Does PostgreSQL do any kind of caching of query results on its own? Suppose I do this ten thousand times in quick succession:
SELECT * FROM table WHERE id = $1;

That is, not as a prepared statement which is executed, but as individual queries.
Will PG actually execute the query each and every time, or will it somehow keep track of the fact that it was recently run, and that nothing has changed in between, and instead of running it again, simply return the last result which it has kept around in RAM?
Or do I need to do this client-side with my own application code?
Many years ago, I heard of &quot;memcached&quot; and stuff like that, but could never figure out how to use it, so I never did. I don't use any kind of &quot;abstraction layer&quot; either which might do this on its own, so I'm purely wondering if PG does this internally and automatically as part of some general optimization/resource-saving mechanism.
It will execute it each time.  It will cache the data it needs to do the execution (assuming that is small enough to stay in cache), but not the results.  Who knows, maybe the results have even changed, what with other people being allowed to do inserts, updates, and deletions at the same time as you are looping over your 10,000 executions.