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PostgreSQL Learning (1)

1. PostgreSQL's special features and reasons for selection

PostgreSQL supports writing stored procedures and functions in multiple programming languages

(2) PostgreSQL supports very powerful user-defined data types

2. PostgreSQL resources

Plantet PostgreSQL (http://planet.postgresql.org) is a collection of PostgreSQL technical blog posts written by core PostgreSQL developers to ordinary users.

articles, including descriptions of new features and instructions for using existing features

(2) PostgreSQL Wiki (https://wiki.postgresql.org) provides tips on various aspects of PostgreSQL and how to migrate values from other databases to PostgreSQL.

PostgreSQL Books(https://www.postgresql.org/docs/books/) provides a list of PostgreSQL bookcases;

PostgreSQL Management Tools

There are four commonly used administrative tools for postgresql: psql, pgAdmin,phpPgAdmin and Administer. PostgreSQL's core development team maintains the first three.

psql is a command-line tool for executing queries

(2) pgAdmin is a widely used open source PostgreSQL graphical interface management tool.

(3) phpPgAdmin Web-based management tool

PostgreSQL default listening port 5432

PostgreSQL database objects

(1) Services

On most operating systems, PostgreSQL is installed as a service (or daemon). Multiple PostgreSQL services can run on the same physical server, but their listening ports cannot

Duplicates, and you cannot share a data store directory.

（2）database

Each PostgreSQL service can contain multiple independent databases

(3)schema

The next logical level of database is schema.

(4)catalog

A catalog is a system-level schema for storing system functions and system metadata. Each database will contain two catalogs by default:

pg_catalog, used to store PostgreSQL system functions, tables, system views, data type converters and data type definitions metadata

The other is information_schema, which stores metadata query views required by ANSI standards. These views comply with ANSI SQL standards and provide PostgreSQL to the outside world in a specified format.

metadata information

The most common views in PostgreSQL information_schema are:

columns view: lists all table columns in the database

tables view: lists all tables in the database (including views)

view: Lists all views and the associated SQL used to build or rebuild the view

4) Variables

(5) Expansion package

(6) Table

In Postgresql, a table belongs first to a schema, and the schema belongs to a database, thus forming a three-level storage structure.

Postgresql tables support two powerful features,

The first type is table inheritance, that is, a table can have parent tables and child tables.

The second is when you create a table, the system automatically creates a custom data type for that table.

(7) External tables and external data wrappers

External tables provide direct access to data from external data sources in the local database

External table mapping relationships are established by configuring the Foreign Data Wrapper (FDW). FDW is a magic bridge between PostgreSQL and external data sources, enabling both sides

Data connectivity.

(8) Tablespace

Tablespaces are physical spaces used to store data

(9) Views

(10) Functions

(11) Built-in programming language

(12) Operator

(13) Types of data

(14) Data Type Converter

(15) Sequence

(16) Lines or records

(17) Trigger

(18) Rules

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