Question :
I have these tables:
DROP TABLE IF EXISTS books;
CREATE TABLE `books` (
`bookId` mediumint(8) UNSIGNED NOT NULL,
`title` varchar(10) NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
ALTER TABLE `books`
ADD PRIMARY KEY (`bookId`),
DROP TABLE IF EXISTS movements;
CREATE TABLE `movements` (
`movementId` mediumint(8) UNSIGNED NOT NULL,
`movementTypeId` tinyint(3) UNSIGNED NOT NULL,
`deletedFlag` tinyint(3) UNSIGNED NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
ALTER TABLE `movements`
ADD PRIMARY KEY (`movementId`),
ADD KEY `movementId` (`movementTypeId`,`deletedFlag`) USING BTREE;
DROP TABLE IF EXISTS movements_types;
CREATE TABLE `movements_types` (
`movementTypeId` mediumint(8) UNSIGNED NOT NULL,
`title` varchar(200) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
ALTER TABLE `movements_types`
ADD PRIMARY KEY (`movementTypeId`);
DROP TABLE IF EXISTS movements_books;
CREATE TABLE `movements_books` (
`movementId` mediumint(8) UNSIGNED NOT NULL,
`bookId` mediumint(8) UNSIGNED NOT NULL,
`bookSize` tinyint(3) UNSIGNED NOT NULL,
`quantity` smallint(5) UNSIGNED NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `books` (`bookId`, `title`) VALUES
(1, 'Harry Potter'),
(2, 'Mysql Join'),
(3, 'Comedy');
INSERT INTO `movements` (`movementId`, `movementTypeId`, `deletedFlag`) VALUES
(7, 1, 0),
(8, 2, 0),
(9, 2, 0);
INSERT INTO `movements_types` (`movementTypeId`, `title`) VALUES
(1, "Bought"),
(2, "Sold");
INSERT INTO `movements_books` (`movementId`, `bookId`, `bookSize`, `quantity`) VALUES
(7, 1, 1, 3),
(7, 1, 2, 3),
(7, 2, 1, 3),
(7, 2, 2, 3),
(8, 1, 1, 2),
(8, 1, 1, 2),
(9, 2, 1, 3);
bookSize is just an integer indicating the size of the book.
movements_books actually has 111824 records, movements has 4534.
deletedFlag is 1 for a deleted movement (I prefer to keep them flagged) and 0 otherwise.
I need help creating indexes and I need these results:
1) sizes sold/bought/available for each book (bookId, bookSize, booksSold, booksBought, booksBought minus booksSold)
2) books sold/bought/available for each book of all size (bookId, booksSold, booksBought, booksBought minus booksSold)
To get the one of the statistics I tried:
SELECT
books.title
movements_books_grouped.bookId,
SUM(IF(movements.movementTypeId=1, movements_books_grouped.quantity, NULL)) AS booksBought,
SUM(IF(movements.movementTypeId=2, movements_books_grouped.quantity, NULL)) AS booksSold,
(
SUM(IF(movements.movementTypeId=1, movements_books_grouped.quantity, 0))-
SUM(IF(movements.movementTypeId=2, movements_books_grouped.quantity, 0))
) AS booksAvailability
FROM
(
SELECT bookId,quantity,movementId FROM movements_books GROUP BY bookId
) AS movements_books_grouped
JOIN movements ON movements.movementId=movements_books_grouped.movementId
JOIN books ON books.bookId=movements_books_grouped.bookId
GROUP BY movements_books_grouped.bookId
ORDER BY books.title
but it’s very slow.
Edit: I needed to add another table to the example because that’s the one that makes really slow the last query. I need to join to this table because I need to order the result by title.
Answer :
I suggest the schema is “over-normalized”. I would suggest any table that lists a ‘movement’ should include the direction (movementTypeId). Perhaps it could be done with a sign instead of an extra column? (Positive for Bought, negative for Sold.)
There are no indexes on movements_books
; maybe other tables?
The GROUP BY bookId
in the subquery is probably wrong.
(cleaned up a little, and fixed missing comma:)
SELECT b.title, mbg.bookId,
SUM(IF(m.movementTypeId=1, mbg.quantity, NULL)) AS booksBought,
SUM(IF(m.movementTypeId=2, mbg.quantity, NULL)) AS booksSold,
( SUM(IF(m.movementTypeId=1, mbg.quantity, 0))-
SUM(IF(m.movementTypeId=2, mbg.quantity, 0))
) AS booksAvailability,
FROM (
SELECT bookId, quantity, movementId
FROM movements_books AS mb AS b
GROUP BY bookId
) AS AS mbg
JOIN movements AS m ON m.movementId = mbg.movementId
JOIN books AS b2 ON b.bookId = mbg.bookId
GROUP BY mbg.bookId
ORDER BY b2.title
movements_books
needs
PRIMARY KEY(bookId, movementId),
INDEX(movementId, bookId)