Data Overview

PostgreSQL data flows pull data directly from your database using either table selection or custom SQL queries. The data structure depends on what you're importing.

Import modes

Mode	Use case	Example
Table or view	Import all or most data from a single table or materialized view.	Pull the customers table as-is.
Custom SQL	Write a query to filter, join, aggregate, or transform data.	SELECT customer_id, COUNT(*) as order_count FROM orders GROUP BY customer_id

Available columns and data types

When you import from PostgreSQL, all columns and their data types come through as-is. Common PostgreSQL data types include:

Numeric types

Type	Description
INTEGER	Whole numbers
BIGINT	Large whole numbers
DECIMAL / NUMERIC	Precise decimal numbers
FLOAT / DOUBLE PRECISION	Floating-point numbers

Text types

Type	Description
VARCHAR / TEXT	Variable-length text
CHAR	Fixed-length text

Date and time types

Type	Description
DATE	Calendar date
TIME	Time of day
TIMESTAMP / TIMESTAMPTZ	Date and time (with or without timezone)

Other types

Type	Description
BOOLEAN	True/False values
UUID	Unique identifiers
JSON / JSONB	JSON objects (imported as text)
ARRAY	Arrays (imported as text)

Common query patterns

Here are useful SQL queries you can paste into the Custom SQL field:

Filter by date range:

SELECT * FROM orders 
WHERE created_at >= '2024-01-01' AND created_at < '2024-02-01'

Aggregate data:

SELECT user_id, COUNT(*) as order_count, SUM(total) as revenue 
FROM orders 
GROUP BY user_id

Join multiple tables:

SELECT c.name, o.order_id, o.total 
FROM customers c 
JOIN orders o ON c.id = o.customer_id 
WHERE o.created_at >= NOW() - INTERVAL '30 days'

Use cases by role

Analysts

Analysts use PostgreSQL data flows to build custom datasets for analysis. Write SQL queries to join tables, aggregate metrics, and filter to specific segments. Export to BigQuery for large-scale analysis or to Google Sheets for quick exploration. Use the Join transformation to combine PostgreSQL data with data from other sources (e.g., marketing platforms).

Finance teams

Product managers

Operations

Platform-specific notes

• IP whitelisting required — Coupler.io connects from fixed IP addresses. You must whitelist these in your PostgreSQL firewall or security group (AWS RDS, Azure Database, etc.).

• Read-only access — Your database user only needs SELECT permissions; no writes or schema changes.

• Large result sets — If your query returns millions of rows, consider filtering by date, aggregating, or using LIMIT to avoid timeouts.

• Connection pooling — PostgreSQL has a connection limit per role. If you run many data flows, you may hit this limit; consider using a connection pooler or increasing max_connections.

• Custom SQL performance — Complex queries with multiple joins or aggregations may take longer. Test in psql or your query tool first.

• JSON/ARRAY types — These are imported as text strings. Parse them in your destination (Google Sheets formulas, BigQuery JSON functions, etc.) if needed.