{"id":36634,"date":"2019-10-31T22:12:47","date_gmt":"2019-10-31T19:12:47","guid":{"rendered":"https:\/\/prohoster.info\/blog\/globaly-mechi-kladentsy-dlya-hraneniya-dannyh-derevya-chast-1\/"},"modified":"2019-10-31T22:12:47","modified_gmt":"2019-10-31T19:12:47","slug":"globaly-mechi-kladentsy-dlya-hraneniya-dannyh-derevya-chast-1","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/administrirovanie\/globaly-mechi-kladentsy-dlya-hraneniya-dannyh-derevya-chast-1","title":{"rendered":"Globals are data storage swords. Trees. Part 1.","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"Globals<\/a><\/noindex> Real database globals are well-known but still, few know how to use this superweapon effectively.<\/p>\n

By using globals for the tasks they excel at, impressive results can be achieved, either in performance or in simplifying the solution.1<\/a><\/noindex>, 2<\/a><\/noindex>).<\/p>\n

Globals are a special way of storing and processing data, fundamentally different from tables in SQL. They appeared in 1966 in the language M(UMPS)<\/a><\/noindex> (an evolutionary development \u2014 Cach\u00e9 ObjectScript<\/a><\/noindex>, later COS) in medical databases and are still actively used<\/a><\/noindex>, as well as penetrating some other areas requiring reliability and high performance: finance, trading, etc.<\/p>\n

Modern DBMS support transactions, logging, replication, and partitioning for globals. That is, they can be built into modern, reliable, distributed, and fast systems.<\/p>\n

Globals do not constrain you within the limits of the relational model. They provide freedom to develop data structures optimized for specific tasks. For many applications, the judicious use of globals can be a truly secret weapon, delivering performance that relational application developers can only dream of.<\/p>\n

Data storage via globals can be used in many modern programming languages, both high-level and low-level. Therefore, in this article, I will focus specifically on globals, not on the language from which they originated.
\n<\/a><\/noindex><\/p>\n

2. How globals work<\/h2>\n

\nLet's first understand how globals work and what their strengths are. Globals can be viewed from different perspectives. In this section of the article, we will look at them as trees or hierarchical data storage.<\/p>\n

Simply put, a global is a persistent array. An array that is automatically saved to disk.
\nIt's hard to imagine anything simpler for data storage. In the code (in COS\/M languages), it differs from an ordinary associative array only by the symbol ^<\/b> before the name.<\/p>\n

To store data in a global, you don't need to learn SQL query language; the commands to work with them are very simple. They can be learned in an hour. <\/p>\n

Let's start with the simplest example. A single-level tree with 2 branches. The examples are written in COS.<\/p>\n

\"Globals<\/p>\n

Set ^a(\"+7926X\") = \"John Sidorov\"\nSet ^a(\"+7916Y\") = \"Sergey Smith\"<\/code><\/pre>\n


\nWhen inserting information into a global (Set command), three things happen automatically:<\/p>\n
    \n
  1. Data is saved to disk.<\/b>\n<\/li>\n
  2. Indexing.<\/b> What is in the parentheses serves as the key (in English literature - \"subscript\"), and what is to the right of the equals sign is the value (\"node value\").\n<\/li>\n
  3. Sorting.<\/b> Data is sorted by key. Thus, during traversal of the array, the first element will be \"Sergey Smith\", and the second will be \"John Sidorov\". When retrieving a user list from the global, the database does not spend time sorting. Moreover, a sorted list can be requested starting from any key, even a non-existent one (the output will start with the first real key that follows the non-existent one).\n<\/li>\n<\/ol>\n
    \nAll these operations occur incredibly quickly. On a home computer, I was achieving values of up to 750,000 inserts\/sec in a single process. On multi-core processors, values can reach tens of millions<\/a><\/noindex> inserts\/sec.<\/p>\n
    Of course, the insert speed itself doesn't say much. For example, you can record information very quickly in text files \u2014 that\u2019s how it is rumored<\/a><\/noindex> the Visa processing works. But in the case of globals, we get a structured, indexed storage that can be easily and quickly worked with in the future.<\/p>\n
    \"Globals<\/p>\n