PostgreSQL

PostgreSQL is an open-source object-relational database management system hosted either in the cloud or on-premise.

Supported editions

All releases of PostgreSQL are supported.

How to connect to PostgreSQL on Workato

The PostgreSQL connector uses basic authentication to authenticate with PostgreSQL. Configured PostgreSQL connection

Field Description
Connection name Give this PostgreSQL connection a unique name that identifies which PostgreSQL instance it is connected to.
On-prem secure agent Choose an on-premise agent if your database is running in a network that does not allow direct connection. Before attempting to connect, make sure you have an active on-premise agent. Refer to the On-premise agent guide for more information.
Username Username to connect to PostgreSQL.
Password Password to connect to PostgreSQL.
Host URL of your hosted server.
Port Port number that your server is running on, typically 5432.
Database name Name of the PostgreSQL database you wish to connect to.
Schema Name of the schema within the PostgreSQL database you wish to connect to. Defaults to public.

Permissions required to connect

At minimum, the database user account must be granted SELECT permission to the database specified in the connection.

If we are trying to connect to a PostgreSQL instance, using a new database user workato, the following example queries can be used.

First, create a new user dedicated to integration use cases with Workato.

CREATE USER workato WITH PASSWORD 'password';

The next step is to grant access to customer table in the schema. In this example, we only wish to grant SELECT and INSERT permissions.

GRANT SELECT,INSERT ON customer TO workato;

Finally, check that this user has the necessary permissions. Run a query to see all grants.

SELECT grantee, table_name, privilege_type
FROM information_schema.role_table_grants
WHERE grantee = 'workato';

This should return the following minimum permission to create a PostgreSQL connection on Workato.

+---------+------------+----------------+
| grantee | table_name | privilege_type |
+---------+------------+----------------+
| workato | customer   | SELECT         |
+---------+------------+----------------+
| workato | customer   | INSERT         |
+---------+------------+----------------+
2 rows in set (0.26 sec)

Working with the PostgreSQL connector

Table, view and stored procedure

The PostgreSQL connector works with all tables, views and stored procedures. These are available in pick lists in each trigger/action or you can provide the exact name.

Table selection from pick list Select a table/view from pick list

Exact table name provided Provide exact table/view name in a text field

In PostgreSQL, unquoted identifiers are case-insensitive. Thus,

SELECT ID FROM USERS

is equivalent to

SELECT ID FROM users

However, quoted identifiers are case-sensitive. Hence,

SELECT ID FROM "USERS"

is NOT equivalent to

SELECT ID FROM "users"

Single row vs batch of rows

PostgreSQL connector can read or write to your database either as a single row or in batches. When using batch triggers/actions, you have to provide the batch size you wish to work with. The batch size can be any number between 1 and 100, with 100 being the maximum batch size.

Batch trigger inputs Batch trigger inputs

Besides the difference in input fields, there is also a difference between the outputs of these 2 types of operations. A trigger that processes rows one at a time will have an output datatree that allows you to map data from that single row.

Single row output Single row output

However, a trigger that processes rows in batches will output them as an array of rows. The Rows datapill indicates that the output is a list containing data for each row in that batch.

Batch trigger output Batch trigger output

As a result, the output of batch triggers/actions needs to be handled differently. This recipe uses a batch trigger for new rows in the users table. The output of the trigger is used in a Salesforce bulk upsert action that requires mapping the Rows datapill into the source list.

Using batch trigger output Using batch trigger output

WHERE condition

This input field is used to filter and identify rows to perform an action on. It is used in multiple triggers and actions in the following ways:

  • filter rows to be picked up in triggers
  • filter rows in Select rows action
  • filter rows to be deleted in Delete rows action

This clause will be used as a WHERE statement in each request. This should follow basic SQL syntax. Refer to this PostgreSQL documentation for a full list of rules for writing PostgreSQL statements.

Operators

Operator Description Example
= Equal WHERE ID = 445
!=
<>
Not equal WHERE ID <> 445
>
>=
Greater than
Greater than or equal to
WHERE PRICE > 10000
<
<=
Less than
Less than or equal to
WHERE PRICE > 10000
IN(...) List of values WHERE ID IN(445, 600, 783)
LIKE Pattern matching with wildcard characters (% and _) WHERE EMAIL LIKE '%@workato.com'
BETWEEN Retrieve values with a range WHERE ID BETWEEN 445 AND 783
IS NULL
IS NOT NULL
NULL values check
Non-NULL values check
WHERE NAME IS NOT NULL

Simple statements

String values must be enclosed in single quotes ('') and columns used must exist in the table.

A simple WHERE condition to filter rows based on values in a single column looks like this.

currency = 'USD'

If used in a Select rows action, this WHERE condition will return all rows that have the value 'USD' in the currency column. Just remember to wrap datapills with single quotes in your inputs.

Using datapills in WHERE condition Using datapills in WHERE condition

Column names with spaces must be enclosed in double quotes (""). For example, currency code must to enclosed in brackets to be used as an identifier. Note that all quoted identifiers are case-sensitive.

"currency code" = 'USD'

In a recipe, remember to use the appropriate quotes for each value/identifier.

WHERE condition with enclosed identifier WHERE condition with enclosed identifier

Complex statements

Your WHERE condition can also contain subqueries. The following query can be used on the users table.

id in (select user_id from tickets where priority = 2)

When used in a Delete rows action, this will delete all rows in the users table where at least one associated row in the tickets table has a value of 2 in the priority column.

Using datapills in WHERE condition with subquery Using datapills in WHERE condition with subquery

Unique key

In all triggers and some actions, this is a required input. Values from this selected column are used to uniquely identify rows in the selected table.

As such, the values in the selected column must be unique. Typically, this column is the primary key of the table (e.g. ID).

When used in a trigger, this column must be incremental. This constraint is required because the trigger uses values from this column to look for new rows. In each poll, the trigger queries for rows with a unique key value greater than the previous greatest value.

Let's use a simple example to illustrate this behavior. We have a New row trigger that processed rows from a table. The unique key configured for this trigger is ID. The last row processed has 100 as it's ID value. In the next poll, the trigger will use ID >= 101 as the condition to look for new rows.

Performance of a trigger can be improved if the column selected to be used as the unique key is indexed.

Sort column

This is required for New/updated row triggers. Values in this selected column are used to identify updated rows.

When a row is updated, the Unique key value remains the same. However, it should have it's timestamp updated to reflect the last updated time. Following this logic, Workato keeps track of values in this column together with values in the selected Unique key column. When a change in the Sort column value is observed, an updated row event will be recorded and processed by the trigger.

For PostgreSQL, only timestamp and timestamp with time zone column types can be used.

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