Commit graph

1824 commits

Author SHA1 Message Date
Amit Langote
c8ec5e0543 Revert "Add soft error handling to some expression nodes"
This reverts commit 7fbc75b26e.

Looks like the LLVM additions may not be totally correct.
2023-10-02 13:48:15 +09:00
Amit Langote
7fbc75b26e Add soft error handling to some expression nodes
This adjusts the expression evaluation code for CoerceViaIO and
CoerceToDomain to handle errors softly if needed.

For CoerceViaIo, this means using InputFunctionCallSafe(), which
provides the option to handle errors softly, instead of calling the
type input function directly.

For CoerceToDomain, this simply entails replacing the ereport() in
ExecEvalConstraintCheck() by errsave().

In both cases, the ErrorSaveContext to be used when evaluating the
expression is stored by ExecInitExprRec() in the expression's struct
in the expression's ExprEvalStep.  The ErrorSaveContext is passed by
setting ExprState.escontext to point to it when calling
ExecInitExprRec() on the expression whose errors are to be handled
softly.

Note that no call site of ExecInitExprRec() has been changed in this
commit, so there's no functional change.  This is intended for
implementing new SQL/JSON expression nodes in future commits that
will use to it suppress errors that may occur during type coercions.

Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
2023-10-02 11:52:28 +09:00
Dean Rasheed
1d5caec221 Fix EvalPlanQual rechecking during MERGE.
Under some circumstances, concurrent MERGE operations could lead to
inconsistent results, that varied according the plan chosen. This was
caused by a lack of rowmarks on the source relation, which meant that
EvalPlanQual rechecking was not guaranteed to return the same source
tuples when re-running the join query.

Fix by ensuring that preprocess_rowmarks() sets up PlanRowMarks for
all non-target relations used in MERGE, in the same way that it does
for UPDATE and DELETE.

Per bug #18103. Back-patch to v15, where MERGE was introduced.

Dean Rasheed, reviewed by Richard Guo.

Discussion: https://postgr.es/m/18103-c4386baab8e355e3%40postgresql.org
2023-09-30 10:52:21 +01:00
Michael Paquier
11c34b342b Show parameters of CALL as constants in pg_stat_statements
This commit changes the query jumbling of CallStmt so as its IN/OUT
parameters are able to show up as constants with a parameter symbol in
pg_stat_statements, like:
CALL proc1($1, $2);
CALL proc2($1, $2, $3);

The transformed FuncExpr is used in the query ID computation instead of
the FuncCall generated by the parser, so as it is sensitive to the OID
of the procedure and its list of input arguments.  The output arguments
are handled in a separate list in CallStmt, which is also included in
the computation.

Tests are added to pg_stat_statements to show how this affects CALL with
IN/OUT parameters as well as overloaded functions.

Like 638d42a3c5 or 31de7e60da, this improves the monitoring of
workloads with a lot of CALL statements, preventing unnecessary bloat
when these use different input (or event output) values.

Author: Sami Imseih
Discussion: https://postgr.es/m/B44FA29D-EBD0-4DD9-ABC2-16F1CB087074@amazon.com
2023-09-28 15:17:55 +09:00
Michael Paquier
bb45156f34 Show names of DEALLOCATE as constants in pg_stat_statements
This commit switches query jumbling so as prepared statement names are
treated as constants in DeallocateStmt.  A boolean field is added to
DeallocateStmt to make a distinction between ALL and named prepared
statements, as "name" was used to make this difference before, NULL
meaning DEALLOCATE ALL.

Prior to this commit, DEALLOCATE was not tracked in pg_stat_statements,
for the reason that it was not possible to treat its name parameter as a
constant.  Now that query jumbling applies to all the utility nodes,
this reason does not apply anymore.

Like 638d42a3c5, this can be a huge advantage for monitoring where
prepared statement names are randomly generated, preventing bloat in
pg_stat_statements.  A couple of tests are added to track the new
behavior.

Author: Dagfinn Ilmari Mannsåker, Michael Paquier
Reviewed-by: Julien Rouhaud
Discussion: https://postgr.es/m/ZMhT9kNtJJsHw6jK@paquier.xyz
2023-08-27 17:27:44 +09:00
Alvaro Herrera
b0e96f3119
Catalog not-null constraints
We now create contype='n' pg_constraint rows for not-null constraints.

We propagate these constraints to other tables during operations such as
adding inheritance relationships, creating and attaching partitions and
creating tables LIKE other tables.  We also spawn not-null constraints
for inheritance child tables when their parents have primary keys.
These related constraints mostly follow the well-known rules of
conislocal and coninhcount that we have for CHECK constraints, with some
adaptations: for example, as opposed to CHECK constraints, we don't
match not-null ones by name when descending a hierarchy to alter it,
instead matching by column name that they apply to.  This means we don't
require the constraint names to be identical across a hierarchy.

For now, we omit them for system catalogs.  Maybe this is worth
reconsidering.  We don't support NOT VALID nor DEFERRABLE clauses
either; these can be added as separate features later (this patch is
already large and complicated enough.)

psql shows these constraints in \d+.

pg_dump requires some ad-hoc hacks, particularly when dumping a primary
key.  We now create one "throwaway" not-null constraint for each column
in the PK together with the CREATE TABLE command, and once the PK is
created, all those throwaway constraints are removed.  This avoids
having to check each tuple for nullness when the dump restores the
primary key creation.

pg_upgrading from an older release requires a somewhat brittle procedure
to create a constraint state that matches what would be created if the
database were being created fresh in Postgres 17.  I have tested all the
scenarios I could think of, and it works correctly as far as I can tell,
but I could have neglected weird cases.

This patch has been very long in the making.  The first patch was
written by Bernd Helmle in 2010 to add a new pg_constraint.contype value
('n'), which I (Álvaro) then hijacked in 2011 and 2012, until that one
was killed by the realization that we ought to use contype='c' instead:
manufactured CHECK constraints.  However, later SQL standard
development, as well as nonobvious emergent properties of that design
(mostly, failure to distinguish them from "normal" CHECK constraints as
well as the performance implication of having to test the CHECK
expression) led us to reconsider this choice, so now the current
implementation uses contype='n' again.  During Postgres 16 this had
already been introduced by commit e056c557ae, but there were some
problems mainly with the pg_upgrade procedure that couldn't be fixed in
reasonable time, so it was reverted.

In 2016 Vitaly Burovoy also worked on this feature[1] but found no
consensus for his proposed approach, which was claimed to be closer to
the letter of the standard, requiring an additional pg_attribute column
to track the OID of the not-null constraint for that column.
[1] https://postgr.es/m/CAKOSWNkN6HSyatuys8xZxzRCR-KL1OkHS5-b9qd9bf1Rad3PLA@mail.gmail.com

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Author: Bernd Helmle <mailings@oopsware.de>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
2023-08-25 13:31:24 +02:00
Etsuro Fujita
9e9931d2bf Re-allow FDWs and custom scan providers to replace joins with pseudoconstant quals.
This was disabled in commit 6f80a8d9c due to the lack of support for
handling of pseudoconstant quals assigned to replaced joins in
createplan.c.  To re-allow it, this patch adds the support by 1)
modifying the ForeignPath and CustomPath structs so that if they
represent foreign and custom scans replacing a join with a scan, they
store the list of RestrictInfo nodes to apply to the join, as in
JoinPaths, and by 2) modifying create_scan_plan() in createplan.c so
that it uses that list in that case, instead of the baserestrictinfo
list, to get pseudoconstant quals assigned to the join, as mentioned in
the commit message for that commit.

Important item for the release notes: this is non-backwards-compatible
since it modifies the ForeignPath and CustomPath structs, as mentioned
above, and changes the argument lists for FDW helper functions
create_foreignscan_path(), create_foreign_join_path(), and
create_foreign_upper_path().

Richard Guo, with some additional changes by me, reviewed by Nishant
Sharma, Suraj Kharage, and Richard Guo.

Discussion: https://postgr.es/m/CADrsxdbcN1vejBaf8a%2BQhrZY5PXL-04mCd4GDu6qm6FigDZd6Q%40mail.gmail.com
2023-08-15 16:45:00 +09:00
Michael Paquier
638d42a3c5 Show GIDs of two-phase commit commands as constants in pg_stat_statements
This relies on the "location" field added to TransactionStmt in 31de7e6,
now applied to the "gid" field used by 2PC commands.  These commands are
now reported like:
COMMIT PREPARED $1
PREPARE TRANSACTION $1
ROLLBACK PREPARED $1

Applying constants for these commands is a huge advantage for workloads
that rely a lot on 2PC commands with different GIDs.  Some tests are
added to track the new behavior.

Reviewed-by: Julien Rouhaud
Discussion: https://postgr.es/m/ZMhT9kNtJJsHw6jK@paquier.xyz
2023-08-12 10:44:15 +09:00
Etsuro Fujita
20f90a0e4d Update comments on CustomPath struct.
Commit e7cb7ee14 allowed custom scan providers to create CustomPath
paths for join relations as well, but missed updating the comments.

Back-patch to all supported branches.

Discussion: https://postgr.es/m/CAPmGK15ODkN%2B%3DhkBCufj1HBW0x5OTb65Xuy7ryXchMdiCMpx_g%40mail.gmail.com
2023-08-03 17:15:00 +09:00
Michael Paquier
31de7e60da Show savepoint names as constants in pg_stat_statements
In pg_stat_statements, savepoint names now show up as constants with a
parameter symbol, using as base query string the one added as a new
entry to the PGSS hash table, leading to:
RELEASE $1
ROLLBACK TO $1
SAVEPOINT $1

Applying constants to these query parts is a huge advantage for
workloads that generate randomly savepoint points, like ORMs (Django is
at the origin of this patch).  The ODBC driver is a second layer that
likes a lot savepoints, though it does not use a random naming pattern.

A "location" field is added to TransactionStmt, now set only for
savepoints.  The savepoint name is ignored by the query jumbling.  The
location can be extended to other query patterns, if required, like 2PC
commands.  Some tests are added to pg_stat_statements for all the query
patterns supported by the parser.

ROLLBACK, ROLLBACK TO SAVEPOINT and ROLLBACK TRANSACTION TO SAVEPOINT
have the same Node representation, so all these are equivalents.  The
same happens for RELEASE and RELEASE SAVEPOINT.

Author: Greg Sabino Mullane
Discussion: https://postgr.es/m/CAKAnmm+2s9PA4OaumwMJReWHk8qvJ_-g1WqxDRDAN1BSUfxyTw@mail.gmail.com
2023-07-27 09:42:33 +09:00
Amit Langote
03734a7fed Add more SQL/JSON constructor functions
This Patch introduces three SQL standard JSON functions:

JSON()
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.

Catversion bumped as this changes ruleutils.c.

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: Andrew Dunstan <andrew@dunslane.net>
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, Álvaro Herrera,
Peter Eisentraut

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
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
2023-07-26 17:08:33 +09:00
Amit Langote
7c7412cae3 Code review for commit b6e1157e7d
b6e1157e7d made some changes to enforce that
JsonValueExpr.formatted_expr is always set and is the expression that
gives a JsonValueExpr its runtime value, but that's not really
apparent from the comments about and the code manipulating
formatted_expr.  This commit fixes that.

Per suggestion from Álvaro Herrera.

Discussion: https://postgr.es/m/20230718155313.3wqg6encgt32adqb%40alvherre.pgsql
2023-07-21 19:15:34 +09:00
Amit Langote
b6e1157e7d Don't include CaseTestExpr in JsonValueExpr.formatted_expr
A CaseTestExpr is currently being put into
JsonValueExpr.formatted_expr as placeholder for the result of
evaluating JsonValueExpr.raw_expr, which in turn is evaluated
separately.  Though, there's no need for this indirection if
raw_expr itself can be embedded into formatted_expr and evaluated
as part of evaluating the latter, especially as there is no
special reason to evaluate it separately.  So this commit makes it
so.  As a result, JsonValueExpr.raw_expr no longer needs to be
evaluated in ExecInterpExpr(), eval_const_exprs_mutator() etc. and
is now only used for displaying the original "unformatted"
expression in ruleutils.c.

While at it, this also removes the function makeCaseTestExpr(),
because the code in makeJsonConstructorExpr() looks more readable
without it IMO and isn't used by anyone else either.

Finally, a note is added in the comment above CaseTestExpr's
definition that JsonConstructorExpr is also using it.

Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
2023-07-13 12:13:58 +09:00
Nathan Bossart
151c22deee Revert MAINTAIN privilege and pg_maintain predefined role.
This reverts the following commits: 4dbdb82513, c2122aae63,
5b1a879943, 9e1e9d6560, ff9618e82a, 60684dd834, 4441fc704d,
and b5d6382496.  A role with the MAINTAIN privilege may be able to
use search_path tricks to escalate privileges to the table owner.
Unfortunately, it is too late in the v16 development cycle to apply
the proposed fix, i.e., restricting search_path when running
maintenance commands.

Bumps catversion.

Reviewed-by: Jeff Davis
Discussion: https://postgr.es/m/E1q7j7Y-000z1H-Hr%40gemulon.postgresql.org
Backpatch-through: 16
2023-07-07 11:25:13 -07:00
David Rowley
c65102006b Remove redundant PARTITION BY columns from WindowClauses
Here we adjust the query planner to have it remove items from a window
clause's PARTITION BY clause in cases where the pathkey for a column in
the PARTITION BY clause is redundant.

Doing this allows the optimization added in 9d9c02ccd to stop window
aggregation early rather than going into "pass-through" mode to find
tuples belonging to the next partition.  Also, when we manage to remove
all PARTITION BY columns, we now no longer needlessly check that the
current tuple belongs to the same partition as the last tuple in
nodeWindowAgg.c.  If the pathkey was redundant then all tuples must
contain the same value for the given redundant column, so there's no point
in checking that during execution.

Author: David Rowley
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/CAApHDvo2ji+hdxrxfXtRtsfSVw3to2o1nCO20qimw0dUGK8hcQ@mail.gmail.com
2023-07-03 12:49:43 +12:00
Michael Paquier
2ecbb0a493 Remove dependency to query text in JumbleQuery()
Since 3db72eb, the query ID of utilities is generated using the Query
structure, making the use of the query string in JumbleQuery()
unnecessary.  This commit removes the argument "querytext" from
JumbleQuery().

Reported-by: Joe Conway
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/ZJlQAWE4COFqHuAV@paquier.xyz
2023-06-28 08:59:36 +09:00
Amit Langote
0f8cfaf892 Retain relkind too in RTE_SUBQUERY entries for views.
47bb9db75 modified the ApplyRetrieveRule()'s conversion of a view's
original RTE_RELATION entry into an RTE_SUBQUERY one to retain relid,
rellockmode, and perminfoindex so that the executor can lock the view
and check its permissions.  It seems better to also retain
relkind for cross-checking that the exception of an
RTE_SUBQUERY entry being allowed to carry relation details only
applies to views, so do so.

Bump catversion because this changes the output format of
RTE_SUBQUERY RTEs.

Suggested-by: David Steele <david@pgmasters.net>
Reviewed-by: David Steele <david@pgmasters.net>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/3953179e-9540-e5d1-a743-4bef368785b0%40pgmasters.net
2023-06-14 12:00:10 +09:00
Andres Freund
a1cd982098 meson: Add dependencies to perl modules to various script invocations
Eventually it is likely worth trying to deal with this in a more expansive
way, by generating dependency files generated within the scripts. But it's not
entirely obvious how to do that in perl and is work more suitable for 17
anyway.

Reported-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Reviewed-by: Tristan Partin <tristan@neon.tech>
Discussion: https://postgr.es/m/87v8g7s6bf.fsf@wibble.ilmari.org
2023-06-09 20:12:16 -07:00
Tom Lane
991a3df227 Fix filtering of "cloned" outer-join quals some more.
We've had multiple issues with the clause_is_computable_at logic that
I introduced in 2489d76c4: it's been known to accept more than one
clone of the same qual at the same plan node, and also to accept no
clones at all.  It's looking impractical to get it 100% right on the
basis of the currently-stored information, so fix it by introducing a
new RestrictInfo field "incompatible_relids" that explicitly shows
which outer joins a given clone mustn't be pushed above.

In principle we could populate this field in every RestrictInfo, but
that would cost space and there doesn't presently seem to be a need
for it in general.  Also, while deconstruct_distribute_oj_quals can
easily fill the field with the remaining members of the commutative
join set that it's considering, computing it in the general case
seems again pretty complicated.  So for now, just fill it for
clone quals.

Along the way, fix a bug that may or may not be only latent:
equivclass.c was generating replacement clauses with is_pushed_down
and has_clone/is_clone markings that didn't match their
required_relids.  This led me to conclude that leaving the clone flags
out of make_restrictinfo's purview wasn't such a great idea after all,
so add them.

Per report from Richard Guo.

Discussion: https://postgr.es/m/CAMbWs48EYi_9-pSd0ORes1kTmTeAjT4Q3gu49hJtYCbSn2JyeA@mail.gmail.com
2023-05-25 10:28:33 -04:00
Tom Lane
0245f8db36 Pre-beta mechanical code beautification.
Run pgindent, pgperltidy, and reformat-dat-files.

This set of diffs is a bit larger than typical.  We've updated to
pg_bsd_indent 2.1.2, which properly indents variable declarations that
have multi-line initialization expressions (the continuation lines are
now indented one tab stop).  We've also updated to perltidy version
20230309 and changed some of its settings, which reduces its desire to
add whitespace to lines to make assignments etc. line up.  Going
forward, that should make for fewer random-seeming changes to existing
code.

Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
2023-05-19 17:24:48 -04:00
Tom Lane
70b42f2790 Fix misbehavior of EvalPlanQual checks with multiple result relations.
The idea of EvalPlanQual is that we replace the query's scan of the
result relation with a single injected tuple, and see if we get a
tuple out, thereby implying that the injected tuple still passes the
query quals.  (In join cases, other relations in the query are still
scanned normally.)  This logic was not updated when commit 86dc90056
made it possible for a single DML query plan to have multiple result
relations, when the query target relation has inheritance or partition
children.  We replaced the output for the current result relation
successfully, but other result relations were still scanned normally;
thus, if any other result relation contained a tuple satisfying the
quals, we'd think the EPQ check passed, even if it did not pass for
the injected tuple itself.  This would lead to update or delete
actions getting performed when they should have been skipped due to
a conflicting concurrent update in READ COMMITTED isolation mode.

Fix by blocking all sibling result relations from emitting tuples
during an EvalPlanQual recheck.  In the back branches, the fix is
complicated a bit by the need to not change the size of struct
EPQState (else we'd have ABI-breaking changes in offsets in
struct ModifyTableState).  Like the back-patches of 3f7836ff6
and 4b3e37993, add a separately palloc'd struct to avoid that.
The logic is the same as in HEAD otherwise.

This is only a live bug back to v14 where 86dc90056 came in.
However, I chose to back-patch the test cases further, on the
grounds that this whole area is none too well tested.  I skipped
doing so in v11 though because none of the test applied cleanly,
and it didn't quite seem worth extra work for a branch with only
six months to live.

Per report from Ante Krešić (via Aleksander Alekseev)

Discussion: https://postgr.es/m/CAJ7c6TMBTN3rcz4=AjYhLPD_w3FFT0Wq_C15jxCDn8U4tZnH1g@mail.gmail.com
2023-05-19 14:26:40 -04:00
Alexander Korotkov
b9a7a82272 Revert "Add USER SET parameter values for pg_db_role_setting"
This reverts commit 096dd80f3c and its fixups beecbe8e50, afdd9f7f0e,
529da086ba, db93e739ac.

Catversion is bumped.

Discussion: https://postgr.es/m/d46f9265-ff3c-6743-2278-6772598233c2%40pgmasters.net
2023-05-17 20:28:57 +03:00
Tom Lane
9df8f903eb Fix some issues with improper placement of outer join clauses.
After applying outer-join identity 3 in the forward direction,
it was possible for the planner to mistakenly apply a qual clause
from above the two outer joins at the now-lower join level.
This can give the wrong answer, since a value that would get nulled
by the now-upper join might not yet be null.

To fix, when we perform such a transformation, consider that the
now-lower join hasn't really completed the outer join it's nominally
responsible for and thus its relid set should not include that OJ's
relid (nor should its output Vars have that nullingrel bit set).
Instead we add those bits when the now-upper join is performed.
The existing rules for qual placement then suffice to prevent
higher qual clauses from dropping below the now-upper join.
There are a few complications from needing to consider transitive
closures in case multiple pushdowns have happened, but all in all
it's not a very complex patch.

This is all new logic (from 2489d76c4) so no need to back-patch.
The added test cases all have the same results as in v15.

Tom Lane and Richard Guo

Discussion: https://postgr.es/m/0b819232-4b50-f245-1c7d-c8c61bf41827@postgrespro.ru
2023-05-17 11:14:04 -04:00
Michael Paquier
d8c3106bb6 Add back SQLValueFunction for SQL keywords
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
2023-05-17 10:19:17 +09:00
Alvaro Herrera
5472743d9e
Revert "Move PartitionPruneInfo out of plan nodes into PlannedStmt"
This reverts commit ec38694894 and its fixup 589bb81649.

This change was intended to support query planning avoiding acquisition
of locks on partitions that were going to be pruned; however, the
overall project took a different direction at [1] and this bit is no
longer needed.  Put things back the way they were as agreed in [2], to
avoid unnecessary complexity.

Discussion: [1] https://postgr.es/m/4191508.1674157166@sss.pgh.pa.us
Discussion: [2] https://postgr.es/m/20230502175409.kcoirxczpdha26wt@alvherre.pgsql
2023-05-04 12:09:59 +02:00
Michael Paquier
8961cb9a03 Fix typos in comments
The changes done in this commit impact comments with no direct
user-visible changes, with fixes for incorrect function, variable or
structure names.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/e8c38840-596a-83d6-bd8d-cebc51111572@gmail.com
2023-05-02 12:23:08 +09:00
Alvaro Herrera
9ce04b50e1
Revert "Catalog NOT NULL constraints" and fallout
This reverts commit e056c557ae and minor later fixes thereof.

There's a few problems in this new feature -- most notably regarding
pg_upgrade behavior, but others as well.  This new feature is not in any
way critical on its own, so instead of scrambling to fix it we revert it
and try again in early 17 with these issues in mind.

Discussion: https://postgr.es/m/3801207.1681057430@sss.pgh.pa.us
2023-04-12 19:29:21 +02:00
Alvaro Herrera
e056c557ae
Catalog NOT NULL constraints
We now create pg_constaint rows for NOT NULL constraints with
contype='n'.

We propagate these constraints during operations such as adding
inheritance relationships, creating and attaching partitions, creating
tables LIKE other tables.  We mostly follow the well-known rules of
conislocal and coninhcount that we have for CHECK constraints, with some
adaptations; for example, as opposed to CHECK constraints, we don't
match NOT NULL ones by name when descending a hierarchy to alter it;
instead we match by column number.  This means we don't require the
constraint names to be identical across a hierarchy.

For now, we omit them from system catalogs.  Maybe this is worth
reconsidering.  We don't support NOT VALID nor DEFERRABLE clauses
either; these can be added as separate features later (this patch is
already large and complicated enough.)

This has been very long in the making.  The first patch was written by
Bernd Helmle in 2010 to add a new pg_constraint.contype value ('n'),
which I (Álvaro) then hijacked in 2011 and 2012, until that one was
killed by the realization that we ought to use contype='c' instead:
manufactured CHECK constraints.  However, later SQL standard
development, as well as nonobvious emergent properties of that design
(mostly, failure to distinguish them from "normal" CHECK constraints as
well as the performance implication of having to test the CHECK
expression) led us to reconsider this choice, so now the current
implementation uses contype='n' again.

In 2016 Vitaly Burovoy also worked on this feature[1] but found no
consensus for his proposed approach, which was claimed to be closer to
the letter of the standard, requiring additional pg_attribute columns to
track the OID of the NOT NULL constraint for that column.
[1] https://postgr.es/m/CAKOSWNkN6HSyatuys8xZxzRCR-KL1OkHS5-b9qd9bf1Rad3PLA@mail.gmail.com

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Author: Bernd Helmle <mailings@oopsware.de>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>

Discussion: https://postgr.es/m/CACA0E642A0267EDA387AF2B%40%5B172.26.14.62%5D
Discussion: https://postgr.es/m/AANLkTinLXMOEMz+0J29tf1POokKi4XDkWJ6-DDR9BKgU@mail.gmail.com
Discussion: https://postgr.es/m/20110707213401.GA27098@alvh.no-ip.org
Discussion: https://postgr.es/m/1343682669-sup-2532@alvh.no-ip.org
Discussion: https://postgr.es/m/CAKOSWNkN6HSyatuys8xZxzRCR-KL1OkHS5-b9qd9bf1Rad3PLA@mail.gmail.com
Discussion: https://postgr.es/m/20220817181249.q7qvj3okywctra3c@alvherre.pgsql
2023-04-07 19:59:57 +02:00
Michael Paquier
1d477a907e Fix row tracking in pg_stat_statements with extended query protocol
pg_stat_statements relies on EState->es_processed to count the number of
rows processed by ExecutorRun().  This proves to be a problem under the
extended query protocol when the result of a query is fetched through
more than one call of ExecutorRun(), as es_processed is reset each time
ExecutorRun() is called.  This causes pg_stat_statements to report the
number of rows calculated in the last execute fetch, rather than the
global sum of all the rows processed.

As pquery.c tells, this is a problem when a portal does not use
holdStore.  For example, DMLs with RETURNING would report a correct
tuple count as these do one execution cycle when the query is first
executed to fill in the portal's store with one ExecutorRun(), feeding
on the portal's store for each follow-up execute fetch depending on the
fetch size requested by the client.

The fix proposed for this issue is simple with the addition of an extra
counter in EState that's preserved across multiple ExecutorRun() calls,
incremented with the value calculated in es_processed.  This approach is
not back-patchable, unfortunately.

Note that libpq does not currently give any way to control the fetch
size when using the extended v3 protocol, meaning that in-core testing
is not possible yet.  This issue can be easily verified with the JDBC
driver, though, with *autocommit disabled*.  Hence, having in-core tests
requires more features, left for future discussion:
- At least two new libpq routines splitting PQsendQueryGuts(), one for
the bind/describe and a second for a series of execute fetches with a
custom fetch size, likely in a fashion similar to what JDBC does.
- A psql meta-command for the execute phase.  This part is not strictly
mandatory, still it could be handy.

Reported-by: Andrew Dunstan (original discovery by Simon Siggs)
Author: Sami Imseih
Reviewed-by: Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/EBE6C507-9EB6-4142-9E4D-38B1673363A7@amazon.com
Discussion: https://postgr.es/m/c90890e7-9c89-c34f-d3c5-d5c763a34bd8@dunslane.net
2023-04-06 09:29:03 +09:00
Tom Lane
16dc2703c5 Support "Right Anti Join" plan shapes.
Merge and hash joins can support antijoin with the non-nullable input
on the right, using very simple combinations of their existing logic
for right join and anti join.  This gives the planner more freedom
about how to order the join.  It's particularly useful for hash join,
since we may now have the option to hash the smaller table instead
of the larger.

Richard Guo, reviewed by Ronan Dunklau and myself

Discussion: https://postgr.es/m/CAMbWs48xh9hMzXzSy3VaPzGAz+fkxXXTUbCLohX1_L8THFRm2Q@mail.gmail.com
2023-04-05 16:59:09 -04:00
Alvaro Herrera
6ee30209a6
SQL/JSON: support the IS JSON predicate
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
2023-03-31 22:34:04 +02:00
Alvaro Herrera
60966f56c3
Fix inconsistencies and style issues in new SQL/JSON code
Reported by Alexander Lakhin.

Discussion: https://postgr.es/m/60483139-5c34-851d-baee-6c0d014e1710@gmail.com
2023-03-30 21:06:31 +02:00
Alvaro Herrera
7081ac46ac
SQL/JSON: add standard JSON constructor functions
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
2023-03-29 12:11:36 +02:00
Tomas Vondra
19d8e2308b Ignore BRIN indexes when checking for HOT updates
When determining whether an index update may be skipped by using HOT, we
can ignore attributes indexed by block summarizing indexes without
references to individual tuples that need to be cleaned up.

A new type TU_UpdateIndexes provides a signal to the executor to
determine which indexes to update - no indexes, all indexes, or only the
summarizing indexes.

This also removes rd_indexattr list, and replaces it with rd_attrsvalid
flag. The list was not used anywhere, and a simple flag is sufficient.

This was originally committed as 5753d4ee32, but then got reverted by
e3fcca0d0d because of correctness issues.

Original patch by Josef Simanek, various fixes and improvements by Tomas
Vondra and me.

Authors: Matthias van de Meent, Josef Simanek, Tomas Vondra
Reviewed-by: Tomas Vondra, Alvaro Herrera
Discussion: https://postgr.es/m/05ebcb44-f383-86e3-4f31-0a97a55634cf@enterprisedb.com
Discussion: https://postgr.es/m/CAFp7QwpMRGcDAQumN7onN9HjrJ3u4X3ZRXdGFT0K5G2JWvnbWg%40mail.gmail.com
2023-03-20 11:02:42 +01:00
Michael Paquier
0e681cf039 Add files related to query jumbling in src/include/nodes/ for meson
This caused ninja clean to not remove the two files generated by
gen_node_support.pl for the query jumbling, for example:
queryjumblefuncs.funcs.c and queryjumblefuncs.switch.c.

Reported-by: Pavel Stehule
Discussion: https://postgr.es/m/CAFj8pRBFiWVRyGYSPziyFuXJbHirNmfWwzbfTyCf8YOdiwK74w@mail.gmail.com
2023-03-18 18:04:04 +09:00
Tom Lane
483bdb2afe Support [NO] INDENT option in XMLSERIALIZE().
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
2023-03-15 16:59:09 -04:00
Peter Eisentraut
822e8e2951 Update comment
There was apparently an attempt here to list all the object types that
ACL_USAGE applies to, but it wasn't complete.  So instead of trying to
keep up, put in a more timeless comment.
2023-03-08 14:22:06 +01:00
Michael Paquier
a4e003338d Refine query jumbling handling for CallStmt
Previously, all the nodes of CallStmt were included in the jumbling,
causing a duplicate in the computation as the transformed state of the
CALL query was included as well as the parsed state (transformed
FuncCall with all the input arguments and potential output arguments).

Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/Y+MRdEq9W9XVa2AB@paquier.xyz
2023-03-08 14:38:35 +09:00
Michael Paquier
d69cd3a2e2 Ignore IntoClause.viewQuery in query jumbling
IntoClause.viewQuery is a copy of the parsed-but-not-rewritten SELECT
clause copied to IntoClause when transforming CreateTableAsStmt for a
materialized view.  Including a second copy of the SELECT Query into the
query jumbling was leading to an incorrect numbering of the Const node
locations, as these would be counted twice instead of once.

This becomes visible once the query normalization is applied to CREATE
MATERIALIZED VIEW in pg_stat_statements in the shape of a query string
using only odd numbers for the normalized constants, (regression tests
added in pg_stat_statements as of de2aca2 would show the difference).
Including the original Query from CreateTableAsStmt is enough for the
query jumbling.

Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/Y+MRdEq9W9XVa2AB@paquier.xyz
2023-03-08 11:41:52 +09:00
Tom Lane
7fee7871b4 Fix some more cases of missed GENERATED-column updates.
If UPDATE is forced to retry after an EvalPlanQual check, it neglected
to repeat GENERATED-column computations, even though those might well
have changed since we're dealing with a different tuple than before.
Fixing this is mostly a matter of looping back a bit further when
we retry.  In v15 and HEAD that's most easily done by altering the API
of ExecUpdateAct so that it includes computing GENERATED expressions.

Also, if an UPDATE in a partitioned table turns into a cross-partition
INSERT operation, we failed to recompute GENERATED columns.  That's a
bug since 8bf6ec3ba allowed partitions to have different generation
expressions; although it seems to have no ill effects before that.
Fixing this is messier because we can now have situations where the same
query needs both the UPDATE-aligned set of GENERATED columns and the
INSERT-aligned set, and it's unclear which set will be generated first
(else we could hack things by forcing the INSERT-aligned set to be
generated, which is indeed how fe9e658f4 made it work for MERGE).
The best fix seems to be to build and store separate sets of expressions
for the INSERT and UPDATE cases.  That would create ABI issues in the
back branches, but so far it seems we can leave this alone in the back
branches.

Per bug #17823 from Hisahiro Kauchi.  The first part of this affects all
branches back to v12 where GENERATED columns were added.

Discussion: https://postgr.es/m/17823-b64909cf7d63de84@postgresql.org
2023-03-06 18:31:27 -05:00
Tom Lane
00b41463c2 Require empty Bitmapsets to be represented as NULL.
When I designed the Bitmapset module, I set things up so that an empty
Bitmapset could be represented either by a NULL pointer, or by an
allocated object all of whose bits are zero.  I've recently come to
the conclusion that that was a bad idea and we should instead have a
convention like the longstanding invariant for Lists, whereby an empty
list is represented by NIL and nothing else.

To do this, we need to fix bms_intersect, bms_difference, and a couple
of other functions to check for having produced an empty result; but
then we can replace bms_is_empty(a) by a simple "a == NULL" test.

This is very likely a (marginal) win performance-wise, because we
call bms_is_empty many more times than those other functions put
together.  However, the real reason to do it is that we have various
places that have hand-implemented a rule about "this Bitmapset
variable must be exactly NULL if empty", so that they can use
checks-for-null in place of bms_is_empty calls in particularly hot
code paths.  That is a really fragile, mistake-prone way to do things,
and I'm surprised that we've seldom been bitten by it.  It's not well
documented at all which variables have this property, so you can't
readily tell which code might be violating those conventions.  By
making the convention universal, we can eliminate a subtle source of
bugs.

Patch by me; thanks to Nathan Bossart and Richard Guo for review.

Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
2023-03-02 11:47:26 -05:00
Tom Lane
141225b251 Mop up some undue familiarity with the innards of Bitmapsets.
nodeAppend.c used non-nullness of appendstate->as_valid_subplans as
a state flag to indicate whether it'd done ExecFindMatchingSubPlans
(or some sufficient approximation to that).  This was pretty
questionable even in the beginning, since it wouldn't really work
right if there are no valid subplans.  It got more questionable
after commit 27e1f1456 added logic that could reduce as_valid_subplans
to an empty set: at that point we were depending on unspecified
behavior of bms_del_members, namely that it'd not return an empty
set as NULL.  It's about to start doing that, which breaks this
logic entirely.  Hence, add a separate boolean flag to signal
whether as_valid_subplans has been computed.

Also fix a previously-cosmetic bug in nodeAgg.c, wherein it ignored
the return value of bms_del_member instead of updating its pointer.

Patch by me; thanks to Nathan Bossart and Richard Guo for review.

Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
2023-03-02 11:37:37 -05:00
Tom Lane
462bb7f128 Remove bms_first_member().
This function has been semi-deprecated ever since we invented
bms_next_member().  Its habit of scribbling on the input bitmapset
isn't great, plus for sufficiently large bitmapsets it would take
O(N^2) time to complete a loop.  Now we have the additional problem
that reducing the input to empty while leaving it still accessible
would violate a planned invariant.  So let's just get rid of it,
after updating the few extant callers to use bms_next_member().

Patch by me; thanks to Nathan Bossart and Richard Guo for review.

Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
2023-03-02 11:34:29 -05:00
Tom Lane
87f3667ec0 Fix MULTIEXPR_SUBLINK with partitioned target tables, yet again.
We already tried to fix this in commits 3f7323cbb et al (and follow-on
fixes), but now it emerges that there are still unfixed cases;
moreover, these cases affect all branches not only pre-v14.  I thought
we had eliminated all cases of making multiple clones of an UPDATE's
target list when we nuked inheritance_planner.  But it turns out we
still do that in some partitioned-UPDATE cases, notably including
INSERT ... ON CONFLICT UPDATE, because ExecInitPartitionInfo thinks
it's okay to clone and modify the parent's targetlist.

This fix is based on a suggestion from Andres Freund: let's stop
abusing the ParamExecData.execPlan mechanism, which was only ever
meant to handle initplans, and instead solve the execution timing
problem by having the expression compiler move MULTIEXPR_SUBLINK steps
to the front of their expression step lists.  This is feasible because
(a) all branches still in support compile the entire targetlist of
an UPDATE into a single ExprState, and (b) we know that all
MULTIEXPR_SUBLINKs do need to be evaluated --- none could be buried
inside a CASE, for example.  There is a minor semantics change
concerning the order of execution of the MULTIEXPR's subquery versus
other parts of the parent targetlist, but that seems like something
we can get away with.  By doing that, we no longer need to worry
about whether different clones of a MULTIEXPR_SUBLINK share output
Params; their usage of that data structure won't overlap.

Per bug #17800 from Alexander Lakhin.  Back-patch to all supported
branches.  In v13 and earlier, we can revert 3f7323cbb and follow-on
fixes; however, I chose to keep the SubPlan.subLinkId field added
in ccbb54c72.  We don't need that anymore in the core code, but it's
cheap enough to fill, and removing a plan node field in a minor
release seems like it'd be asking for trouble.

Andres Freund and Tom Lane

Discussion: https://postgr.es/m/17800-ff90866b3906c964@postgresql.org
2023-02-25 14:44:14 -05:00
Tom Lane
e9a20e451f When removing a relation from the query, drop its RelOptInfo.
In commit b78f6264e I opined that it was "too risky" to delete a
relation's RelOptInfo from the planner's data structures when we have
realized that we don't need to join to it; so instead we just marked
it as a dead relation.  In hindsight that judgment seems flawed: any
subsequent access to such a dead relation is arguably a bug in
itself, so leaving the RelOptInfo present just helps to mask bugs.
Let's delete it instead, allowing removal of the whole notion of a
"dead relation".  So far as the regression tests can find, this
requires no other code changes, except for one Assert in equivclass.c
that was very dubiously not complaining about access to a dead rel.

Discussion: https://postgr.es/m/229905.1676062220@sss.pgh.pa.us
2023-02-13 13:35:38 -05:00
Michael Paquier
2a507f6fd8 Mark more nodes with attribute no_query_jumble
This commit removes most of the Plan and Path nodes, which should never
be included in the query jumbling because we ignore these in Query
nodes.  This is facilitated by making no_query_jumble an inherited
attribute, like no_copy, no_equal and no_read when the supertype of a
node is found as marked with that.

RawStmt is not used in parsed queries, so it can be removed from the
query jumbling.  A couple of nodes defined in pathnodes.h, plannodes.h
and primnodes.h with NodeTag as supertype need to be marked
individually.

Forcing the execution of the query jumbling code with compute_query_id =
auto while pg_stat_statements is loaded brings the code coverage of
queryjumblefuncs.funcs.c to 95.6%.

The core code does not yet include a way to enforce the execution in
query jumbling except in pg_stat_statements, so the numbers I am
mentioning above will not reflect on the default coverage report with
just what is done in this commit.

Reported-by: Tom Lane
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/3344827.1675809127@sss.pgh.pa.us
2023-02-13 09:07:33 +09:00
Michael Paquier
9e8b694d81 Fix typo in parsenodes.h
Introduced in a61b1f7 when RTEPermissionInfo got added.  Issue spotted
while reviewing the area for a different patch.
2023-02-10 15:37:41 +09:00
Michael Paquier
9ba37b2cb6 Include values of A_Const nodes in query jumbling
Like the implementation for node copy, write and read, this node
requires a custom implementation so as the query jumbling is able to
consider the correct value assigned to it, depending on its type (int,
float, bool, string, bitstring).

Based on a dump of pg_stat_statements from the regression database, this
would confuse the query jumbling of the following queries:
- SET.
- COPY TO with SELECT queries.
- START TRANSACTION with different isolation levels.
- ALTER TABLE with default expressions.
- CREATE TABLE with partition bounds.

Note that there may be a long-term argument in tracking the location of
such nodes so as query strings holding such nodes could be normalized,
but this is left as a separate discussion.

Oversight in 3db72eb.

Discussion: https://postgr.es/m/Y9+HuYslMAP6yyPb@paquier.xyz
2023-02-07 09:03:54 +09:00
David Rowley
e9aaf06328 Remove dead NoMovementScanDirection code
Here remove some dead code from heapgettup() and heapgettup_pagemode()
which was trying to support NoMovementScanDirection scans.  This code can
never be reached as standard_ExecutorRun() never calls ExecutePlan with
NoMovementScanDirection.

Additionally, plans which were scanning an unordered index would use
NoMovementScanDirection rather than ForwardScanDirection.  There was no
real need for this, so here we adjust this so we use ForwardScanDirection
for unordered index scans.  A comment in pathnodes.h claimed that
NoMovementScanDirection was used for PathKey reasons, but if that was
true, it no longer is, per code in build_index_paths().

This does change the non-text format of the EXPLAIN output so that
unordered index scans now have a "Forward" scan direction rather than
"NoMovement".  The text format of EXPLAIN has not changed.

Author: Melanie Plageman
Reviewed-by: Tom Lane, David Rowley
Discussion: https://postgr.es/m/CAAKRu_bvkhka0CZQun28KTqhuUh5ZqY=_T8QEqZqOL02rpi2bw@mail.gmail.com
2023-02-01 10:52:41 +13:00
Michael Paquier
3db72ebcbe Generate code for query jumbling through gen_node_support.pl
This commit changes the query jumbling code in queryjumblefuncs.c to be
generated automatically based on the information of the nodes in the
headers of src/include/nodes/ by using gen_node_support.pl.  This
approach offers many advantages:
- Support for query jumbling for all the utility statements, based on the
state of their parsed Nodes and not only their query string.  This will
greatly ease the switch to normalize the information of some DDLs, like
SET or CALL for example (this is left unchanged and should be part of a
separate discussion).  With this feature, the number of entries stored
for utilities in pg_stat_statements is reduced (for example now
"CHECKPOINT" and "checkpoint" mean the same thing with the same query
ID).
- Documentation of query jumbling directly in the structure definition
of the nodes.  Since this code has been introduced in pg_stat_statements
and then moved to code, the reasons behind the choices of what should be
included in the jumble are rather sparse.  Note that some explanation is
added for the most relevant parts, as a start.
- Overall code reduction and more consistency with the other parts
generating read, write and copy depending on the nodes.

The query jumbling is controlled by a couple of new node attributes,
documented in nodes/nodes.h:
- custom_query_jumble, to mark a Node as having a custom
implementation.
- no_query_jumble, to ignore entirely a Node.
- query_jumble_ignore, to ignore a field in a Node.
- query_jumble_location, to mark a location in a Node, for
normalization.  This can apply only to int fields, with "location" in
their name (only Const as of this commit).

There should be no compatibility impact on pg_stat_statements, as the
new code applies the jumbling to the same fields for each node (its
regression tests have no modification, for one).

Some benchmark of the query jumbling between HEAD and this commit for
SELECT and DMLs has proved that this new code does not cause a
performance regression, with computation times close for both methods.
For utility queries, the new method is slower than the previous method
of calculating a hash of the query string, though we are talking about
extra ns-level changes based on what I measured, which is unnoticeable
even for OLTP workloads as a query ID is calculated once per query
post-parse analysis.

Author: Michael Paquier
Reviewed-by: Peter Eisentraut
Discussion: https://postgr.es/m/Y5BHOUhX3zTH/ig6@paquier.xyz
2023-01-31 15:24:05 +09:00