• Comparison of common technologies and schemes of database recovery subsystem (I)


    Author: Xiao Chen / big data open laboratory For transactional database, the key function is to ensure the acid attribute of things, in which atomicity and persistence depend on the recovery subsystem. If it is found that the transaction cannot continue during the transaction, it needs to be rolled back with the recovery subsystem; Or […]

  • DMA controller of STM32 network


    The block diagram of STM32 network controller is as follows: ​ In the previous article, we have explained: ①External PHY Intereface:《STM32 network circuit design》 ② MAC controller:《Stm32mac controller》 Next, we will explain part ③, DMA controller of STM32 network. 01. DMA controller operation DMA has an autonomous transmit and receive engine and a CSR (control […]

  • Basic data structure and algorithm merging and sorting


    origin Recently read < < my first algorithm book > > ([Japan] Ishida Baohui; Miyazaki Xiuyi)This series of notes is intended to use golang exercises Merge sort The merge sort algorithm divides the sequence into two subsequences with the same length, When it is impossible to further divide (that is, there is only one data […]

  • [redis basic] client


    Redis uses a single thread to handle the access of multiple clients. Therefore, as redis development, operation and maintenance personnel, they need to understand the communication protocol between redis server and client, as well as the use method of redis client in mainstream programming language. At the same time, they also need to understand the […]

  • Log file sync log wait


    When the user session (foreground process) commits (or rolls back), the redo information of the session needs to be brushed into the redo log file. The user session will use LGWR to write all redo requests required in the log buffer to the redo log file. When the LGWR completes, it will notify the user […]

  • Analysis of Kafka principle (3) – buffer for producer message sending


    1. Overall message sending process(1) The first step is to wait for metadata pull, as mentioned last time.(2) The metadata is in place, and the topic and key are serialized.(3) Select partition. There are three cases A if the sequence number of the partition is specified in the message, use the specified sequence number first. […]

  • Redis string implementation: simple dynamic string – the difference between SDS and C string


    2.1 definition of SDS struct { //The number of bytes used in buf is equal to the length of the string saved in SDS int len; //Unused byte length in buf int free; //Byte array to hold string char[] buf; } 2.2 difference between SDS and C string C string SDS The complexity of getting […]

  • SQL server creates a primary key auto increment column. We can use


    SQL 588988 server creates a primary key auto increment column. We can use “id int identity (1,1) not null primary key” to create it in one step, while Oracle creates a primary key auto increment column, which is different from SQL server. The steps are a little more complex, as follows: –1. Create tableCREATE TABLE […]

  • Learn a Linux command every day (43): dmesg


    Yesterday’s recommendation:Learn a Linux command every day (42): unzip Command introduction Dmesg command is used to display system startup information and diagnose system faults. The kernel will store the system boot information in the ring buffer, which can be viewed with the dmesg command. The boot information is saved in the / var / log […]

  • Insert buffer of key features of MySQL InnoDB


    What is insert buffer? Insert buffer, also known as insert buffer, is one of the key features of InnoDB storage engine. We often understand a part of the buffer pool when inserting buffer. This understanding is one-sided. Part of the information of insert buffer is in memory, and the other part exists in physical pages […]

  • Learn a Linux command every day (49): Free


    Yesterday’s recommendation:Learn a Linux command every day (48): Top Command introduction The free command is used to display the memory usage, the total amount of available and used physical memory and swap memory, and the buffer used by the kernel. Syntax format free [options] Option description -b  # Displays memory usage in bytes -k  # Displays […]

  • IOS development interview only needs to know these, and the technology basically passes the customs! (UI)


    1、 Uiview and calayer Single responsibility principle UIViewbyCALayerProvide content, handle touch and other events, and participate in the response chain CALayerResponsible for displaying contentcontents 2、 Event delivery and view response chain: If the event is passed all the way to UIApplictionIf it’s still not handled, it will be ignored 3、 Image display principle 1.CPU: output […]