What is the difference between using the COPY INTO and UNLOAD commands in Snowflake?

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What is the difference between using the COPY INTO and UNLOAD commands in Snowflake?

Daniel Steinhold Answered question August 18, 2023
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The Snowflake platform provides two primary commands for moving data in and out of tables: **`COPY INTO`** and **`UNLOAD`**. While both commands are used to facilitate data movement, they serve distinct purposes and are used in different scenarios. Here’s a comparison of the two commands:

**COPY INTO:**

1. **Purpose:**
The **`COPY INTO`** command is primarily used to load data into Snowflake tables from external sources. It is used for data ingestion and is often part of the ETL (Extract, Transform, Load) process.
2. **Direction:**
Data flows into Snowflake tables from external sources using the **`COPY INTO`** command.
3. **Data Movement:**
The command moves data from external stages (internal or external) to Snowflake tables.
4. **Usage:**
– Used for loading data into Snowflake.
– Often used when preparing data for analysis, reporting, and querying.
5. **Examples of Use Cases:**
– Importing data from files in cloud storage (e.g., Amazon S3, Azure Blob Storage) into Snowflake.
– Loading data from on-premises sources into Snowflake.
– Integrating data from external systems into Snowflake tables.

**UNLOAD:**

1. **Purpose:**
The **`UNLOAD`** command is used to export data from Snowflake tables to external storage platforms or files. It is used for data extraction.
2. **Direction:**
Data flows out of Snowflake tables to external locations using the **`UNLOAD`** command.
3. **Data Movement:**
The command generates data files from Snowflake tables and stores them in external stages (internal or external).
4. **Usage:**
– Used for unloading data from Snowflake.
– Often used for archiving, sharing, backups, and data migration.
5. **Examples of Use Cases:**
– Exporting data from Snowflake to files in cloud storage (e.g., Amazon S3, Azure Blob Storage).
– Creating backups of data for disaster recovery purposes.
– Sharing data with external parties or other organizations.

**Key Differences:**

– **`COPY INTO`** is used for loading data into Snowflake, while **`UNLOAD`** is used for unloading data from Snowflake.
– **`COPY INTO`** moves data into Snowflake tables, while **`UNLOAD`** generates data files from Snowflake tables.
– **`COPY INTO`** typically involves loading structured or semi-structured data, while **`UNLOAD`** generates data files in various formats (CSV, Parquet, etc.).
– **`COPY INTO`** is often part of the data preparation process for analysis, while **`UNLOAD`** is used for data extraction, sharing, and archiving.

In summary, the choice between using the **`COPY INTO`** and **`UNLOAD`** commands depends on whether you’re moving data into or out of Snowflake and the specific purpose you have in mind (e.g., data loading, data unloading, archiving, sharing).

Daniel Steinhold Answered question August 18, 2023