add postgres
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@ -5,8 +5,282 @@ repo: https://git.postgresql.org/gitweb/?p=postgresql.git
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---
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# Postgres
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PostgreSQL is an advanced, open-source, object-relational database management system. It is renowned for its scalability, reliability, and compliance with the SQL standard. PostgreSQL supports both SQL (relational) and JSON (non-relational) querying, making it highly versatile.
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#wip
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Postgres database
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timescaledb
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https://github.com/pgvector/pgvector
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## Extensions
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PostgreSQL can be extended via extensions:
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- [TimescaleDB](./TimescaleDB.md) - Time-series data
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- [pgVector](./pgvector.md) - Vector database functions
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- [PostGIS](./PostGIS.md) - Spatial data
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## psql
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**psql** is a terminal-based front end to PostgreSQL. It allows users to interact with PostgreSQL databases by executing SQL queries, managing database objects, and performing administrative tasks.
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To start psql, open your terminal or command prompt and type:
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```bash
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psql
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```
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### Connecting to a Database
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You can specify the database name, user, host, and port when launching psql:
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```bash
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psql -d database_name -U username -h hostname -p port
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```
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Alternatively, you can use environment variables:
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```bash
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export PGDATABASE=mydb
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export PGUSER=myuser
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export PGPASSWORD=mypassword
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export PGHOST=localhost
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export PGPORT=5432
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psql
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```
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### Listing Databases and Tables
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- **List Databases:**
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```sql
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\l
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```
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- **List Tables in the Current Database:**
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```sql
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\dt
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```
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- **List All Schemas:**
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```sql
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\dn
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```
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### Creating and Dropping Databases/Tables
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- **Create a Database:**
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```sql
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CREATE DATABASE mydb;
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```
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- **Drop a Database:**
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```sql
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DROP DATABASE mydb;
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```
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- **Create a Table:**
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```sql
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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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username VARCHAR(50) NOT NULL,
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email VARCHAR(100) NOT NULL
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);
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```
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- **Drop a Table:**
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```sql
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DROP TABLE users;
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```
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### Running SQL Queries
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Execute standard SQL commands to interact with your data.
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**Example: Inserting Data**
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```sql
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INSERT INTO users (username, email) VALUES ('john_doe', 'john@example.com');
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```
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**Example: Querying Data**
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```sql
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SELECT * FROM users;
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```
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**Example: Updating Data**
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```sql
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UPDATE users SET email = 'john.doe@example.com' WHERE username = 'john_doe';
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```
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**Example: Deleting Data**
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```sql
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DELETE FROM users WHERE username = 'john_doe';
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```
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## Meta-Commands
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psql provides a set of meta-commands (prefixed with `\`) that facilitate various tasks.
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### Common Meta-Commands
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- **Help on Meta-Commands:**
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```sql
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\?
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```
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- **Help on SQL Commands:**
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```sql
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\h
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```
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- **Describe a Table:**
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```sql
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\d table_name
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```
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- **List All Tables, Views, and Sequences:**
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```sql
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\dt
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```
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- **List All Indexes:**
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```sql
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\di
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```
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- **Exit psql:**
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```sql
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\q
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```
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## Data Types
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### 1. **Numeric Types**
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- **Small Integer Types**
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- `SMALLINT` (2 bytes): Range from -32,768 to +32,767
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- **Integer Types**
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- `INTEGER` or `INT` (4 bytes): Range from -2,147,483,648 to +2,147,483,647
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- **Big Integer Types**
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- `BIGINT` (8 bytes): Range from -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807
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- **Decimal/Exact Types**
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- `DECIMAL` or `NUMERIC` (variable size): User-defined precision and scale
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- **Floating-Point Types**
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- `REAL` (4 bytes): Single precision floating-point number
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- `DOUBLE PRECISION` (8 bytes): Double precision floating-point number
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- **Serial Types (Auto-Incrementing)**
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- `SERIAL` (4 bytes): Auto-incrementing integer (small range)
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- `BIGSERIAL` (8 bytes): Auto-incrementing integer (large range)
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- `SMALLSERIAL` (2 bytes): Auto-incrementing integer (smaller range)
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### 2. **Monetary Type**
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- `MONEY`: Stores currency amounts with a fixed fractional precision
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### 3. **Character Types**
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- **Fixed-Length Strings**
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- `CHAR(n)` or `CHARACTER(n)`: Fixed length (padded with spaces)
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- **Variable-Length Strings**
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- `VARCHAR(n)` or `CHARACTER VARYING(n)`: Variable length with a limit
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- **Text**
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- `TEXT`: Variable length with no specific limit
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### 4. **Binary Data Types**
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- **Binary Large Object**
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- `BYTEA`: Stores binary strings (byte arrays)
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### 5. **Date/Time Types**
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- **Date and Time**
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- `DATE`: Calendar date (year, month, day)
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- `TIME` (no time zone): Time of day (without time zone)
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- `TIMETZ` (with time zone): Time of day (with time zone)
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- `TIMESTAMP` (no time zone): Date and time without time zone
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- `TIMESTAMPTZ` (with time zone): Date and time with time zone
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- **Intervals**
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- `INTERVAL`: Time span (e.g., days, months, hours)
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### 6. **Boolean Type**
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- `BOOLEAN`: Stores `TRUE`, `FALSE`, or `NULL`
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### 7. **UUID Type**
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- `UUID`: Stores Universally Unique Identifiers (128-bit values)
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### 8. **Enumerated Types**
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- `ENUM`: User-defined enumerated type (a static set of values)
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### 9. **Geometric Types**
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- `POINT`: Stores a geometric point (x, y)
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- `LINE`: Infinite line
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- `LSEG`: Line segment
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- `BOX`: Rectangular box
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- `PATH`: Geometric path (multiple points)
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- `POLYGON`: Closed geometric figure
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- `CIRCLE`: Circle
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### 10. **Network Address Types**
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- `CIDR`: IPv4 or IPv6 network block
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- `INET`: IPv4 or IPv6 address
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- `MACADDR`: MAC address
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- `MACADDR8`: MAC address (EUI-64 format)
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### 11. **Bit String Types**
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- **Fixed-Length Bit Strings**
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- `BIT(n)`: Fixed-length bit string
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- **Variable-Length Bit Strings**
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- `BIT VARYING(n)`: Variable-length bit string
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### 12. **Text Search Types**
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- `TSVECTOR`: Text search document
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- `TSQUERY`: Text search query
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### 13. **JSON Types**
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- `JSON`: Textual JSON data
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- `JSONB`: Binary JSON data (more efficient for indexing)
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### 14. **Array Types**
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- `ARRAY`: Allows any data type to be stored as an array (e.g., `INTEGER[]`, `TEXT[]`)
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### 15. **Range Types**
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- `INT4RANGE`: Range of `INTEGER`
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- `INT8RANGE`: Range of `BIGINT`
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- `NUMRANGE`: Range of `NUMERIC`
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- `TSRANGE`: Range of `TIMESTAMP WITHOUT TIME ZONE`
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- `TSTZRANGE`: Range of `TIMESTAMP WITH TIME ZONE`
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- `DATERANGE`: Range of `DATE`
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### 16. **Composite Types**
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- User-defined types that consist of multiple fields of various types
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### 17. **Object Identifier Types (OID)**
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- `OID`: Object identifier (used internally by PostgreSQL)
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- `REGCLASS`, `REGPROC`, `REGTYPE`: Special types for referencing classes, procedures, and types by OID or name
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### 18. **Pseudo-Types**
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- `ANY`: Accepts any data type
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- `ANYARRAY`: Accepts any array data type
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- `ANYELEMENT`: Represents any type of element
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- `ANYENUM`: Accepts any `ENUM` type
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- `ANYNONARRAY`: Any non-array type
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- `VOID`: No data (used with functions that return no value)
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- `TRIGGER`: Used in triggers
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- `LANGUAGE_HANDLER`: Used internally for language support
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## Docker-Compose
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```yml
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services:
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postgres:
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image: postgres:17
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container_name: postgres
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environment:
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POSTGRES_USER: myuser
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POSTGRES_PASSWORD: mypassword
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POSTGRES_DB: mydb
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ports:
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- "5432:5432"
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volumes:
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- ./postgres:/var/lib/postgresql/data
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restart: always
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```
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