[MDEV-18922] Alter on long unique varchar column makes result null - Jira

Details

Type: Bug
Status: Closed (View Workflow)
Priority: Blocker
Resolution: Fixed
Affects Version/s: 10.4.3
Fix Version/s: 10.4.4
Component/s: Server
Labels:
None
Environment:
All

Description

#MDEV-18922 Alter on long unique varchar column makes result null

CREATE TABLE t1 (b int, a  varchar(4000));

INSERT INTO t1 VALUES (1, 2),(2,3),(3,4);

ALTER TABLE t1 ADD UNIQUE INDEX (a);

SELECT * FROM t1;

SELECT a FROM t1;

drop table t1;

Result

CREATE TABLE t1 (b int, a  varchar(4000));

INSERT INTO t1 VALUES (1, 2),(2,3),(3,4);

ALTER TABLE t1 ADD UNIQUE INDEX (a);

SELECT * FROM t1;

b       a

1       2

2       3

3       4

SELECT a FROM t1;

NULL

NULL

NULL

drop table t1;

Attachments

Issue Links

causes

MDEV-18941 HEAP index is no longer used

Closed

is caused by

MDEV-371 Unique indexes for blobs

Closed

is part of

MDEV-18901 Wrong results after ADD UNIQUE INDEX(blob_column)

Closed

Activity

Sachin Setiya (Inactive) added a comment - 2019-03-14 09:28

Even this is giving NULL

# with VARCHAR(79) or blob  all results are correct

CREATE TABLE t1 (a int);

INSERT INTO t1 VALUES (1),(2);

ALTER TABLE t1 ADD UNIQUE (a) using hash;

# returns 2 rows with a=NULL, instead of rows 1,2

SELECT * FROM t1;

drop table t1;

While this is not giving NULL which is strange

# with VARCHAR(79) or blob  all results are correct

CREATE TABLE t1 (a blob);

INSERT INTO t1 VALUES (1),(2);

ALTER TABLE t1 ADD UNIQUE (a) using hash;

# returns 2 rows with a=NULL, instead of rows 1,2

SELECT * FROM t1;

drop table t1;

So the field which stores the result in table->record itself is affected , while the fields which store the data pointer is not affected.

Sachin Setiya (Inactive) added a comment - 2019-03-14 09:28 Even this is giving NULL # with VARCHAR (79) or blob all results are correct CREATE TABLE t1 (a int ); INSERT INTO t1 VALUES (1),(2); ALTER TABLE t1 ADD UNIQUE (a) using hash; # returns 2 rows with a= NULL , instead of rows 1,2 SELECT * FROM t1; drop table t1; While this is not giving NULL which is strange # with VARCHAR (79) or blob all results are correct CREATE TABLE t1 (a blob); INSERT INTO t1 VALUES (1),(2); ALTER TABLE t1 ADD UNIQUE (a) using hash; # returns 2 rows with a= NULL , instead of rows 1,2 SELECT * FROM t1; drop table t1; So the field which stores the result in table->record itself is affected , while the fields which store the data pointer is not affected.

People

Assignee:: Sachin Setiya (Inactive)

Reporter:: Sachin Setiya (Inactive)

Votes:: 0 Vote for this issue

Watchers:: 2 Start watching this issue

Dates

Created:: 2019-03-14 09:21

Updated:: 2019-03-22 06:20

Resolved:: 2019-03-17 08:31

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