Analyze Sentiment

As part of the AI-powered app you are building for Margie’s Travel, you want to provide users with information on the sentiment of individual reviews and the overall sentiment of all reviews for a given rental property. To accomplish this, use the azure_ai extension in an Azure Database for PostgreSQL flexible server to integrate sentiment analysis functionality into your database.

Before you start

You need an Azure subscription with administrative rights.

Deploy resources into your Azure subscription

This step guides you through using Azure CLI commands from the Azure Cloud Shell to create a resource group and run a Bicep script to deploy the Azure services necessary for completing this exercise into your Azure subscription.

Open a web browser and navigate to the Azure portal.
Select the Cloud Shell icon in the Azure portal toolbar to open a new Cloud Shell pane at the bottom of your browser window.

If prompted, select the required options to open a Bash shell. If you have previously used a PowerShell console, switch it to a Bash shell.
At the Cloud Shell prompt, enter the following to clone the GitHub repo containing exercise resources:
```
 git clone https://github.com/MicrosoftLearning/mslearn-postgresql.git
```
Next, you run three commands to define variables to reduce redundant typing when using Azure CLI commands to create Azure resources. The variables represent the name to assign to your resource group (RG_NAME), the Azure region (REGION) into which resources will be deployed, and a randomly generated password for the PostgreSQL administrator login (ADMIN_PASSWORD).

In the first command, the region assigned to the corresponding variable is eastus, but you can also replace it with a location of your preference. However, if replacing the default, you must select another Azure region that supports abstractive summarization to ensure you can complete all of the tasks in the modules in this learning path.
```
 REGION=eastus
```
The following command assigns the name to be used for the resource group that will house all the resources used in this exercise. The resource group name assigned to the corresponding variable is rg-learn-postgresql-ai-$REGION, where $REGION is the location you specified above. However, you can change it to any other resource group name that suits your preference.
```
 RG_NAME=rg-learn-postgresql-ai-$REGION
```
The final command randomly generates a password for the PostgreSQL admin login. Make sure you copy it to a safe place to use later to connect to your PostgreSQL flexible server.
```
 a=()
 for i in {a..z} {A..Z} {0..9}; 
     do
     a[$RANDOM]=$i
     done
 ADMIN_PASSWORD=$(IFS=; echo "${a[*]::18}")
 echo "Your randomly generated PostgreSQL admin user's password is:"
 echo $ADMIN_PASSWORD
```
If you have access to more than one Azure subscription, and your default subscription is not the one in which you want to create the resource group and other resources for this exercise, run this command to set the appropriate subscription, replacing the <subscriptionName|subscriptionId> token with either the name or ID of the subscription you want to use:
```
 az account set --subscription <subscriptionName|subscriptionId>
```
Run the following Azure CLI command to create your resource group:
```
 az group create --name $RG_NAME --location $REGION
```
Finally, use the Azure CLI to execute a Bicep deployment script to provision Azure resources in your resource group:
```
 az deployment group create --resource-group $RG_NAME --template-file "mslearn-postgresql/Allfiles/Labs/Shared/deploy.bicep" --parameters restore=false adminLogin=pgAdmin adminLoginPassword=$ADMIN_PASSWORD
```
The Bicep deployment script provisions the Azure services required to complete this exercise into your resource group. The resources deployed include an Azure Database for PostgreSQL flexible server, Azure OpenAI, and an Azure AI Language service. The Bicep script also performs some configuration steps, such as adding the azure_ai and vector extensions to the PostgreSQL server’s allowlist (via the azure.extensions server parameter), creating a database named rentals on the server, and adding a deployment named embedding using the text-embedding-ada-002 model to your Azure OpenAI service. Note that the Bicep file is shared by all modules in this learning path, so you may only use some of the deployed resources in some exercises.

The deployment typically takes several minutes to complete. You can monitor it from the Cloud Shell or navigate to the Deployments page for the resource group you created above and observe the deployment progress there.
Close the Cloud Shell pane once your resource deployment is complete.

Troubleshooting deployment errors

You may encounter a few errors when running the Bicep deployment script. The most common messages and the steps to resolve them are:

If you previously ran the Bicep deployment script for this learning path and subsequently deleted the resources, you may receive an error message like the following if you are attempting to rerun the script within 48 hours of deleting the resources:

  {"code": "InvalidTemplateDeployment", "message": "The template deployment 'deploy' is not valid according to the validation procedure. The tracking id is '4e87a33d-a0ac-4aec-88d8-177b04c1d752'. See inner errors for details."}
    
  Inner Errors:
  {"code": "FlagMustBeSetForRestore", "message": "An existing resource with ID '/subscriptions/{subscriptionId}/resourceGroups/rg-learn-postgresql-ai-eastus/providers/Microsoft.CognitiveServices/accounts/{accountName}' has been soft-deleted. To restore the resource, you must specify 'restore' to be 'true' in the property. If you don't want to restore existing resource, please purge it first."}

If you receive this message, modify the azure deployment group create command above to set the restore parameter equal to true and rerun it.

If the selected region is restricted from provisioning specific resources, you must set the REGION variable to a different location and rerun the commands to create the resource group and run the Bicep deployment script.

  {"status":"Failed","error":{"code":"DeploymentFailed","target":"/subscriptions/{subscriptionId}/resourceGroups/{resourceGrouName}/providers/Microsoft.Resources/deployments/{deploymentName}","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.","details":[{"code":"ResourceDeploymentFailure","target":"/subscriptions/{subscriptionId}/resourceGroups/{resourceGrouName}/providers/Microsoft.DBforPostgreSQL/flexibleServers/{serverName}","message":"The resource write operation failed to complete successfully, because it reached terminal provisioning state 'Failed'.","details":[{"code":"RegionIsOfferRestricted","message":"Subscriptions are restricted from provisioning in this region. Please choose a different region. For exceptions to this rule please open a support request with Issue type of 'Service and subscription limits'. See https://review.learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-request-quota-increase for more details."}]}]}}

If the script is unable to create an AI resource due to the requirement to accept the responsible AI agreement, you may experience the following error; in which case use the Azure Portal user interface to create an Azure AI Services resource, and then re-run the deployment script.

  {"code": "InvalidTemplateDeployment", "message": "The template deployment 'deploy' is not valid according to the validation procedure. The tracking id is 'f8412edb-6386-4192-a22f-43557a51ea5f'. See inner errors for details."}
     
  Inner Errors:
  {"code": "ResourceKindRequireAcceptTerms", "message": "This subscription cannot create TextAnalytics until you agree to Responsible AI terms for this resource. You can agree to Responsible AI terms by creating a resource through the Azure Portal then trying again. For more detail go to https://go.microsoft.com/fwlink/?linkid=2164190"}

Connect to your database using psql in the Azure Cloud Shell

In this task, you connect to the rentals database on your Azure Database for PostgreSQL server using the psql command-line utility from the Azure Cloud Shell.

In the Azure portal, navigate to your newly created Azure Database for PostgreSQL flexible server instance.
In the resource menu, under Settings, select Databases select Connect for the rentals database.
At the “Password for user pgAdmin” prompt in the Cloud Shell, enter the randomly generated password for the pgAdmin login.

Once logged in, the psql prompt for the rentals database is displayed.

Populate the database with sample data

Before you can analyze the sentiment of rental property reviews using the azure_ai extension, you must add sample data to your database. Add a table to the rentals database and populate it with customer reviews so you have data on which to perform sentiment analysis.

Run the following command to create a table named reviews for storing property reviews submitted by customers:

 DROP TABLE IF EXISTS reviews;

 CREATE TABLE reviews (
     id int,
     listing_id int, 
     date date,
     comments text
 );

Next, use the COPY command to populate the table with data from a CSV file. Execute the command below to load customer reviews into the reviews table:
```
 \COPY reviews FROM 'mslearn-postgresql/Allfiles/Labs/Shared/reviews.csv' CSV HEADER
```
The command output should be COPY 354, indicating that 354 rows were written into the table from the CSV file.

Install and configure the `azure_ai` extension

Before using the azure_ai extension, you must install it into your database and configure it to connect to your Azure AI Services resources. The azure_ai extension allows you to integrate the Azure OpenAI and Azure AI Language services into your database. To enable the extension in your database, follow these steps:

Execute the following command at the psql prompt to verify that the azure_ai and the vector extensions were successfully added to your server’s allowlist by the Bicep deployment script you ran when setting up your environment:
```
 SHOW azure.extensions;
```
The command displays the list of extensions on the server’s allowlist. If everything was correctly installed, your output must include azure_ai and vector, like this:
```
  azure.extensions 
 ------------------
  azure_ai,vector
```
Before an extension can be installed and used in an Azure Database for PostgreSQL flexible server database, it must be added to the server’s allowlist, as described in how to use PostgreSQL extensions.
Now, you are ready to install the azure_ai extension using the CREATE EXTENSION command.
```
 CREATE EXTENSION IF NOT EXISTS azure_ai;
```
CREATE EXTENSION loads a new extension into the database by running its script file. This script typically creates new SQL objects such as functions, data types, and schemas. An error is thrown if an extension of the same name already exists. Adding IF NOT EXISTS allows the command to execute without throwing an error if it is already installed.

Connect Your Azure AI Services Account

The Azure AI services integrations included in the azure_cognitive schema of the azure_ai extension provide a rich set of AI Language features accessible directly from the database. Sentiment analysis capabilities are enabled through the Azure AI Language service.

To successfully make calls against your Azure AI Language services using the azure_ai extension, you must provide its endpoint and key to the extension. Using the same browser tab where the Cloud Shell is open, navigate to your Language service resource in the Azure portal and select the Keys and Endpoint item under Resource Management from the left-hand navigation menu.

[!Note]

If you received the message NOTICE: extension "azure_ai" already exists, skipping CREATE EXTENSION when installing the azure_ai extension above and have previously configured the extension with your Language service endpoint and key, you can use the azure_ai.get_setting() function to confirm those settings are correct, and then skip step 2 if they are.

Copy your endpoint and access key values, then in the commands below, replace the {endpoint} and {api-key} tokens with values you copied from the Azure portal. Run the commands from the psql command prompt in the Cloud Shell to add your values to the azure_ai.settings table.
```
 SELECT azure_ai.set_setting('azure_cognitive.endpoint', '{endpoint}');
```
```
 SELECT azure_ai.set_setting('azure_cognitive.subscription_key', '{api-key}');
```

Review the Analyze Sentiment Capabilities of the Extension

In this task, you use the azure_cognitive.analyze_sentiment() function to evaluate reviews of rental property listings.

For the remainder of this exercise, you work exclusively in the Cloud Shell, so it may be helpful to expand the pane within your browser window by selecting the Maximize button at the top right of the Cloud Shell pane.
When working with psql in the Cloud Shell, enabling the extended display for query results may be helpful, as it improves the readability of output for subsequent commands. Execute the following command to allow the extended display to be automatically applied.
```
 \x auto
```

The sentiment analysis capabilities of the azure_ai extension are found within the azure_cognitive schema. You use the analyze_sentiment() function. Use the \df meta-command to examine the function by running:

 \df azure_cognitive.analyze_sentiment

The meta-command output shows the function’s schema, name, result data type, and arguments. This information helps you understand how to interact with the function from your queries.

The output shows three overloads of the analyze_sentiment() function, allowing you to review their differences. The Argument data types property in the output reveals the list of arguments the three function overloads expect:

Argument	Type	Default	Description
text	`text` or `text[]`		The text(s) for which sentiment should be analyzed.
language_text	`text` or `text[]`		Language code (or array of language codes) representing the language of the text to analyze for sentiment. Review the list of supported languages to retrieve the necessary language codes.
batch_size	`integer`	10	Only for the two overload expecting an input of `text[]`. Specifies the number of records to process at a time.
disable_service_logs	`boolean`	false	Flag indicating whether to turn off service logs.
timeout_ms	`integer`	NULL	Timeout in milliseconds after which the operation is stopped.
throw_on_error	`boolean`	true	Flag indicating whether the function should, on error, throw an exception resulting in a rollback of the wrapping transaction.
max_attempts	`integer`	1	Number of times to retry the call to Azure AI Services in the event of a failure.
retry_delay_ms	`integer`	1000	Amount of time, in milliseconds, to wait before attempting to retry calling the Azure AI Services endpoint.

It is also imperative to understand the structure of the data type that a function returns so you can correctly handle the output in your queries. Run the following command to inspect the sentiment_analysis_result type:
```
 \dT+ azure_cognitive.sentiment_analysis_result
```
The output of the above command reveals the sentiment_analysis_result type is a tuple. You can dig further into the structure of that tuple by running the following command to look at the columns contained within the sentiment_analysis_result type:
```
 \d+ azure_cognitive.sentiment_analysis_result
```
The output of that command should look similar to the following:
```
                  Composite type "azure_cognitive.sentiment_analysis_result"
      Column     |     Type         | Collation | Nullable | Default | Storage  | Description 
 ----------------+------------------+-----------+----------+---------+----------+-------------
  sentiment      | text             |           |          |         | extended | 
  positive_score | double precision |           |          |         | plain    | 
  neutral_score  | double precision |           |          |         | plain    | 
  negative_score | double precision |           |          |         | plain    |
```
The azure_cognitive.sentiment_analysis_result is a composite type containing the sentiment predictions of the input text. It includes the sentiment, which can be positive, negative, neutral, or mixed, and the scores for positive, neutral, and negative aspects found in the text. The scores are represented as real numbers between 0 and 1. For example, in (neutral, 0.26, 0.64, 0.09), the sentiment is neutral, with a positive score of 0.26, neutral of 0.64, and negative at 0.09.

Analyze the sentiment of reviews

Now that you have reviewed the analyze_sentiment() function and the sentiment_analysis_result it returns, let’s put the function to use. Execute the following simple query, which performs sentiment analysis on a handful of comments in the reviews table:
```
 SELECT
     id,
     azure_cognitive.analyze_sentiment(comments, 'en') AS sentiment
 FROM reviews
 WHERE id <= 10
 ORDER BY id;
```
From the two records analyzed, note the sentiment values in the output, (mixed,0.71,0.09,0.2) and (positive,0.99,0.01,0). These represent the sentiment_analysis_result returned by the analyze_sentiment() function in the above query. The analysis was performed over the comments field in the reviews table.

[!Note]

Using the analyze_sentiment() function inline lets you quickly analyze the text’s sentiment within your queries. While this works well for a small number of records, it may not be ideal for analyzing the sentiment of a large number of records or updating all the records in a table that may contain tens of thousands of reviews or more.
Another approach that can be useful for longer reviews is to analyze the sentiment of each sentence within it. To do this, use the overload of the analyze_sentiment() function, which accepts an array of text.
```
 SELECT
     azure_cognitive.analyze_sentiment(ARRAY_REMOVE(STRING_TO_ARRAY(comments, '.'), ''), 'en') AS sentence_sentiments
 FROM reviews
 WHERE id = 1;
```
In the above query, you used PostgreSQL’s STRING_TO_ARRAY function. Additionally, the ARRAY_REMOVE function was used to remove any array elements that are empty strings, as these will cause errors with the analyze_sentiment() function.

The output from the query allows you to get a better understanding of the mixed sentiment assigned to the overall review. The sentences are a mixture of positive, neutral, and negative sentiments.
The previous two queries returned the sentiment_analysis_result directly from the query. However, you will likely want to retrieve the underlying values within the sentiment_analysis_result tuple. Execute the following query that looks for overwhelmingly positive reviews and extracts the sentiment components into individual fields:
```
 WITH cte AS (
     SELECT id, comments, azure_cognitive.analyze_sentiment(comments, 'en') AS sentiment FROM reviews
 )
 SELECT
     id,
     (sentiment).sentiment,
     (sentiment).positive_score,
     (sentiment).neutral_score,
     (sentiment).negative_score,
     comments
 FROM cte
 WHERE (sentiment).positive_score > 0.98
 LIMIT 5;
```
The above query uses a common table expression or CTE to get the sentiment scores for all records in the reviews table. It then selects the sentiment composite type columns from the sentiment_analysis_result returned by the CTE to extract the individual values from tuple.

Store Sentiment in the Reviews Table

For the rental property recommendation system you are building for Margie’s Travel, you want to store sentiment ratings in the database so you do not have to make calls and incur costs every time sentiment assessments are requested. Performing sentiment analysis on the fly can be great for small numbers of records or analyzing data in near-real time. Still, adding the sentiment data into the database for use in your application makes sense for your stored reviews. To do this, you want to alter the reviews table to add columns for storing the sentiment assessment and the positive, neutral, and negative scores.

Run the following query to update the reviews table so it can store sentiment details:

 ALTER TABLE reviews
 ADD COLUMN sentiment varchar(10),
 ADD COLUMN positive_score numeric,
 ADD COLUMN neutral_score numeric,
 ADD COLUMN negative_score numeric;

Next, you want to update the existing records in the reviews table with their sentiment value and associated scores.

 WITH cte AS (
     SELECT id, azure_cognitive.analyze_sentiment(comments, 'en') AS sentiment FROM reviews
 )
 UPDATE reviews AS r
 SET
     sentiment = (cte.sentiment).sentiment,
     positive_score = (cte.sentiment).positive_score,
     neutral_score = (cte.sentiment).neutral_score,
     negative_score = (cte.sentiment).negative_score
 FROM cte
 WHERE r.id = cte.id;

Executing this query takes a long time because the comments for every review in the table are sent individually to the Language service’s endpoint for analysis. Sending records in batches is more efficient when dealing with many records.

Let’s run the query below to perform the same update action, but this time send comments from the reviews table in batches of 10 (this is the maximum batch size allowed) and evaluate the difference in performance.
```
 WITH cte AS (
     SELECT azure_cognitive.analyze_sentiment(ARRAY(SELECT comments FROM reviews ORDER BY id), 'en', batch_size => 10) as sentiments
 ),
 sentiment_cte AS (
     SELECT
         ROW_NUMBER() OVER () AS id,
         sentiments AS sentiment
     FROM cte
 )
 UPDATE reviews AS r
 SET
     sentiment = (sentiment_cte.sentiment).sentiment,
     positive_score = (sentiment_cte.sentiment).positive_score,
     neutral_score = (sentiment_cte.sentiment).neutral_score,
     negative_score = (sentiment_cte.sentiment).negative_score
 FROM sentiment_cte
 WHERE r.id = sentiment_cte.id;
```
While this query is a bit more complex, using two CTEs, it is much more performant. In this query, the first CTE analyzes the sentiment of batches of review comments, and the second extracts the resulting table of sentiment_analysis_results into a new table containing an id based on the ordinal position and ``sentiment_analysis_result` for each row. The second CTE can then be used in the update statement to write the values into the database.
Next, run a query to observe the update results, searching for reviews with a negative sentiment, starting with the most negative first.
```
 SELECT
     id,
     negative_score,
     comments
 FROM reviews
 WHERE sentiment = 'negative'
 ORDER BY negative_score DESC;
```

Clean up

Once you have completed this exercise, delete the Azure resources you created. You are charged for the configured capacity, not how much the database is used. Follow these instructions to delete your resource group and all resources you created for this lab.

Open a web browser and navigate to the Azure portal, and on the home page, select Resource groups under Azure services.
In the filter for any field search box, enter the name of the resource group you created for this lab, and then select your resource group from the list.
On the Overview page of your resource group, select Delete resource group.
In the confirmation dialog, enter the resource group name you are deleting to confirm and then select Delete.