技术大牛养成指南:吃的草够多,你也能成为大牛(附思维导图)

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Support for window functions (a.k.a. analytic functions) is a frequent user request. Window functions have long been part of standard SQL (SQL 503). See blog post by Dag Wanvik here as well as blog post by Guilhem Bichot here.

窗口函数有一种生活使用最好的妙招 ,首先是常规的SQL聚合功能函数和特殊的窗口函数。

5.7本来的JSON_MERGE() 函数在8.0版本中为减少merge操作的不明确性,而被弃用。

MySQL 8.0 adds JSON functions related to space usage for a given JSON object. The JSON_STORAGE_SIZE() returns the actual size in bytes for a JSON datatype. The JSON_STORAGE_FREE() returns the free space of a JSON binary type in bytes, including fragmentation and padding saved for inplace update.

JSON_MERGE_PATCH() 函数可执行JavaScript的语法,在合并时处于重复键值对时可能性优先取舍第俩个文档的键值对,并删除第本来文档对应的重复键值。

6、可管理性:远程管理,Undo表空间管理,快速DDL

MySQL 8.0 gives better performance for sorting/grouping JSON values by using variable length sort keys. Preliminary benchmarks shows from 1.2 to 18 times improvement in sorting, depending on use case.

Window functions come in two flavors: SQL aggregate functions used as window functions and specialized window functions. This is the set of aggregate functions in MySQL that support windowing: COUNT, SUM, AVG, MIN, MAX, BIT_OR, BIT_AND, BIT_XOR, STDDEV_POP (and its synonyms STD, STDDEV), STDDEV_SAMP, VAR_POP (and its synonym VARIANCE) and VAR_SAMP. The set of specialized window functions are: RANK, DENSE_RANK, PERCENT_RANK, CUME_DIST, NTILE, ROW_NUMBER, FIRST_VALUE, LAST_VALUE, NTH_VALUE, LEADand LAG

2、对JSON的支持:扩充语法,新函数,排序增强,JSON列次要更新。基于JSON表的结构,还还要调用SQL话语出理 JSON数据。

7、JSON 改进型的排序

4、Reliability DDL statements have become atomic and crash safe, meta-data is stored in a single, transactional data dictionary. Powered by InnoDB!

MySQL 8.0 extends the syntax for ranges in JSON path expressions. For example SELECT JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[1 to 3]'); results in [2, 3, 4].

但在什么都有有场景下,有马上获得(不等待歌曲锁)数据的需求。使用NOWAIT参数后可能性请求的数据中包括了被锁住的行,将马上会收到查询失败的报错信息。使用SKIP LOCKED参数后,返回的数据可能性跳过被锁住的行。

MySQL 8.0 给SQL的上锁子句带来了NOWAIT和SKIP LOCKED本来可选项。在本来的版本中,当行数据被UPDATE可能性SELECT ... FOR UPDATE话语上锁后,什么都有有的事务还要等待歌曲锁释放可以访问这行数据。

8、性能:InnoDB在读/写负载,高IO负载,热数据高并发竞争等场景表现更好。新增的资源组结构给用户在特定负载和特定硬件情况下将用户多线程 池映射到指定的CPU上的可选项

7、Security OpenSSL improvements, new default authentication, SQL Roles, breaking up the super privilege, password strength, and more.

nfiguration Variables, and Error Logging.

面向开发人员的结构

在5.7版本中亲戚亲戚朋友引入了新的优化器建议的语法,借助你这些新的语法,优化器建议还还要被用/*+ */国际包裹起来,直接贴到 SELECT | INSERT | REPLACE | UPDATE | DELETE关键字的后边。

The new syntax introduced is a subset of the SQL standard syntax, described in SQL:2016, 9.39 SQL/JSON path language: syntax and semantics. See also Bug#79052reported by Roland Bouman.

The above represents some of the highlights and I encourage you to further drill into the complete series of Milestone blog posts—8.0.0, 8.0.1, 8.0.2, 8.0.3, and 8.0.4 —and even further down in to the individual worklogs with their specifications and implementation details. Or perhaps you prefer to just look at the source code at github.com/mysql.

MySQL Developers want new features and MySQL 8.0 delivers many new and much requested features in areas such as SQL, JSON, Regular Expressions, and GIS. Developers also want to be able to store Emojis, thus UTF8MB4 is now the default character set in 8.0. Finally there are improvements in Datatypes, with bit-wise operations on BINARY datatypes and improved IPv6 and UUID functions.

6、Manageability Remote management, Undo tablespace management, and new instant DDL.

一方面,正序查找要比逆序查找减慢;

MySQL 8.0 delivers GROUPING(), SQL_FEATURE T433. The GROUPING() function distinguishes super-aggregate rows from regular grouped rows. GROUP BY extensions such as ROLLUP produce super-aggregate rows where the set of all values is represented by null. Using the GROUPING() function, you can distinguish a null representing the set of all values in a super-aggregate row from a NULL in a regular row. GROUPING is a frequently requested SQL feature. See feature requests 3156 and 45053. Thank you to Zoe Dong and Shane Adams for code contributions in feature request 45053 ! See blog post by Chaithra Gopalareddy here.

In 5.7 we introduced a new hint syntax for optimizer hints. With the new syntax, hints can be specified directly after the SELECT | INSERT | REPLACE | UPDATE | DELETEkeywords in an SQL statement, enclosed in /*+ */ style comments. (See 5.7 blog post by Sergey Glukhov here). In MySQL 8.0 we complete the picture by fully utilizing this new style:

8.0版本增加了还还要接收JSON原生数据类型和用字符串形式表达的JSON,并返回一行缩进的易读的JSON格式化后的的字符串。

MySQL 8.0 带来了支持递归的公用表表达式的功能。非递归的公用表表达式可能性允许由from子句派生的临时表的原因分析分析还还要被多次引用,因而被解释为改进型的派生表(from子句中的临时表)。

1、JSON path表达式中扩展的范围性语法

MySQL 8.0 adds a hint called SET_VAR. The SET_VAR hint will set the value for a given system variable for the next statement only. Thus the value will be reset to the previous value after the statement is over. See blog post by Sergey Glukhov here.

7、安全性:OpenSSL的改进,新的默认验证最好的妙招 ,SQL角色权限,分解super权限,密码强度提升等等

8.0版本增加了和指定JSON对象空间占用相关的函数,JSON_STORAGE_SIZE() 还还要用字节为单位返回JSON某个数据类型的实际大小, JSON_STORAGE_FREE() 还还要返回该JSON数据类型的剩余空间(包括碎片和用来适应更改后处于长度变化的入党入党积极分子空间)

MySQL 8.0 delivers SQL window functions. Similar to grouped aggregate functions, window functions perform some calculation on a set of rows, e.g. COUNT or SUM. But where a grouped aggregate collapses this set of rows into a single row, a window function will perform the aggregation for each row in the result set.

4、降序索引

MySQL 8.0 adds hints for JOIN_FIXED_ORDER, JOIN_ORDER, JOIN_PREFIX, and JOIN_SUFFIX. This allows the user to control table order for the join execution.

3、JSON 聚合函数

5、JSON 美化函数

MySQL 8.0 增加了还还要在JSON数据上使用SQL出理 工具的JSON 表函数。JSON_TABLE()函数还还要创建JSON数据的关系型视图。还还要将JSON数据估算到关系型的行列之中,用户还还要对此函数返回的数据按照常规关系型数据表的最好的妙招 进行SQL运算。

We prefer the new style of optimizer hints as preferred over the old-style hints and setting of optimizer_switch values. By not being inter-mingled with SQL, the new hints can be injected in many places in a query string. They also have clearer semantics in being a hint (vs directive).

个人面,真正的降序索引在复合的order by话语(即有asc又有desc)中,还还要提高索引利用率,消除filesort。

SQL

常规的聚合功能函数如:COUNT,SUM等函数。而窗口函数专有的则是RANK, DENSE_RANK, PERCENT_RANK, CUME_DIST, NTILE, ROW_NUMBER, FIRST_VALUE, LAST_VALUE, NTH_VALUE, LEADand LAG等函数。

2、JSON Extended syntax, new functions, improved sorting, and partial updates. With JSON table functions you can use the SQL machinery for JSON data.

1、窗口函数

MySQL 8.0带来了标准SQL的窗口函数功能,窗口函数与分组聚合函数相相似 的是都提供了对一组行数据的统计计算。但与分组聚合函数将多行合并成一行不同是窗口函数会在结果结果集中展现每一行的聚合。

1、SQL方面:窗口函数,公共表达式,NOWAIT, SKIP LOCKED, 降序索引,分组,正则表达式,字符集,CBO优化模式,直方图

MySQL 8.0 带来了GROUPING()分组函数,你这些功能还还要把group by子句扩展功能(如ROLLUP)产生的过聚合NULL值,通过0和1进行区分,1为NULL,本来就还还要在having子句中对过聚合的无效值进行过滤。

非常高兴的向亲戚亲戚朋友提前大选MySQL 8.0 GA版本发布,MySQL 8.0是本来得到全面增强且极具吸引力的新版本。不限于下面几点:

MySQL 8.0 delivers NOWAIT and SKIP LOCKED alternatives in the SQL locking clause. Normally, when a row is locked due to an UPDATE or a SELECT ... FOR UPDATE, any other transaction will have to wait to access that locked row. In some use cases there is a need to either return immediately if a row is locked or ignore locked rows. A locking clause using NOWAIT will never wait to acquire a row lock. Instead, the query will fail with an error. A locking clause using SKIP LOCKED will never wait to acquire a row lock on the listed tables. Instead, the locked rows are skipped and not read at all. NOWAIT and SKIP LOCKED are frequently requested SQL features. See for example feature request 49763 . We also want to say thank you to Kyle Oppenheim for his code contribution! See blog post by Martin Hansson here.

8、Performance InnoDB is significantly better at Read/Write workloads, IO bound workloads, and high contention “hot spot” workloads. Added Resource Group feature to give users an option optimize for specific workloads on specific hardware by mapping user threads to CPUs.

1、SQL Window functions, Common Table Expressions, NOWAIT and SKIP LOCKED, Descending Indexes, Grouping, Regular Expressions, Character Sets, Cost Model, and Histograms.

8.0版本通过使用变长的排序键提升了JSON排序分组的性能。在什么都有有场景下,Preliminary 的压测结果出先了1.2到18倍的提升。

8、JSON的次要更新

否则,8.0版本提供了在逻辑上区分差异的最好的妙招 ,还还要在行群克隆的情况下传输并应用到从库上。

The existing JSON_MERGE() function is deprecated in MySQL 8.0 to remove ambiguity for the merge operation. See also proposal in Bug#81283 and blog post by Morgan Tocker here.

MySQL 8.0 adds support for partial update for the JSON_REMOVE(), JSON_SET() and JSON_REPLACE() functions. If only some parts of a JSON document are updated, we want to give information to the handler about what was changed, so that the storage engine and replication don’t need to write the full document. In a replicated environment, it cannot be guaranteed that the layout of a JSON document is exactly the same on the slave and the master, so the physical diffs cannot be used to reduce the network I/O for row-based replication. Thus, MySQL 8.0 provides logical diffs that row-based replication can send over the wire and reapply on the slave. See blog post by Knut Anders Hatlen here.

MySQL 8.0 adds a JSON_PRETTY() function in MySQL. The function accepts either a JSON native data-type or string representation of JSON and returns a JSON formatted string in a human-readable way with new lines and indentation.

相对于已经 的优化器建议和优化器结构开关参数,亲戚亲戚朋友更倾向于推荐新形式的优化器建议模式,新形式的优化器建议还还要在不侵入SQL话语(指修改话语的非注释的业务次要)的情况下,注入查询话语的什么都有有位置。与直接修改话语的优化器建议相比,新形势的优化器建议在SQL语义上更加清晰。

MySQL 8.0应面向MySQL开发人员的需求,带来了SQL,JSON,正则表达式,地理信息系统等方面的结构,可能性什么都有有开发人员有存储EmoJi表情的需求,在新版本中UTF8MB4成为默认的字符集。除此之外,还有对Binary数据类型按位操作,和对IPV6和UUID函数的改进。

5、分组函数

MySQL 8.0 增加了用于生成JSON阵列的聚合函数JSON_ARRAYAGG(),和用于生成JSON对象的JSON_OBJECTAGG()函数,令多行的JSON文档组合成JSON阵列可能性JSON对象成为可能性。

6、优化器建议

The JSON_MERGE_PATCH() function implements the semantics of JavaScript (and other scripting languages) specified by RFC7396, i.e. it removes duplicates by precedence of the second document. For example, JSON_MERGE('{"a":1,"b":2 }','{"a":3,"c":4 }');# returns {"a":3,"b":2,"c":4}.

在已经 的群克隆环境中可能性无法确保JSON文档的排列(layout)在主从上完整版一致,什么都有有在基于行的群克隆情况下物理文件的差异从可以 用来削减传输群克隆信息带来的网络IO消耗。

JSON

8.0版本追加了新的JSON函数,并还还要提高在排序与分组JSON数据情况下的性能。

8.0版本增加了SET_VAR,该优化器建议还还要设定本来只在下三根话语中生效的的系统参数。

5、可观察性:对P_S,I_S,配置参数,错误日志的记录有显著增强5、Observability Significant enhancements to Performance Schema, Information Schema, Co

MySQL 8.0 delivers [Recursive] Common Table Expressions (CTEs). Non-recursive CTEs can be explained as “improved derived tables” as it allow the derived table to be referenced more than once. A recursive CTE is a set of rows which is built iteratively: from an initial set of rows, a process derives new rows, which grow the set, and those new rows are fed into the process again, producing more rows, and so on, until the process produces no more rows. CTE is a commonly requested SQL feature, see for example feature request 16244 and 32174 . See blog posts by Guilhem Bichot here, here, here, and here.

MySQL 8.0 adds the aggregation functions JSON_ARRAYAGG() to generate JSON arrays and JSON_OBJECTAGG() to generate JSON objects . This makes it possible to combine JSON documents in multiple rows into a JSON array or a JSON object. See blog post by Catalin Besleaga here.

而递归的公用表表达式则由一组原始数据,经过出理 后得到新的一组数据,再被带入出理 得到更多的新数据,循环往复直到再也无法产生更多新数据为止。公用表达式也是本来用户呼声频繁的SQL功能。

We proudly announce General Availability of MySQL 8.0. Download now! MySQL 8.0 is an extremely exciting new version of the world’s most popular open source database with improvements across the board. Some key enhancements include:

3、GIS Geography support. Spatial Reference Systems (SRS), as well as SRS aware spatial datatypes, spatial indexes, and spatial functions.

3、对地理信息系统的支持—空间引用系统(SRS),包括SRS空间数据类型,空间索引,空间函数

The JSON_MERGE_PRESERVE() function has the semantics of JSON_MERGE() implemented in MySQL 5.7 which preserves all values, for example JSON_MERGE('{"a": 1,"b":2}','{"a":3,"c":4}'); # returns {"a":[1,3],"b":2,"c":4}.

MySQL 8.0 带来了对降序索引的支持。在 8.0降序索引中,数据被倒序组织,正向查找。而在已经 的版本中,难能可贵支持创建降序排列的索引,但难能可贵现最好的妙招 是通过创建常见的正序索引,否则进行反向查找来实现的。

本文作者:张锐志

在8.0的版本中亲戚亲戚朋友又加入了新的姿势:

JSON_MERGE_PRESERVE()函数与5.7版本中的JSON_MERGE()含义相同,全是在合并的已经 保留所有值。

4、可靠性:DDL话语支持原子性和崩溃安全恢复(元信息数据被处于了本来基于InnoDB的单独事务性数据字典中)。

MySQL 8.0 扩展了JSON path表达式中范围性的语法,比如:SELECT JSON_EXTRACT('[1, 2, 3, 4, 5]', '$[1 to 3]');还还要得出[2, 3, 4]的结果。

8.0版本增加了对 JSON_REMOVE(), JSON_SET() 和 JSON_REPLACE() 函数的次要更新的支持。可能性JSON文档的某次要被更新,亲戚亲戚朋友会将更改的详情给到句柄。本来存储引擎和群克隆关系就从不写入整个JSON文档。

2、JSON表函数

2、公用表表达式(CTE)

MySQL 8.0 delivers support for indexes in descending order. Values in such an index are arranged in descending order, and we scan it forward. Before 8.0, when a user create a descending index, we created an ascending index and scanned it backwards. One benefit is that forward index scans are faster than backward index scans. Another benefit of a real descending index is that it enables us to use indexes instead of filesort for an ORDER BY clause with mixed ASC/DESC sort key parts. Descending Indexes is a frequently requested SQL feature. See for example feature request 13375 . See blog post by Chaithra Gopalareddy here.

原文发布时间为:2018-05-15

4、JSON 合并函数

对窗口函数的支持上,是用户呼声比较频繁。窗口函数早在SQL503规范中就成为了标准SQL的一次要。

3、新的NOWAIT、SKIP LOCKED选项

MySQL 8.0 adds hints for INDEX_MERGE and NO_INDEX_MERGE. This allows the user to control index merge behavior for an individual query without changing the optimizer switch.

8.0版本增加了JOIN_FIXED_ORDER, JOIN_ORDER, JOIN_PREFIX, 和 JOIN_SUFFIX,允许用户控制join表关联的顺序。

MySQL 8.0 adds new JSON functions and improves performance for sorting and grouping JSON values.

MySQL 8.0 adds JSON table functions which enables the use of the SQL machinery for JSON data. JSON_TABLE() creates a relational view of JSON data. It maps the result of a JSON data evaluation into relational rows and columns. The user can query the result returned by the function as a regular relational table using SQL, e.g. join, project, and aggregate.

6、JSON 文件大小函数

以上是8.0版本的次要亮点,我(原文作者)推荐您仔细阅读GA版本前2个版本的发布信息,甚至你这些结构和实现最好的妙招 的的项目日志。可能性您还还要取舍直接在Github上阅读源码。