Re: Parallel Btree index scan

[Rakesh Kumar]

> And what is the difference between index scan and index only scan.

Index scan:  Index lookup for key access plus read from data blocks to satisfy 
the query.

Index only scan: Index lookup for key access plus read from index pages itself 
to satisfy query. In other words, entire query can
be satisfied by index without bothering to go into data pages.  For eg: select 
count(*) from table where col1 = 123. Assuming col1
 is indexed, there is no need to visit data blocks.