Explain (buffers, parse) in postgresql

Question

I am new to postgresql and I am trying to understand explain (buffers, analysis) instructions. I have a request and I execute it using an explanation (buffers, analysis).

The first time I execute it, the performance is worse than the second time. Also, the first time I get the read option next to the hit, and the second time the read does not exist.

Can someone help me understand?

Answer 1

The first time you select, the pages heat up - they are loaded into the cache as soon as they are in RAM - all subsequent selections will be faster (RAM speed is higher).

Accordingly, it buffersshows that read when pages are not in the cache, cos postgres reads them and does not read when they are warm, so the cache gets ...

Update with docs :

BUFFERS

. , , , , , , , . , , , . ; ; temp , , , , . , ; , . , node , . . , ANALYZE . FALSE.

.