway for the upcoming generic-subscripting patch, since extensions might make different tradeoffs about whether to throw errors. Commit 558d77f20 attempted to lay groundwork for that by asking check_functions_in_node whether a SubscriptingRef contains leaky functions; but that idea fails now that the implementation methods of a SubscriptingRef are not SQL-visible functions that could be marked leakproof or not.) Back-patch to 9.6. While 9.5 has the same issue, the code's a bit different. It seems quite unlikely that we'd introduce any actual bug in the short time 9.5 has left to live, so the work/risk/reward balance isn't attractive for changing 9.5. Discussion: https://postgr.es/m/3143742.1607368115@sss.pgh.pa.us	5 years ago
Heikki Linnakangas	0a2bc5d61e	Move per-agg and per-trans duplicate finding to the planner. ... This has the advantage that the cost estimates for aggregates can count the number of calls to transition and final functions correctly. Bump catalog version, because views can contain Aggrefs. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/b2e3536b-1dbc-8303-c97e-89cb0b4a9a48%40iki.fi	5 years ago
Tom Lane	8e1f37c07a	Rethink the generation rule for fmgroids.h macros. ... Traditionally, the names of fmgroids.h macros for pg_proc OIDs have been constructed from the prosrc field. But sometimes the same C function underlies multiple pg_proc entries, forcing us to make an arbitrary choice of which OID to reference; the other entries are then not namable via fmgroids.h. Moreover, we could not have macros at all for pg_proc entries that aren't for C-coded functions. Instead, use the proname field, and append the proargtypes field (replacing inter-argument spaces with underscores) if proname is not unique. Special-casing unique entries such as F_OIDEQ removes the need to change a lot of code. Indeed, I can only find two places in the tree that need to be adjusted; while this changes quite a few existing entries in fmgroids.h, few of them are referenced from C code. With this patch, all entries in pg_proc.dat have macros in fmgroids.h. Discussion: https://postgr.es/m/472274.1604258384@sss.pgh.pa.us	5 years ago
Tom Lane	c8ab970179	Fix list-munging bug that broke SQL function result coercions. ... Since commit 913bbd88d, check_sql_fn_retval() can either insert type coercion steps in-line in the Query that produces the SQL function's results, or generate a new top-level Query to perform the coercions, if modifying the Query's output in-place wouldn't be safe. However, it appears that the latter case has never actually worked, because the code tried to inject the new Query back into the query list it was passed ... which is not the list that will be used for later processing when we execute the SQL function "normally" (without inlining it). So we ended up with no coercion happening at run-time, leading to wrong results or crashes depending on the datatypes involved. While the regression tests look like they cover this area well enough, through a huge bit of bad luck all the test cases that exercise the separate-Query path were checking either inline-able cases (which accidentally didn't have the bug) or cases that are no-ops at runtime (e.g., varchar to text), so that the failure to perform the coercion wasn't obvious. The fact that the cases that don't work weren't allowed at all before v13 probably contributed to not noticing the problem sooner, too. To fix, get rid of the separate "flat" list of Query nodes and instead pass the real two-level list that is going to be used later. I chose to make the same change in check_sql_fn_statements(), although that has no actual bug, just so that we don't need that data structure at all. This is an API change, as evidenced by the adjustments needed to callers outside functions.c. That's a bit scary to be doing in a released branch, but so far as I can tell from a quick search, there are no outside callers of these functions (and they are sufficiently specific to our semantics for SQL-language functions that it's not apparent why any extension would need to call them). In any case, v13 already changed the API of check_sql_fn_retval() compared to prior branches. Per report from pinker. Back-patch to v13 where this code came in. Discussion: https://postgr.es/m/1603050466566-0.post@n3.nabble.com	5 years ago
Tom Lane	2072932407	Suppress unnecessary RelabelType nodes in yet more cases. ... Commit a477bfc1d fixed eval_const_expressions() to ensure that it didn't generate unnecessary RelabelType nodes, but I failed to notice that some other places in the planner had the same issue. Really noplace in the planner should be using plain makeRelabelType(), for fear of generating expressions that should be equal() to semantically equivalent trees, but aren't. An example is that because canonicalize_ec_expression() failed to be careful about this, we could end up with an equivalence class containing both a plain Const, and a Const-with-RelabelType representing exactly the same value. So far as I can tell this led to no visible misbehavior, but we did waste a bunch of cycles generating and evaluating "Const = Const-with-RelabelType" to prove such entries are redundant. Hence, move the support function added by a477bfc1d to where it can be more generally useful, and use it in the places where planner code previously used makeRelabelType. Back-patch to v12, like the previous patch. While I have no concrete evidence of any real misbehavior here, it's certainly possible that I overlooked a case where equivalent expressions that aren't equal() could cause a user-visible problem. In any case carrying extra RelabelType nodes through planning to execution isn't very desirable. Discussion: https://postgr.es/m/1311836.1597781384@sss.pgh.pa.us	5 years ago
Tom Lane	1e7629d2c9	Be more careful about the shape of hashable subplan clauses. ... nodeSubplan.c expects that the testexpr for a hashable ANY SubPlan has the form of one or more OpExprs whose LHS is an expression of the outer query's, while the RHS is an expression over Params representing output columns of the subquery. However, the planner only went as far as verifying that the clauses were all binary OpExprs. This works 99.99% of the time, because the clauses have the right shape when emitted by the parser --- but it's possible for function inlining to break that, as reported by PegoraroF10. To fix, teach the planner to check that the LHS and RHS contain the right things, or more accurately don't contain the wrong things. Given that this has been broken for years without anyone noticing, it seems sufficient to just give up hashing when it happens, rather than go to the trouble of commuting the clauses back again (which wouldn't necessarily work anyway). While poking at that, I also noticed that nodeSubplan.c had a baked-in assumption that the number of hash clauses is identical to the number of subquery output columns. Again, that's fine as far as parser output goes, but it's not hard to break it via function inlining. There seems little reason for that assumption though --- AFAICS, the only thing it's buying us is not having to store the number of hash clauses explicitly. Adding code to the planner to reject such cases would take more code than getting nodeSubplan.c to cope, so I fixed it that way. This has been broken for as long as we've had hashable SubPlans, so back-patch to all supported branches. Discussion: https://postgr.es/m/1549209182255-0.post@n3.nabble.com	5 years ago
Andres Freund	e07633646a	code: replace 'master' with 'leader' where appropriate. ... Leader already is the more widely used terminology, but a few places didn't get the message. Author: Andres Freund Reviewed-By: David Steele Discussion: https://postgr.es/m/20200615182235.x7lch5n6kcjq4aue@alap3.anarazel.de	5 years ago
Alvaro Herrera	17cc133f01	Dial back -Wimplicit-fallthrough to level 3 ... The additional pain from level 4 is excessive for the gain. Also revert all the source annotation changes to their original wordings, to avoid back-patching pain. Discussion: https://postgr.es/m/31166.1589378554@sss.pgh.pa.us	5 years ago
Alvaro Herrera	3e9744465d	Add -Wimplicit-fallthrough to CFLAGS and CXXFLAGS ... Use it at level 4, a bit more restrictive than the default level, and tweak our commanding comments to FALLTHROUGH. (However, leave zic.c alone, since it's external code; to avoid the warnings that would appear there, change CFLAGS for that file in the Makefile.) Author: Julien Rouhaud <rjuju123@gmail.com> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/20200412081825.qyo5vwwco3fv4gdo@nol Discussion: https://postgr.es/m/flat/E1fDenm-0000C8-IJ@gemulon.postgresql.org	5 years ago
Tom Lane	a477bfc1df	Suppress unnecessary RelabelType nodes in more cases. ... eval_const_expressions sometimes produced RelabelType nodes that were useless because they just relabeled an expression to the same exposed type it already had. This is worth avoiding because it can cause two equivalent expressions to not be equal(), preventing recognition of useful optimizations. In the test case added here, an unpatched planner fails to notice that the "sqli = constant" clause renders a sort step unnecessary, because one code path produces an extra RelabelType and another doesn't. Fix by ensuring that eval_const_expressions_mutator's T_RelabelType case will not add in an unnecessary RelabelType. Also save some code by sharing a subroutine with the effectively-equivalent cases for CollateExpr and CoerceToDomain. (CollateExpr had no bug, and I think that the case couldn't arise with CoerceToDomain, but it seems prudent to do the same check for all three cases.) Back-patch to v12. In principle this has been wrong all along, but I haven't seen a case where it causes visible misbehavior before v12, so refrain from changing stable branches unnecessarily. Per investigation of a report from Eric Gillum. Discussion: https://postgr.es/m/CAMmjdmvAZsUEskHYj=KT9sTukVVCiCSoe_PBKOXsncFeAUDPCQ@mail.gmail.com	6 years ago
Tom Lane	913bbd88dc	Improve the handling of result type coercions in SQL functions. ... Use the parser's standard type coercion machinery to convert the output column(s) of a SQL function's final SELECT or RETURNING to the type(s) they should have according to the function's declared result type. We'll allow any case where an assignment-level coercion is available. Previously, we failed unless the required coercion was a binary-compatible one (and the documentation ignored this, falsely claiming that the types must match exactly). Notably, the coercion now accounts for typmods, so that cases where a SQL function is declared to return a composite type whose columns are typmod-constrained now behave as one would expect. Arguably this aspect is a bug fix, but the overall behavioral change here seems too large to consider back-patching. A nice side-effect is that functions can now be inlined in a few cases where we previously failed to do so because of type mismatches. Discussion: https://postgr.es/m/18929.1574895430@sss.pgh.pa.us	6 years ago
Bruce Momjian	7559d8ebfa	Update copyrights for 2020 ... Backpatch-through: update all files in master, backpatch legal files through 9.4	6 years ago
Tom Lane	5ee190f8ec	Rationalize use of list_concat + list_copy combinations. ... In the wake of commit 1cff1b95a, the result of list_concat no longer shares the ListCells of the second input. Therefore, we can replace "list_concat(x, list_copy(y))" with just "list_concat(x, y)". To improve call sites that were list_copy'ing the first argument, or both arguments, invent "list_concat_copy()" which produces a new list sharing no ListCells with either input. (This is a bit faster than "list_concat(list_copy(x), y)" because it makes the result list the right size to start with.) In call sites that were not list_copy'ing the second argument, the new semantics mean that we are usually leaking the second List's storage, since typically there is no remaining pointer to it. We considered inventing another list_copy variant that would list_free the second input, but concluded that for most call sites it isn't worth worrying about, given the relative compactness of the new List representation. (Note that in cases where such leakage would happen, the old code already leaked the second List's header; so we're only discussing the size of the leak not whether there is one. I did adjust two or three places that had been troubling to free that header so that they manually free the whole second List.) Patch by me; thanks to David Rowley for review. Discussion: https://postgr.es/m/11587.1550975080@sss.pgh.pa.us	6 years ago
Tom Lane	7266d0997d	Allow functions-in-FROM to be pulled up if they reduce to constants. ... This allows simplification of the plan tree in some common usage patterns: we can get rid of a join to the function RTE. In principle we could pull up any immutable expression, but restricting it to Consts avoids the risk that multiple evaluations of the expression might cost more than we can save. (Possibly this could be improved in future --- but we've more or less promised people that putting a function in FROM guarantees single evaluation, so we'd have to tread carefully.) To do this, we need to rearrange when eval_const_expressions() happens for expressions in function RTEs. I moved it to inline_set_returning_functions(), which already has to iterate over every function RTE, and in consequence renamed that function to preprocess_function_rtes(). A useful consequence is that inline_set_returning_function() no longer has to do this for itself, simplifying that code. In passing, break out pull_up_simple_subquery's code that knows where everything that needs pullup_replace_vars() processing is, so that the new pull_up_constant_function() routine can share it. We'd gotten away with one-and-a-half copies of that code so far, since pull_up_simple_values() could assume that a lot of cases didn't apply to it --- but I don't think pull_up_constant_function() can make any simplifying assumptions. Might as well make pull_up_simple_values() use it too. (Possibly this refactoring should go further: maybe we could share some of the code to fill in the pullup_replace_vars_context struct? For now, I left it that the callers fill that completely.) Note: the one existing test case that this patch changes has to be changed because inlining its function RTEs would destroy the point of the test, namely to check join order. Alexander Kuzmenkov and Aleksandr Parfenov, reviewed by Antonin Houska and Anastasia Lubennikova, and whacked around some more by me Discussion: https://postgr.es/m/402356c32eeb93d4fed01f66d6c7fe2d@postgrespro.ru	6 years ago
Tom Lane	d97b714a21	Avoid using lcons and list_delete_first where it's easy to do so. ... Formerly, lcons was about the same speed as lappend, but with the new List implementation, that's not so; with a long List, data movement imposes an O(N) cost on lcons and list_delete_first, but not lappend. Hence, invent list_delete_last with semantics parallel to list_delete_first (but O(1) cost), and change various places to use lappend and list_delete_last where this can be done without much violence to the code logic. There are quite a few places that construct result lists using lcons not lappend. Some have semantic rationales for that; I added comments about it to a couple that didn't have them already. In many such places though, I think the coding is that way only because back in the dark ages lcons was faster than lappend. Hence, switch to lappend where this can be done without causing semantic changes. In ExecInitExprRec(), this results in aggregates and window functions that are in the same plan node being executed in a different order than before. Generally, the executions of such functions ought to be independent of each other, so this shouldn't result in visibly different query results. But if you push it, as one regression test case does, you can show that the order is different. The new order seems saner; it's closer to the order of the functions in the query text. And we never documented or promised anything about this, anyway. Also, in gistfinishsplit(), don't bother building a reverse-order list; it's easy now to iterate backwards through the original list. It'd be possible to go further towards removing uses of lcons and list_delete_first, but it'd require more extensive logic changes, and I'm not convinced it's worth it. Most of the remaining uses deal with queues that probably never get long enough to be worth sweating over. (Actually, I doubt that any of the changes in this patch will have measurable performance effects either. But better to have good examples than bad ones in the code base.) Patch by me, thanks to David Rowley and Daniel Gustafsson for review. Discussion: https://postgr.es/m/21272.1563318411@sss.pgh.pa.us	6 years ago
Tom Lane	1cff1b95ab	Represent Lists as expansible arrays, not chains of cons-cells. ... Originally, Postgres Lists were a more or less exact reimplementation of Lisp lists, which consist of chains of separately-allocated cons cells, each having a value and a next-cell link. We'd hacked that once before (commit d0b4399d8) to add a separate List header, but the data was still in cons cells. That makes some operations -- notably list_nth() -- O(N), and it's bulky because of the next-cell pointers and per-cell palloc overhead, and it's very cache-unfriendly if the cons cells end up scattered around rather than being adjacent. In this rewrite, we still have List headers, but the data is in a resizable array of values, with no next-cell links. Now we need at most two palloc's per List, and often only one, since we can allocate some values in the same palloc call as the List header. (Of course, extending an existing List may require repalloc's to enlarge the array. But this involves just O(log N) allocations not O(N).) Of course this is not without downsides. The key difficulty is that addition or deletion of a list entry may now cause other entries to move, which it did not before. For example, that breaks foreach() and sister macros, which historically used a pointer to the current cons-cell as loop state. We can repair those macros transparently by making their actual loop state be an integer list index; the exposed "ListCell *" pointer is no longer state carried across loop iterations, but is just a derived value. (In practice, modern compilers can optimize things back to having just one loop state value, at least for simple cases with inline loop bodies.) In principle, this is a semantics change for cases where the loop body inserts or deletes list entries ahead of the current loop index; but I found no such cases in the Postgres code. The change is not at all transparent for code that doesn't use foreach() but chases lists "by hand" using lnext(). The largest share of such code in the backend is in loops that were maintaining "prev" and "next" variables in addition to the current-cell pointer, in order to delete list cells efficiently using list_delete_cell(). However, we no longer need a previous-cell pointer to delete a list cell efficiently. Keeping a next-cell pointer doesn't work, as explained above, but we can improve matters by changing such code to use a regular foreach() loop and then using the new macro foreach_delete_current() to delete the current cell. (This macro knows how to update the associated foreach loop's state so that no cells will be missed in the traversal.) There remains a nontrivial risk of code assuming that a ListCell * pointer will remain good over an operation that could now move the list contents. To help catch such errors, list.c can be compiled with a new define symbol DEBUG_LIST_MEMORY_USAGE that forcibly moves list contents whenever that could possibly happen. This makes list operations significantly more expensive so it's not normally turned on (though it is on by default if USE_VALGRIND is on). There are two notable API differences from the previous code: * lnext() now requires the List's header pointer in addition to the current cell's address. * list_delete_cell() no longer requires a previous-cell argument. These changes are somewhat unfortunate, but on the other hand code using either function needs inspection to see if it is assuming anything it shouldn't, so it's not all bad. Programmers should be aware of these significant performance changes: * list_nth() and related functions are now O(1); so there's no major access-speed difference between a list and an array. * Inserting or deleting a list element now takes time proportional to the distance to the end of the list, due to moving the array elements. (However, it typically *doesn't* require palloc or pfree, so except in long lists it's probably still faster than before.) Notably, lcons() used to be about the same cost as lappend(), but that's no longer true if the list is long. Code that uses lcons() and list_delete_first() to maintain a stack might usefully be rewritten to push and pop at the end of the list rather than the beginning. * There are now list_insert_nth...() and list_delete_nth...() functions that add or remove a list cell identified by index. These have the data-movement penalty explained above, but there's no search penalty. * list_concat() and variants now copy the second list's data into storage belonging to the first list, so there is no longer any sharing of cells between the input lists. The second argument is now declared "const List *" to reflect that it isn't changed. This patch just does the minimum needed to get the new implementation in place and fix bugs exposed by the regression tests. As suggested by the foregoing, there's a fair amount of followup work remaining to do. Also, the ENABLE_LIST_COMPAT macros are finally removed in this commit. Code using those should have been gone a dozen years ago. Patch by me; thanks to David Rowley, Jesper Pedersen, and others for review. Discussion: https://postgr.es/m/11587.1550975080@sss.pgh.pa.us	6 years ago
Michael Paquier	c74d49d41c	Fix many typos and inconsistencies ... Author: Alexander Lakhin Discussion: https://postgr.es/m/af27d1b3-a128-9d62-46e0-88f424397f44@gmail.com	6 years ago
Tom Lane	8255c7a5ee	Phase 2 pgindent run for v12. ... Switch to 2.1 version of pg_bsd_indent. This formats multiline function declarations "correctly", that is with additional lines of parameter declarations indented to match where the first line's left parenthesis is. Discussion: https://postgr.es/m/CAEepm=0P3FeTXRcU5B2W3jv3PgRVZ-kGUXLGfd42FFhUROO3ug@mail.gmail.com	6 years ago
Tom Lane	e04a3905e4	Improve planner's understanding of strictness of type coercions. ... PG type coercions are generally strict, ie a NULL input must produce a NULL output (or, in domain cases, possibly an error). The planner's understanding of that was a bit incomplete though, so improve it: * Teach contain_nonstrict_functions() that CoerceViaIO can always be considered strict. Previously it believed that only if the underlying I/O functions were marked strict, which is often but not always true. * Teach clause_is_strict_for() that CoerceViaIO, ArrayCoerceExpr, ConvertRowtypeExpr, CoerceToDomain can all be considered strict. Previously it knew nothing about any of them. The main user-visible impact of this is that IS NOT NULL predicates can be proven to hold from expressions involving casts in more cases than before, allowing partial indexes with such predicates to be used without extra pushups. This reduces the surprise factor for users, who may well be used to ordinary (function-call-based) casts being known to be strict. Per a gripe from Samuel Williams. This doesn't rise to the level of a bug, IMO, so no back-patch. Discussion: https://postgr.es/m/27571.1550617881@sss.pgh.pa.us	7 years ago
Tom Lane	1571bc0f06	Fix incorrect strictness test for ArrayCoerceExpr expressions. ... The recursion in contain_nonstrict_functions_walker() was done wrong, causing the strictness check to be bypassed for a parse node that is the immediate input of an ArrayCoerceExpr node. This could allow, for example, incorrect decisions about whether a strict SQL function can be inlined. I didn't add a regression test, because (a) the bug is so narrow and (b) I couldn't think of a test case that wasn't dependent on a large number of other behaviors, to the point where it would likely soon rot to the point of not testing what it was intended to. I broke this in commit c12d570fa, so back-patch to v11. Discussion: https://postgr.es/m/27571.1550617881@sss.pgh.pa.us	7 years ago
Tom Lane	74dfe58a59	Allow extensions to generate lossy index conditions. ... For a long time, indxpath.c has had the ability to extract derived (lossy) index conditions from certain operators such as LIKE. For just as long, it's been obvious that we really ought to make that capability available to extensions. This commit finally accomplishes that, by adding another API for planner support functions that lets them create derived index conditions for their functions. As proof of concept, the hardwired "special index operator" code formerly present in indxpath.c is pushed out to planner support functions attached to LIKE and other relevant operators. A weak spot in this design is that an extension needs to know OIDs for the operators, datatypes, and opfamilies involved in the transformation it wants to make. The core-code prototypes use hard-wired OID references but extensions don't have that option for their own operators etc. It's usually possible to look up the required info, but that may be slow and inconvenient. However, improving that situation is a separate task. I want to do some additional refactorization around selfuncs.c, but that also seems like a separate task. Discussion: https://postgr.es/m/15193.1548028093@sss.pgh.pa.us	7 years ago
Tom Lane	a391ff3c3d	Build out the planner support function infrastructure. ... Add support function requests for estimating the selectivity, cost, and number of result rows (if a SRF) of the target function. The lack of a way to estimate selectivity of a boolean-returning function in WHERE has been a recognized deficiency of the planner since Berkeley days. This commit finally fixes it. In addition, non-constant estimates of cost and number of output rows are now possible. We still fall back to looking at procost and prorows if the support function doesn't service the request, of course. To make concrete use of the possibility of estimating output rowcount for SRFs, this commit adds support functions for array_unnest(anyarray) and the integer variants of generate_series; the lack of plausible rowcount estimates for those, even when it's obvious to a human, has been a repeated subject of complaints. Obviously, much more could now be done in this line, but I'm mostly just trying to get the infrastructure in place. Discussion: https://postgr.es/m/15193.1548028093@sss.pgh.pa.us	7 years ago
Tom Lane	1fb57af920	Create the infrastructure for planner support functions. ... Rename/repurpose pg_proc.protransform as "prosupport". The idea is still that it names an internal function that provides knowledge to the planner about the behavior of the function it's attached to; but redesign the API specification so that it's not limited to doing just one thing, but can support an extensible set of requests. The original purpose of simplifying a function call is handled by the first request type to be invented, SupportRequestSimplify. Adjust all the existing transform functions to handle this API, and rename them fron "xxx_transform" to "xxx_support" to reflect the potential generalization of what they do. (Since we never previously provided any way for extensions to add transform functions, this change doesn't create an API break for them.) Also add DDL and pg_dump support for attaching a support function to a user-defined function. Unfortunately, DDL access has to be restricted to superusers, at least for now; but seeing that support functions will pretty much have to be written in C, that limitation is just theoretical. (This support is untested in this patch, but a follow-on patch will add cases that exercise it.) Discussion: https://postgr.es/m/15193.1548028093@sss.pgh.pa.us	7 years ago
Tom Lane	1a8d5afb0d	Refactor the representation of indexable clauses in IndexPaths. ... In place of three separate but interrelated lists (indexclauses, indexquals, and indexqualcols), an IndexPath now has one list "indexclauses" of IndexClause nodes. This holds basically the same information as before, but in a more useful format: in particular, there is now a clear connection between an indexclause (an original restriction clause from WHERE or JOIN/ON) and the indexquals (directly usable index conditions) derived from it. We also change the ground rules a bit by mandating that clause commutation, if needed, be done up-front so that what is stored in the indexquals list is always directly usable as an index condition. This gets rid of repeated re-determination of which side of the clause is the indexkey during costing and plan generation, as well as repeated lookups of the commutator operator. To minimize the added up-front cost, the typical case of commuting a plain OpExpr is handled by a new special-purpose function commute_restrictinfo(). For RowCompareExprs, generating the new clause properly commuted to begin with is not really any more complex than before, it's just different --- and we can save doing that work twice, as the pretty-klugy original implementation did. Tracking the connection between original and derived clauses lets us also track explicitly whether the derived clauses are an exact or lossy translation of the original. This provides a cheap solution to getting rid of unnecessary rechecks of boolean index clauses, which previously seemed like it'd be more expensive than it was worth. Another pleasant (IMO) side-effect is that EXPLAIN now always shows index clauses with the indexkey on the left; this seems less confusing. This commit leaves expand_indexqual_conditions() and some related functions in a slightly messy state. I didn't bother to change them any more than minimally necessary to work with the new data structure, because all that code is going to be refactored out of existence in a follow-on patch. Discussion: https://postgr.es/m/22182.1549124950@sss.pgh.pa.us	7 years ago
Alvaro Herrera	558d77f20e	Renaming for new subscripting mechanism ... Over at patch https://commitfest.postgresql.org/21/1062/ Dmitry wants to introduce a more generic subscription mechanism, which allows subscripting not only arrays but also other object types such as JSONB. That functionality is introduced in a largish invasive patch, out of which this internal renaming patch was extracted. Author: Dmitry Dolgov Reviewed-by: Tom Lane, Arthur Zakirov Discussion: https://postgr.es/m/CA+q6zcUK4EqPAu7XRRO5CCjMwhz5zvg+rfWuLzVoxp_5sKS6=w@mail.gmail.com	7 years ago
Tom Lane	f09346a9c6	Refactor planner's header files. ... Create a new header optimizer/optimizer.h, which exposes just the planner functions that can be used "at arm's length", without need to access Paths or the other planner-internal data structures defined in nodes/relation.h. This is intended to provide the whole planner API seen by most of the rest of the system; although FDWs still need to use additional stuff, and more thought is also needed about just what selfuncs.c should rely on. The main point of doing this now is to limit the amount of new #include baggage that will be needed by "planner support functions", which I expect to introduce later, and which will be in relevant datatype modules rather than anywhere near the planner. This commit just moves relevant declarations into optimizer.h from other header files (a couple of which go away because everything got moved), and adjusts #include lists to match. There's further cleanup that could be done if we want to decide that some stuff being exposed by optimizer.h doesn't belong in the planner at all, but I'll leave that for another day. Discussion: https://postgr.es/m/11460.1548706639@sss.pgh.pa.us	7 years ago
Tom Lane	a1b8c41e99	Make some small planner API cleanups. ... Move a few very simple node-creation and node-type-testing functions from the planner's clauses.c to nodes/makefuncs and nodes/nodeFuncs. There's nothing planner-specific about them, as evidenced by the number of other places that were using them. While at it, rename and_clause() etc to is_andclause() etc, to clarify that they are node-type-testing functions not node-creation functions. And use "static inline" implementations for the shortest ones. Also, modify flatten_join_alias_vars() and some subsidiary functions to take a Query not a PlannerInfo to define the join structure that Vars should be translated according to. They were only using the "parse" field of the PlannerInfo anyway, so this just requires removing one level of indirection. The advantage is that now parse_agg.c can use flatten_join_alias_vars() without the horrid kluge of creating an incomplete PlannerInfo, which will allow that file to be decoupled from relation.h in a subsequent patch. Discussion: https://postgr.es/m/11460.1548706639@sss.pgh.pa.us	7 years ago
Tom Lane	4be058fe9e	In the planner, replace an empty FROM clause with a dummy RTE. ... The fact that "SELECT expression" has no base relations has long been a thorn in the side of the planner. It makes it hard to flatten a sub-query that looks like that, or is a trivial VALUES() item, because the planner generally uses relid sets to identify sub-relations, and such a sub-query would have an empty relid set if we flattened it. prepjointree.c contains some baroque logic that works around this in certain special cases --- but there is a much better answer. We can replace an empty FROM clause with a dummy RTE that acts like a table of one row and no columns, and then there are no such corner cases to worry about. Instead we need some logic to get rid of useless dummy RTEs, but that's simpler and covers more cases than what was there before. For really trivial cases, where the query is just "SELECT expression" and nothing else, there's a hazard that adding the extra RTE makes for a noticeable slowdown; even though it's not much processing, there's not that much for the planner to do overall. However testing says that the penalty is very small, close to the noise level. In more complex queries, this is able to find optimizations that we could not find before. The new RTE type is called RTE_RESULT, since the "scan" plan type it gives rise to is a Result node (the same plan we produced for a "SELECT expression" query before). To avoid confusion, rename the old ResultPath path type to GroupResultPath, reflecting that it's only used in degenerate grouping cases where we know the query produces just one grouped row. (It wouldn't work to unify the two cases, because there are different rules about where the associated quals live during query_planner.) Note: although this touches readfuncs.c, I don't think a catversion bump is required, because the added case can't occur in stored rules, only plans. Patch by me, reviewed by David Rowley and Mark Dilger Discussion: https://postgr.es/m/15944.1521127664@sss.pgh.pa.us	7 years ago
Peter Eisentraut	7c079d7417	Allow generalized expression syntax for partition bounds ... Previously, only literals were allowed. This change allows general expressions, including functions calls, which are evaluated at the time the DDL command is executed. Besides offering some more functionality, it simplifies the parser structures and removes some inconsistencies in how the literals were handled. Author: Kyotaro Horiguchi, Tom Lane, Amit Langote Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com> Discussion: https://www.postgresql.org/message-id/flat/9f88b5e0-6da2-5227-20d0-0d7012beaa1c@lab.ntt.co.jp/	7 years ago
Tom Lane	68a13f28be	Don't believe MinMaxExpr is leakproof without checking. ... MinMaxExpr invokes the btree comparison function for its input datatype, so it's only leakproof if that function is. Many such functions are indeed leakproof, but others are not, and we should not just assume that they are. Hence, adjust contain_leaked_vars to verify the leakproofness of the referenced function explicitly. I didn't add a regression test because it would need to depend on some particular comparison function being leaky, and that's a moving target, per discussion. This has been wrong all along, so back-patch to supported branches. Discussion: https://postgr.es/m/31042.1546194242@sss.pgh.pa.us	7 years ago
Bruce Momjian	97c39498e5	Update copyright for 2019 ... Backpatch-through: certain files through 9.4	7 years ago
Tom Lane	6f19a8c41f	Teach eval_const_expressions to constant-fold LEAST/GREATEST expressions. ... Doing this requires an assumption that the invoked btree comparison function is immutable. We could check that explicitly, but in other places such as contain_mutable_functions we just assume that it's true, so we may as well do likewise here. (If the comparison function's behavior isn't immutable, the sort order in indexes built with it would be unstable, so it seems certainly wrong for it not to be so.) Vik Fearing Discussion: https://postgr.es/m/c6e8504c-4c43-35fa-6c8f-3c0b80a912cc@2ndquadrant.com	7 years ago
Tom Lane	04fe805a17	Drop no-op CoerceToDomain nodes from expressions at planning time. ... If a domain has no constraints, then CoerceToDomain doesn't really do anything and can be simplified to a RelabelType. This not only eliminates cycles at execution, but allows the planner to optimize better (for instance, match the coerced expression to an index on the underlying column). However, we do have to support invalidating the plan later if a constraint gets added to the domain. That's comparable to the case of a change to a SQL function that had been inlined into a plan, so all the necessary logic already exists for plans depending on functions. We need only duplicate or share that logic for domains. ALTER DOMAIN ADD/DROP CONSTRAINT need to be taught to send out sinval messages for the domain's pg_type entry, since those operations don't update that row. (ALTER DOMAIN SET/DROP NOT NULL do update that row, so no code change is needed for them.) Testing this revealed what's really a pre-existing bug in plpgsql: it caches the SQL-expression-tree expansion of type coercions and had no provision for invalidating entries in that cache. Up to now that was only a problem if such an expression had inlined a SQL function that got changed, which is unlikely though not impossible. But failing to track changes of domain constraints breaks an existing regression test case and would likely cause practical problems too. We could fix that locally in plpgsql, but what seems like a better idea is to build some generic infrastructure in plancache.c to store standalone expressions and track invalidation events for them. (It's tempting to wonder whether plpgsql's "simple expression" stuff could use this code with lower overhead than its current use of the heavyweight plancache APIs. But I've left that idea for later.) Other stuff fixed in passing: * Allow estimate_expression_value() to drop CoerceToDomain unconditionally, effectively assuming that the coercion will succeed. This will improve planner selectivity estimates for cases involving estimatable expressions that are coerced to domains. We could have done this independently of everything else here, but there wasn't previously any need for eval_const_expressions_mutator to know about CoerceToDomain at all. * Use a dlist for plancache.c's list of cached plans, rather than a manually threaded singly-linked list. That eliminates a potential performance problem in DropCachedPlan. * Fix a couple of inconsistencies in typecmds.c about whether operations on domains drop RowExclusiveLock on pg_type. Our common practice is that DDL operations do drop catalog locks, so standardize on that choice. Discussion: https://postgr.es/m/19958.1544122124@sss.pgh.pa.us	7 years ago
Andrew Gierth	5613da4cc7	Optimize nested ConvertRowtypeExpr nodes. ... A ConvertRowtypeExpr is used to translate a whole-row reference of a child to that of a parent. The planner produces nested ConvertRowtypeExpr while translating whole-row reference of a leaf partition in a multi-level partition hierarchy. Executor then translates the whole-row reference from the leaf partition into all the intermediate parent's whole-row references before arriving at the final whole-row reference. It could instead translate the whole-row reference from the leaf partition directly to the top-most parent's whole-row reference skipping any intermediate translations. Ashutosh Bapat, with tests by Kyotaro Horiguchi and some editorialization by me. Reviewed by Andres Freund, Pavel Stehule, Kyotaro Horiguchi, Dmitry Dolgov, Tom Lane.	7 years ago
Tom Lane	14a158f9bf	Fix interaction of CASE and ArrayCoerceExpr. ... An array-type coercion appearing within a CASE that has a constant (after const-folding) test expression was mangled by the planner, causing all the elements of the resulting array to be equal to the coerced value of the CASE's test expression. This is my oversight in commit c12d570fa: that changed ArrayCoerceExpr to use a subexpression involving a CaseTestExpr, and I didn't notice that eval_const_expressions needed an adjustment to keep from folding such a CaseTestExpr to a constant when it's inside a suitable CASE. This is another in what's getting to be a depressingly long line of bugs associated with misidentification of the referent of a CaseTestExpr. We're overdue to redesign that mechanism; but any such fix is unlikely to be back-patchable into v11. As a stopgap, fix eval_const_expressions to do what it must here. Also add a bunch of comments pointing out the restrictions and assumptions that are needed to make this work at all. Also fix a related oversight: contain_context_dependent_node() was not aware of the relationship of ArrayCoerceExpr to CaseTestExpr. That was somewhat fail-soft, in that the outcome of a wrong answer would be to prevent optimizations that could have been made, but let's fix it while we're at it. Per bug #15471 from Matt Williams. Back-patch to v11 where the faulty logic came in. Discussion: https://postgr.es/m/15471-1117f49271989bad@postgresql.org	7 years ago
Amit Kapila	14e9b2a752	Prohibit pushing subqueries containing window function calculation to ... workers. Allowing window function calculation in workers leads to inconsistent results because if the input row ordering is not fully deterministic, the output of window functions might vary across workers. The fix is to treat them as parallel-restricted. In the passing, improve the coding pattern in max_parallel_hazard_walker so that it has a chain of mutually-exclusive if ... else if ... else if ... else if ... IsA tests. Reported-by: Marko Tiikkaja Bug: 15324 Author: Amit Kapila Reviewed-by: Tom Lane Backpatch-through: 9.6 Discussion: https://postgr.es/m/CAL9smLAnfPJCDUUG4ckX2iznj53V7VSMsYefzZieN93YxTNOcw@mail.gmail.com	7 years ago
Tom Lane	662d12aea1	Avoid crash in eval_const_expressions if a Param's type changes. ... Since commit 6719b238e it's been possible for the values of plpgsql record field variables to be exposed to the planner as Params. (Before that, plpgsql never supplied values for such variables during planning, so that the problematic code wasn't reached.) Other places that touch potentially-type-mutable Params either cope gracefully or do runtime-test-and-ereport checks that the type is what they expect. But eval_const_expressions() just had an Assert, meaning that it either failed the assertion or risked crashes due to using an incompatible value. In this case, rather than throwing an ereport immediately, we can just not perform a const-substitution in case of a mismatch. This seems important for the same reason that the Param fetch was speculative: we might not actually reach this part of the expression at runtime. Test case will follow in a separate commit. Patch by me, pursuant to bug report from Andrew Gierth. Back-patch to v11 where the previous commit appeared. Discussion: https://postgr.es/m/87wotkfju1.fsf@news-spur.riddles.org.uk	7 years ago
Peter Eisentraut	a8677e3ff6	Support named and default arguments in CALL ... We need to call expand_function_arguments() to expand named and default arguments. In PL/pgSQL, we also need to deal with named and default INOUT arguments when receiving the output values into variables. Author: Pavel Stehule <pavel.stehule@gmail.com>	8 years ago
Andrew Dunstan	16828d5c02	Fast ALTER TABLE ADD COLUMN with a non-NULL default ... Currently adding a column to a table with a non-NULL default results in a rewrite of the table. For large tables this can be both expensive and disruptive. This patch removes the need for the rewrite as long as the default value is not volatile. The default expression is evaluated at the time of the ALTER TABLE and the result stored in a new column (attmissingval) in pg_attribute, and a new column (atthasmissing) is set to true. Any existing row when fetched will be supplied with the attmissingval. New rows will have the supplied value or the default and so will never need the attmissingval. Any time the table is rewritten all the atthasmissing and attmissingval settings for the attributes are cleared, as they are no longer needed. The most visible code change from this is in heap_attisnull, which acquires a third TupleDesc argument, allowing it to detect a missing value if there is one. In many cases where it is known that there will not be any (e.g. catalog relations) NULL can be passed for this argument. Andrew Dunstan, heavily modified from an original patch from Serge Rielau. Reviewed by Tom Lane, Andres Freund, Tomas Vondra and David Rowley. Discussion: https://postgr.es/m/31e2e921-7002-4c27-59f5-51f08404c858@2ndQuadrant.com	8 years ago
Tom Lane	877cdf11ea	Mop-up for letting VOID-returning SQL functions end with a SELECT. ... Part of the intent in commit fd1a421fe was to allow SQL functions that are declared to return VOID to contain anything, including an unrelated final SELECT, the same as SQL-language procedures can. However, the planner's inlining logic didn't get that memo. Fix it, and add some regression tests covering this area, since evidently we had none. In passing, clean up some typos in comments in create_function_3.sql, and get rid of its none-too-safe assumption that DROP CASCADE notice output is immutably ordered. Per report from Prabhat Sahu. Discussion: https://postgr.es/m/CANEvxPqxAj6nNHVcaXxpTeEFPmh24Whu+23emgjiuKrhJSct0A@mail.gmail.com	8 years ago
Peter Eisentraut	fd1a421fe6	Add prokind column, replacing proisagg and proiswindow ... The new column distinguishes normal functions, procedures, aggregates, and window functions. This replaces the existing columns proisagg and proiswindow, and replaces the convention that procedures are indicated by prorettype == 0. Also change prorettype to be VOIDOID for procedures. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Michael Paquier <michael@paquier.xyz>	8 years ago
Peter Eisentraut	9e945f8626	Fix Latin spelling ... "c.f." should be "cf.".	8 years ago