How do I handle pagination in PI Web API responses?

PI Web API returns paginated results for large datasets. Here's how to handle pagination correctly.

Default Behavior

• Most endpoints return a maximum of 1000 items per request.
• The response includes a Links object with First, Previous, Next, and Last URLs.

Pagination Parameters

Parameter	Description
startIndex	Zero-based index of the first item to return
maxCount	Maximum number of items per page (default: 1000)
selectedFields	Reduce response size by selecting specific fields

Python Example

import requests

def get_all_items(url, auth):
    all_items = []
    start_index = 0
    max_count = 1000
    
    while True:
        response = requests.get(
            url,
            params={
                "startIndex": start_index,
                "maxCount": max_count
            },
            auth=auth, verify=False
        ).json()
        
        items = response.get("Items", [])
        all_items.extend(items)
        
        # Check if there are more pages
        links = response.get("Links", {})
        if "Next" not in links or len(items) < max_count:
            break
        
        start_index += max_count
    
    return all_items

# Usage
all_points = get_all_items(
    f"{base_url}/dataservers/{server_webid}/points",
    auth=("domain\\user", "password")
)
print(f"Total points: {len(all_points)}")

For Recorded Values

Use time-based pagination instead of index-based:

# Get recorded values in chunks
params = {
    "startTime": "2024-01-01",
    "endTime": "2024-01-31",
    "maxCount": 10000
}
response = requests.get(
    f"{base_url}/streams/{web_id}/recorded",
    params=params, auth=auth, verify=False
).json()

Tips

• Use selectedFields to reduce payload size and improve performance.
• For very large queries, use PI Web API batch to parallelize.
• Don't set maxCount higher than needed — it increases response time.
• Consider using startTime/endTime chunking for time-series data instead of index pagination.