QnA Maker knowledge base limits and boundaries

QnA Maker limits provided below are a combination of the Azure Search pricing tier limits and the QnA Maker pricing tier limits. You need to know both sets of limits to understand how many knowledge bases you can create per resource and how large each knowledge base can grow.

Knowledge bases

The maximum number of knowledge bases is based on Azure Search tier limits.

Azure Search tier Free Basic S1 S2 S3 S3 HD
Maximum number of published knowledge bases allowed 2 14 49 199 199 2,999

For example, if your tier has 15 allowed indexes, you can publish 14 knowledge bases (1 index per published knowledge base). The fifteenth index, testkb, is used for all the knowledge bases for authoring and testing.

Extraction Limits

Maximum number of files

The maximum number of files that can be extracted and maximum file size is based on your QnA Maker pricing tier limits.

The maximum number of deep-links that can be crawled for extraction of QnAs from a URL page is 20.

Metadata Limits

Maximum number of metadata fields per knowledge base is based on your Azure Search tier limits.

Azure Search tier Free Basic S1 S2 S3 S3 HD
Maximum metadata fields per QnA Maker service (across all KBs) 1,000 100* 1,000 1,000 1,000 1,000

Knowledge Base content limits

Overall limits on the content in the knowledge base:

  • Length of answer text: 25,000
  • Length of question text: 1,000
  • Length of metadata key/value text: 100
  • Supported characters for metadata name: Alphabets, digits and _
  • Supported characters for metadata value: All except : and |
  • Length of file name: 200
  • Supported file formats: ".tsv", ".pdf", ".txt", ".docx", ".xlsx".
  • Maximum number of alternate questions: 300
  • Maximum number of question-answer pairs: Depends on the Azure Search tier chosen. A question and answer pair maps to a document on Azure Search index.
  • URL/HTML page: 1 million characters

Create Knowledge base call limits:

These represent the limits for each create knowledge base action; that is, clicking Create KB or calling the CreateKnowledgeBase API.

  • Maximum number of alternate questions per answer: 300
  • Maximum number of URLs: 10
  • Maximum number of files: 10

Update Knowledge base call limits

These represent the limits for each update action; that is, clicking Save and train or calling the UpdateKnowledgeBase API.

  • Length of each source name: 300
  • Maximum number of alternate questions added or deleted: 300
  • Maximum number of metadata fields added or deleted: 10
  • Maximum number of URLs that can be refreshed: 5

Next steps

Learn when and how to change service tiers:

  • QnA Maker: When you need to have more source files or bigger documents in your knowledge base, beyond your current tier, upgrade your QnA Maker service pricing tier.
  • App Service: When your knowledge base needs to serve more requests from your client app, upgrade your app service pricing tier.
  • Azure Search: When you plan to have many knowledge bases, upgrade your Azure Search service pricing tier.