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Bug#15581: COALESCE function truncates mutli-byte TINYTEXT values

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field.cc:
  BLOB variations have number-in-bytes limit,
  unlike CHAR/VARCHAR which have number-of-characters limits.
  A tinyblob column can store up to 255 bytes.
  In the case of basic Latin letters (which use 1 byte per character)
  we can store up to 255 characters in a tinyblob column.
  When passing an utf8 tinyblob column as an argument into
  a function (e.g. COALESCE) we need to reserve 3*255 bytes.
  I.e. multiply length in bytes to mbcharlen for the character set.
  Although in reality a tinyblob column can never be 3*255 bytes long,
  we need to set max_length to multiply to make fix_length_and_dec()
  of the function-caller (e.g. COALESCE) calculate the correct max_length
  for the column being created.

ctype_utf8.result, ctype_utf8.test:
  Adding test case.


mysql-test/t/ctype_utf8.test:
  Adding test case.
mysql-test/r/ctype_utf8.result:
  Adding test case.
sql/field.cc:
  Bug#15581: COALESCE function truncates mutli-byte TINYTEXT values
  BLOB variations have byte limits,
  unlike CHAR/VARCHAR which have number-of-character limits.
  It means tinyblob can store up to 255 bytes.
  All of them can be basic latin letters which use 1 byte
  per character.
  I.e. we can store up to 255 characters in a tinyblob column.
  When passing a tinyblob column as an argument into
  a function (for example COALESCE or CONCAT) we
  need to reserve 3*255 bytes in the case of utf-8.
  I.e. multiply length in bytes to mbcharlen for the
  character set.
This commit is contained in:
unknown 2005-12-19 15:52:10 +04:00
parent 52c0440085
commit e1c6141340
3 changed files with 21 additions and 3 deletions
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8
mysql-test/r/ctype_utf8.result
View file

@ -1070,3 +1070,11 @@ char(a)
1
2
drop table t1;
CREATE TABLE t1 (t TINYTEXT CHARACTER SET utf8);
INSERT INTO t1 VALUES(REPEAT('a', 100));
CREATE TEMPORARY TABLE t2 SELECT COALESCE(t) AS bug FROM t1;
SELECT LENGTH(bug) FROM t2;
LENGTH(bug)
100
DROP TABLE t2;
DROP TABLE t1;

10
mysql-test/t/ctype_utf8.test
View file

@ -882,4 +882,14 @@ set names utf8;
select distinct char(a) from t1;
drop table t1;
#
# Bug#15581: COALESCE function truncates mutli-byte TINYTEXT values
#
CREATE TABLE t1 (t TINYTEXT CHARACTER SET utf8);
INSERT INTO t1 VALUES(REPEAT('a', 100));
CREATE TEMPORARY TABLE t2 SELECT COALESCE(t) AS bug FROM t1;
SELECT LENGTH(bug) FROM t2;
DROP TABLE t2;
DROP TABLE t1;
# End of 4.1 tests

6
sql/field.cc
View file

@ -6949,11 +6949,11 @@ uint32 Field_blob::max_length()
switch (packlength)
{
case 1:
return 255;
return 255 * field_charset->mbmaxlen;
case 2:
return 65535;
return 65535 * field_charset->mbmaxlen;
case 3:
return 16777215;
return 16777215 * field_charset->mbmaxlen;
case 4:
return (uint32) 4294967295U;
default: