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* Add back SQLValueFunction for SQL keywordsMichael Paquier2023-05-171-4/+28
| | | | | | | | | | | | | | | | | | | | | | | | This is equivalent to a revert of f193883 and fb32748, with the addition that the declaration of the SQLValueFunction node needs to gain a couple of node_attr for query jumbling. The performance impact of removing the function call inlining is proving to be too huge for some workloads where these are used. A worst-case test case of involving only simple SELECT queries with a SQL keyword is proving to lead to a reduction of 10% in TPS via pgbench and prepared queries on a high-end machine. None of the tests I ran back for this set of changes saw such a huge gap, but Alexander Lakhin and Andres Freund have found that this can be noticeable. Keeping the older performance would mean to do more inlining in the executor when using COERCE_SQL_SYNTAX for a function expression, similarly to what SQLValueFunction does. This requires more redesign work and there is little time until 16beta1 is released, so for now reverting the change is the best way forward, bringing back the previous performance. Bump catalog version. Reported-by: Alexander Lakhin Discussion: https://postgr.es/m/b32bed1b-0746-9b20-1472-4bdc9ca66d52@gmail.com
* Code review for recent SQL/JSON commitsAlvaro Herrera2023-04-041-163/+257
| | | | | | | | | | | | | | | | | | | | | | | | - At the last minute and for no particularly good reason, I changed the WITHOUT token to be marked especially for lookahead, from the one in WITHOUT TIME to the one in WITHOUT UNIQUE. Study of upcoming patches (where a new WITHOUT ARRAY WRAPPER clause is added) showed me that the former was better, so put it back the way the original patch had it. - update exprTypmod() for JsonConstructorExpr to return the typmod of the RETURNING clause, as a comment there suggested. Perhaps it's possible for this to make a difference with datetime types, but I didn't try to build a test case. - The nodeFuncs.c support code for new nodes was calling walker() directly instead of the WALK() macro as introduced by commit 1c27d16e6e5c. Modernize that. Also add exprLocation() support for a couple of nodes that missed it. Lastly, reorder the code more sensibly. The WITHOUT_LA -> WITHOUT change means that stored rules containing either WITHOUT TIME ZONE or WITHOUT UNIQUE KEYS would change representation. Therefore, bump catversion. Discussion: https://postgr.es/m/20230329181708.e64g2tpy7jyufqkr@alvherre.pgsql
* SQL/JSON: support the IS JSON predicateAlvaro Herrera2023-03-311-0/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces the SQL standard IS JSON predicate. It operates on text and bytea values representing JSON, as well as on the json and jsonb types. Each test has IS and IS NOT variants and supports a WITH UNIQUE KEYS flag. The tests are: IS JSON [VALUE] IS JSON ARRAY IS JSON OBJECT IS JSON SCALAR These should be self-explanatory. The WITH UNIQUE KEYS flag makes these return false when duplicate keys exist in any object within the value, not necessarily directly contained in the outermost object. Author: Nikita Glukhov <n.gluhov@postgrespro.ru> Author: Teodor Sigaev <teodor@sigaev.ru> Author: Oleg Bartunov <obartunov@gmail.com> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Amit Langote <amitlangote09@gmail.com> Author: Andrew Dunstan <andrew@dunslane.net> Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/CAF4Au4w2x-5LTnN_bxky-mq4=WOqsGsxSpENCzHRAzSnEd8+WQ@mail.gmail.com Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org
* SQL/JSON: add standard JSON constructor functionsAlvaro Herrera2023-03-291-0/+221
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit introduces the SQL/JSON standard-conforming constructors for JSON types: JSON_ARRAY() JSON_ARRAYAGG() JSON_OBJECT() JSON_OBJECTAGG() Most of the functionality was already present in PostgreSQL-specific functions, but these include some new functionality such as the ability to skip or include NULL values, and to allow duplicate keys or throw error when they are found, as well as the standard specified syntax to specify output type and format. Author: Nikita Glukhov <n.gluhov@postgrespro.ru> Author: Teodor Sigaev <teodor@sigaev.ru> Author: Oleg Bartunov <obartunov@gmail.com> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Amit Langote <amitlangote09@gmail.com> Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/CAF4Au4w2x-5LTnN_bxky-mq4=WOqsGsxSpENCzHRAzSnEd8+WQ@mail.gmail.com Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org
* Make Vars be outer-join-aware.Tom Lane2023-01-301-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Traditionally we used the same Var struct to represent the value of a table column everywhere in parse and plan trees. This choice predates our support for SQL outer joins, and it's really a pretty bad idea with outer joins, because the Var's value can depend on where it is in the tree: it might go to NULL above an outer join. So expression nodes that are equal() per equalfuncs.c might not represent the same value, which is a huge correctness hazard for the planner. To improve this, decorate Var nodes with a bitmapset showing which outer joins (identified by RTE indexes) may have nulled them at the point in the parse tree where the Var appears. This allows us to trust that equal() Vars represent the same value. A certain amount of klugery is still needed to cope with cases where we re-order two outer joins, but it's possible to make it work without sacrificing that core principle. PlaceHolderVars receive similar decoration for the same reason. In the planner, we include these outer join bitmapsets into the relids that an expression is considered to depend on, and in consequence also add outer-join relids to the relids of join RelOptInfos. This allows us to correctly perceive whether an expression can be calculated above or below a particular outer join. This change affects FDWs that want to plan foreign joins. They *must* follow suit when labeling foreign joins in order to match with the core planner, but for many purposes (if postgres_fdw is any guide) they'd prefer to consider only base relations within the join. To support both requirements, redefine ForeignScan.fs_relids as base+OJ relids, and add a new field fs_base_relids that's set up by the core planner. Large though it is, this commit just does the minimum necessary to install the new mechanisms and get check-world passing again. Follow-up patches will perform some cleanup. (The README additions and comments mention some stuff that will appear in the follow-up.) Patch by me; thanks to Richard Guo for review. Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
* Update copyright for 2023Bruce Momjian2023-01-021-1/+1
| | | | Backpatch-through: 11
* Replace SQLValueFunction by COERCE_SQL_SYNTAXMichael Paquier2022-11-211-23/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This switch impacts 9 patterns related to a SQL-mandated special syntax for function calls: - LOCALTIME [ ( typmod ) ] - LOCALTIMESTAMP [ ( typmod ) ] - CURRENT_TIME [ ( typmod ) ] - CURRENT_TIMESTAMP [ ( typmod ) ] - CURRENT_DATE Five new entries are added to pg_proc to compensate the removal of SQLValueFunction to provide backward-compatibility and making this change transparent for the end-user (for example for the attribute generated when a keyword is specified in a SELECT or in a FROM clause without an alias, or when specifying something else than an Iconst to the parser). The parser included a set of checks coming from the files in charge of holding the C functions used for the SQLValueFunction calls (as of transformSQLValueFunction()), which are now moved within each function's execution path, so this reduces the dependencies between the execution and the parsing steps. As of this change, all the SQL keywords use the same paths for their work, relying only on COERCE_SQL_SYNTAX. Like fb32748, no performance difference has been noticed, while the perf profiles get reduced with ExecEvalSQLValueFunction() gone. Bump catalog version. Reviewed-by: Corey Huinker, Ted Yu Discussion: https://postgr.es/m/YzaG3MoryCguUOym@paquier.xyz
* Switch SQLValueFunction on "name" to use COERCE_SQL_SYNTAXMichael Paquier2022-11-201-8/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit changes six SQL keywords to use COERCE_SQL_SYNTAX rather than relying on SQLValueFunction: - CURRENT_ROLE - CURRENT_USER - USER - SESSION_USER - CURRENT_CATALOG - CURRENT_SCHEMA Among the six, "user", "current_role" and "current_catalog" require specific SQL functions to allow ruleutils.c to map them to the SQL keywords these require when using COERCE_SQL_SYNTAX. Having pg_proc.proname match with the keyword ensures that the compatibility remains the same when projecting any of these keywords in a FROM clause to an attribute name when an alias is not specified. This is covered by the tests added in 2e0d80c, making sure that a correct mapping happens with each SQL keyword. The three others (current_schema, session_user and current_user) already have pg_proc entries for this job, so this brings more consistency between the way such keywords are treated in the parser, the executor and ruleutils.c. SQLValueFunction is reduced to half its contents after this change, simplifying its logic a bit as there is no need to enforce a C collation anymore for the entries returning a name as a result. I have made a few performance tests, with a million-ish calls to these keywords without seeing a difference in run-time or in perf profiles (ExecEvalSQLValueFunction() is removed from the profiles). The remaining SQLValueFunctions are now related to timestamps and dates. Bump catalog version. Reviewed-by: Corey Huinker Discussion: https://postgr.es/m/YzaG3MoryCguUOym@paquier.xyz
* Fix pg_stat_statements for MERGEAlvaro Herrera2022-09-271-2/+2
| | | | | | | | | | | | We weren't jumbling the merge action list, so wildly different commands would be considered to use the same query ID. Add that, mention it in the docs, and some test lines. Backpatch to 15. Author: Tatsu <bt22nakamorit@oss.nttdata.com> Reviewed-by: Julien Rouhaud <rjuju123@gmail.com> Discussion: https://postgr.es/m/d87e391694db75a038abc3b2597828e8@oss.nttdata.com
* Revise tree-walk APIs to improve spec compliance & silence warnings.Tom Lane2022-09-201-307/+304
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | expression_tree_walker and allied functions have traditionally declared their callback functions as, say, "bool (*walker) ()" to allow for variation in the declared types of the callback functions' context argument. This is apparently going to be forbidden by the next version of the C standard, and the latest version of clang warns about that. In any case it's always been pretty poor for error-detection purposes, so fixing it is a good thing to do. What we want to do is change the callback argument declarations to be like "bool (*walker) (Node *node, void *context)", which is correct so far as expression_tree_walker and friends are concerned, but not change the actual callback functions. Strict compliance with the C standard would require changing them to declare their arguments as "void *context" and then cast to the appropriate context struct type internally. That'd be very invasive and it would also introduce a bunch of opportunities for future bugs, since we'd no longer have any check that the correct sort of context object is passed by outside callers or internal recursion cases. Therefore, we're just going to ignore the standard's position that "void *" isn't necessarily compatible with struct pointers. No machine built in the last forty or so years actually behaves that way, so it's not worth introducing bug hazards for compatibility with long-dead hardware. Therefore, to silence these compiler warnings, introduce a layer of macro wrappers that cast the supplied function name to the official argument type. Thanks to our use of -Wcast-function-type, this will still produce a warning if the supplied function is seriously incompatible with the required signature, without going as far as the official spec restriction does. This method fixes the problem without any need for source code changes outside nodeFuncs.h/.c. However, it is an ABI break because the physically called functions now have names ending in "_impl". Hence we can only fix it this way in HEAD. In the back branches, we'll have to settle for disabling -Wdeprecated-non-prototype. Discussion: https://postgr.es/m/CA+hUKGKpHPDTv67Y+s6yiC8KH5OXeDg6a-twWo_xznKTcG0kSA@mail.gmail.com
* Revert SQL/JSON featuresAndrew Dunstan2022-09-011-486/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The reverts the following and makes some associated cleanups: commit f79b803dc: Common SQL/JSON clauses commit f4fb45d15: SQL/JSON constructors commit 5f0adec25: Make STRING an unreserved_keyword. commit 33a377608: IS JSON predicate commit 1a36bc9db: SQL/JSON query functions commit 606948b05: SQL JSON functions commit 49082c2cc: RETURNING clause for JSON() and JSON_SCALAR() commit 4e34747c8: JSON_TABLE commit fadb48b00: PLAN clauses for JSON_TABLE commit 2ef6f11b0: Reduce running time of jsonb_sqljson test commit 14d3f24fa: Further improve jsonb_sqljson parallel test commit a6baa4bad: Documentation for SQL/JSON features commit b46bcf7a4: Improve readability of SQL/JSON documentation. commit 112fdb352: Fix finalization for json_objectagg and friends commit fcdb35c32: Fix transformJsonBehavior commit 4cd8717af: Improve a couple of sql/json error messages commit f7a605f63: Small cleanups in SQL/JSON code commit 9c3d25e17: Fix JSON_OBJECTAGG uniquefying bug commit a79153b7a: Claim SQL standard compliance for SQL/JSON features commit a1e7616d6: Rework SQL/JSON documentation commit 8d9f9634e: Fix errors in copyfuncs/equalfuncs support for JSON node types. commit 3c633f32b: Only allow returning string types or bytea from json_serialize commit 67b26703b: expression eval: Fix EEOP_JSON_CONSTRUCTOR and EEOP_JSONEXPR size. The release notes are also adjusted. Backpatch to release 15. Discussion: https://postgr.es/m/40d2c882-bcac-19a9-754d-4299e1d87ac7@postgresql.org
* Fix incorrect tests for SRFs in relation_can_be_sorted_early().Tom Lane2022-08-031-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | Commit fac1b470a thought we could check for set-returning functions by testing only the top-level node in an expression tree. This is wrong in itself, and to make matters worse it encouraged others to make the same mistake, by exporting tlist.c's special-purpose IS_SRF_CALL() as a widely-visible macro. I can't find any evidence that anyone's taken the bait, but it was only a matter of time. Use expression_returns_set() instead, and stuff the IS_SRF_CALL() genie back in its bottle, this time with a warning label. I also added a couple of cross-reference comments. After a fair amount of fooling around, I've despaired of making a robust test case that exposes the bug reliably, so no test case here. (Note that the test case added by fac1b470a is itself broken, in that it doesn't notice if you remove the code change. The repro given by the bug submitter currently doesn't fail either in v15 or HEAD, though I suspect that may indicate an unrelated bug.) Per bug #17564 from Martijn van Oosterhout. Back-patch to v13, as the faulty patch was. Discussion: https://postgr.es/m/17564-c7472c2f90ef2da3@postgresql.org
* Harden range_table_mutator() against null RangeTblEntry.subquery.Tom Lane2022-06-261-12/+4
| | | | | | | | | | | | | | | | | | | | Commit 64919aaab made pull_up_simple_subquery set rte->subquery = NULL after doing the deed, so that we don't waste cycles copying a now-useless subquery tree around. This turns out to create a core dump hazard in range_table_mutator, which supposes that that field is never NULL. Apparently none of our own code invokes query_tree_mutator or range_table_mutator on the top Query after subquery pullup; but it wouldn't be surprising if outside code does, and anyway I'm working on a v16 patch that will need it. We can fix this cleanly by just getting rid of the special-case handling of this field and treating it more like all the rest. I think the special case might be left over from a time when QTW_DONT_COPY_QUERY was the default behavior, but that was eons ago. Thanks to Dean Rasheed for review. Discussion: https://postgr.es/m/545569.1656107045@sss.pgh.pa.us
* Pre-beta mechanical code beautification.Tom Lane2022-05-121-7/+8
| | | | | Run pgindent, pgperltidy, and reformat-dat-files. I manually fixed a couple of comments that pgindent uglified.
* JSON_TABLEAndrew Dunstan2022-04-041-0/+27
| | | | | | | | | | | | | | | | This feature allows jsonb data to be treated as a table and thus used in a FROM clause like other tabular data. Data can be selected from the jsonb using jsonpath expressions, and hoisted out of nested structures in the jsonb to form multiple rows, more or less like an outer join. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu (whose name I previously misspelled), Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
* RETURNING clause for JSON() and JSON_SCALAR()Andrew Dunstan2022-03-311-2/+18
| | | | | | | | | | | | | | | This patch is extracted from a larger patch that allowed setting the default returned value from these functions to json or jsonb. That had problems, but this piece of it is fine. For these functions only json or jsonb can be specified in the RETURNING clause. Extracted from an original patch from Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* SQL JSON functionsAndrew Dunstan2022-03-301-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | This Patch introduces three SQL standard JSON functions: JSON() (incorrectly mentioned in my commit message for f4fb45d15c) JSON_SCALAR() JSON_SERIALIZE() JSON() produces json values from text, bytea, json or jsonb values, and has facilitites for handling duplicate keys. JSON_SCALAR() produces a json value from any scalar sql value, including json and jsonb. JSON_SERIALIZE() produces text or bytea from input which containis or represents json or jsonb; For the most part these functions don't add any significant new capabilities, but they will be of use to users wanting standard compliant JSON handling. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* SQL/JSON query functionsAndrew Dunstan2022-03-291-1/+185
| | | | | | | | | | | | | | | | | | | | | | | | | | | This introduces the SQL/JSON functions for querying JSON data using jsonpath expressions. The functions are: JSON_EXISTS() JSON_QUERY() JSON_VALUE() All of these functions only operate on jsonb. The workaround for now is to cast the argument to jsonb. JSON_EXISTS() tests if the jsonpath expression applied to the jsonb value yields any values. JSON_VALUE() must return a single value, and an error occurs if it tries to return multiple values. JSON_QUERY() must return a json object or array, and there are various WRAPPER options for handling scalar or multi-value results. Both these functions have options for handling EMPTY and ERROR conditions. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* IS JSON predicateAndrew Dunstan2022-03-281-0/+26
| | | | | | | | | | | | | | | | | | | | | | | | | This patch intrdocuces the SQL standard IS JSON predicate. It operates on text and bytea values representing JSON as well as on the json and jsonb types. Each test has an IS and IS NOT variant. The tests are: IS JSON [VALUE] IS JSON ARRAY IS JSON OBJECT IS JSON SCALAR IS JSON WITH | WITHOUT UNIQUE KEYS These are mostly self-explanatory, but note that IS JSON WITHOUT UNIQUE KEYS is true whenever IS JSON is true, and IS JSON WITH UNIQUE KEYS is true whenever IS JSON is true except it IS JSON OBJECT is true and there are duplicate keys (which is never the case when applied to jsonb values). Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* Add support for MERGE SQL commandAlvaro Herrera2022-03-281-3/+56
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* SQL/JSON constructorsAndrew Dunstan2022-03-271-0/+152
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces the SQL/JSON standard constructors for JSON: JSON() JSON_ARRAY() JSON_ARRAYAGG() JSON_OBJECT() JSON_OBJECTAGG() For the most part these functions provide facilities that mimic existing json/jsonb functions. However, they also offer some useful additional functionality. In addition to text input, the JSON() function accepts bytea input, which it will decode and constuct a json value from. The other functions provide useful options for handling duplicate keys and null values. This series of patches will be followed by a consolidated documentation patch. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* Common SQL/JSON clausesAndrew Dunstan2022-03-271-0/+66
| | | | | | | | | | | | | | | | | This introduces some of the building blocks used by the SQL/JSON constructor and query functions. Specifically, it provides node executor and grammar support for the FORMAT JSON [ENCODING foo] clause, and values decorated with it, and for the RETURNING clause. The following SQL/JSON patches will leverage these. Nikita Glukhov (who probably deserves an award for perseverance). Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* Revert "Common SQL/JSON clauses"Andrew Dunstan2022-03-221-66/+0
| | | | | | This reverts commit 865fe4d5df560a6f5353da652018ff876978ad2d. This has caused issues with a significant number of buildfarm members
* Common SQL/JSON clausesAndrew Dunstan2022-03-221-0/+66
| | | | | | | | | | | | | | | | | This introduces some of the building blocks used by the SQL/JSON constructor and query functions. Specifically, it provides node executor and grammar support for the FORMAT JSON [ENCODING foo] clause, and values decorated with it, and for the RETURNING clause. The following SQL/JSON patches will leverage these. Nikita Glukhov (who probably deserves an award for perseverance). Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup. Erik Rijkers, Zihong Yu and Himanshu Upadhyaya. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
* Fix assorted missing logic for GroupingFunc nodes.Tom Lane2022-03-211-0/+2
| | | | | | | | | | | | | | | | | | | | | | The planner needs to treat GroupingFunc like Aggref for many purposes, in particular with respect to processing of the argument expressions, which are not to be evaluated at runtime. A few places hadn't gotten that memo, notably including subselect.c's processing of outer-level aggregates. This resulted in assertion failures or wrong plans for cases in which a GROUPING() construct references an outer aggregation level. Also fix missing special cases for GroupingFunc in cost_qual_eval (resulting in wrong cost estimates for GROUPING(), although it's not clear that that would affect plan shapes in practice) and in ruleutils.c (resulting in excess parentheses in pretty-print mode). Per bug #17088 from Yaoguang Chen. Back-patch to all supported branches. Richard Guo, Tom Lane Discussion: https://postgr.es/m/17088-e33882b387de7f5c@postgresql.org
* Add Boolean nodePeter Eisentraut2022-01-171-0/+1
| | | | | | | | | | Before, SQL-level boolean constants were represented by a string with a cast, and internal Boolean values in DDL commands were usually represented by Integer nodes. This takes the place of both of these uses, making the intent clearer and having some amount of type safety. Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/8c1a2e37-c68d-703c-5a83-7a6077f4f997@enterprisedb.com
* Make pg_get_expr() more bulletproof.Tom Lane2022-01-091-0/+42
| | | | | | | | | | | | | | | | | | | | | | Since this function is defined to accept pg_node_tree values, it could get applied to any nodetree that can appear in a cataloged pg_node_tree column. Some such cases can't be supported --- for example, its API doesn't allow providing referents for more than one relation --- but we should try to throw a user-facing error rather than an internal error when encountering such a case. In support of this, extend expression_tree_walker/mutator to be sure they'll work on any such node tree (which basically means adding support for relpartbound node types). That allows us to run pull_varnos and check for the case of multiple relations before we start processing the tree. The alternative of changing the low-level error thrown for an out-of-range varno isn't appealing, because that could mask actual bugs in other usages of ruleutils. Per report from Justin Pryzby. This is basically cosmetic, so no back-patch. Discussion: https://postgr.es/m/20211219205422.GT17618@telsasoft.com
* Update copyright for 2022Bruce Momjian2022-01-071-1/+1
| | | | Backpatch-through: 10
* Remove Value node structPeter Eisentraut2021-09-091-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | The Value node struct is a weird construct. It is its own node type, but most of the time, it actually has a node type of Integer, Float, String, or BitString. As a consequence, the struct name and the node type don't match most of the time, and so it has to be treated specially a lot. There doesn't seem to be any value in the special construct. There is very little code that wants to accept all Value variants but nothing else (and even if it did, this doesn't provide any convenient way to check it), and most code wants either just one particular node type (usually String), or it accepts a broader set of node types besides just Value. This change removes the Value struct and node type and replaces them by separate Integer, Float, String, and BitString node types that are proper node types and structs of their own and behave mostly like normal node types. Also, this removes the T_Null node tag, which was previously also a possible variant of Value but wasn't actually used outside of the Value contained in A_Const. Replace that by an isnull field in A_Const. Reviewed-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/5ba6bc5b-3f95-04f2-2419-f8ddb4c046fb@enterprisedb.com
* Improve slightly misleading comments in nodeFuncs.cDavid Rowley2021-04-101-25/+44
| | | | | | | | | | | | | | | | There were some comments in nodeFuncs.c that, depending on your interpretation of the word "result", could lead you to believe that the comments were badly copied and pasted from somewhere else. If you thought of "result" as the return value of the function that the comment is written in, then you'd be misled. However, if you'd correctly interpreted "result" to mean the result type of the given node type, you'd not have seen any issues. Here we do a small cleanup to try to prevent any future misinterpretations. Per wording suggestion from Tom Lane. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/CAApHDvp+Bw=2Qiu5=uXMKfC7gd0+B=4JvexVgGJU=am2g9a1CA@mail.gmail.com
* Rework planning and execution of UPDATE and DELETE.Tom Lane2021-03-311-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Allow configurable LZ4 TOAST compression.Robert Haas2021-03-191-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is now a per-column COMPRESSION option which can be set to pglz (the default, and the only option in up until now) or lz4. Or, if you like, you can set the new default_toast_compression GUC to lz4, and then that will be the default for new table columns for which no value is specified. We don't have lz4 support in the PostgreSQL code, so to use lz4 compression, PostgreSQL must be built --with-lz4. In general, TOAST compression means compression of individual column values, not the whole tuple, and those values can either be compressed inline within the tuple or compressed and then stored externally in the TOAST table, so those properties also apply to this feature. Prior to this commit, a TOAST pointer has two unused bits as part of the va_extsize field, and a compessed datum has two unused bits as part of the va_rawsize field. These bits are unused because the length of a varlena is limited to 1GB; we now use them to indicate the compression type that was used. This means we only have bit space for 2 more built-in compresison types, but we could work around that problem, if necessary, by introducing a new vartag_external value for any further types we end up wanting to add. Hopefully, it won't be too important to offer a wide selection of algorithms here, since each one we add not only takes more coding but also adds a build dependency for every packager. Nevertheless, it seems worth doing at least this much, because LZ4 gets better compression than PGLZ with less CPU usage. It's possible for LZ4-compressed datums to leak into composite type values stored on disk, just as it is for PGLZ. It's also possible for LZ4-compressed attributes to be copied into a different table via SQL commands such as CREATE TABLE AS or INSERT .. SELECT. It would be expensive to force such values to be decompressed, so PostgreSQL has never done so. For the same reasons, we also don't force recompression of already-compressed values even if the target table prefers a different compression method than was used for the source data. These architectural decisions are perhaps arguable but revisiting them is well beyond the scope of what seemed possible to do as part of this project. However, it's relatively cheap to recompress as part of VACUUM FULL or CLUSTER, so this commit adjusts those commands to do so, if the configured compression method of the table happens not to match what was used for some column value stored therein. Dilip Kumar. The original patches on which this work was based were written by Ildus Kurbangaliev, and those were patches were based on even earlier work by Nikita Glukhov, but the design has since changed very substantially, since allow a potentially large number of compression methods that could be added and dropped on a running system proved too problematic given some of the architectural issues mentioned above; the choice of which specific compression method to add first is now different; and a lot of the code has been heavily refactored. More recently, Justin Przyby helped quite a bit with testing and reviewing and this version also includes some code contributions from him. Other design input and review from Tomas Vondra, Álvaro Herrera, Andres Freund, Oleg Bartunov, Alexander Korotkov, and me. Discussion: http://postgr.es/m/20170907194236.4cefce96%40wp.localdomain Discussion: http://postgr.es/m/CAFiTN-uUpX3ck%3DK0mLEk-G_kUQY%3DSNOTeqdaNRR9FMdQrHKebw%40mail.gmail.com
* SEARCH and CYCLE clausesPeter Eisentraut2021-02-011-1/+41
| | | | | | | | | | | | 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
* Re-implement pl/pgsql's expression and assignment parsing.Tom Lane2021-01-041-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | Invent new RawParseModes that allow the core grammar to handle pl/pgsql expressions and assignments directly, and thereby get rid of a lot of hackery in pl/pgsql's parser. This moves a good deal of knowledge about pl/pgsql into the core code: notably, we have to invent a CoercionContext that matches pl/pgsql's (rather dubious) historical behavior for assignment coercions. That's getting away from the original idea of pl/pgsql as an arm's-length extension of the core, but really we crossed that bridge a long time ago. The main advantage of doing this is that we can now use the core parser to generate FieldStore and/or SubscriptingRef nodes to handle assignments to pl/pgsql variables that are records or arrays. That fixes a number of cases that had never been implemented in pl/pgsql assignment, such as nested records and array slicing, and it allows pl/pgsql assignment to support the datatype-specific subscripting behaviors introduced in commit c7aba7c14. There are cosmetic benefits too: when a syntax error occurs in a pl/pgsql expression, the error report no longer includes the confusing "SELECT" keyword that used to get prefixed to the expression text. Also, there seem to be some small speed gains. Discussion: https://postgr.es/m/4165684.1607707277@sss.pgh.pa.us
* Update copyright for 2021Bruce Momjian2021-01-021-1/+1
| | | | Backpatch-through: 9.5
* Support subscripting of arbitrary types, not only arrays.Tom Lane2020-12-091-10/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Add for_each_from, to simplify loops starting from non-first list cells.Tom Lane2020-09-281-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have a dozen or so places that need to iterate over all but the first cell of a List. Prior to v13 this was typically written as for_each_cell(lc, lnext(list_head(list))) Commit 1cff1b95a changed these to for_each_cell(lc, list, list_second_cell(list)) This patch introduces a new macro for_each_from() which expresses the start point as a list index, allowing these to be written as for_each_from(lc, list, 1) This is marginally more efficient, since ForEachState.i can be initialized directly instead of backing into it from a ListCell address. It also seems clearer and less typo-prone. Some of the remaining uses of for_each_cell() look like they could profitably be changed to for_each_from(), but here I confined myself to changing uses of list_second_cell(). Also, fix for_each_cell_setup() and for_both_cell_setup() to const-ify their arguments; that's a simple oversight in 1cff1b95a. Back-patch into v13, on the grounds that (1) the const-ification is a minor bug fix, and (2) it's better for back-patching purposes if we only have two ways to write these loops rather than three. In HEAD, also remove list_third_cell() and list_fourth_cell(), which were also introduced in 1cff1b95a, and are unused as of cc99baa43. It seems unlikely that any third-party code would have started to use them already; anyone who has can be directed to list_nth_cell instead. Discussion: https://postgr.es/m/CAApHDvpo1zj9KhEpU2cCRZfSM3Q6XGdhzuAS2v79PH7WJBkYVA@mail.gmail.com
* Suppress unnecessary RelabelType nodes in yet more cases.Tom Lane2020-08-191-13/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Update copyrights for 2020Bruce Momjian2020-01-011-1/+1
| | | | Backpatch-through: update all files in master, backpatch legal files through 9.4
* Prevent overly-aggressive collapsing of joins to RTE_RESULT relations.Tom Lane2019-12-141-46/+61
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RTE_RESULT simplification logic added by commit 4be058fe9 had a flaw: it would collapse out a RTE_RESULT that is due to compute a PlaceHolderVar, and reassign the PHV to the parent join level, even if another input relation of the join contained a lateral reference to the PHV. That can't work because the PHV would be computed too late. In practice it led to failures of internal sanity checks later in planning (either assertion failures or errors such as "failed to construct the join relation"). To fix, add code to check for the presence of such PHVs in relevant portions of the query tree. Notably, this required refactoring range_table_walker so that a caller could ask to walk individual RTEs not the whole list. (It might be a good idea to refactor range_table_mutator in the same way, if only to keep those functions looking similar; but I didn't do so here as it wasn't necessary for the bug fix.) This exercise also taught me that find_dependent_phvs(), as it stood, could only safely be used on the entire Query, not on subtrees. Adjust its API to reflect that; which in passing allows it to have a fast path for the common case of no PHVs anywhere. Per report from Will Leinweber. Back-patch to v12 where the bug was introduced. Discussion: https://postgr.es/m/CALLb-4xJMd4GZt2YCecMC95H-PafuWNKcmps4HLRx2NHNBfB4g@mail.gmail.com
* Add a reverse-translation column number array to struct AppendRelInfo.Tom Lane2019-12-021-0/+1
| | | | | | | | | | | This provides for cheaper mapping of child columns back to parent columns. The one existing use-case in examine_simple_variable() would hardly justify this by itself; but an upcoming bug fix will make use of this array in a mainstream code path, and it seems likely that we'll find other uses for it as we continue to build out the partitioning infrastructure. Discussion: https://postgr.es/m/12424.1575168015@sss.pgh.pa.us
* Make the order of the header file includes consistent in backend modules.Amit Kapila2019-11-121-2/+1
| | | | | | | | | | | Similar to commits 7e735035f2 and dddf4cdc33, this commit makes the order of header file inclusion consistent for backend modules. In the passing, removed a couple of duplicate inclusions. Author: Vignesh C Reviewed-by: Kuntal Ghosh and Amit Kapila Discussion: https://postgr.es/m/CALDaNm2Sznv8RR6Ex-iJO6xAdsxgWhCoETkaYX=+9DW3q0QCfA@mail.gmail.com
* Selectively include window frames in expression walks/mutates.Andrew Gierth2019-10-031-0/+105
| | | | | | | | | | | | | | | | | | | | query_tree_walker and query_tree_mutator were skipping the windowClause of the query, without regard for the fact that the startOffset and endOffset in a WindowClause node are expression trees that need to be processed. This was an oversight in commit ec4be2ee6 from 2010 which added the expression fields; the main symptom is that function parameters in window frame clauses don't work in inlined functions. Fix (as conservatively as possible since this needs to not break existing out-of-tree callers) and add tests. Backpatch all the way, since this has been broken since 9.0. Per report from Alastair McKinley; fix by me with kibitzing and review from Tom Lane. Discussion: https://postgr.es/m/DB6PR0202MB2904E7FDDA9D81504D1E8C68E3800@DB6PR0202MB2904.eurprd02.prod.outlook.com
* Represent Lists as expansible arrays, not chains of cons-cells.Tom Lane2019-07-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Phase 2 pgindent run for v12.Tom Lane2019-05-221-1/+1
| | | | | | | | | 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
* Refactor the representation of indexable clauses in IndexPaths.Tom Lane2019-02-091-0/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Renaming for new subscripting mechanismAlvaro Herrera2019-02-011-31/+33
| | | | | | | | | | | | 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
* Rename nodes/relation.h to nodes/pathnodes.h.Tom Lane2019-01-291-1/+1
| | | | | | | | | | | | | The old name of this file was never a very good indication of what it was for. Now that there's also access/relation.h, we have a potential confusion hazard as well, so let's rename it to something more apropos. Per discussion, "pathnodes.h" is reasonable, since a good fraction of the file is Path node definitions. While at it, tweak a couple of other headers that were gratuitously importing relation.h into modules that don't need it. Discussion: https://postgr.es/m/7719.1548688728@sss.pgh.pa.us
* In the planner, replace an empty FROM clause with a dummy RTE.Tom Lane2019-01-281-8/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Split QTW_EXAMINE_RTES flag into QTW_EXAMINE_RTES_BEFORE/_AFTER.Tom Lane2019-01-251-3/+11
| | | | | | | | | | | | | This change allows callers of query_tree_walker() to choose whether to visit an RTE before or after visiting the contents of the RTE (i.e., prefix or postfix tree order). All existing users of QTW_EXAMINE_RTES want the QTW_EXAMINE_RTES_BEFORE behavior, but an upcoming patch will want QTW_EXAMINE_RTES_AFTER, and it seems like a potentially useful change on its own. Andreas Karlsson (extracted from CTE inlining patch) Discussion: https://postgr.es/m/8810.1542402910@sss.pgh.pa.us
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