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MDEV-31303 Key not used when IN clause has both signed and usigned values

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Summary:

This patch enables possible index optimization when
the WHERE clause has an IN condition of the form:

signed_or_unsigned_column IN (signed_or_unsigned_constant,
                              signed_or_unsigned_constant
                              [,signed_or_unsigned_constant]*)

when the IN list constants are of different signess, e.g.:
  WHERE signed_column   IN (signed_constant, unsigned_constant ...)
  WHERE unsigned_column IN (signed_constant, unsigned_constant ...)

Details:

In a condition like:
   WHERE unsigned_predicant IN (1, LONGLONG_MAX + 1)

comparison handlers for individual (predicant,value) pairs are
calculated as follows:

* unsigned_predicant and 1 produce &type_handler_newdecimal
* unsigned_predicant and (LONGLONG_MAX + 1) produce &type_handler_slonglong

The old code decided that it could not use bisection because
the two pairs had different comparison handlers.
As a result, bisection was not allowed, and, in case of
an indexed integer column predicant the index on the column was not used.

The new code catches special cases like:
    signed_predicant   IN (signed_constant, unsigned_constant)
    unsigned_predicant IN (signed_constant, unsigned_constant)

It enables bisection using in_longlong, which supports a mixture
of predicant and values of different signess.
In case when the predicant is an indexed column this change
automatically enables index range optimization.

Thanks to Vicențiu Ciorbaru for proposing the idea and for preparing MTR tests.
This commit is contained in:
Alexander Barkov
2023-08-29 11:51:01 +04:00
committed by Vicențiu-Marian Ciorbaru
parent e938d7c18f
commit 53499cd1ea
4 changed files with 113 additions and 3 deletions
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9
mysql-test/main/func_debug.result
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@ -912,7 +912,8 @@ a IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED))
Warnings:
Note 1105 DBUG: [0] arg=1 handler=0 (bigint)
Note 1105 DBUG: [1] arg=2 handler=1 (decimal)
Note 1105 DBUG: types_compatible=no bisect=no
Note 1105 DBUG: found a mix of UINT and SINT
Note 1105 DBUG: types_compatible=yes bisect=yes
SELECT a IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED),NULL) FROM t1;
a IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED),NULL)
Warnings:
@ -950,7 +951,8 @@ a NOT IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED))
Warnings:
Note 1105 DBUG: [0] arg=1 handler=0 (bigint)
Note 1105 DBUG: [1] arg=2 handler=1 (decimal)
Note 1105 DBUG: types_compatible=no bisect=no
Note 1105 DBUG: found a mix of UINT and SINT
Note 1105 DBUG: types_compatible=yes bisect=yes
SELECT a NOT IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED),NULL) FROM t1;
a NOT IN (CAST(1 AS SIGNED), CAST(1 AS UNSIGNED),NULL)
Warnings:
@ -1624,7 +1626,8 @@ a b
Warnings:
Note 1105 DBUG: [0] arg=1 handler=0 (bigint)
Note 1105 DBUG: [1] arg=2 handler=1 (decimal)
Note 1105 DBUG: types_compatible=no bisect=no
Note 1105 DBUG: found a mix of UINT and SINT
Note 1105 DBUG: types_compatible=yes bisect=no
DROP TABLE t1;
#
# MDEV-11554 Wrong result for CASE on a mixture of signed and unsigned expressions