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Fix check_exclusion_or_unique_constraint for UNIQUE NULLS NOT DISTINCT.

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Adjusting this function was overlooked in commit 94aa7cc5f.  The only
visible symptom (so far) is that INSERT ... ON CONFLICT could go into
an endless loop when inserting a null that has a conflict.

Richard Guo and Tom Lane, per bug #17558 from Andrew Kesper

Discussion: https://postgr.es/m/17558-3f6599ffcf52fd4a@postgresql.org
This commit is contained in:
Tom Lane 2022-08-04 14:16:26 -04:00
parent 4c7b16312e
commit 3419d51e19
3 changed files with 18 additions and 10 deletions
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18
src/backend/executor/execIndexing.c
View File

@ -699,13 +699,19 @@ check_exclusion_or_unique_constraint(Relation heap, Relation index,
}
/*
* If any of the input values are NULL, the constraint check is assumed to
* pass (i.e., we assume the operators are strict).
* If any of the input values are NULL, and the index uses the default
* nulls-are-distinct mode, the constraint check is assumed to pass (i.e.,
* we assume the operators are strict). Otherwise, we interpret the
* constraint as specifying IS NULL for each column whose input value is
* NULL.
*/
for (i = 0; i < indnkeyatts; i++)
if (!indexInfo->ii_NullsNotDistinct)
{
if (isnull[i])
return true;
for (i = 0; i < indnkeyatts; i++)
{
if (isnull[i])
return true;
}
}
/*
@ -717,7 +723,7 @@ check_exclusion_or_unique_constraint(Relation heap, Relation index,
for (i = 0; i < indnkeyatts; i++)
{
ScanKeyEntryInitialize(&scankeys[i],
0,
isnull[i] ? SK_ISNULL | SK_SEARCHNULL : 0,
i + 1,
constr_strats[i],
InvalidOid,

5
src/test/regress/expected/constraints.out
View File

@ -449,15 +449,16 @@ DROP TABLE UNIQUE_TBL;
CREATE TABLE UNIQUE_TBL (i int UNIQUE NULLS NOT DISTINCT, t text);
INSERT INTO UNIQUE_TBL VALUES (1, 'one');
INSERT INTO UNIQUE_TBL VALUES (2, 'two');
INSERT INTO UNIQUE_TBL VALUES (1, 'three');
INSERT INTO UNIQUE_TBL VALUES (1, 'three'); -- fail
ERROR: duplicate key value violates unique constraint "unique_tbl_i_key"
DETAIL: Key (i)=(1) already exists.
INSERT INTO UNIQUE_TBL VALUES (4, 'four');
INSERT INTO UNIQUE_TBL VALUES (5, 'one');
INSERT INTO UNIQUE_TBL (t) VALUES ('six');
INSERT INTO UNIQUE_TBL (t) VALUES ('seven');
INSERT INTO UNIQUE_TBL (t) VALUES ('seven'); -- fail
ERROR: duplicate key value violates unique constraint "unique_tbl_i_key"
DETAIL: Key (i)=(null) already exists.
INSERT INTO UNIQUE_TBL (t) VALUES ('eight') ON CONFLICT DO NOTHING; -- no-op
SELECT * FROM UNIQUE_TBL;
i | t
---+------

5
src/test/regress/sql/constraints.sql
View File

@ -310,11 +310,12 @@ CREATE TABLE UNIQUE_TBL (i int UNIQUE NULLS NOT DISTINCT, t text);
INSERT INTO UNIQUE_TBL VALUES (1, 'one');
INSERT INTO UNIQUE_TBL VALUES (2, 'two');
INSERT INTO UNIQUE_TBL VALUES (1, 'three');
INSERT INTO UNIQUE_TBL VALUES (1, 'three'); -- fail
INSERT INTO UNIQUE_TBL VALUES (4, 'four');
INSERT INTO UNIQUE_TBL VALUES (5, 'one');
INSERT INTO UNIQUE_TBL (t) VALUES ('six');
INSERT INTO UNIQUE_TBL (t) VALUES ('seven');
INSERT INTO UNIQUE_TBL (t) VALUES ('seven'); -- fail
INSERT INTO UNIQUE_TBL (t) VALUES ('eight') ON CONFLICT DO NOTHING; -- no-op
SELECT * FROM UNIQUE_TBL;