Re: PostgreSQL, Asynchronous I/O, Buffered I/O and why did fsync-gate not affect Oracle or MySQL?

On 5/2/21 8:46 AM, Pól Ua Laoínecháin wrote:
[snip]

Now, I'm not quite sure that I completely comprehend matters: Is there
a difference between Asynchronous I/O and Buffered I/O?

* Asynchronous (a-syn-chron-ous) is an adjective which means "not together with time".
* Buffered means "read more than you need at the moment, and then do processing to/from a cache".

They are not mutually exclusive.

Their antonyms are
* Synchronous (syn-chron-ous): together with time.
* Direct, where you read/write only what you need at the moment, directly to/from the IO device.

Thus, async IO is where you tell the IO subsystem that you need something, and then go off and do something else; the IO system interrupts you when the data has been delivered.
Synchronous IO is where you request IO and then wait for the data.