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[Alexey Botchkov <holyfoot@xxxxxxxxxxxx>]

Hello, Vicențiu.

In the SELECT you mentioned
SELECT 1 FROM t1 NATURAL LEFT JOIN t1 AS t2
the SPATIAL key should not be used, just doesn't fit.

And I must note that i couldn't reproduce the testcase as it was described.
What i got was:
+------+-------------+-------+------+---------------+------+---------+------+------+------------------------------------------------+
| id   | select_type | table | type | possible_keys | key  | key_len | 
ref  | rows | Extra                                          |
+------+-------------+-------+------+---------------+------+---------+------+------+------------------------------------------------+
|    1 | SIMPLE      | t1    | ALL  | NULL          | NULL | NULL | NULL 
|    2 |                                                |
|    1 | SIMPLE      | t2    | ALL  | a             | NULL | NULL | NULL 
|    2 | Range checked for each record (index map: 0x1) |
+------+-------------+-------+------+---------------+------+---------+------+------+------------------------------------------------+

The TABLE:create_key_part_by_field wasn't called during the process.
What function actually returns the key_length of 0? The 
Field_geom::pack_length() returns not-zero for me.

Best regards.
HF


09.03.2015 16:44, Vicențiu Ciorbaru wrote:
> Hi Holyfoot!
>
> I've made some changes regarding key_length computation to fix 
> MDEV-6838. Changing this seems to have lead to us discovering another 
> issue outlined in MDEV-7682 (that I've just created).
>
> It seems that the spatial key returns a key_length of 0. I've spoken 
> to Sergei Petrunia and we are not sure about this particular case. 
> pack_length returns a bigger number (12). According to the other 
> comments in the code, pack_length also returns the length field 
> associated with the column, but we are only interested in the length 
> of the column field, without any metadata information. The function 
> TABLE:create_key_part_by_field adds the metadata length itself afterwards.
>
> Do you have any input on this issue, namely why the key_length is 
> returned as 0 for the LINESTRING column?
>
> Regards,
> Vicentiu