mysql storage engines

mysql storage engines

The maximum table space size is four billion database pages (64TB) and the minimum table space size is slightly larger than 10MB. used in read-only or read-mostly workloads in Web and data MyISAM was the default MySQL storage engine prior to the MySQL server version 5.5.5. Enables a MySQL DBA or developer to logically group a series of The value in the Support column indicates whether an engine can be used. To enable the BLACKHOLE storage engine (in case of MySQL build from source), invoke CMake with the -DWITH_BLACKHOLE_STORAGE_ENGINE option. Where can I obtain complete documentation for MySQL storage engines? InnoDB is mostly used general-purpose storage engine and as of MySQL 5.5 and later it is the default engine. The SEs usually are implemented as key/value databases, but not necessarily have to. The following example shows how to create and use a MEMORY table : Indexes : The MEMORY storage engine supports both HASH and BTREE indexes. These tables can be used in 7. table for exporting data to a spreadsheet and a few The InnoDB internal maximum key length is 3500 bytes, but MySQL itself restricts this to 3072 bytes (combined index key in a multi-column index). Blackhole: SphinX is a great full-text search engine for MySQL. 6.9 The ARCHIVE Storage Engine. In MySQL 5.6, issuing the CREATE TABLE statement without an ENGINE= clause creates an InnoDB table. Sphinx As MySQL Storage Engine (SphinxSE) By Nedim Hadzimahmutovic <[email protected]> Version: v1.0 Last Change: May 9, 2010. Merge: MySQL Language Structure, Connecting to and disconnecting from MySQL, Exporting and importing data between mysql and microsoft excel, Scala Programming Exercises, Practice, Solution. The ARCHIVE storage engine is included in MySQL binary distributions. MyISAM Storage Engine. copy of the data. during normal operation, and only use CSV tables during the To create a MERGE table, you must specify a UNION=(list-of-tables) option (indicates which MyISAM tables to use) in the CREAE TABLE statement. A value of YES, from them. When you create a BLACKHOLE table, the server creates a table format file (.frm) in the database directory. For answers to commonly asked questions about MySQL storage engines, Before MySQL 5.5 was launched, the default storage engine for MySQL was MyISAM. Its use default.). You must have SELECT, DELETE, and UPDATE privileges on the MyISAM tables that you map to a MERGE table. You can create tables Its tables are really text files with comma-separated values. 6. 5. The ARCHIVE engine uses zlib lossless data compression (see http://www.zlib.net/). While all of MySQL’s storage engines are reasonably efficient, using the wrong storage engine can hinder your application … table. It's "consistent nonlocking reads" increases performance when used in a multiuser environment. InnoDB has maximum performance when processing large data volumes. MySQL Table Types/Storage Engines. List of Storage Engines supported by your MySQL installation. different use cases in mind. The following command display the status information of the server's storage engines. Only mysql is supported as the scheme value at this point. The BLACKHOLE storage engine acts as a "black hole" that accepts data but returns an empty result. The BLACKHOLE storage engine supports all kinds of indexes. It’s not recommended to randomly choose an engine, but many developers are happy to use either MyISAM or InnoDB, although other options are also available. MySQL Storage Engines – Types and Details. The current default is the InnoDB storage engine. Maximum 64 number of indexes and 16 number of columns per index are allowed. InnoDB and MEMORY tables in a single query. Up to 63-bit file length large files are supported on file systems and operating systems that support large files. Row-level locking (locks are placed on single records (rows)) system increase multi-user concurrency and performance. A storage engine is a software module MySQL uses to create, read, or update data from a database. When you create an EXAMPLE table : To enable the EXAMPLE storage engine if you build MySQL from source, invoke CMake with the -DWITH_EXAMPLE_STORAGE_ENGINE option. Storage engines are MySQL components that handle the SQL operations for different table types. primary keys. Benefit from all the features of MySQL while using RocksDB as backend storage Get started. that same format. Data volume can fit entirely in memory without causing the operating system to swap out virtual memory pages. InnoDB storage engine or the The Blackhole storage engine accepts but does not store data, InnoDB permits a foreign key to reference any index column or group of columns.  current, 5.6  The ARCHIVE storage engine is used to store large amounts of unindexed data in a very small footprint. MySQL Tutorial 56 - Indexes and Foreign Key Constraints for our Bank System - Duration: 6:24. Tables with VARCHAR columns may have fixed or dynamic row length. NULL values are permitted in indexed columns. Table-level locking Accepts data to store but always returns empty. NDBCLUSTER): This clustered Adding a USING clause you can specify one or the other for a given index. In MySQL the datas are stored as files in any one of the types in storage engines. To enable this storage engine (if you build MySQL from source), invoke CMake with the -DWITH_ARCHIVE_STORAGE_ENGINE option. Example: also contains a description of the pluggable storage engine host_name: The host name or IP address of the remote server. InnoDB tables with tables The AUTO_INCREMENT column can have either a unique or nonunique index. Storage engines are MySQL components that handle the SQL operations Querying the current storage engine of a table. The EXAMPLE storage engine is a stub engine that does nothing and serve as an example in the MySQL source code that clarify how to begin writing new storage engines. To enable this storage engine if you build MySQL from source, invoke configure with the --with-archive-storage-engine option. As of MySQL 5.6, it is necessary to use ENGINE clause to specify the MyISAM storage engine because InnoDB is the default engine. This storage engine is known as a high-reliability and a high-performance storage engine and its key advantages include supporting row-level locking, foreign keys and following the ACID model. Each of these techniques employs different storage mechanisms, indexing facilities, locking levels and ultimately provides a range of different functions and capabilities. CSV: When you create an ARCHIVE table, the server creates a table format file (.frm extension) in the database directory. InnoDB is the default and most general-purpose storage engine, and Oracle recommends using it for tables except for specialized use cases. to coarser granularity locks) and Oracle-style consistent crash-recovery capabilities to protect user data. In CREATE TABLE STATEMENT you can add ENGINE table option to mention a storage engine. Good for VLDB environments such as data warehousing. This engine serves as an example in the MySQL source code that Internal handling of one AUTO_INCREMENT column per table is supported. identical MyISAM tables and reference them as It also support row-level locking. The index file has an .MYI (MYIndex) extension. limits the performance in read/write workloads, so it is often Stores data in Comma Separated Value format in a text file. Each MyISAM table is stored on disk in three files. 9. logical database from many physical servers. New Storage Engines in MySQL 5. Implemented in the server, rather than in the storage engine. Storage engines (underlying software component) are MySQL components, that can handle the SQL operations for different table types to store and manage information in a database. In this chapter, we will talk about MySQL storage engines. The following example at first we have created three tables with two rows then merge it into one table use MERGE storage engine : Security issue: If a user has access to MyISAM table, say t1, that user can create a MERGE table m1 that accesses t1. Here is an example : The following SHOW TABLE STATUS statement shows the properties of the tables (belongs to 'tutorial' database). Secondary indexes is a type of InnoDB index that represents a subset of table columns. Support for a true VARCHAR type; a VARCHAR column starts with a length stored in one or two bytes. InnoDB is a storage engine for MySQL that balances high reliability and high performance. Depending on the storage engine the table's index and data may be stored in one or more other files. Depending on the storage engine the table's index and data may be stored in one or more other files. typically keep the data in InnoDB tables overview of some storage engines provided with MySQL, with MySQL supports many kinds of storage engines that provide different capabilities and characteristics. from other MySQL storage engines As it currently stands, this question is not a good fit for our Q&A format. By Jithin on August 4th, 2016. If you want to convert a table form one storage engine to another, use an ALTER TABLE statement. InnoDB is Stores all data in RAM, for fast access in environments that By default, MySQL 5.7 supports ten storage engines (InnoDB, MyISAM, Memory, CSV, Archive, Blackhole, NDB, Merge, Federated, and Example). For example, an application might use mostly InnoDB is covered in Chapter 15, The InnoDB Storage Engine. You can put the data file and index file in different directories on different physical devices to get more speed with the DATA DIRECTORY and INDEX DIRECTORY table options to CREATE TABLE. (The CREATE TABLE statement in MySQL 5.7 creates InnoDB tables by default.). InnoDB provides a method that improves scalability and performance of SQL statements that insert rows into tables with AUTO_INCREMENT columns. Viewed 17k times 3. The server creates a table format file (.frm extension) and a data file (.csv extension) in the database directory when you create a CSV table. InnoDB allows a foreign key constraint to reference a non-unique key. InnoDB supports FOREIGN KEY constraints to maintain data integrity. It provides transaction-safe (ACID compliant) tables, supports FOREIGN KEY referential-integrity constraints. MyRocks has 2x better compression compared to compressed InnoDB, 3-4x better compression compared to uncompressed InnoDB, meaning you use less space. As of MySQL 5.5, it is the default MySQL storage engine. No data is stored on the local tables. To determine which storage engines your server supports by using the SHOW ENGINES statement. InnoDB. clustered indexes to reduce I/O for common queries based on information about InnoDB, see Inserting a value into an AUTO_INCREMENT column less than the current maximum column value. require quick lookups of non-critical data. The user name for the connection, must have been created on the remote server, and have suitable privileges to perform the required actions like SELECT, INSERT, UPDATE, and so forth on the remote table. scheme : A recognized connection protocol. InnoDB support for FULLTEXT indexes is available in MySQL 5.6 and later. Queries Editions, on the MySQL website. There are two types of storage engines in MySQL: transactional and non-transactional. This is the default storage engine for MySQL 5.5 and higher. As of MySQL 5.5 and later, it is the default storage engine. Greater Space Efficiency. The storage MySQL It is possible to mix MEMORY tables for temporary workspaces. The storage engine is included in MySQL binary distributions. A.2.1. The maximum row length except for variable-length columns (VARBINARY, VARCHAR, BLOB and TEXT), is about 8000 bytes for the default page size of 16KB. To include the FEDERATED storage engine (in case of MySQL build from source), invoke CMake with the -DWITH_FEDERATED_STORAGE_ ENGINE option. You can set the default storage engine for the current session by setting the default_storage_engine variable using set command. These compact, unindexed tables are intended for storing and InnoDB also supports FOREIGN for different table types. While MySQL supports multiple storage engines with varying capabilities, not all of them are optimized for crash recovery and data durability. The following example shows how to create and use a CSV table : You can can read, modify the 'color.CSV' file by spreadsheet applications such as Microsoft Excel or StarOffice Calc. Maximum 1017 columns are allowed in a table (raised in MySQL 5.6.9 from the earlier limit of 1000). cases are decreasing; InnoDB with its buffer “stub” that does nothing. Offers the ability to link separate MySQL servers to create one As previously stated, InnoDB is the default storage engine in MySQL versions 5.5 and higher. Internally InnoDB supports row sizes larger than 65,535 bytes, but MySQL itself imposes a row-size limit of 65,535 for the combined size of all columns. For example, the InnoDB tables support transaction, whereas MyISAM does not. archived, or security audit information. primarily of interest to developers. The default storage engine in MySQL 5.7. illustrates how to begin writing new storage engines. NO, or DEFAULT indicates that Support for foreign keys is available in MySQL Cluster NDB 7.3 and later. Each MyISAM table is represented by three files: Formatfile: Stores the definition of the table structure (mytable.frm) Chapter 14, The InnoDB Storage Engine. The mysqld (Known as MySQL Server) process is killed in the middle of a write. SHOW ENGINES statement. Tables using the compressed row format with MyISAM are read only. There are many storage engines available in MySQL and they are used for different purposes. engines available might depend on which edition of MySQL you are See the discussion later in this section. The following table provides an To examine the source for the EXAMPLE engine, look in the storage/example directory of a MySQL source distribution. Here is a list of the best mysql storage engines. For those unaccustomed to working with NDB, unexpected behaviors can arise due to its distributed nature with regard to transactions, foreign keys, table limits, and other characteristics. See Chapter 16, Alternative Storage Engines.That chapter contains information about all MySQL storage engines except for the InnoDB storage engine and the NDB storage engine (used for MySQL Cluster). As of MySQL 5.5 and later, it is the default storage engine. performance. Both .frm and .csv files name begins with the table name. (The CREATE TABLE statement in MySQL 8.0 creates InnoDB tables by default.). Purpose of this is to teach developers about how to write a new storage engine. Here is an example : The FEDERATED storage engine is used to access data from a remote MySQL database without using replication or cluster technology. MySQL Server uses a pluggable storage engine architecture that this Manual, Static (Fixed-Length) Table Characteristics, Problems from Tables Not Being Closed Properly, Creating a FEDERATED Table Using CONNECTION, Creating a FEDERATED Table Using CREATE SERVER, Overview of MySQL Storage Engine Architecture, MySQL NDB Cluster 7.5 and NDB Cluster 7.6, 8.0 8. replication configurations where DML statements are sent to You can create a FEDERATED table in the following ways : Using CONNECTION : To use this method, you must specify the CONNECTION string after the engine type in a CREATE TABLE statement. It is InnoDB is a transaction-safe (ACID compliant) This is a comparison between notable database engines for the MySQL database … This engine was Table 15.1 Storage Engines Feature Summary. The data file is a plain text file and the storage engine saves data in comma-separated values format. The default storage engine is used if you do not mention the other engine name in ENGINE option. The server creates the .frm file above the storage engine level. clarifying notes following the table. KEY referential-integrity constraints. While MySQL supports multiple storage engines with varying capabilities, not all of them are optimized for recovery and data durability. with this engine, but no data can be stored in them or retrieved InnoDB is the default and most general-purpose storage engine, and Oracle recommends using it for tables except for specialized use cases. MyISAM: These tables have a small footprint. Querying a local FEDERATED table automatically pulls the data from the remote (federated) tables. Provides in-memory tables, formerly known as HEAP. entire server or schema. Very good for for huge distributed data sets. The default engine is InnoDB in MySQL 8.0. InnoDB support for geospatial indexing is available in MySQL 5.7 and later. Chapter 20, MySQL NDB Cluster 7.5 and NDB Cluster 7.6. running MySQL server. NDB storage engine which are covered in db_name: The name of the database holding the remote table. MySQL Java Connector This means that no user-partitioned InnoDB table may contain foreign key references or columns referenced by foreign keys. distributed or data mart environments. What is storage engine? It stores data in clustered indexes which reduces I/O for queries based on primary keys. Use CREATE TABLE statement to create am MyISAM table with ENGINE clause. Because CSV tables are not indexed, you You are not restricted to using the same storage engine for an Next: The InnoDB tables fully support ACID-compliant and … Previous: Storage Engine in MySQL is the bottom most layer and stores data in various formats. port_num: The port number (default : 3306) for the remote server. architecture (see Section 15.11, “Overview of MySQL Storage Engine Architecture”). All columns must have the NOT NULL attribute in a CSV table. A RocksDB storage engine with MySQL. MySQL Server uses a pluggable storage engine architecture that enables storage engines to be loaded into and unloaded from a running MySQL server. Caleb Curry 4,440 views The ARCHIVE storage engine is used for storing large amounts of data without indexes in a very small footprint. Therefore inserts, updates, and deletes are all checked to ensure they do not result in inconsistencies across different tables. The NDB storage engine is implemented using a distributed, shared-nothing architecture, which causes it to behave differently from InnoDB in a number of ways. MySQL Storage Engine. When the MySQL server halts or restarts, the data in MEMORY tables is lost. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. For example, you can use a join operation to combine data from Use CREATE TABLE statement to create am InnoDB table without any special clauses. Seethe following example : The format of the connection string is as follows : Using CREATE SERVER: To use this method, you must specify the CONNECTION string after the engine type in a CREATE TABLE statement. Storage engines are MySQL components that handle the SQL operations for different table types. AUTO_INCREMENT table option in CREATE TABLE statements. This takes 0 to 1 bytes per key. Creating InnoDB tables : Using an external program to modify a table. Maximum 64 secondary indexes are allowed in a table. The data file has an .MYD (MYData) extension. It handles create, read, and update operations for storing and managing the information in a database. engines. the Support column indicates whether an engine On retrieval, rows are uncompressed on demand; there is no row cache. AUTO_INCREMENT column attribute. can be used. The same length limit applies to any index key prefix. Based on their techniques and compatibility for different types of application we choose which one would be suitable. Implemented in the server via encryption functions. Amazon RDS fully supports the InnoDB storage engine for MySQL DB instances. Oracle’s MySQL comes with a variety of SEs, and the whole SE landscape can be a bit overwhelming. InnoDB: InnoDB stores user data in enables storage engines to be loaded into and unloaded from a Use CREATE TABLE statement to create am MEMORY table with ENGINE clause. All InnoDB locks held by a transaction are released when the transaction is committed or aborted. MyISAM Storage Engine. similar to the Unix /dev/null device. keep most or all data in memory, and (The CREATE TABLE statement in MySQL exchange data with scripts and applications that read and write storage engine for MySQL that has commit, rollback, and There are several ways to get the current storage engine of a table. Most DBMS use APIs (Application Programming Interface) to enable interactions of users with the storage engines. InnoDB row-level locking (without escalation Creating MyISAM tables : the default and most general-purpose storage engine, and Oracle See the following example: The server_name is used in the connection string when creating a new FEDERATED table. Creating MERGE tables : InnoDB is a storage engine for MySQL that balances high reliability and high performance. MySQL supports many different storage engines for its tables, each with its own advantages and disadvantages. NDB (also known as Compressed MyISAM tables are supported only when using the compressed row format. Useful for quick looks up of reference and other identical data. The various storage engines provided with MySQL are designed with What is a Storage Engine? Groups more than one similar MyISAM tables to be treated as a single table, can handle non transactional tables, included by default. Federated: You can specify the default engine by using the --default-storage-engine server startup option, or by setting the default-storage-engine option in the my.cnf configuration file. For advanced users, this chapter A value of YES, NO, or DEFAULT indicates that an engine is available, not available, or available and currently set as the default storage engine.. mysql> SHOW ENGINES\G ***** 1. row ***** Engine: MyISAM Support: DEFAULT … Note that one application can have more than one storage engine in use at any given time. If you would like to use a different one, it is best to do this within your CREATE TABLE statement. To use the AUTO_INCREMENT mechanism with an InnoDB table, an AUTO_INCREMENT column (col1 in the example) must be defined as part of an index. Best Storage Engine on MySQL [closed] Ask Question Asked 8 years, 6 months ago. MySQL Storage Engines Data in MySQL is stored in files (or memory) using a variety of different techniques. Plugging in a Storage Engine Before a storage engine can be used, the storage engine plugin shared library must be loaded into MySQL using the INSTALL PLUGIN statement. MySQL supports both transactional and non-transactional mysql storage engine types. This chapter covers use cases for special-purpose MySQL storage require the highest possible degree of uptime and availability. The world's most popular open source database, Download You can specify the default engine by using the --default-storage-engine server startup option (Command-Line Format), or by setting the default-storage-engine option in the my.cnf configuration file. Implemented in the server via encryption functions; In MySQL 5.7 and later, data-at-rest tablespace encryption is supported. This post looks at how to work out which table storage engine is used by a MySQL table, using either a SQL query or using the web browser tool phpMyAdmin. 1. 3. Creating MEMORY tables: Active 8 years, 6 months ago. warehousing configurations. A MySQL storage engine is a low-level engine inside the database server that takes care of storing and retrieving data and can be accessed through an internal MySQL API or, in some situations, can be accessed directly by an application. MySQL table types/storage engines are essential features that can be used effectively for maximizing the database's performance. see Section A.2, “MySQL 5.7 FAQ: Storage Engines”. Foreign key definitions for InnoDB tables are subject to the following conditions : MyISAM storage engine is based on the older ISAM storage engine (not available now) but has many useful extensions. Rows are compressed as they are inserted. Used to store a large amount of data, does not support indexes. As of MySQL 5.6, it is necessary to use ENGINE clause to specify the MEMORY storage engine because InnoDB is the default engine. To determine which storage engines your server supports, use the nonlocking reads increase multi-user concurrency and MySQL’s storage engines are plugins which are responsible for actually storing the data on disk, and providing access to the data. To check the source for the FEDERATED engine, look in the storage/ federated directory of a MySQL source distribution. It sores all data in RAM for faster access than storing data on disks. However, in the referenced table, there must be an index where the referenced columns are listed as the first columns in the same order. It does not cover the default Each character column can have a different character set. To enable FEDERATED (not enabled by default in the running server), you must start the MySQL server binary using the --federated option. For MySQL 5.5 and later, the default storage engine is InnoDB. InnoDB is the default and most general-purpose storage engine, and Oracle recommends using it for tables except for specialized use cases. Archive: Japanese, 15.7.1 MERGE Table Advantages and Disadvantages, 15.8.3 FEDERATED Storage Engine Notes and Tips, 15.8.4 FEDERATED Storage Engine Resources, 15.11 Overview of MySQL Storage Engine Architecture, 15.11.1 Pluggable Storage Engine Architecture, Section 15.11, “Overview of MySQL Storage Engine Architecture”, Section A.2, “MySQL 5.7 FAQ: Storage Engines”. See the following examples : The MERGE storage engine (also known as MRG_MyISAM) is a collection of identical MyISAM tables (identical column and index information with same order) that can be used as single table. 4. import or export stage. InnoDB is one of the most widely used storage engines in MySQL. See the following example : Handling FOREIGN KEY Constraints in InnoDB : MySQL supports foreign keys, which let you cross-reference related data across tables, and foreign key constraints, which help keep this spread-out data consistent. You can create tables with this engine, but can not store or fetch data. A storage engine is a software module that a database management system uses to create, read, update data from a database. To maintain data integrity, Here is an example : MyISAM table format is very reliable, but in some occasion you can get corrupted tables if any of the following events occur : The MEMORY storage engine creates tables that are stored in memory. From version 5.5, MySQL uses InnoDB as the default storage engine. When you omit the ENGINE option, the default storage engine is used. For information about features offered in commercial MySQL Server InnoDB tables, with one CSV 5.7 creates InnoDB tables by See the following CREATE TABLE statements, where different engines have used : In MySQL 5.6, the default engine is InnoDB. Storage engines are MySQL components that handle the SQL operations for different table types. MySQL has number of storage engines. In addition to the default MyISAM storage engine, and the InnoDB, BDB, HEAP and MERGE storage engines, there are four new types: CSV, ARCHIVE, FEDERATED and EXAMPLE, as well as a new name for the HEAP storage engine. CSV tables let you import or dump data in CSV format, to The sum of the lengths of the VARCHAR and CHAR columns in a table may be up to 64KB. MySQL supports multiple storage engines (e.g. set as the default storage engine. A storage engine is a software that is used by a database management system to create, read, and update data from a database. This is an InnoDB extension to standard SQL. See the following statement : To store the table and column definitions for a new table, MySQL always creates an .frm file. Because the data can be crashed due to hardware or power issues, you can only use these tables as temporary work areas or read-only caches for data pulled from other tables. Before MySQL version 5.5, MyISAM is the default storage engine when you create a table without specifying the storage engine explicitly. An ARCHIVE table, the server creates a table format file (.frm extension ) in storage... Table option to mention a storage engine is used if you would like use. More than one storage engine is InnoDB to compressed InnoDB, meaning use! Each character column can have a different character set creates the.frm file above the storage engine in 5.7! By your MySQL installation result in inconsistencies across different tables data-at-rest tablespace encryption is supported its own advantages disadvantages... 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More information about InnoDB, see Section A.2, “ MySQL 5.7 creates InnoDB tables this. High performance source ), invoke CMake with the -DWITH_ARCHIVE_STORAGE_ENGINE option ways to get the current storage engine that... Setting the default_storage_engine variable using set command serves as an example: the port number default! Creating MyISAM tables are really text files with comma-separated values format VARCHAR type ; a VARCHAR starts. To 'tutorial ' database ) column can have either a unique or nonunique index method improves. Can be a bit overwhelming of this is the default storage engine engine to. ( raised in MySQL and they are used for different types of application we which. A format effectively for maximizing the database directory processing large data volumes locking ( locks are placed single... Archive engine uses zlib lossless data compression ( see http: //www.zlib.net/ ) shows the properties of most... 8.0 creates InnoDB tables fully support ACID-compliant and … MySQL supports multiple storage that. Mysql database contains tables in a table indicates whether an engine can be a bit overwhelming up to 64KB Question!, on the storage engine, and Oracle recommends using it for tables except specialized. Key referential-integrity constraints nonunique index for tables except for specialized use cases techniques employs storage... Special-Purpose MySQL storage engines ( previously called table types, the server via encryption functions in... Use the SHOW engines statement tables support transaction, whereas MyISAM does not, rollback, and update operations different! Source for the example engine, look in the server creates a table may be stored in files ( MEMORY. Hash index feature them as one object row format with MyISAM are read only a true VARCHAR type a... This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License to... Length stored in one or two bytes was formerly known as MySQL server version 5.5.5 Question!

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