mysql speed up update statement for copying values between tables - mysql

Question

I have 2 tables where I am trying to copy values from migrate table to regular table. It seems to take awhile. (10 minutes for 43k records)
UPDATE phppos_sales_items,phppos_sales_items_migrate
SET
phppos_sales_items.subtotal = phppos_sales_items_migrate.subtotal,
phppos_sales_items.tax = phppos_sales_items_migrate.tax,
phppos_sales_items.total = phppos_sales_items_migrate.total,
phppos_sales_items.profit = phppos_sales_items_migrate.profit
WHERE
phppos_sales_items.sale_id = phppos_sales_items_migrate.sale_id and
phppos_sales_items.line = phppos_sales_items_migrate.line and
phppos_sales_items.item_id = phppos_sales_items_migrate.item_id;
Migrate Table
CREATE TABLE `phppos_sales_items_migrate` (
`sale_id` int(10) NOT NULL DEFAULT '0',
`item_id` int(10) NOT NULL DEFAULT '0',
`line` int(11) NOT NULL DEFAULT '0',
`subtotal` decimal(23,10) DEFAULT NULL,
`total` decimal(23,10) DEFAULT NULL,
`tax` decimal(23,10) DEFAULT NULL,
`profit` decimal(23,10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
sales_items
CREATE TABLE `phppos_sales_items` (
`sale_id` int(10) NOT NULL DEFAULT '0',
`item_id` int(10) NOT NULL DEFAULT '0',
`rule_id` int(10) DEFAULT NULL,
`rule_discount` decimal(23,10) DEFAULT NULL,
`description` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`serialnumber` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`line` int(11) NOT NULL DEFAULT '0',
`quantity_purchased` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
`item_cost_price` decimal(23,10) NOT NULL,
`item_unit_price` decimal(23,10) NOT NULL,
`regular_item_unit_price_at_time_of_sale` decimal(23,10) DEFAULT NULL,
`discount_percent` decimal(15,3) NOT NULL DEFAULT '0.000',
`commission` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
`subtotal` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
`tax` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
`total` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
`profit` decimal(23,10) NOT NULL DEFAULT '0.0000000000',
PRIMARY KEY (`sale_id`,`item_id`,`line`),
KEY `item_id` (`item_id`),
KEY `phppos_sales_items_ibfk_3` (`rule_id`),
CONSTRAINT `phppos_sales_items_ibfk_1` FOREIGN KEY (`item_id`) REFERENCES `phppos_items` (`item_id`),
CONSTRAINT `phppos_sales_items_ibfk_2` FOREIGN KEY (`sale_id`) REFERENCES `phppos_sales` (`sale_id`),
CONSTRAINT `phppos_sales_items_ibfk_3` FOREIGN KEY (`rule_id`) REFERENCES `phppos_price_rules` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Is there any way to speed this up?

Answer 1

decimal(23,10) is excessive, especially for integral values, such as quantity_purchased. Shrinking the datatypes will help speed some.
Use a "multi-table Update" with JOIN ... ON ... syntax.
Let's see the output from
EXPLAIN
SELECT * FROM phppos_sales_items AS i
JOIN phppos_sales_items_migrate AS m
ON i.sale_id = m.sale_id
and i.line = m.line
and i.item_id = m.item_id;
If you have a new enough version of MySQL, also provide EXPLAIN UPDATE ...
Any chance there are new rows in migrate? If so, won't you need INSERT ... ON DUPLICATE KEY UPDATE ...?
43K rows in which table? How many in the other table?

Answer 2

In my opinion, adding Index to the Target Table are worth to try.
Since two tables are comparing the three columns for merging it, you might better to adding index to the phppos_sales_items_migrate table for (sale_id,item_id,line) columns.
Good Luck
PS. FYI, adding indexes to the table also take costs for updating and inserting thus minimize to the comparing columns.