update table takes long time in mysql? - mysql

Question

CREATE TABLE fa (
book varchar(100) DEFAULT NULL,
PRODUCTION varchar(1000) DEFAULT NULL,
VENDOR_LEVEL varchar(100) DEFAULT NULL,
BOOK_NO int(10) DEFAULT NULL,
UNSTABLE_TIME_PERIOD varchar(100) DEFAULT NULL,
`PERIOD_YEAR` int(10) DEFAULT NULL,
promo_3_visuals_manual_drag int(10) DEFAULT NULL,
BOOK_NO int(10) DEFAULT NULL,
PRODUCT_LEVEL_DIST varchar(100) DEFAULT NULL,
PRODUCT_LEVEL_ACV_TREND varchar(100) DEFAULT NULL,
KEY book (BOOK_NO),
KEY period (PERIOD_YEAR)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
Index we added to column
Index : BOOK_NO and PERIODIC_YEAR has added
we cant add unique nor primary key to both column as it has plenty of duplicate values in it.
There are 46 millions rows.
We tried partitioning to period year and catno for sub partition, but doesn't worked as it is still takes long time
When i run the update query :
update fa set UNSTABLE_TIME_PERIOD = NULL where BOOK_NO = 0 and periodic_year = 201502;
It taking me more than 7 min , how can i OPTIMIZE the query?

Answer 1

Instead of creating 2 different keys, create single composite key for both the columns like:
KEY book_period (BOOK_NO, PERIOD_YEAR)
Also, first filter the records based on the column which will return the small set of records as compare to other.
If you think BOOK_NO will return less number of records as compare to PERIOD_YEAR, Use BOOK_NO first in where clause else use PERIOD_YEAR first and create the key accordingly.

Answer 2

As Álvaro González said, you should use some sort of key (eg. a Primary Key).
Adding a Primary Key:
CREATE TABLE fa (
<your_id>,
{...},
PRIMARY KEY(<your_id>),
{...}
)
or
CREATE TABLE fa (
<your_id> PRIMARY KEY,
{...}
)
It'd be a good idea to make your PRIMARY KEY AUTO_INCREMENT too for convenience, but this is not essenitial.