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docs (level 101): fix typos, punctuation, formatting (#160)

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* docs: formatted for readability

* docs: rephrased and added punctuation

* docs: fix typos, punctuation, formatting

* docs: fix typo and format

* docs: fix caps and formatting

* docs: fix punctuation and formatting

* docs: capitalized SQL commands, fixed puntuation, formatting

* docs: fix punctuation

* docs: fix punctuation and formatting

* docs: fix caps,punctuation and formatting

* docs: fix links, punctuation, formatting

* docs: fix code block formatting

* docs: fix punctuation, indentation and formatting
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Jana R
2024-07-28 17:38:19 +05:30
committed by GitHub
parent bdcc6856ed
commit 4239ecf473
58 changed files with 1522 additions and 1367 deletions
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courses/level101/databases_sql/mysql.md
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@@ -6,25 +6,21 @@ MySQL architecture enables you to select the right storage engine for your needs
Application layer:
* Connection handling - each client gets its own connection which is cached for the duration of access)
* Authentication - server checks (username,password,host) info of client and allows/rejects connection
* Security: server determines whether the client has privileges to execute each query (check with _show privileges_ command)
* Connection handling: each client gets its own connection which is cached for the duration of access
* Authentication: server checks (username, password, host) info of client and allows/rejects connection
* Security: server determines whether the client has privileges to execute each query (check with `SHOW PRIVILEGES` command)
Server layer:
* Services and utilities - backup/restore, replication, cluster etc
* SQL interface - clients run queries for data access and manipulation
* SQL parser - creates a parse tree from the query (lexical/syntactic/semantic analysis and code generation)
* Optimizer - optimizes queries using various algorithms and data available to it(table level stats), modifies queries, order of scanning, indexes to use etc. (check with explain command)
* Caches and buffers - cache stores query results, buffer pool(InnoDB) stores table and index data in [LRU](https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(LRU)) fashion
* Services and utilities: backup/restore, replication, cluster, etc
* SQL interface: clients run queries for data access and manipulation
* SQL parser: creates a parse tree from the query (lexical/syntactic/semantic analysis and code generation)
* Optimizer: optimizes queries using various algorithms and data available to it (table-level stats), modifies queries, order of scanning, indexes to use, etc. (check with `EXPLAIN` command)
* Caches and buffers: cache stores query results, buffer pool (InnoDB) stores table and index data in [LRU](https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(LRU)) fashion
Storage engine options:
* InnoDB: most widely used, transaction support, ACID compliant, supports row-level locking, crash recovery and multi-version concurrency control. Default since MySQL 5.5+.
* InnoDB: most-widely used, transaction support, ACID compliant, supports row-level locking, crash recovery and multi-version concurrency control. Default since MySQL 5.5+.
* MyISAM: fast, does not support transactions, provides table-level locking, great for read-heavy workloads, mostly in web and data warehousing. Default upto MySQL 5.1.
* Archive: optimised for high speed inserts, compresses data as it is inserted, does not support transactions, ideal for storing and retrieving large amounts of seldom referenced historical, archived data
* Memory: tables in memory. Fastest engine, supports table-level locking, does not support transactions, ideal for creating temporary tables or quick lookups, data is lost after a shutdown
@@ -35,4 +31,4 @@ It is possible to migrate from one storage engine to another. But this migration
General guideline is to use InnoDB unless you have a specific need for one of the other storage engines.
Running `mysql> SHOW ENGINES; `shows you the supported engines on your MySQL server.
Running `mysql> SHOW ENGINES;` shows you the supported engines on your MySQL server.