> probably I can even do it without a temp table...

looks good! :)

DROP TABLE IF EXISTS t_tree_insert;

CREATE TABLE `t_tree_insert` (
    `f_node_id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `f_parent_id` INT(10) UNSIGNED NULL DEFAULT '0',
    `f_name` VARCHAR(200) NOT NULL,
    `f_sort` FLOAT NULL DEFAULT NULL,
    PRIMARY KEY (`f_node_id`),
    UNIQUE INDEX `sort` (`f_parent_id`, `f_sort`),
    INDEX `f_parent_id` (`f_parent_id`),
    FULLTEXT INDEX `f_name` (`f_name`)
)
COMMENT='test tree move operations'
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=0
;


insert into t_tree_insert values
    (130, 1, 'other array', 1)
  , (142, 2, 'B06', 1)
  , (143, 2, 'B2L', 2)
  , (144, 2, 'B2M', 3)
  , (200, 2, 'INSERT', 3.5)
  , (145, 2, 'B2N', 4)
  , (146, 2, 'B2O', 5)
  , (150, 3, 'other array', 1)

;

select * from t_tree_insert order by f_parent_id, f_sort;

set @sort=0;

replace 
   into t_tree_insert 
   (f_node_id, f_parent_id, f_name, f_sort)
   select f_node_id, f_parent_id, f_name, (@sort:=@sort+1) as f_sort
      from  t_tree_insert as T
      where f_parent_id = 2
      order by T.f_sort
;
     


select * from t_tree_insert order by f_parent_id, f_sort;

[download]

Cheers Rolf
(addicted to the Perl Programming Language and ☆☆☆☆ :)
Wikisyntax for the Monastery

UPDATE

But I'm suspecting that temporarily dropping the "unique index" constraint and only updating the row f_sort is considerably faster for larger tables.

In reply to Re^2: [OT] MySQL recalibrating a sort-index by LanX
in thread [OT] MySQL recalibrating a sort-index by LanX

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