Sequential Scan
Short Description
The Sequential Scan node Reads all the pages in the table to return required data
Detailed Description​
Reads all the pages in the table to return required data in the order they appear on disc. Filters can be applied to return specified rows, but they must be read first in order to do this. Sequential scans are very efficient at reading small tables and large proportions of large tables. They are not efficient at reading a small number of rows from a large table. In this case, indexed access may be more efficient.
Additional Links​
- PostgreSQL Documentation - Using Explain
- pgAnalyze - Explain
- eTutorials - Understanding How PostgreSQL Executes a Query
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