maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Sanja!

On May 04, Olaksandr Byslkin wrote:

still haven't fixed the typo? :)

> revision-id: eb9fab76fb4322a7821e6502e6303ed381624429 (mariadb-10.1.13-18-geb9fab7)
> parent(s): 732adec0a4c75d99389230feeb0deca0ad668de7
> committer: Oleksandr Byelkin
> timestamp: 2016-05-04 19:15:31 +0200
> message:
> 
> MDEV-9531: GROUP_CONCAT with ORDER BY inside takes a lot of memory while it's executed
> 
> Limitation added to Red-Black tree.
> 
> diff --git a/include/my_tree.h b/include/my_tree.h
> index f8be55f..f1916b9 100644
> --- a/include/my_tree.h
> +++ b/include/my_tree.h
> @@ -57,11 +57,14 @@ typedef struct st_tree_element {
>  } TREE_ELEMENT;
>  
>  #define ELEMENT_CHILD(element, offs) (*(TREE_ELEMENT**)((char*)element + offs))
> +#define R_ELEMENT_CHILD(element, offs) ((TREE_ELEMENT**)((char*)element + offs))

what does "R_ELEMENT_CHILD" mean? What's "R"?

>  
>  typedef struct st_tree {
>    TREE_ELEMENT *root,null_element;
>    TREE_ELEMENT **parents[MAX_TREE_HEIGHT];
> +  TREE_ELEMENT *free_element;

why do you need a free_element pointer?

>    uint offset_to_key,elements_in_tree,size_of_element;
> +  uint elements_limit, del_direction;

why do you need to support different directions here?

>    size_t memory_limit, allocated;
>    qsort_cmp2 compare;
>    void *custom_arg;
> diff --git a/mysql-test/r/mysqld--help.result b/mysql-test/r/mysqld--help.result
> index bef0390..3699b18 100644
> --- a/mysql-test/r/mysqld--help.result
> +++ b/mysql-test/r/mysqld--help.result
> @@ -240,6 +240,9 @@ The following options may be given as the first argument:
>   --group-concat-max-len=# 
>   The maximum length of the result of function 
>   GROUP_CONCAT()
> + --group-concat-max-mem=# 
> + The maximum memory used to calculate result of function
> + GROUP_CONCAT()

No, please. There is group_concat_max_len already, it's all that user
needs. There is no reason why one might need to configure a second limit
on for the GROUP_CONCAT.

>   --gtid-domain-id=#  Used with global transaction ID to identify logically
>   independent replication streams. When events can
>   propagate through multiple parallel paths (for example

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx