What does this mean?
cost=0.11..288531.38
Does that mean the cost is between 0.11 and 288,531.38? That’s a huge range…too big to be useful, so just want to be sure.
>Solution :
This isn’t a range. As the docs explain:
The numbers that are quoted in parentheses are (left to right):
- Estimated start-up cost. This is the time expended before the output phase can begin, e.g., time to do the sorting in a sort node.
- Estimated total cost. This is stated on the assumption that the plan node is run to completion, i.e., all available rows are retrieved. In practice a node’s parent node might stop short of reading all available rows….
- Estimated number of rows output by this plan node. Again, the node is assumed to be run to completion.
- Estimated average width of rows output by this plan node (in bytes).
That means the operator with cost 0.11..288531.38 has a small startup cost but a high overall cost.