I have a MYSQL InnoDB table table with the following columns (table and column names changed): date (PK, DATE) var_a (PK, FK, INT) var_b (PK, FK, INT) rel_ab (DECIMAL) where rel_ab is a column that describes a relationship between 2…
When I use hexdump -C demo.ibd to learn how mysql store data, I meet some problems. This is my demo table. CREATE TABLE `demo` ( `id` int NOT NULL, `age` int NOT NULL, `name` varchar(20000) DEFAULT NULL, PRIMARY KEY (`id`)…
I've noticed that full text searches in MySQL do not seem to speed up when reducing the search pool with additional where clauses or joins. For example: SELECT * FROM `blog_posts` WHERE `id` = 1 AND MATCH (post_body) AGAINST ('+mango…
Suppose I'm a PHP application and I start an innodb transaction with mysqli_begin_transaction and it returns true. Then I do a series of inserts. As far as I am aware --- as a PHP application ---, all inserts went in…
In an attempt to overcome deadlocks on the combat server, I reached a dead end. There are 2 tables: First: create table table_1 ( id int auto_increment primary key, data1 text null, data2 text null ); Second: create table table_2…
I am using mysql innodb database. I thought I had understood the locking mechanism of mysql. But I found an example, which conflicts with my understanding.See the example below (verified in version 5.7.32 with rc isolation level). create table Create…
Having a table such as follows: CREATE TABLE Associations ( obj_id int unsigned NOT NULL, attr_id int unsigned NOT NULL, assignment Double NOT NULL PRIMARY KEY (`obj_id`, `attr_id`), ); this should occupy 16 bytes per row. So the overhead per…
Connection1: BEGIN; SELECT * FROM world.city WHERE ID = 130 FOR SHARE; Connection2: SELECT engine, thread_id, object_schema, object_name, lock_type, lock_mode, lock_status, lock_data FROM performance_schema.data_locks; +--------+-----------+---------------+-------------+-----------+---------------+-------------+-----------+ | engine | thread_id | object_schema | object_name | lock_type | lock_mode | lock_status |…
I have a Wordpress Database with two tables with this structure Table 1 "location" id, postID, address 1, 123, park ave 2, 234, washington ave 3, 345, wall st 4, 456, park ave 5, 567, wall st Table 2 "posts"…
I've seen many threads about this error, but the solutions I've found don't seem to be applicable in my case. I've received a rather large (~150Go) dump file from an Oracle database. I converted it to a MySQL one, using…