Create secodary indexes in DynamoDB example

Each item in DynamoDB table consists of:

• hash key
• range key (on which results are ranged)
• attributes

Fast query lookups are possible only on:

• hash key or hash + range key together
• but not on attributes

To enable fast query lookups on attributes we can create Global Secondary Index (GSI)

For example assume we have a table with game scores:

Target: Count total score by all games with one GameTitle:

As simple scan by GameTitle will be slow (because it is not hash key), we can create index GameTitleIndex which will give fast TopScores for certain GameTitle:

Results will be ranged(sorted) by range key.

Based on https://www.youtube.com/watch?v=qNhiFdDAWJU