Take the results of a set-returning function, and return them as if they were rows read from a table.

Postgres considers functions to be volatile unless specified otherwise (immutable or stable), which can affect query planning.

Function Scan fields

• Parent Relationship

• Parallel Aware

• Function Name

• Schema

• Alias

• Startup Cost

• Total Cost

• Plan Rows

• Plan Width

• Actual Startup Time

• Actual Total Time

• Actual Rows

• Actual Loops

• Disabled

• Output

• Filter

• Rows Removed by Filter

• Function Call

• Shared Hit Blocks

• Shared Read Blocks

• Shared Dirtied Blocks

• Shared Written Blocks

• Local Hit Blocks

• Local Read Blocks

• Local Dirtied Blocks

• Local Written Blocks

• Temp Read Blocks

• Temp Written Blocks

• Shared I/O Read Time

• Shared I/O Write Time

• Local I/O Read Time

• Local I/O Write Time

• Temp I/O Read Time

• Temp I/O Write Time

• Workers

Related official docs

• Function Volatility Categories

Further reading

• Bad estimate on a function scan – Stack Overflow