Array is a linear table data structure. It uses a group of contiguous memory space to store a group of data of the same type. Find elements fast: through the index, you can quickly access the element at the specified locationLinear table & non-linear representationIn a non-linear table, the data is not a simple context.time complexityThe array supports random access, and the time complexity of random access according to the subscript is O(1)Insert operationThe time complexity is O(n), assumi

OverviewFirst-in-first-out (FIFO—first in first out), only allows delete operations at the front of the table (front), and inserts at the back of the table (rear)TailThe end of the insert operation becomes the end of the lineRightThe end that performs the delete operation becomes the counterpartyJoin the teamInserting a queue element in the queue is called enqueueLeave the teamAnd removing a queue element from the queue is called dequeueOne-way queue (Queue)You can only insert data at one end an

Slow query log slow_query_log starts and stops recording the slow query log. Slow_query_log_file is not started by default. Slow_query_log_file specifies the storage path and file of the slow query log. It is saved in the MySQL data directory by default. long_query_time specifies the threshold for recording the SQL execution time of the slow query log. The default value is 10 seconds, usually changed to 0.001 seconds, which is 1 millisecond, may be more appropriate log_queries_not_using_indexes

Transaction overviewTransaction is one of the important characteristics of a database system that distinguishes it from all other file systems. A transaction is a set of atomic SQL statements or an independent unit of workTransaction characteristics1. Atomicity A transaction must be regarded as an inseparable smallest unit of work. All operations in the entire transaction are either submitted successfully or all failed. For a transaction, it is impossible to perform only part of the operations.