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Commit 1fa7c9a3 authored by Alexander Barkov's avatar Alexander Barkov
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MDEV-31724 Compressed varchar values lost on joins when sorting on columns from joined table(s) 

Field_varstring::get_copy_func() did not take into account
that functions do_varstring1[_mb], do_varstring2[_mb] do not support
compressed data.

Changing the return value of Field_varstring::get_copy_func()
to `do_field_string` if there is a compresion and truncation
at the same time. This fixes the problem, so now it works as follows:
- val_str() uncompresses the data
- The prefix is then calculated on the uncompressed data

Additionally, introducing two new copying functions
- do_varstring1_no_truncation()
- do_varstring2_no_truncation()

Using new copying functions in cases when:
- a Field_varstring with length_bytes==1 is changing to a longer
    Field_varstring with length_bytes==1
- a Field_varstring with length_bytes==2 is changing to a longer
    Field_varstring with length_bytes==2

In these cases we don't care neither of compression nor
of multi-byte prefixes: the entire data gets fully copied
from the source column to the target column as is.

This is a kind of new optimization, but this also was needed
to preserve existing MTR test results.
parent dd19ba18
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mysql-test/main/column_compression.result
View file @ 1fa7c9a3
......@@ -2672,3 +2672,241 @@ SET column_compression_threshold=0;
INSERT INTO t1 VALUES('aa');
SET column_compression_threshold=DEFAULT;
DROP TABLE t1;
#
# MDEV-31724 Compressed varchar values lost on joins when sorting on columns from joined table(s)
#
CREATE TABLE t1 (
id int(10) unsigned not null,
txt varchar(5000) COMPRESSED NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_bin;
CREATE TABLE t2 (
id int(10) unsigned not null,
n1 bigint(20) NOT NULL,
n2 bigint(20) NOT NULL,
n3 bigint(20) NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_bin;
INSERT INTO t1 VALUES
(1, 'short string < 100 chars'),
(2, 'long string = 99 chars '),
(3, 'long string = 100 chars !'),
(4, 'long string = 101 chars !');
INSERT INTO t2 VALUES
(1, 24, 1, 1),
(2, 99, 2, 2),
(3, 100, 3, 3),
(4, 101, 4, 4);
SELECT txt, v.* FROM t1 LEFT JOIN t2 v ON t1.id = v.id;
txt id n1 n2 n3
short string < 100 chars 1 24 1 1
long string = 99 chars 2 99 2 2
long string = 100 chars ! 3 100 3 3
long string = 101 chars ! 4 101 4 4
SELECT txt, v.* FROM t1 LEFT JOIN t2 v ON t1.id = v.id ORDER BY v.n1;
txt id n1 n2 n3
short string < 100 chars 1 24 1 1
long string = 99 chars 2 99 2 2
long string = 100 chars ! 3 100 3 3
long string = 101 chars ! 4 101 4 4
SELECT txt, v.* FROM t1 JOIN t2 v ON t1.id = v.id;
txt id n1 n2 n3
short string < 100 chars 1 24 1 1
long string = 99 chars 2 99 2 2
long string = 100 chars ! 3 100 3 3
long string = 101 chars ! 4 101 4 4
SELECT txt, v.* FROM t1 JOIN t2 v ON t1.id = v.id ORDER BY v.n1;
txt id n1 n2 n3
short string < 100 chars 1 24 1 1
long string = 99 chars 2 99 2 2
long string = 100 chars ! 3 100 3 3
long string = 101 chars ! 4 101 4 4
DROP TABLE t1, t2;
CREATE OR REPLACE TABLE t1 (
id INT NOT NULL PRIMARY KEY,
txt varchar(5000) COMPRESSED NOT NULL DEFAULT ''
) CHARSET=utf8mb3;
INSERT INTO t1 VALUES
(1, REPEAT('a', 10)),
(2, REPEAT('b', 99)),
(3, REPEAT('c', 100)),
(4, REPEAT('d', 121));
SELECT txt, sysdate(6) FROM t1 ORDER BY 2;
txt sysdate(6)
aaaaaaaaaa <sysdate>
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb <sysdate>
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc <sysdate>
ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd <sysdate>
DROP TABLE t1;
CREATE FUNCTION f1(imax INT, jmax INT) RETURNS TEXT
BEGIN
DECLARE res TEXT DEFAULT 'x';
FOR i IN 0..imax
DO
FOR j IN 0..jmax
DO
SET res=CONCAT(res, ' ', i, ' ', j);
END FOR;
END FOR;
RETURN res;
END;
$$
SET @@column_compression_threshold=32;
# VARCHAR1, 8bit, truncation
CREATE TABLE t1 (a VARCHAR(254) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(6,6));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
197 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 6 6 0 6 1 6 2 6 3 6 4 6 5 6 6
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(4) COMPRESSED CHARACTER SET latin1;
Warnings:
Warning 1265 Data truncated for column 'a' at row 1
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 1
SELECT LENGTH(a), a FROM t1;
LENGTH(a) a
4 x 0
DROP TABLE t1;
CREATE TABLE t1 (a VARCHAR(254) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (REPEAT('a',254));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
254 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(4) COMPRESSED CHARACTER SET latin1;
Warnings:
Warning 1265 Data truncated for column 'a' at row 1
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 1
SELECT LENGTH(a), a FROM t1;
LENGTH(a) a
4 aaaa
DROP TABLE t1;
# VARCHAR1, 8bit, no truncation
CREATE TABLE t1 (a VARCHAR(250) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(6,6));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
197 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 6 6 0 6 1 6 2 6 3 6 4 6 5 6 6
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(254) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 0
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
197 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 6 6 0 6 1 6 2 6 3 6 4 6 5 6 6
DROP TABLE t1;
# VARCHAR2, 8bit, truncation
CREATE TABLE t1 (a VARCHAR(32000) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(256) COMPRESSED CHARACTER SET latin1;
Warnings:
Warning 1265 Data truncated for column 'a' at row 1
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 1
Column_decompressions 1
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
256 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 1 17 1 18 1 19 1 20 1 21 1 22
DROP TABLE t1;
# VARCHAR2, 8bit, no truncation
CREATE TABLE t1 (a VARCHAR(32000) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a, 30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a, 30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(32001) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 0
SELECT LENGTH(a), LEFT(a,30), RIGHT(a, 30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a, 30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
DROP TABLE t1;
# VARCHAR1, multi-byte, truncation
CREATE TABLE t1 (a VARCHAR(80) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(3,3));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
65 x 0 0 0 1 0 2 0 3 1 0 1 1 1 2 0 2 1 2 2 2 3 3 0 3 1 3 2 3 3
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(1) COMPRESSED CHARACTER SET utf8mb3;
Warnings:
Warning 1265 Data truncated for column 'a' at row 1
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 1
SELECT LENGTH(a), a FROM t1;
LENGTH(a) a
1 x
DROP TABLE t1;
# VARCHAR1, multi-byte, no truncation
CREATE TABLE t1 (a VARCHAR(80) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(3,3));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
65 x 0 0 0 1 0 2 0 3 1 0 1 1 1 2 0 2 1 2 2 2 3 3 0 3 1 3 2 3 3
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(81) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 0
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
65 x 0 0 0 1 0 2 0 3 1 0 1 1 1 2 0 2 1 2 2 2 3 3 0 3 1 3 2 3 3
DROP TABLE t1;
# VARCHAR2, multi-byte, truncation
CREATE TABLE t1 (a VARCHAR(10000) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(256) COMPRESSED CHARACTER SET utf8mb3;
Warnings:
Warning 1265 Data truncated for column 'a' at row 1
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 1
Column_decompressions 1
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
256 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 1 17 1 18 1 19 1 20 1 21 1 22
DROP TABLE t1;
# VARCHAR2, multi-byte, no truncation
CREATE TABLE t1 (a VARCHAR(10000) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(10001) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
Variable_name Value
Column_compressions 0
Column_decompressions 0
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
LENGTH(a) LEFT(a,30) RIGHT(a,30)
5505 x 0 0 0 1 0 2 0 3 0 4 0 5 0 6 31 27 31 28 31 29 31 30 31 31
DROP TABLE t1;
SET @@column_compression_threshold=DEFAULT;
DROP FUNCTION f1;
#
# End of 10.4 tests
#
mysql-test/main/column_compression.test
View file @ 1fa7c9a3
......@@ -266,3 +266,178 @@ SET column_compression_threshold=0;
INSERT INTO t1 VALUES('aa');
SET column_compression_threshold=DEFAULT;
DROP TABLE t1;
--echo #
--echo # MDEV-31724 Compressed varchar values lost on joins when sorting on columns from joined table(s)
--echo #
CREATE TABLE t1 (
id int(10) unsigned not null,
txt varchar(5000) COMPRESSED NOT NULL DEFAULT '',
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_bin;
CREATE TABLE t2 (
id int(10) unsigned not null,
n1 bigint(20) NOT NULL,
n2 bigint(20) NOT NULL,
n3 bigint(20) NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_bin;
INSERT INTO t1 VALUES
(1, 'short string < 100 chars'),
(2, 'long string = 99 chars '),
(3, 'long string = 100 chars !'),
(4, 'long string = 101 chars !');
INSERT INTO t2 VALUES
(1, 24, 1, 1),
(2, 99, 2, 2),
(3, 100, 3, 3),
(4, 101, 4, 4);
SELECT txt, v.* FROM t1 LEFT JOIN t2 v ON t1.id = v.id;
SELECT txt, v.* FROM t1 LEFT JOIN t2 v ON t1.id = v.id ORDER BY v.n1;
SELECT txt, v.* FROM t1 JOIN t2 v ON t1.id = v.id;
SELECT txt, v.* FROM t1 JOIN t2 v ON t1.id = v.id ORDER BY v.n1;
DROP TABLE t1, t2;
CREATE OR REPLACE TABLE t1 (
id INT NOT NULL PRIMARY KEY,
txt varchar(5000) COMPRESSED NOT NULL DEFAULT ''
) CHARSET=utf8mb3;
INSERT INTO t1 VALUES
(1, REPEAT('a', 10)),
(2, REPEAT('b', 99)),
(3, REPEAT('c', 100)),
(4, REPEAT('d', 121));
--replace_column 2 <sysdate>
--sorted_result
SELECT txt, sysdate(6) FROM t1 ORDER BY 2;
DROP TABLE t1;
DELIMITER $$;
CREATE FUNCTION f1(imax INT, jmax INT) RETURNS TEXT
BEGIN
DECLARE res TEXT DEFAULT 'x';
FOR i IN 0..imax
DO
FOR j IN 0..jmax
DO
SET res=CONCAT(res, ' ', i, ' ', j);
END FOR;
END FOR;
RETURN res;
END;
$$
DELIMITER ;$$
# Let's override the default threshold (100) to force
# comression for VARCHAR1+MB, for example, for:
# VARCHAR(80) CHARACTER SET utf8mb3
SET @@column_compression_threshold=32;
--echo # VARCHAR1, 8bit, truncation
CREATE TABLE t1 (a VARCHAR(254) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(6,6));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(4) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), a FROM t1;
DROP TABLE t1;
CREATE TABLE t1 (a VARCHAR(254) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (REPEAT('a',254));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(4) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), a FROM t1;
DROP TABLE t1;
--echo # VARCHAR1, 8bit, no truncation
CREATE TABLE t1 (a VARCHAR(250) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(6,6));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(254) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
DROP TABLE t1;
--echo # VARCHAR2, 8bit, truncation
CREATE TABLE t1 (a VARCHAR(32000) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(256) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
DROP TABLE t1;
--echo # VARCHAR2, 8bit, no truncation
CREATE TABLE t1 (a VARCHAR(32000) COMPRESSED CHARACTER SET latin1);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a, 30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(32001) COMPRESSED CHARACTER SET latin1;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a, 30) FROM t1;
DROP TABLE t1;
--echo # VARCHAR1, multi-byte, truncation
CREATE TABLE t1 (a VARCHAR(80) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(3,3));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(1) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), a FROM t1;
DROP TABLE t1;
--echo # VARCHAR1, multi-byte, no truncation
CREATE TABLE t1 (a VARCHAR(80) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(3,3));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(81) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
DROP TABLE t1;
--echo # VARCHAR2, multi-byte, truncation
CREATE TABLE t1 (a VARCHAR(10000) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(256) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
DROP TABLE t1;
--echo # VARCHAR2, multi-byte, no truncation
CREATE TABLE t1 (a VARCHAR(10000) COMPRESSED CHARACTER SET utf8mb3);
INSERT INTO t1 VALUES (f1(31,31));
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
FLUSH STATUS;
ALTER IGNORE TABLE t1 MODIFY a VARCHAR(10001) COMPRESSED CHARACTER SET utf8mb3;
SHOW STATUS LIKE 'Column%compressions';
SELECT LENGTH(a), LEFT(a,30), RIGHT(a,30) FROM t1;
DROP TABLE t1;
SET @@column_compression_threshold=DEFAULT;
DROP FUNCTION f1;
--echo #
--echo # End of 10.4 tests
--echo #
sql/field_conv.cc
View file @ 1fa7c9a3
......@@ -532,6 +532,40 @@ static void do_expand_string(Copy_field *copy)
}
/*
Copy from a Field_varstring with length_bytes==1
into another Field_varstring with length_bytes==1
when the target column is not shorter than the source column.
We don't need to calculate the prefix in this case. It works for
- non-compressed and compressed columns
- single byte and multi-byte character sets
*/
static void do_varstring1_no_truncation(Copy_field *copy)
{
uint length= (uint) *(uchar*) copy->from_ptr;
DBUG_ASSERT(length <= copy->to_length - 1);
*(uchar*) copy->to_ptr= (uchar) length;
memcpy(copy->to_ptr+1, copy->from_ptr + 1, length);
}
/*
Copy from a Field_varstring with length_bytes==2
into another Field_varstring with length_bytes==2
when the target column is not shorter than the source column.
We don't need to calculate the prefix in this case. It works for
- non-compressed and compressed columns
- single byte and multi-byte character sets
*/
static void do_varstring2_no_truncation(Copy_field *copy)
{
uint length= uint2korr(copy->from_ptr);
DBUG_ASSERT(length <= copy->to_length - HA_KEY_BLOB_LENGTH);
int2store(copy->to_ptr, length);
memcpy(copy->to_ptr + HA_KEY_BLOB_LENGTH,
copy->from_ptr + HA_KEY_BLOB_LENGTH, length);
}
static void do_varstring1(Copy_field *copy)
{
uint length= (uint) *(uchar*) copy->from_ptr;
......@@ -776,6 +810,21 @@ Field::Copy_func *Field_varstring::get_copy_func(const Field *from) const
length_bytes != ((const Field_varstring*) from)->length_bytes ||
!compression_method() != !from->compression_method())
return do_field_string;
if (field_length >= from->field_length)
return length_bytes == 1 ? do_varstring1_no_truncation :
do_varstring2_no_truncation;
if (compression_method())
{
/*
Truncation is going to happen, so we need to calculate prefixes.
Can't calculate prefixes directly on compressed data,
need to go through val_str() to uncompress.
*/
return do_field_string;
}
return length_bytes == 1 ?
(from->charset()->mbmaxlen == 1 ? do_varstring1 : do_varstring1_mb) :
(from->charset()->mbmaxlen == 1 ? do_varstring2 : do_varstring2_mb);
......
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