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This article mainly introduces PostgreSQL how to read the source code, the article is very detailed, has a certain reference value, interested friends must read it!

Bottom-up approach

     starts with a bottom-up approach. To put it simply, it is to read and practice from a specific small function point, and then gradually expand the small function up to a large module, just like planting a small tree, fertilizing and watering every day. If the method is proper, it can naturally grow into a towering tree.

     takes reading the source code of PG as an example. Through psql, you can start from the minimum method / function of inserting a row of data (PageAddItemExtended). After deeply understanding the function, use gdb to track the call stack of the function, and gradually trace back to the top call entry function or main function according to the function information of the call stack. Each up-tracking layer has a complete and thorough understanding of the data structures, macro definitions and dependent subfunctions related to the functions in that layer. Through such a process, the knowledge system associated with the inserted data is established, such as Page storage structure, Buffer management, WAL log related management, SQL parsing execution, front and back interface and other related knowledge. With this context, with the relevant data structure as the basis, it is relatively easy to understand other operations, such as UPDATE/DELETE and other DML, CREATE TABLE/ALTER TABLE and other DDL statements, SELECT and other query statements.

Top-down approach

     and bottom-up approach is relative to the top-down approach, you can use this method to establish the architecture of the source code at the initial stage of reading the source code, which is conducive to global control, just like the original big tree, if you start to pay attention to a certain leaf, a branch, naturally without feeling, but if you look at the whole tree from the main trunk, you can basically see the whole picture of the tree.

Can      use a top-down approach when reading details? My personal experience is not suitable, so let's take a big tree as an analogy. Starting from the main trunk, there are N sub-trunks, entering from a sub-trunk, M branches, from the branch into the sub-branches, and X sub-branches, unless the brain capacity is large enough, the details will be daunting.

The above is all the content of this article "how to read the source code of PostgreSQL". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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