# FAQ

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<summary>What's the difference between a storage account key and a SAS token?</summary>

A **storage account key** is a full-access credential that grants read/write permissions to your entire storage account. A **SAS token** is a time-limited, scoped token that can restrict access to specific containers or operations. Coupler.io requires a **storage account key** (primary or secondary), not a SAS token.

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<summary>Can I sync files from multiple containers in one data flow?</summary>

No. Each data flow connects to a single container. To sync from multiple containers, create separate data flows for each and use **Append transformations** to combine them into one destination table.

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<summary>Do I need to manually upload files to Azure, or can Coupler.io push data there?</summary>

Coupler.io only reads from Azure Blob Storage. To get data into Azure, you must upload files through your application, a scheduled export, or Azure's native tools. Once files are in your container, Coupler.io syncs them to your destination.

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<summary>What happens if a file changes between refreshes?</summary>

If a file is modified after the last sync, and the start date is before that modification time, the entire updated file syncs on the next refresh. Coupler.io doesn't detect row-level changes — it re-syncs the whole file.

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<summary>Can I filter files by name pattern without using glob?</summary>

No. You must use glob patterns (e.g., `data/*.csv`, `reports/2024/*.parquet`) to match multiple files. For a single file, just enter the exact path (e.g., `myfile.csv`).

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<summary>How often can I refresh my data flow?</summary>

You can refresh as often as you want — hourly, daily, or even every few minutes. However, if files don't change that frequently, more refreshes waste resources. Schedule refreshes to align with how often your files are updated in Azure.

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<summary>Does Coupler.io support incremental syncs from Azure Blob Storage?</summary>

Partially. You can use the **start date** filter to sync only files modified after a certain time, which reduces redundant imports. However, Coupler.io doesn't track individual row changes within files — each refresh re-syncs entire files if they're modified.

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<summary>What if my CSV has special characters or encoding issues?</summary>

Coupler.io expects standard UTF-8 encoding. If your CSV uses a different encoding (e.g., Latin-1, Windows-1252), open it in a text editor, re-save as UTF-8, and re-upload to Azure. Special characters like quotes and commas must be properly escaped in CSV format.

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<summary>Can I join Azure Blob Storage data with data from other sources?</summary>

Yes! Use **Join transformations** to combine files from Azure with data from your CRM, database, or ad platform. For example, join a customer list (CSV from Azure) with sales data (from Salesforce) on a common ID column.

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{% hint style="info" %}
For more details on supported file formats and import patterns, see the **Data Overview** section. For connection troubleshooting, check **Common Issues**.
{% endhint %}