Tag：Indexes
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Time：2021-10-27
preface On Tuesday, the second week after joining the new company, I met another project that needs technical support: I need to participate in the verification of ES multi cluster data backup scheme. In this project, I need to pay attention to the interoperability of the two clusters. Es clusters are deployed in different k8s […]
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Time：2021-10-27
1. Basic selector 1.1 ID selector: //Select the element with ID mydiv, which is the fastest $(“#myDiv”) Type 1.2 selector: //Select all elements whose class attribute is red $(“.red”) 1.3 element selector: //Select all div elements $(“div”) 1.4 wildcard selector: //Select all elements $(“*”) 1.5 compound selector: //Check all span elements and all elements with […]
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Time：2021-10-26
After stumbling and stumbling, our mongodb series of tutorials finally came to an end. From the first one on November 21 to now, we have been wandering for a while, but fortunately there is no unfinished work. Well, here I’ll list all the articles in this series for my friends to search and view. 1.Installing […]
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Time：2021-10-24
introduce This blog will introduce the following knowledge: Index introduction Indexing principle Data structure of index (binary tree — > balanced binary tree — > b tree — > b + tree) Clustered index and secondary index MySQL index management Syntax for creating and deleting indexes Test after index creation (change in query speed) How […]
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Time：2021-10-24
1. IntroductionThe dictionary uses a hash table as the underlying implementation. A dictionary contains two hash tables. One HT [0] is used normally, and HT [1] will be used when rehash. A hash table contains multiple hash table nodes, and each hash table node stores a key value pair in the dictionary. The database in […]
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Time：2021-10-23
Series articles： MySQL – new to MySQL Operation database Modify delete table Create database tables MySQL data management and DML statements DQL (date query language) database query statement affair Indexes JDBC Database operation Database connection pool affair MySQL advanced optimization Index (ALI protocol) Index data structure B + tree Hash Take col2 as an example. […]
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Time：2021-10-23
innodb_flush_log_at_trx_commit You can define the transaction submission method of MySQL MySQL write files have two caches. One is the log buffer defined in memory, and the other is the OS cache mapped from disk to memory. MySQL can call flush to actively refresh the log buffer to the disk memory mapping, or call fsync to […]
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Time：2021-10-22
introduce 1. What is a lock Lock is a mechanism by which a computer coordinates multiple processes or threads to access a resource concurrently. We call it lock mechanism 2. Why use the lock mechanism Because in the database, in addition to the contention of traditional computing resources (such as CPU, ram, I / O, […]
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Time：2021-10-22
background start At the beginning of the story, there is a need to solve the problem of very slow loading data. The key program has been running in the production environment for quite a long time. It is reasonable that there will be no problem, at least in terms of the stability of online operation. […]
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Time：2021-10-22
OpenMLDB Summary This week, 8 pull requests were merged, 5 pull requests were added, 11 issues were closed and 20 issues were added. A total of 84 documents were modified, 6677 lines of code were added and 511 lines of code were deleted. Merged Pull Requests feat: support spark.master config to run job in yarn […]
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Time：2021-10-21
preface A skip list is an ordered data structureOrdered linked listIt solves the efficiency problem of finding a value in the ordered linked list. Jump table supports averageO(logn)In most cases, the efficiency of node search with the worst o (n) complexity is comparable to that of balanced tree, and the implementation is simpler. Redis uses […]
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Time：2021-10-21
More welcome to the blog:https://imjianjian.github.io Mongodb version: 3.4 consult your documentation find() Query all db.collection.find({}) db.collection.find() Document query //Query all documents with name = “Jian” db.collection.find({“collection”:”jianjian”}) Conditional Operator $LT less than $GT greater than $GTE is greater than or equal to $LTE less than or equal to $ne is not equal to $all inclusive $in […]
