Highlighting with ts_headline in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the ts_headline function do in PostgreSQL?

ts_headline highlights search terms in text by returning snippets with matching words emphasized.

beginner

Which input types does ts_headline require?

It needs the original text and a tsquery representing the search terms.

intermediate

How can you customize the highlight tags in ts_headline?

By passing options like StartSel and StopSel to set custom HTML tags for highlighting.

intermediate

What is the purpose of the MaxFragments option in ts_headline?

It limits how many separate highlighted snippets are returned from the text.

advanced

True or False: ts_headline can only highlight plain text, not HTML content.

False. ts_headline can handle HTML by using the HighlightAll option to avoid breaking tags.

What is the main use of ts_headline in PostgreSQL?

A To sort query results

B To create full-text indexes

C To highlight search terms in text snippets

D To convert text to lowercase

ts_headline highlights matching search terms in text snippets for easier reading.

Which of these is NOT an option you can set in ts_headline?

A SortOrder

B StopSel

C MaxFragments

D StartSel

SortOrder is not an option for ts_headline. The others control highlighting behavior.

What type of data does ts_headline return?

A A boolean value

B A highlighted text snippet

C A numeric score

D A list of matching words

ts_headline returns a text snippet with highlighted search terms.

If you want to change the highlight tags to <em> and </em>, which option do you set?

A TagStart = '<em>', TagEnd = '</em>'

B HighlightTag = 'em'

C Emphasize = true

D StartSel = '<em>', StopSel = '</em>'

Use StartSel and StopSel to define custom highlight tags.

What happens if you do not provide a tsquery to ts_headline?

A It returns an error

B It returns the original text without highlights

C It highlights all words

D It returns an empty string

ts_headline requires a tsquery to know which words to highlight; otherwise, it errors.

Explain how ts_headline works and how you can customize its output.

Think about what inputs it needs and how it marks matching words.

Describe a real-life scenario where using ts_headline would improve user experience.

Imagine searching a large text and wanting to see matches clearly.