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How does MySQL allocate memory?
Memory is allocated only for unexpectedly large strings. For each table having BLOB columns, a buffer is enlarged dynamically to read in larger BLOB values. If you scan a table, the buffer grows as large as the largest BLOB value. MySQL requires memory and descriptors for the table cache.
How does MySQL partitioning work?
Partitioning is a way in which a database (MySQL in this case) splits its actual data down into separate tables, but still get treated as a single table by the SQL layer. Otherwise, the storage engine does a scatter-gather, and queries ALL partitions in a UNION that is not concurrent.
Does MySQL support in memory stack table?
The MEMORY storage engine supports both HASH and BTREE indexes. 1, “How MySQL Uses Indexes”. MEMORY tables can have up to 64 indexes per table, 16 columns per index and a maximum key length of 3072 bytes.
Is MySQL in-memory?
It does not qualify it as in in-memory database. There are other systems that also offer in-memory options; like SQLite. An example of an in-memory database is voltdb. redis is sometimes referred to as an in-memory database, but strictly speaking, its a key/value store.
What do you need to know about MySQL partitions?
MySQL partitioning is about altering – ideally, optimizing – the way the database engine physically stores data. It allows you to distribute portions of table data (a.k.a. partitions) across the file system based on a set of user-defined rules (a.k.a. the “partitioning function”).
Is there a way to disable partitioning in MySQL?
To disable partitioning support, you can start the MySQL Server with the –skip-partition option, in which case the value of have_partitioning is DISABLED. How to partition a table?
Which is the Order of the partitioning columns in MySQL?
The order of the column names in the partitioning column list and the value lists do not have to be the same as the order of the table column definitions in CREATE TABLE statement. The first three columns have participated in partitioning COLUMNS clause, in the order col1, col2, col3.
How to delete old data from MySQL partition?
Deleting Old Data: In the above example, if logs from 2013 need to be deleted, you can simply use ALTER TABLE userslogs DROP PARTITION from_2013_or_less; to delete all rows. This process will take almost no time, whereas running DELETE FROM userslogs WHERE YEAR (created) <= 2013; could take minutes if there are lots of rows to delete.