Storage Engines

https://dev.mysql.com/doc/refman/5.7/en/storage-engines.html
Compare: Table 15.1 Storage Engines Feature Summary

Feature MyISAM Memory InnoDB Archive NDB
Storage limits 256TB RAM 64TB None 384EB
Transactions No No Yes No Yes
Locking granularity Table Table Row Row Row
MVCC No No Yes No No
Geospatial data type support Yes No Yes Yes Yes
Geospatial indexing support Yes No Yes[a] No No
B-tree indexes Yes Yes Yes No No
T-tree indexes No No No No Yes
Hash indexes No Yes No[b] No Yes
Full-text search indexes Yes No Yes[c] No No
Clustered indexes No No Yes No No
Data caches No N/A Yes No Yes
Index caches Yes N/A Yes No Yes
Compressed data Yes[d] No Yes[e] Yes No
Encrypted data[f] Yes Yes Yes Yes Yes
Cluster database support No No No No Yes
Replication support[g] Yes Limited[h] Yes Yes Yes
Foreign key support No No Yes No Yes[i]
Backup / point-in-time recovery[j] Yes Yes Yes Yes Yes
Query cache support Yes Yes Yes Yes Yes
Update statistics for data dictionary Yes Yes Yes Yes Yes
CREATE TABLE t1 (i INT) ENGINE = INNODB;

InnoDB: default in MySQL 5.7. 
    transaction-safe (ACID compliant):commit, rollback, and crash-recovery
    row-level locking (without escalation to coarser granularity locks) 
    Oracle-style consistent nonlocking reads
    clustered indexes to reduce I/O for common queries based on primary keys
    FOREIGN KEY referential-integrity constraints
MyISAM: 
    Table-level locking. 
    often used in read-only or read-mostly workloads.
Merge: 
    logically group a series of identical MyISAM tables and reference them as one object.     
Memory or HEAP:
    Its use cases are decreasing:
        InnoDB with its buffer pool memory area
        NDBCLUSTER provides fast key-value lookups for huge distributed data sets
NDB or NDBCLUSTER: highest possible degree of uptime and availability.
Federated: link separate MySQL servers to create one logical database
CSV: Its tables are really text files with comma-separated values.
Archive: compact, unindexed tables
Blackhole: 
    not store data, Queries always return an empty set. 
    can be used in replication configurations
Example: illustrates how to begin writing new storage engines.

MySQL Cluster

http://severalnines.com/blog/mysql-docker-introduction-docker-swarm-mode-and-multi-host-networking
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndb-innodb-engines.html

JSON

MySQL 5.7+

https://dev.mysql.com/doc/refman/5.7/en/json.html

CREATE TABLE t1 (jdoc JSON);
INSERT INTO t1 VALUES('{"key1": "value1", "key2": "value2"}');

SELECT JSON_ARRAY('a', 1, NOW());
SELECT JSON_OBJECT('key1', 1, 'key2', 'abc');
SELECT JSON_MERGE('["a", 1]', '{"key": "value"}');

SET @j = JSON_OBJECT('key', 'value');
SELECT @j;

# escape quote character
'{"mascot": "... \\"Sakila\\"."}'
JSON_OBJECT("mascot", "... \"Sakila\".")
JSON_OBJECT('mascot', '... "Sakila".')    # NO_BACKSLASH_ESCAPES

# JSON values is case sensitive
SELECT CAST('null' AS JSON); # `null`, `true`, and `false` always lowercase

SELECT col->"$.mascot" FROM qtest;          # "... \"Sakila\"."
SELECT sentence->>"$.mascot" FROM facts;    # ... "Sakila".

ORDER BY CAST(JSON_EXTRACT(jdoc, '$.id') AS UNSIGNED)

MariaDB 10.2+

https://mariadb.com/resources/blog/json-mariadb-102

CREATE TABLE products(id INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
price DECIMAL(9,2) NOT NULL,
stock INTEGER NOT NULL,
attr VARCHAR(1024),
CHECK (attr IS NULL OR JSON_VALID(attr)));

INSERT INTO products VALUES(NULL, 'Blouse', 17, 15, '{"colour": "white"}');
UPDATE products SET attr = JSON_REPLACE(attr, '$.colour', 'red') WHERE name = 'Blouse';

ALTER TABLE products ADD attr_colour VARCHAR(32) AS (JSON_VALUE(attr, '$.colour'));

CREATE INDEX products_attr_colour_ix ON products(attr_colour);
EXPLAIN SELECT * FROM products WHERE attr_colour = 'white';     # verify index

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