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DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE; reduces performance during execution - each record in the table is locked for deletion
Indexes are useful for many applications but come with some limitations. Consider the following SQL statement: SELECT first_name FROM people WHERE last_name = 'Smith';. To process this statement without an index the database software must look at the last_name column on every row in the table (this is known as a full table scan).
If the table had 1,000,000 records, then a specific record could be located with at most 20 comparisons: ⌈ log 2 (1,000,000) ⌉ = 20. Large databases have historically been kept on disk drives. The time to read a record on a disk drive far exceeds the time needed to compare keys once the record is available due to seek time and a rotational ...
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
LAMP—Linux Apache MySQL Perl; LAMP—Linux Apache MySQL PHP; LAMP—Linux Apache MySQL Python; LAN—Local Area Network; LBA—Logical Block Addressing; LB—Load Balancer; LCD—Liquid Crystal Display; LCR—Least Cost Routing; LCOS—Liquid Crystal On Silicon; LDAP—Lightweight Directory Access Protocol; LE—Logical Extents; LED—Light ...
() operations, which force us to visit every node in ascending order (such as printing the entire list), provide the opportunity to perform a behind-the-scenes derandomization of the level structure of the skip-list in an optimal way, bringing the skip list to () search time. (Choose the level of the i'th finite node to be 1 plus the number ...
In a statement, Stack Exchange confirmed that 11% of moderators had ceased content moderation in response to this policy. [25] This would grow to more than 23% of all moderators on the network by June 22, including more than 70% of all Stack Overflow moderators.
A classification of SQL injection attacking vector as of 2010. In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker).