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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.
This commit is contained in:
istruewing@chilla.local
@@ -882,4 +882,148 @@ CREATE TABLE t1 (c1 TEXT) AVG_ROW_LENGTH=70100 MAX_ROWS=4100100100;
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SHOW TABLE STATUS LIKE 't1';
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DROP TABLE t1;
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#
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# Bug#26231 - select count(*) on myisam table returns wrong value
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# when index is used
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#
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CREATE TABLE t1 (c1 TEXT NOT NULL, KEY c1 (c1(10))) ENGINE=MyISAM;
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# Fill at least two key blocks. "Tab, A" must be in both blocks.
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INSERT INTO t1 VALUES
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)), (CHAR(9,65)),
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(''), (''), (''), (''),
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(' B'), (' B'), (' B'), (' B');
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SELECT DISTINCT COUNT(*) FROM t1 WHERE c1 = '';
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SELECT DISTINCT length(c1), c1 FROM t1 WHERE c1 = '';
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SELECT DISTINCT COUNT(*) FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
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SELECT DISTINCT length(c1), c1 FROM t1 IGNORE INDEX (c1) WHERE c1 = '';
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SELECT DISTINCT length(c1), c1 FROM t1 ORDER BY c1;
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DROP TABLE t1;
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--echo End of 4.1 tests
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