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* Fix crashes with CREATE SCHEMA AUTHORIZATION and schema elementsMichael Paquier2023-04-281-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | CREATE SCHEMA AUTHORIZATION with appended schema elements can lead to crashes when comparing the schema name of the query with the schemas used in the qualification of some clauses in the elements' queries. The origin of the problem is that the transformation routine for the elements listed in a CREATE SCHEMA query uses as new, expected, schema name the one listed in CreateSchemaStmt itself. However, depending on the query, CreateSchemaStmt.schemaname may be NULL, being computed instead from the role specification of the query given by the AUTHORIZATION clause, that could be either: - A user name string, with the new schema name being set to the same value as the role given. - Guessed from CURRENT_ROLE, SESSION_ROLE or CURRENT_ROLE, with a new schema name computed from the security context where CREATE SCHEMA is running. Regression tests are added for CREATE SCHEMA with some appended elements (some of them with schema qualifications), covering also some role specification patterns. While on it, this simplifies the context structure used during the transformation of the elements listed in a CREATE SCHEMA query by removing the fields for the role specification and the role type. They were not used, and for the role specification this could be confusing as the schema name may by extracted from that at the beginning of CreateSchemaCommand(). This issue exists for a long time, so backpatch down to all the versions supported. Reported-by: Song Hongyu Author: Michael Paquier Reviewed-by: Richard Guo Discussion: https://postgr.es/m/17909-f65c12dfc5f0451d@postgresql.org Backpatch-through: 11
* SQL/JSON: support the IS JSON predicateAlvaro Herrera2023-03-311-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Support [NO] INDENT option in XMLSERIALIZE().Tom Lane2023-03-151-0/+1
| | | | | | | | | | | | | | This adds the ability to pretty-print XML documents ... according to libxml's somewhat idiosyncratic notions of what's pretty, anyway. One notable divergence from a strict reading of the spec is that libxml is willing to collapse empty nodes "<node></node>" to just "<node/>", whereas SQL and the underlying XML spec say that this option should only result in whitespace tweaks. Nonetheless, it seems close enough to justify using the SQL-standard syntax. Jim Jones, reviewed by Peter Smith and myself Discussion: https://postgr.es/m/2f5df461-dad8-6d7d-4568-08e10608a69b@uni-muenster.de
* Make Vars be outer-join-aware.Tom Lane2023-01-302-1/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Allow parallel aggregate on string_agg and array_aggDavid Rowley2023-01-231-0/+2
| | | | | | | | | | | | | | This adds combine, serial and deserial functions for the array_agg() and string_agg() aggregate functions, thus allowing these aggregates to partake in partial aggregations. This allows both parallel aggregation to take place when these aggregates are present and also allows additional partition-wise aggregation plan shapes to include plans that require additional aggregation once the partially aggregated results from the partitions have been combined. Author: David Rowley Reviewed-by: Andres Freund, Tomas Vondra, Stephen Frost, Tom Lane Discussion: https://postgr.es/m/CAKJS1f9sx_6GTcvd6TMuZnNtCh0VhBzhX6FZqw17TgVFH-ga_A@mail.gmail.com
* Move queryjumble.c code to src/backend/nodes/Michael Paquier2023-01-211-1/+1
| | | | | | | | | | | | | This will ease a follow-up move that will generate automatically this code. The C file is renamed, for consistency with the node-related files whose code are generated by gen_node_support.pl: - queryjumble.c -> queryjumblefuncs.c - utils/queryjumble.h -> nodes/queryjumble.h Per a suggestion from Peter Eisentraut. Reviewed-by: Peter Eisentraut Discussion: https://postgr.es/m/Y5BHOUhX3zTH/ig6@paquier.xyz
* Update copyright for 2023Bruce Momjian2023-01-0222-22/+22
| | | | Backpatch-through: 11
* Convert the reg* input functions to report (most) errors softly.Tom Lane2022-12-271-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | This is not really complete, but it catches most cases of practical interest. The main omissions are: * regtype, regprocedure, and regoperator parse type names by calling the main grammar, so any grammar-detected syntax error will still be a hard error. Also, if one includes a type modifier in such a type specification, errors detected by the typmodin function will be hard errors. * Lookup errors are handled just by passing missing_ok = true to the relevant catalog lookup function. Because we've used quite a restrictive definition of "missing_ok", this means that edge cases such as "the named schema exists, but you lack USAGE permission on it" are still hard errors. It would make sense to me to replace most/all missing_ok parameters with an escontext parameter and then allow these additional lookup failure cases to be trapped too. But that's a job for some other day. Discussion: https://postgr.es/m/3342239.1671988406@sss.pgh.pa.us
* Rework query relation permission checkingAlvaro Herrera2022-12-062-1/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, information about the permissions to be checked on relations mentioned in a query is stored in their range table entries. So the executor must scan the entire range table looking for relations that need to have permissions checked. This can make the permission checking part of the executor initialization needlessly expensive when many inheritance children are present in the range range. While the permissions need not be checked on the individual child relations, the executor still must visit every range table entry to filter them out. This commit moves the permission checking information out of the range table entries into a new plan node called RTEPermissionInfo. Every top-level (inheritance "root") RTE_RELATION entry in the range table gets one and a list of those is maintained alongside the range table. This new list is initialized by the parser when initializing the range table. The rewriter can add more entries to it as rules/views are expanded. Finally, the planner combines the lists of the individual subqueries into one flat list that is passed to the executor for checking. To make it quick to find the RTEPermissionInfo entry belonging to a given relation, RangeTblEntry gets a new Index field 'perminfoindex' that stores the corresponding RTEPermissionInfo's index in the query's list of the latter. ExecutorCheckPerms_hook has gained another List * argument; the signature is now: typedef bool (*ExecutorCheckPerms_hook_type) (List *rangeTable, List *rtePermInfos, bool ereport_on_violation); The first argument is no longer used by any in-core uses of the hook, but we leave it in place because there may be other implementations that do. Implementations should likely scan the rtePermInfos list to determine which operations to allow or deny. Author: Amit Langote <amitlangote09@gmail.com> Discussion: https://postgr.es/m/CA+HiwqGjJDmUhDSfv-U2qhKJjt9ST7Xh9JXC_irsAQ1TAUsJYg@mail.gmail.com
* Record dependencies of a cast on other casts that it requires.Tom Lane2022-10-171-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | When creating a cast that uses a conversion function, we've historically allowed the input and result types to be binary-compatible with the function's input and result types, rather than necessarily being identical. This means that the new cast is logically dependent on the binary-compatible cast or casts that it references: if those are defined by pg_cast entries, and you try to restore the new cast without having defined them, it'll fail. Hence, we should make pg_depend entries to record these dependencies so that pg_dump knows that there is an ordering requirement. This is not the only place where we allow such shortcuts; aggregate functions for example are similarly lax, and in principle should gain similar dependencies. However, for now it seems sufficient to fix the cast-versus-cast case, as pg_dump's other ordering heuristics should keep it out of trouble for other object types. Per report from David Turoň; thanks also to Robert Haas for preliminary investigation. I considered back-patching, but seeing that this issue has existed for many years without previous reports, it's not clear it's worth the trouble. Moreover, back-patching wouldn't be enough to ensure that the new pg_depend entries exist in existing databases anyway. Discussion: https://postgr.es/m/OF0A160F3E.578B15D1-ONC12588DA.003E4857-C12588DA.0045A428@notes.linuxbox.cz
* Rename parser token REF to REF_P to avoid a symbol conflict.Tom Lane2022-10-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | In the latest version of Apple's macOS SDK, <sys/socket.h> fails to compile if "REF" is #define'd as something. Apple may or may not agree that this is a bug, and even if they do accept the bug report I filed, they probably won't fix it very quickly. In the meantime, our back branches will all fail to compile gram.y. v15 and HEAD currently escape the problem thanks to the refactoring done in 98e93a1fc, but that's purely accidental. Moreover, since that patch removed a widely-visible inclusion of <netdb.h>, back-patching it seems too likely to break third-party code. Instead, change the token's code name to REF_P, following our usual convention for naming parser tokens that are likely to have symbol conflicts. The effects of that should be localized to the grammar and immediately surrounding files, so it seems like a safer answer. Per project policy that we want to keep recently-out-of-support branches buildable on modern systems, back-patch all the way to 9.2. Discussion: https://postgr.es/m/1803927.1665938411@sss.pgh.pa.us
* Introduce SYSTEM_USERMichael Paquier2022-09-291-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | SYSTEM_USER is a reserved keyword of the SQL specification that, roughly described, is aimed at reporting some information about the system user who has connected to the database server. It may include implementation-specific information about the means by the user connected, like an authentication method. This commit implements SYSTEM_USER as of auth_method:identity, where "auth_method" is a keyword about the authentication method used to log into the server (like peer, md5, scram-sha-256, gss, etc.) and "identity" is the authentication identity as introduced by 9afffcb (peer sets authn to the OS user name, gss to the user principal, etc.). This format has been suggested by Tom Lane. Note that thanks to d951052, SYSTEM_USER is available to parallel workers. Bump catalog version. Author: Bertrand Drouvot Reviewed-by: Jacob Champion, Joe Conway, Álvaro Herrera, Michael Paquier Discussion: https://postgr.es/m/7e692b8c-0b11-45db-1cad-3afc5b57409f@amazon.com
* Harmonize more lexer function parameter names.Peter Geoghegan2022-09-221-1/+1
| | | | | | | | | Make sure that function declarations use names that exactly match the corresponding names from function definitions for several "lexer adjacent" backend functions. These were missed by commit aab06442. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
* Harmonize more parameter names in bulk.Peter Geoghegan2022-09-204-5/+5
| | | | | | | | | | | | | | | | Make sure that function declarations use names that exactly match the corresponding names from function definitions in optimizer, parser, utility, libpq, and "commands" code, as well as in remaining library code. Do the same for all code related to frontend programs (with the exception of pg_dump/pg_dumpall related code). Like other recent commits that cleaned up function parameter names, this commit was written with help from clang-tidy. Later commits will handle ecpg and pg_dump/pg_dumpall. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
* Move gramparse.h to src/backend/parserJohn Naylor2022-09-142-76/+0
| | | | | | | | | | | | | This header is semi-private, being used only in files related to raw parsing, so move to the backend directory where those files live. This allows removal of Makefile rules that symlink gram.h to src/include/parser, since gramparse.h can now include gram.h from within the same directory. This has the side-effect of no longer installing gram.h and gramparse.h, but there doesn't seem to be a good reason to continue doing so. Per suggestion from Andres Freund and Peter Eisentraut Discussion: https://www.postgresql.org/message-id/20220904181759.px6uosll6zbxcum5%40awork3.anarazel.de
* Revert SQL/JSON featuresAndrew Dunstan2022-09-012-29/+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
* Update comment in gramparse.hJohn Naylor2022-08-181-1/+1
| | | | src/common/keywords.c hasn't included this header since afb0d0712.
* Make subquery aliases optional in the FROM clause.Dean Rasheed2022-07-201-2/+5
| | | | | | | | | | | | | | This allows aliases for sub-SELECTs and VALUES clauses in the FROM clause to be omitted. This is an extension of the SQL standard, supported by some other database systems, and so eases the transition from such systems, as well as removing the minor inconvenience caused by requiring these aliases. Patch by me, reviewed by Tom Lane. Discussion: https://postgr.es/m/CAEZATCUCGCf82=hxd9N5n6xGHPyYpQnxW8HneeH+uP7yNALkWA@mail.gmail.com
* Make STRING an unreserved_keyword.Tom Lane2022-05-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | Commit 1a36bc9db (SQL/JSON query functions) introduced STRING as a type_func_name_keyword, thereby breaking applications that use "string" as a table name, column name, function parameter name, etc. That seems like a pretty bad thing, not least because the SQL spec says that STRING is an unreserved keyword. This is easy enough to fix so far as the core grammar is concerned. However, doing so causes some ECPG test cases to fail, specifically those that use "string" as a typedef name. It turns out this is because portions of the ECPG grammar allow type_func_name_keywords but not unreserved_keywords as typedef names. That's pretty horrid, and it's mildly astonishing that we've not heard complaints about it before. We can fix two of those uses trivially, but the ones in the var_type production are less easy. As a stopgap, hard-code STRING as an allowed alternative in var_type. Per report from Alastair McKinley. Discussion: https://postgr.es/m/3661437.1653855582@sss.pgh.pa.us
* Pre-beta mechanical code beautification.Tom Lane2022-05-122-3/+3
| | | | | Run pgindent, pgperltidy, and reformat-dat-files. I manually fixed a couple of comments that pgindent uglified.
* Apply PGDLLIMPORT markings broadly.Robert Haas2022-04-082-3/+3
| | | | | | | | | | | Up until now, we've had a policy of only marking certain variables in the PostgreSQL header files with PGDLLIMPORT, but now we've decided to mark them all. This means that extensions running on Windows should no longer operate at a disadvantage as compared to extensions running on Linux: if the variable is present in a header file, it should be accessible. Discussion: http://postgr.es/m/CA+TgmoYanc1_FSfimhgiWSqVyP5KKmh5NP2BWNwDhO8Pg2vGYQ@mail.gmail.com
* Allow granting SET and ALTER SYSTEM privileges on GUC parameters.Tom Lane2022-04-061-0/+1
| | | | | | | | | | | | | | | | | | | | This patch allows "PGC_SUSET" parameters to be set by non-superusers if they have been explicitly granted the privilege to do so. The privilege to perform ALTER SYSTEM SET/RESET on a specific parameter can also be granted. Such privileges are cluster-wide, not per database. They are tracked in a new shared catalog, pg_parameter_acl. Granting and revoking these new privileges works as one would expect. One caveat is that PGC_USERSET GUCs are unaffected by the SET privilege --- one could wish that those were handled by a revocable grant to PUBLIC, but they are not, because we couldn't make it robust enough for GUCs defined by extensions. Mark Dilger, reviewed at various times by Andrew Dunstan, Robert Haas, Joshua Brindle, and myself Discussion: https://postgr.es/m/3D691E20-C1D5-4B80-8BA5-6BEB63AF3029@enterprisedb.com
* PLAN clauses for JSON_TABLEAndrew Dunstan2022-04-051-0/+1
| | | | | | | | | | | | | | | | | | | | These clauses allow the user to specify how data from nested paths are joined, allowing considerable freedom in shaping the tabular output of JSON_TABLE. PLAN DEFAULT allows the user to specify the global strategies when dealing with sibling or child nested paths. The is often sufficient to achieve the necessary goal, and is considerably simpler than the full PLAN clause, which allows the user to specify the strategy to be used for each named nested path. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
* JSON_TABLEAndrew Dunstan2022-04-042-0/+6
| | | | | | | | | | | | | | | | 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
* SQL JSON functionsAndrew Dunstan2022-03-301-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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 Dunstan2022-03-291-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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/+1
| | | | | | | | | | | | | | | | | | | | | | | | | 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 Herrera2022-03-285-3/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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/+2
| | | | | | | | | | | | | | | | | 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 Dunstan2022-03-221-2/+0
| | | | | | This reverts commit 865fe4d5df560a6f5353da652018ff876978ad2d. This has caused issues with a significant number of buildfarm members
* Common SQL/JSON clausesAndrew Dunstan2022-03-221-0/+2
| | | | | | | | | | | | | | | | | 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
* Add parse_analyze_withcb()Peter Eisentraut2022-03-091-0/+5
| | | | | | | | | This extracts code from pg_analyze_and_rewrite_withcb() into a separate function that mirrors the existing parse_analyze_fixedparams() and parse_analyze_varparams(). Reviewed-by: Nathan Bossart <bossartn@amazon.com> Discussion: https://www.postgresql.org/message-id/flat/c67ce276-52b4-0239-dc0e-39875bf81840@enterprisedb.com
* Add pg_analyze_and_rewrite_varparams()Peter Eisentraut2022-03-071-1/+1
| | | | | | | | | | | | | | | | | | | | | This new function extracts common code from PrepareQuery() and exec_parse_message(). It is then exactly analogous to the existing pg_analyze_and_rewrite_fixedparams() and pg_analyze_and_rewrite_withcb(). To unify these two code paths, this makes PrepareQuery() now subject to log_parser_stats. Also, both paths now invoke TRACE_POSTGRESQL_QUERY_REWRITE_START(). PrepareQuery() no longer checks whether a utility statement was specified. The grammar doesn't allow that anyway, and exec_parse_message() supports it, so restricting it doesn't seem necessary. This also adds QueryEnvironment support to the *varparams functions, for consistency with its cousins, even though it is not used right now. Reviewed-by: Nathan Bossart <bossartn@amazon.com> Discussion: https://www.postgresql.org/message-id/flat/c67ce276-52b4-0239-dc0e-39875bf81840@enterprisedb.com
* Parse/analyze function renamingPeter Eisentraut2022-03-042-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are three parallel ways to call parse/analyze: with fixed parameters, with variable parameters, and by supplying your own parser callback. Some of the involved functions were confusingly named and made this API structure more confusing. This patch renames some functions to make this clearer: parse_analyze() -> parse_analyze_fixedparams() pg_analyze_and_rewrite() -> pg_analyze_and_rewrite_fixedparams() (Otherwise one might think this variant doesn't accept parameters, but in fact all three ways accept parameters.) pg_analyze_and_rewrite_params() -> pg_analyze_and_rewrite_withcb() (Before, and also when considering pg_analyze_and_rewrite(), one might think this is the only way to pass parameters. Moreover, the parser callback doesn't necessarily need to parse only parameters, it's just one of the things it could do.) parse_fixed_parameters() -> setup_parse_fixed_parameters() parse_variable_parameters() -> setup_parse_variable_parameters() (These functions don't actually do any parsing, they just set up callbacks to use during parsing later.) This patch also adds some const decorations to the fixed-parameters API, so the distinction from the variable-parameters API is more clear. Reviewed-by: Nathan Bossart <bossartn@amazon.com> Discussion: https://www.postgresql.org/message-id/flat/c67ce276-52b4-0239-dc0e-39875bf81840@enterprisedb.com
* Fix failure to validate the result of select_common_type().Tom Lane2022-01-291-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Although select_common_type() has a failure-return convention, an apparent successful return just provides a type OID that *might* work as a common supertype; we've not validated that the required casts actually exist. In the mainstream use-cases that doesn't matter, because we'll proceed to invoke coerce_to_common_type() on each input, which will fail appropriately if the proposed common type doesn't actually work. However, a few callers didn't read the (nonexistent) fine print, and thought that if they got back a nonzero OID then the coercions were sure to work. This affects in particular the recently-added "anycompatible" polymorphic types; we might think that a function/operator using such types matches cases it really doesn't. A likely end result of that is unexpected "ambiguous operator" errors, as for example in bug #17387 from James Inform. Another, much older, case is that the parser might try to transform an "x IN (list)" construct to a ScalarArrayOpExpr even when the list elements don't actually have a common supertype. It doesn't seem desirable to add more checking to select_common_type itself, as that'd just slow down the mainstream use-cases. Instead, write a separate function verify_common_type that performs the missing checks, and add a call to that where necessary. Likewise add verify_common_type_from_oids to go with select_common_type_from_oids. Back-patch to v13 where the "anycompatible" types came in. (The symptom complained of in bug #17387 doesn't appear till v14, but that's just because we didn't get around to converting || to use anycompatible till then.) In principle the "x IN (list)" fix could go back all the way, but I'm not currently convinced that it makes much difference in real-world cases, so I won't bother for now. Discussion: https://postgr.es/m/17387-5dfe54b988444963@postgresql.org
* Update copyright for 2022Bruce Momjian2022-01-0722-22/+22
| | | | Backpatch-through: 10
* Remove Value node structPeter Eisentraut2021-09-091-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Disable anonymous record hash support except in special casesPeter Eisentraut2021-09-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 01e658fa74 added hash support for row types. This also added support for hashing anonymous record types, using the same approach that the type cache uses for comparison support for record types: It just reports that it works, but it might fail at run time if a component type doesn't actually support the operation. We get away with that for comparison because most types support that. But some types don't support hashing, so the current state can result in failures at run time where the planner chooses hashing over sorting, whereas that previously worked if only sorting was an option. We do, however, want the record hashing support for path tracking in recursive unions, and the SEARCH and CYCLE clauses built on that. In that case, hashing is the only plan option. So enable that, this commit implements the following approach: The type cache does not report that hashing is available for the record type. This undoes that part of 01e658fa74. Instead, callers that require hashing no matter what can override that result themselves. This patch only touches the callers to make the aforementioned recursive query cases work, namely the parse analysis of unions, as well as the hash_array() function. Reported-by: Sait Talha Nisanci <sait.nisanci@microsoft.com> Bug: #17158 Discussion: https://www.postgresql.org/message-id/flat/17158-8a2ba823982537a4%40postgresql.org
* Cleanup some aggregate code in the executorDavid Rowley2021-07-041-5/+0
| | | | | | | | | | | | | | | | | | | | | Here we alter the code that calls build_pertrans_for_aggref() so that the function no longer needs to special-case whether it's dealing with an aggtransfn or an aggcombinefn. This allows us to reuse the build_aggregate_transfn_expr() function and just get rid of the build_aggregate_combinefn_expr() completely. All of the special case code that was in build_pertrans_for_aggref() has been moved up to the calling functions. This saves about a dozen lines of code in nodeAgg.c and a few dozen more in parse_agg.c Also, rename a few variables in nodeAgg.c to try to make it more clear that we're working with either a aggtransfn or an aggcombinefn. Some of the old names would have you believe that we were always working with an aggtransfn. Discussion: https://postgr.es/m/CAApHDvptMQ9FmF0D67zC_w88yVnoNVR2+kkOQGUrCmdxWxLULQ@mail.gmail.com
* Reconsider the handling of procedure OUT parameters.Tom Lane2021-06-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 2453ea142 redefined pg_proc.proargtypes to include the types of OUT parameters, for procedures only. While that had some advantages for implementing the SQL-spec behavior of DROP PROCEDURE, it was pretty disastrous from a number of other perspectives. Notably, since the primary key of pg_proc is name + proargtypes, this made it possible to have multiple procedures with identical names + input arguments and differing output argument types. That would make it impossible to call any one of the procedures by writing just NULL (or "?", or any other data-type-free notation) for the output argument(s). The change also seems likely to cause grave confusion for client applications that examine pg_proc and expect the traditional definition of proargtypes. Hence, revert the definition of proargtypes to what it was, and undo a number of complications that had been added to support that. To support the SQL-spec behavior of DROP PROCEDURE, when there are no argmode markers in the command's parameter list, we perform the lookup both ways (that is, matching against both proargtypes and proallargtypes), succeeding if we get just one unique match. In principle this could result in ambiguous-function failures that would not happen when using only one of the two rules. However, overloading of procedure names is thought to be a pretty rare usage, so this shouldn't cause many problems in practice. Postgres-specific code such as pg_dump can defend against any possibility of such failures by being careful to specify argmodes for all procedure arguments. This also fixes a few other bugs in the area of CALL statements with named parameters, and improves the documentation a little. catversion bump forced because the representation of procedures with OUT arguments changes. Discussion: https://postgr.es/m/3742981.1621533210@sss.pgh.pa.us
* SQL-standard function bodyPeter Eisentraut2021-04-071-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds support for writing CREATE FUNCTION and CREATE PROCEDURE statements for language SQL with a function body that conforms to the SQL standard and is portable to other implementations. Instead of the PostgreSQL-specific AS $$ string literal $$ syntax, this allows writing out the SQL statements making up the body unquoted, either as a single statement: CREATE FUNCTION add(a integer, b integer) RETURNS integer LANGUAGE SQL RETURN a + b; or as a block CREATE PROCEDURE insert_data(a integer, b integer) LANGUAGE SQL BEGIN ATOMIC INSERT INTO tbl VALUES (a); INSERT INTO tbl VALUES (b); END; The function body is parsed at function definition time and stored as expression nodes in a new pg_proc column prosqlbody. So at run time, no further parsing is required. However, this form does not support polymorphic arguments, because there is no more parse analysis done at call time. Dependencies between the function and the objects it uses are fully tracked. A new RETURN statement is introduced. This can only be used inside function bodies. Internally, it is treated much like a SELECT statement. psql needs some new intelligence to keep track of function body boundaries so that it doesn't send off statements when it sees semicolons that are inside a function body. Tested-by: Jaime Casanova <jcasanov@systemguards.com.ec> Reviewed-by: Julien Rouhaud <rjuju123@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/1c11f1eb-f00c-43b7-799d-2d44132c02d7@2ndquadrant.com
* Move pg_stat_statements query jumbling to core.Bruce Momjian2021-04-071-1/+3
| | | | | | | | | | | | | | | | | | | Add compute_query_id GUC to control whether a query identifier should be computed by the core (off by default). It's thefore now possible to disable core queryid computation and use pg_stat_statements with a different algorithm to compute the query identifier by using a third-party module. To ensure that a single source of query identifier can be used and is well defined, modules that calculate a query identifier should throw an error if compute_query_id specified to compute a query id and if a query idenfitier was already calculated. Discussion: https://postgr.es/m/20210407125726.tkvjdbw76hxnpwfi@nol Author: Julien Rouhaud Reviewed-by: Alvaro Herrera, Nitin Jadhav, Zhihong Yu
* Fix use of cursor sensitivity terminologyPeter Eisentraut2021-04-071-0/+1
| | | | | | | | | | | | | | | | | | | | | Documentation and comments in code and tests have been using the terms sensitive/insensitive cursor incorrectly relative to the SQL standard. (Cursor sensitivity is only relevant for changes made in the same transaction as the cursor, not for concurrent changes in other sessions.) Moreover, some of the behavior of PostgreSQL is incorrect according to the SQL standard, confusing the issue further. (WHERE CURRENT OF changes are not visible in insensitive cursors, but they should be.) This change corrects the terminology and removes the claim that sensitive cursors are supported. It also adds a test case that checks the insensitive behavior in a "correct" way, using a change command not using WHERE CURRENT OF. Finally, it adds the ASENSITIVE cursor option to select the default asensitive behavior, per SQL standard. There are no changes to cursor behavior in this patch. Discussion: https://www.postgresql.org/message-id/flat/96ee8b30-9889-9e1b-b053-90e10c050e85%40enterprisedb.com
* Allow an alias to be attached to a JOIN ... USINGPeter Eisentraut2021-03-312-1/+5
| | | | | | | | | | | | | | | This allows something like SELECT ... FROM t1 JOIN t2 USING (a, b, c) AS x where x has the columns a, b, c and unlike a regular alias it does not hide the range variables of the tables being joined t1 and t2. Per SQL:2016 feature F404 "Range variable for common column names". Reviewed-by: Vik Fearing <vik.fearing@2ndquadrant.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/flat/454638cf-d563-ab76-a585-2564428062af@2ndquadrant.com
* Add p_names field to ParseNamespaceItemPeter Eisentraut2021-03-311-2/+8
| | | | | | | | | | | | ParseNamespaceItem had a wired-in assumption that p_rte->eref describes the table and column aliases exposed by the nsitem. This relaxes this by creating a separate p_names field in an nsitem. This is mainly preparation for a patch for JOIN USING aliases, but it saves one indirection in common code paths, so it's possibly a win on its own. Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://www.postgresql.org/message-id/785329.1616455091@sss.pgh.pa.us
* Extended statistics on expressionsTomas Vondra2021-03-272-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow defining extended statistics on expressions, not just just on simple column references. With this commit, expressions are supported by all existing extended statistics kinds, improving the same types of estimates. A simple example may look like this: CREATE TABLE t (a int); CREATE STATISTICS s ON mod(a,10), mod(a,20) FROM t; ANALYZE t; The collected statistics are useful e.g. to estimate queries with those expressions in WHERE or GROUP BY clauses: SELECT * FROM t WHERE mod(a,10) = 0 AND mod(a,20) = 0; SELECT 1 FROM t GROUP BY mod(a,10), mod(a,20); This introduces new internal statistics kind 'e' (expressions) which is built automatically when the statistics object definition includes any expressions. This represents single-expression statistics, as if there was an expression index (but without the index maintenance overhead). The statistics is stored in pg_statistics_ext_data as an array of composite types, which is possible thanks to 79f6a942bd. CREATE STATISTICS allows building statistics on a single expression, in which case in which case it's not possible to specify statistics kinds. A new system view pg_stats_ext_exprs can be used to display expression statistics, similarly to pg_stats and pg_stats_ext views. ALTER TABLE ... ALTER COLUMN ... TYPE now treats indexes the same way it treats indexes, i.e. it drops and recreates the statistics. This means all statistics are reset, and we no longer try to preserve at least the functional dependencies. This should not be a major issue in practice, as the functional dependencies actually rely on per-column statistics, which were always reset anyway. Author: Tomas Vondra Reviewed-by: Justin Pryzby, Dean Rasheed, Zhihong Yu Discussion: https://postgr.es/m/ad7891d2-e90c-b446-9fe2-7419143847d7%40enterprisedb.com
* ALTER TABLE ... DETACH PARTITION ... CONCURRENTLYAlvaro Herrera2021-03-251-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow a partition be detached from its partitioned table without blocking concurrent queries, by running in two transactions and only requiring ShareUpdateExclusive in the partitioned table. Because it runs in two transactions, it cannot be used in a transaction block. This is the main reason to use dedicated syntax: so that users can choose to use the original mode if they need it. But also, it doesn't work when a default partition exists (because an exclusive lock would still need to be obtained on it, in order to change its partition constraint.) In case the second transaction is cancelled or a crash occurs, there's ALTER TABLE .. DETACH PARTITION .. FINALIZE, which executes the final steps. The main trick to make this work is the addition of column pg_inherits.inhdetachpending, initially false; can only be set true in the first part of this command. Once that is committed, concurrent transactions that use a PartitionDirectory will include or ignore partitions so marked: in optimizer they are ignored if the row is marked committed for the snapshot; in executor they are always included. As a result, and because of the way PartitionDirectory caches partition descriptors, queries that were planned before the detach will see the rows in the detached partition and queries that are planned after the detach, won't. A CHECK constraint is created that duplicates the partition constraint. This is probably not strictly necessary, and some users will prefer to remove it afterwards, but if the partition is re-attached to a partitioned table, the constraint needn't be rechecked. Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/20200803234854.GA24158@alvherre.pgsql
* Allow configurable LZ4 TOAST compression.Robert Haas2021-03-191-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
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