EXPLAINcommand to see what query plan a planner creates
EXPLAIN, if you want to see the execution plan without running it, or use a transaction and do an immediate rollback.
A sequential scan (or seq scan) reads the rows from the table, in order.
Time it took to generate the query plan from the parsed query and optimize it. It does not include parsing or rewriting.
The time shown by
EXPLAIN ANALYZEincludes executor start-up and shut-down time, as well as the time to run any triggers that are fired. Doesn't include parsing, rewriting, or planning time.
The number of rows, per-loop, that the planner expects to be returned by the operation.
The estimated average size of each row returned by the operation, in bytes.
The estimated cost of returning the first row.
The estimated cost of returning all rows, by the operation and its descendents.