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Commit 396f84aa authored by unknown's avatar unknown
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Bug#26231 - select count(*) on myisam table returns wrong value 

            when index is used

When the table contained TEXT columns with empty contents
('', zero length, but not NULL) _and_ strings starting with
control characters like tabulator or newline, the empty values
were not found in a "records in range" estimate. Hence count(*)
missed these records.

The reason was a different set of search flags used for key
insert and key range estimation.

I decided to fix the set of flags used in range estimation.
Otherwise millions of databases around the world would require
a repair after an upgrade.

The consequence is that the manual must be fixed, which claims
that TEXT columns are compared with "end space padding". This
is true for CHAR/VARCHAR but wrong for TEXT. See also bug 21335.


myisam/mi_range.c:
  Bug#26231 - select count(*) on myisam table returns wrong value
              when index is used
  Added SEARCH_UPDATE to the search flags so that it compares
  like write/update/delete operations do. Only so it expects
  the keys at the place where they have been inserted.
myisam/mi_search.c:
  Bug#26231 - select count(*) on myisam table returns wrong value
              when index is used
  Added some comments to explain how _mi_get_binary_pack_key()
  works.
mysql-test/r/myisam.result:
  Bug#26231 - select count(*) on myisam table returns wrong value
              when index is used
  Added a test.
mysql-test/t/myisam.test:
  Bug#26231 - select count(*) on myisam table returns wrong value
              when index is used
  Added test result.
parent da9c659c
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Inline Side-by-side
Showing with 364 additions and 8 deletions
myisam/mi_range.c
View file @ 396f84aa
...@@ -145,8 +145,42 @@ static ha_rows _mi_record_pos(MI_INFO *info, const byte *key, uint key_len, ...@@ -145,8 +145,42 @@ static ha_rows _mi_record_pos(MI_INFO *info, const byte *key, uint key_len,
if (!(nextflag & (SEARCH_FIND | SEARCH_NO_FIND | SEARCH_LAST))) if (!(nextflag & (SEARCH_FIND | SEARCH_NO_FIND | SEARCH_LAST)))
key_len=USE_WHOLE_KEY; key_len=USE_WHOLE_KEY;
/*
my_handler.c:mi_compare_text() has a flag 'skip_end_space'.
This is set in my_handler.c:ha_key_cmp() in dependence on the
compare flags 'nextflag' and the column type.
TEXT columns are of type HA_KEYTYPE_VARTEXT. In this case the
condition is skip_end_space= ((nextflag & (SEARCH_FIND |
SEARCH_UPDATE)) == SEARCH_FIND).
SEARCH_FIND is used for an exact key search. The combination
SEARCH_FIND | SEARCH_UPDATE is used in write/update/delete
operations with a comment like "Not real duplicates", whatever this
means. From the condition above we can see that 'skip_end_space' is
always false for these operations. The result is that trailing space
counts in key comparison and hence, emtpy strings ('', string length
zero, but not NULL) compare less that strings starting with control
characters and these in turn compare less than strings starting with
blanks.
When estimating the number of records in a key range, we request an
exact search for the minimum key. This translates into a plain
SEARCH_FIND flag. Using this alone would lead to a 'skip_end_space'
compare. Empty strings would be expected above control characters.
Their keys would not be found because they are located below control
characters.
This is the reason that we add the SEARCH_UPDATE flag here. It makes
the key estimation compare in the same way like key write operations
do. Olny so we will find the keys where they have been inserted.
Adding the flag unconditionally does not hurt as it is used in the
above mentioned condition only. So it can safely be used together
with other flags.
*/
pos=_mi_search_pos(info,keyinfo,key_buff,key_len, pos=_mi_search_pos(info,keyinfo,key_buff,key_len,
nextflag | SEARCH_SAVE_BUFF, nextflag | SEARCH_SAVE_BUFF | SEARCH_UPDATE,
info->s->state.key_root[inx]); info->s->state.key_root[inx]);
if (pos >= 0.0) if (pos >= 0.0)
{ {
......
myisam/mi_search.c
View file @ 396f84aa
...@@ -918,11 +918,16 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag, ...@@ -918,11 +918,16 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
/* /*
Keys are compressed the following way: Keys are compressed the following way:
prefix length Packed length of prefix for the prev key. (1 or 3 bytes) prefix length Packed length of prefix common with prev key (1 or 3 bytes)
for each key segment: for each key segment:
[is null] Null indicator if can be null (1 byte, zero means null) [is null] Null indicator if can be null (1 byte, zero means null)
[length] Packed length if varlength (1 or 3 bytes) [length] Packed length if varlength (1 or 3 bytes)
key segment 'length' bytes of key segment value
pointer Reference to the data file (last_keyseg->length). pointer Reference to the data file (last_keyseg->length).
get_key_length() is a macro. It gets the prefix length from 'page'
and puts it into 'length'. It increments 'page' by 1 or 3, depending
on the packed length of the prefix length.
*/ */
get_key_length(length,page); get_key_length(length,page);
if (length) if (length)
...@@ -935,34 +940,44 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag, ...@@ -935,34 +940,44 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
my_errno=HA_ERR_CRASHED; my_errno=HA_ERR_CRASHED;
DBUG_RETURN(0); /* Wrong key */ DBUG_RETURN(0); /* Wrong key */
} }
from=key; from_end=key+length; /* Key is packed against prev key, take prefix from prev key. */
from= key;
from_end= key + length;
} }
else else
{ {
from=page; from_end=page_end; /* Not packed key */ /* Key is not packed against prev key, take all from page buffer. */
from= page;
from_end= page_end;
} }
/* /*
The trouble is that key is split in two parts: The trouble is that key can be split in two parts:
The first part is in from ...from_end-1. The first part (prefix) is in from .. from_end - 1.
The second part starts at page The second part starts at page.
The split can be at every byte position. So we need to check for
the end of the first part before using every byte.
*/ */
for (keyseg=keyinfo->seg ; keyseg->type ;keyseg++) for (keyseg=keyinfo->seg ; keyseg->type ;keyseg++)
{ {
if (keyseg->flag & HA_NULL_PART) if (keyseg->flag & HA_NULL_PART)
{ {
/* If prefix is used up, switch to rest. */
if (from == from_end) { from=page; from_end=page_end; } if (from == from_end) { from=page; from_end=page_end; }
if (!(*key++ = *from++)) if (!(*key++ = *from++))
continue; /* Null part */ continue; /* Null part */
} }
if (keyseg->flag & (HA_VAR_LENGTH | HA_BLOB_PART | HA_SPACE_PACK)) if (keyseg->flag & (HA_VAR_LENGTH | HA_BLOB_PART | HA_SPACE_PACK))
{ {
/* Get length of dynamic length key part */ /* If prefix is used up, switch to rest. */
if (from == from_end) { from=page; from_end=page_end; } if (from == from_end) { from=page; from_end=page_end; }
/* Get length of dynamic length key part */
if ((length= (*key++ = *from++)) == 255) if ((length= (*key++ = *from++)) == 255)
{ {
/* If prefix is used up, switch to rest. */
if (from == from_end) { from=page; from_end=page_end; } if (from == from_end) { from=page; from_end=page_end; }
length= (uint) ((*key++ = *from++)) << 8; length= (uint) ((*key++ = *from++)) << 8;
/* If prefix is used up, switch to rest. */
if (from == from_end) { from=page; from_end=page_end; } if (from == from_end) { from=page; from_end=page_end; }
length+= (uint) ((*key++ = *from++)); length+= (uint) ((*key++ = *from++));
} }
...@@ -982,20 +997,33 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag, ...@@ -982,20 +997,33 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
key+=length; key+=length;
from+=length; from+=length;
} }
/*
Last segment (type == 0) contains length of data pointer.
If we have mixed key blocks with data pointer and key block pointer,
we have to copy both.
*/
length=keyseg->length+nod_flag; length=keyseg->length+nod_flag;
if ((tmp=(uint) (from_end-from)) <= length) if ((tmp=(uint) (from_end-from)) <= length)
{ {
/* Remaining length is less or equal max possible length. */
memcpy(key+tmp,page,length-tmp); /* Get last part of key */ memcpy(key+tmp,page,length-tmp); /* Get last part of key */
*page_pos= page+length-tmp; *page_pos= page+length-tmp;
} }
else else
{ {
/*
Remaining length is greater than max possible length.
This can happen only if we switched to the new key bytes already.
'page_end' is calculated with MI_MAX_KEY_BUFF. So it can be far
behind the real end of the key.
*/
if (from_end != page_end) if (from_end != page_end)
{ {
DBUG_PRINT("error",("Error when unpacking key")); DBUG_PRINT("error",("Error when unpacking key"));
my_errno=HA_ERR_CRASHED; my_errno=HA_ERR_CRASHED;
DBUG_RETURN(0); /* Error */ DBUG_RETURN(0); /* Error */
} }
/* Copy data pointer and, if appropriate, key block pointer. */
memcpy((byte*) key,(byte*) from,(size_t) length); memcpy((byte*) key,(byte*) from,(size_t) length);
*page_pos= from+length; *page_pos= from+length;
} }
......
mysql-test/r/myisam.result
View file @ 396f84aa
...@@ -944,4 +944,154 @@ SHOW TABLE STATUS LIKE 't1'; ...@@ -944,4 +944,154 @@ SHOW TABLE STATUS LIKE 't1';
Name Engine Version Row_format Rows Avg_row_length Data_length Max_data_length Index_length Data_free Auto_increment Create_time Update_time Check_time Collation Checksum Create_options Comment Name Engine Version Row_format Rows Avg_row_length Data_length Max_data_length Index_length Data_free Auto_increment Create_time Update_time Check_time Collation Checksum Create_options Comment
t1 MyISAM 9 Dynamic X X X 72057594037927935 X X X X X X latin1_swedish_ci X max_rows=4100100100 avg_row_length=70100 t1 MyISAM 9 Dynamic X X X 72057594037927935 X X X X X X latin1_swedish_ci X max_rows=4100100100 avg_row_length=70100
DROP TABLE t1; DROP TABLE t1;
CREATE TABLE t1 (c1 TEXT NOT NULL, KEY c1 (c1(10))) ENGINE=MyISAM;
INSERT INTO t1 VALUES
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(''), (''), (''), (''),
(' B'), (' B'), (' B'), (' B');
SELECT DISTINCT COUNT(*) FROM t1 WHERE c1 = '';
COUNT(*)
4
SELECT DISTINCT length(c1), c1 FROM t1 WHERE c1 = '';
length(c1) c1
0
SELECT DISTINCT COUNT(*) FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
COUNT(*)
4
SELECT DISTINCT length(c1), c1 FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
length(c1) c1
0
SELECT DISTINCT length(c1), c1 FROM t1 ORDER BY c1;
length(c1) c1
0
2 A
2 B
DROP TABLE t1;
End of 4.1 tests End of 4.1 tests
mysql-test/t/myisam.test
View file @ 396f84aa
...@@ -882,4 +882,148 @@ CREATE TABLE t1 (c1 TEXT) AVG_ROW_LENGTH=70100 MAX_ROWS=4100100100; ...@@ -882,4 +882,148 @@ CREATE TABLE t1 (c1 TEXT) AVG_ROW_LENGTH=70100 MAX_ROWS=4100100100;
SHOW TABLE STATUS LIKE 't1'; SHOW TABLE STATUS LIKE 't1';
DROP TABLE t1; DROP TABLE t1;
#
# Bug#26231 - select count(*) on myisam table returns wrong value
# when index is used
#
CREATE TABLE t1 (c1 TEXT NOT NULL, KEY c1 (c1(10))) ENGINE=MyISAM;
# Fill at least two key blocks. "Tab, A" must be in both blocks.
INSERT INTO t1 VALUES
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
(''), (''), (''), (''),
(' B'), (' B'), (' B'), (' B');
SELECT DISTINCT COUNT(*) FROM t1 WHERE c1 = '';
SELECT DISTINCT length(c1), c1 FROM t1 WHERE c1 = '';
SELECT DISTINCT COUNT(*) FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
SELECT DISTINCT length(c1), c1 FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
SELECT DISTINCT length(c1), c1 FROM t1 ORDER BY c1;
DROP TABLE t1;
--echo End of 4.1 tests --echo End of 4.1 tests
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