1998-12-04 16:36:51 +01:00
|
|
|
--
|
2000-01-06 07:41:55 +01:00
|
|
|
-- CASE
|
1998-12-04 16:36:51 +01:00
|
|
|
-- Test the case statement
|
1999-02-23 08:30:05 +01:00
|
|
|
--
|
|
|
|
|
|
|
|
CREATE TABLE CASE_TBL (
|
|
|
|
i integer,
|
|
|
|
f double precision
|
|
|
|
);
|
|
|
|
|
|
|
|
CREATE TABLE CASE2_TBL (
|
|
|
|
i integer,
|
|
|
|
j integer
|
|
|
|
);
|
|
|
|
|
|
|
|
INSERT INTO CASE_TBL VALUES (1, 10.1);
|
|
|
|
INSERT INTO CASE_TBL VALUES (2, 20.2);
|
|
|
|
INSERT INTO CASE_TBL VALUES (3, -30.3);
|
|
|
|
INSERT INTO CASE_TBL VALUES (4, NULL);
|
|
|
|
|
|
|
|
INSERT INTO CASE2_TBL VALUES (1, -1);
|
|
|
|
INSERT INTO CASE2_TBL VALUES (2, -2);
|
|
|
|
INSERT INTO CASE2_TBL VALUES (3, -3);
|
|
|
|
INSERT INTO CASE2_TBL VALUES (2, -4);
|
|
|
|
INSERT INTO CASE2_TBL VALUES (1, NULL);
|
|
|
|
INSERT INTO CASE2_TBL VALUES (NULL, -6);
|
1998-12-04 16:36:51 +01:00
|
|
|
|
|
|
|
--
|
1999-02-23 08:30:05 +01:00
|
|
|
-- Simplest examples without tables
|
1998-12-04 16:36:51 +01:00
|
|
|
--
|
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
SELECT '3' AS "One",
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
|
|
|
WHEN 1 < 2 THEN 3
|
1999-02-23 08:30:05 +01:00
|
|
|
END AS "Simple WHEN";
|
1998-12-04 16:36:51 +01:00
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
SELECT '<NULL>' AS "One",
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
|
|
|
WHEN 1 > 2 THEN 3
|
1999-02-23 08:30:05 +01:00
|
|
|
END AS "Simple default";
|
1998-12-04 16:36:51 +01:00
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
SELECT '3' AS "One",
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
|
|
|
WHEN 1 < 2 THEN 3
|
|
|
|
ELSE 4
|
1999-02-23 08:30:05 +01:00
|
|
|
END AS "Simple ELSE";
|
1998-12-04 16:36:51 +01:00
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
SELECT '4' AS "One",
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
|
|
|
WHEN 1 > 2 THEN 3
|
|
|
|
ELSE 4
|
1999-02-23 08:30:05 +01:00
|
|
|
END AS "ELSE default";
|
1998-12-04 16:36:51 +01:00
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
SELECT '6' AS "One",
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
|
|
|
WHEN 1 > 2 THEN 3
|
|
|
|
WHEN 4 < 5 THEN 6
|
|
|
|
ELSE 7
|
1999-02-23 08:30:05 +01:00
|
|
|
END AS "Two WHEN with default";
|
1998-12-04 16:36:51 +01:00
|
|
|
|
2017-03-12 00:36:50 +01:00
|
|
|
|
|
|
|
SELECT '7' AS "None",
|
|
|
|
CASE WHEN random() < 0 THEN 1
|
|
|
|
END AS "NULL on no matches";
|
|
|
|
|
2005-02-02 22:49:09 +01:00
|
|
|
-- Constant-expression folding shouldn't evaluate unreachable subexpressions
|
|
|
|
SELECT CASE WHEN 1=0 THEN 1/0 WHEN 1=1 THEN 1 ELSE 2/0 END;
|
|
|
|
SELECT CASE 1 WHEN 0 THEN 1/0 WHEN 1 THEN 1 ELSE 2/0 END;
|
|
|
|
|
|
|
|
-- However we do not currently suppress folding of potentially
|
|
|
|
-- reachable subexpressions
|
|
|
|
SELECT CASE WHEN i > 100 THEN 1/0 ELSE 0 END FROM case_tbl;
|
|
|
|
|
2005-01-17 04:39:37 +01:00
|
|
|
-- Test for cases involving untyped literals in test expression
|
|
|
|
SELECT CASE 'a' WHEN 'a' THEN 1 ELSE 2 END;
|
|
|
|
|
1998-12-04 16:36:51 +01:00
|
|
|
--
|
|
|
|
-- Examples of targets involving tables
|
|
|
|
--
|
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT
|
1998-12-04 16:36:51 +01:00
|
|
|
CASE
|
1999-05-07 01:09:30 +02:00
|
|
|
WHEN i >= 3 THEN i
|
|
|
|
END AS ">= 3 or Null"
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL;
|
1998-12-04 16:36:51 +01:00
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT
|
1999-05-07 01:09:30 +02:00
|
|
|
CASE WHEN i >= 3 THEN (i + i)
|
1999-02-23 08:30:05 +01:00
|
|
|
ELSE i
|
1998-12-04 16:36:51 +01:00
|
|
|
END AS "Simplest Math"
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL;
|
1998-12-04 16:36:51 +01:00
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT i AS "Value",
|
1999-02-23 08:30:05 +01:00
|
|
|
CASE WHEN (i < 0) THEN 'small'
|
|
|
|
WHEN (i = 0) THEN 'zero'
|
|
|
|
WHEN (i = 1) THEN 'one'
|
|
|
|
WHEN (i = 2) THEN 'two'
|
1998-12-04 16:36:51 +01:00
|
|
|
ELSE 'big'
|
|
|
|
END AS "Category"
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL;
|
1998-12-04 16:36:51 +01:00
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT
|
1999-02-23 08:30:05 +01:00
|
|
|
CASE WHEN ((i < 0) or (i < 0)) THEN 'small'
|
|
|
|
WHEN ((i = 0) or (i = 0)) THEN 'zero'
|
|
|
|
WHEN ((i = 1) or (i = 1)) THEN 'one'
|
|
|
|
WHEN ((i = 2) or (i = 2)) THEN 'two'
|
1998-12-04 16:36:51 +01:00
|
|
|
ELSE 'big'
|
|
|
|
END AS "Category"
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL;
|
1998-12-04 16:36:51 +01:00
|
|
|
|
|
|
|
--
|
|
|
|
-- Examples of qualifications involving tables
|
|
|
|
--
|
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
--
|
|
|
|
-- NULLIF() and COALESCE()
|
|
|
|
-- Shorthand forms for typical CASE constructs
|
2013-04-20 17:04:41 +02:00
|
|
|
-- defined in the SQL standard.
|
1999-02-23 08:30:05 +01:00
|
|
|
--
|
|
|
|
|
|
|
|
SELECT * FROM CASE_TBL WHERE COALESCE(f,i) = 4;
|
|
|
|
|
|
|
|
SELECT * FROM CASE_TBL WHERE NULLIF(f,i) = 2;
|
|
|
|
|
1999-05-07 01:09:30 +02:00
|
|
|
SELECT COALESCE(a.f, b.i, b.j)
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL a, CASE2_TBL b;
|
|
|
|
|
|
|
|
SELECT *
|
|
|
|
FROM CASE_TBL a, CASE2_TBL b
|
1999-05-07 01:09:30 +02:00
|
|
|
WHERE COALESCE(a.f, b.i, b.j) = 2;
|
1999-02-23 08:30:05 +01:00
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT NULLIF(a.i,b.i) AS "NULLIF(a.i,b.i)",
|
1999-02-23 08:30:05 +01:00
|
|
|
NULLIF(b.i, 4) AS "NULLIF(b.i,4)"
|
|
|
|
FROM CASE_TBL a, CASE2_TBL b;
|
|
|
|
|
2020-12-15 21:54:06 +01:00
|
|
|
SELECT *
|
1999-02-23 08:30:05 +01:00
|
|
|
FROM CASE_TBL a, CASE2_TBL b
|
|
|
|
WHERE COALESCE(f,b.i) = 2;
|
|
|
|
|
2021-04-02 11:01:49 +02:00
|
|
|
-- Tests for constant subexpression simplification
|
|
|
|
|
|
|
|
explain (costs off)
|
|
|
|
SELECT * FROM CASE_TBL WHERE NULLIF(1, 2) = 2;
|
|
|
|
|
|
|
|
explain (costs off)
|
|
|
|
SELECT * FROM CASE_TBL WHERE NULLIF(1, 1) IS NOT NULL;
|
|
|
|
|
|
|
|
explain (costs off)
|
|
|
|
SELECT * FROM CASE_TBL WHERE NULLIF(1, null) = 2;
|
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
--
|
|
|
|
-- Examples of updates involving tables
|
|
|
|
--
|
|
|
|
|
|
|
|
UPDATE CASE_TBL
|
1999-05-07 01:09:30 +02:00
|
|
|
SET i = CASE WHEN i >= 3 THEN (- i)
|
1999-02-23 08:30:05 +01:00
|
|
|
ELSE (2 * i) END;
|
|
|
|
|
|
|
|
SELECT * FROM CASE_TBL;
|
|
|
|
|
|
|
|
UPDATE CASE_TBL
|
|
|
|
SET i = CASE WHEN i >= 2 THEN (2 * i)
|
|
|
|
ELSE (3 * i) END;
|
|
|
|
|
|
|
|
SELECT * FROM CASE_TBL;
|
|
|
|
|
|
|
|
UPDATE CASE_TBL
|
|
|
|
SET i = CASE WHEN b.i >= 2 THEN (2 * j)
|
|
|
|
ELSE (3 * j) END
|
|
|
|
FROM CASE2_TBL b
|
|
|
|
WHERE j = -CASE_TBL.i;
|
|
|
|
|
|
|
|
SELECT * FROM CASE_TBL;
|
|
|
|
|
Fix two errors with nested CASE/WHEN constructs.
ExecEvalCase() tried to save a cycle or two by passing
&econtext->caseValue_isNull as the isNull argument to its sub-evaluation of
the CASE value expression. If that subexpression itself contained a CASE,
then *isNull was an alias for econtext->caseValue_isNull within the
recursive call of ExecEvalCase(), leading to confusion about whether the
inner call's caseValue was null or not. In the worst case this could lead
to a core dump due to dereferencing a null pointer. Fix by not assigning
to the global variable until control comes back from the subexpression.
Also, avoid using the passed-in isNull pointer transiently for evaluation
of WHEN expressions. (Either one of these changes would have been
sufficient to fix the known misbehavior, but it's clear now that each of
these choices was in itself dangerous coding practice and best avoided.
There do not seem to be any similar hazards elsewhere in execQual.c.)
Also, it was possible for inlining of a SQL function that implements the
equality operator used for a CASE comparison to result in one CASE
expression's CaseTestExpr node being inserted inside another CASE
expression. This would certainly result in wrong answers since the
improperly nested CaseTestExpr would be caused to return the inner CASE's
comparison value not the outer's. If the CASE values were of different
data types, a crash might result; moreover such situations could be abused
to allow disclosure of portions of server memory. To fix, teach
inline_function to check for "bare" CaseTestExpr nodes in the arguments of
a function to be inlined, and avoid inlining if there are any.
Heikki Linnakangas, Michael Paquier, Tom Lane
Report: https://github.com/greenplum-db/gpdb/pull/327
Report: <4DDCEEB8.50602@enterprisedb.com>
Security: CVE-2016-5423
2016-08-08 16:33:46 +02:00
|
|
|
--
|
|
|
|
-- Nested CASE expressions
|
|
|
|
--
|
|
|
|
|
|
|
|
-- This test exercises a bug caused by aliasing econtext->caseValue_isNull
|
Faster expression evaluation and targetlist projection.
This replaces the old, recursive tree-walk based evaluation, with
non-recursive, opcode dispatch based, expression evaluation.
Projection is now implemented as part of expression evaluation.
This both leads to significant performance improvements, and makes
future just-in-time compilation of expressions easier.
The speed gains primarily come from:
- non-recursive implementation reduces stack usage / overhead
- simple sub-expressions are implemented with a single jump, without
function calls
- sharing some state between different sub-expressions
- reduced amount of indirect/hard to predict memory accesses by laying
out operation metadata sequentially; including the avoidance of
nearly all of the previously used linked lists
- more code has been moved to expression initialization, avoiding
constant re-checks at evaluation time
Future just-in-time compilation (JIT) has become easier, as
demonstrated by released patches intended to be merged in a later
release, for primarily two reasons: Firstly, due to a stricter split
between expression initialization and evaluation, less code has to be
handled by the JIT. Secondly, due to the non-recursive nature of the
generated "instructions", less performance-critical code-paths can
easily be shared between interpreted and compiled evaluation.
The new framework allows for significant future optimizations. E.g.:
- basic infrastructure for to later reduce the per executor-startup
overhead of expression evaluation, by caching state in prepared
statements. That'd be helpful in OLTPish scenarios where
initialization overhead is measurable.
- optimizing the generated "code". A number of proposals for potential
work has already been made.
- optimizing the interpreter. Similarly a number of proposals have
been made here too.
The move of logic into the expression initialization step leads to some
backward-incompatible changes:
- Function permission checks are now done during expression
initialization, whereas previously they were done during
execution. In edge cases this can lead to errors being raised that
previously wouldn't have been, e.g. a NULL array being coerced to a
different array type previously didn't perform checks.
- The set of domain constraints to be checked, is now evaluated once
during expression initialization, previously it was re-built
every time a domain check was evaluated. For normal queries this
doesn't change much, but e.g. for plpgsql functions, which caches
ExprStates, the old set could stick around longer. The behavior
around might still change.
Author: Andres Freund, with significant changes by Tom Lane,
changes by Heikki Linnakangas
Reviewed-By: Tom Lane, Heikki Linnakangas
Discussion: https://postgr.es/m/20161206034955.bh33paeralxbtluv@alap3.anarazel.de
2017-03-14 23:45:36 +01:00
|
|
|
-- with the isNull argument of the inner CASE's CaseExpr evaluation. After
|
Fix two errors with nested CASE/WHEN constructs.
ExecEvalCase() tried to save a cycle or two by passing
&econtext->caseValue_isNull as the isNull argument to its sub-evaluation of
the CASE value expression. If that subexpression itself contained a CASE,
then *isNull was an alias for econtext->caseValue_isNull within the
recursive call of ExecEvalCase(), leading to confusion about whether the
inner call's caseValue was null or not. In the worst case this could lead
to a core dump due to dereferencing a null pointer. Fix by not assigning
to the global variable until control comes back from the subexpression.
Also, avoid using the passed-in isNull pointer transiently for evaluation
of WHEN expressions. (Either one of these changes would have been
sufficient to fix the known misbehavior, but it's clear now that each of
these choices was in itself dangerous coding practice and best avoided.
There do not seem to be any similar hazards elsewhere in execQual.c.)
Also, it was possible for inlining of a SQL function that implements the
equality operator used for a CASE comparison to result in one CASE
expression's CaseTestExpr node being inserted inside another CASE
expression. This would certainly result in wrong answers since the
improperly nested CaseTestExpr would be caused to return the inner CASE's
comparison value not the outer's. If the CASE values were of different
data types, a crash might result; moreover such situations could be abused
to allow disclosure of portions of server memory. To fix, teach
inline_function to check for "bare" CaseTestExpr nodes in the arguments of
a function to be inlined, and avoid inlining if there are any.
Heikki Linnakangas, Michael Paquier, Tom Lane
Report: https://github.com/greenplum-db/gpdb/pull/327
Report: <4DDCEEB8.50602@enterprisedb.com>
Security: CVE-2016-5423
2016-08-08 16:33:46 +02:00
|
|
|
-- evaluating the vol(null) expression in the inner CASE's second WHEN-clause,
|
|
|
|
-- the isNull flag for the case test value incorrectly became true, causing
|
|
|
|
-- the third WHEN-clause not to match. The volatile function calls are needed
|
|
|
|
-- to prevent constant-folding in the planner, which would hide the bug.
|
|
|
|
|
2016-08-25 15:57:09 +02:00
|
|
|
-- Wrap this in a single transaction so the transient '=' operator doesn't
|
|
|
|
-- cause problems in concurrent sessions
|
|
|
|
BEGIN;
|
|
|
|
|
Fix two errors with nested CASE/WHEN constructs.
ExecEvalCase() tried to save a cycle or two by passing
&econtext->caseValue_isNull as the isNull argument to its sub-evaluation of
the CASE value expression. If that subexpression itself contained a CASE,
then *isNull was an alias for econtext->caseValue_isNull within the
recursive call of ExecEvalCase(), leading to confusion about whether the
inner call's caseValue was null or not. In the worst case this could lead
to a core dump due to dereferencing a null pointer. Fix by not assigning
to the global variable until control comes back from the subexpression.
Also, avoid using the passed-in isNull pointer transiently for evaluation
of WHEN expressions. (Either one of these changes would have been
sufficient to fix the known misbehavior, but it's clear now that each of
these choices was in itself dangerous coding practice and best avoided.
There do not seem to be any similar hazards elsewhere in execQual.c.)
Also, it was possible for inlining of a SQL function that implements the
equality operator used for a CASE comparison to result in one CASE
expression's CaseTestExpr node being inserted inside another CASE
expression. This would certainly result in wrong answers since the
improperly nested CaseTestExpr would be caused to return the inner CASE's
comparison value not the outer's. If the CASE values were of different
data types, a crash might result; moreover such situations could be abused
to allow disclosure of portions of server memory. To fix, teach
inline_function to check for "bare" CaseTestExpr nodes in the arguments of
a function to be inlined, and avoid inlining if there are any.
Heikki Linnakangas, Michael Paquier, Tom Lane
Report: https://github.com/greenplum-db/gpdb/pull/327
Report: <4DDCEEB8.50602@enterprisedb.com>
Security: CVE-2016-5423
2016-08-08 16:33:46 +02:00
|
|
|
CREATE FUNCTION vol(text) returns text as
|
|
|
|
'begin return $1; end' language plpgsql volatile;
|
|
|
|
|
|
|
|
SELECT CASE
|
|
|
|
(CASE vol('bar')
|
|
|
|
WHEN 'foo' THEN 'it was foo!'
|
|
|
|
WHEN vol(null) THEN 'null input'
|
|
|
|
WHEN 'bar' THEN 'it was bar!' END
|
|
|
|
)
|
|
|
|
WHEN 'it was foo!' THEN 'foo recognized'
|
|
|
|
WHEN 'it was bar!' THEN 'bar recognized'
|
|
|
|
ELSE 'unrecognized' END;
|
|
|
|
|
|
|
|
-- In this case, we can't inline the SQL function without confusing things.
|
|
|
|
CREATE DOMAIN foodomain AS text;
|
|
|
|
|
|
|
|
CREATE FUNCTION volfoo(text) returns foodomain as
|
|
|
|
'begin return $1::foodomain; end' language plpgsql volatile;
|
|
|
|
|
|
|
|
CREATE FUNCTION inline_eq(foodomain, foodomain) returns boolean as
|
|
|
|
'SELECT CASE $2::text WHEN $1::text THEN true ELSE false END' language sql;
|
|
|
|
|
|
|
|
CREATE OPERATOR = (procedure = inline_eq,
|
|
|
|
leftarg = foodomain, rightarg = foodomain);
|
|
|
|
|
|
|
|
SELECT CASE volfoo('bar') WHEN 'foo'::foodomain THEN 'is foo' ELSE 'is not foo' END;
|
|
|
|
|
2016-08-25 15:57:09 +02:00
|
|
|
ROLLBACK;
|
|
|
|
|
2016-12-22 21:01:27 +01:00
|
|
|
-- Test multiple evaluation of a CASE arg that is a read/write object (#14472)
|
|
|
|
-- Wrap this in a single transaction so the transient '=' operator doesn't
|
|
|
|
-- cause problems in concurrent sessions
|
|
|
|
BEGIN;
|
|
|
|
|
|
|
|
CREATE DOMAIN arrdomain AS int[];
|
|
|
|
|
|
|
|
CREATE FUNCTION make_ad(int,int) returns arrdomain as
|
|
|
|
'declare x arrdomain;
|
|
|
|
begin
|
|
|
|
x := array[$1,$2];
|
|
|
|
return x;
|
|
|
|
end' language plpgsql volatile;
|
|
|
|
|
|
|
|
CREATE FUNCTION ad_eq(arrdomain, arrdomain) returns boolean as
|
|
|
|
'begin return array_eq($1, $2); end' language plpgsql;
|
|
|
|
|
|
|
|
CREATE OPERATOR = (procedure = ad_eq,
|
|
|
|
leftarg = arrdomain, rightarg = arrdomain);
|
|
|
|
|
|
|
|
SELECT CASE make_ad(1,2)
|
|
|
|
WHEN array[2,4]::arrdomain THEN 'wrong'
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WHEN array[2,5]::arrdomain THEN 'still wrong'
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WHEN array[1,2]::arrdomain THEN 'right'
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|
END;
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ROLLBACK;
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|
|
2018-10-30 20:26:11 +01:00
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|
-- Test interaction of CASE with ArrayCoerceExpr (bug #15471)
|
|
|
|
BEGIN;
|
|
|
|
|
|
|
|
CREATE TYPE casetestenum AS ENUM ('e', 'f', 'g');
|
|
|
|
|
|
|
|
SELECT
|
|
|
|
CASE 'foo'::text
|
|
|
|
WHEN 'foo' THEN ARRAY['a', 'b', 'c', 'd'] || enum_range(NULL::casetestenum)::text[]
|
|
|
|
ELSE ARRAY['x', 'y']
|
|
|
|
END;
|
|
|
|
|
|
|
|
ROLLBACK;
|
|
|
|
|
1999-02-23 08:30:05 +01:00
|
|
|
--
|
|
|
|
-- Clean up
|
|
|
|
--
|
|
|
|
|
|
|
|
DROP TABLE CASE_TBL;
|
|
|
|
DROP TABLE CASE2_TBL;
|