The <function>pg_buffercache_evict()</function> function takes a buffer

identifier, as shown in the <structfield>bufferid</structfield> column of

the <structname>pg_buffercache</structname> view. It returns information

about whether the buffer was evicted and flushed. The buffer_evicted

about whether the buffer was evicted and flushed.

The <structfield>buffer_evicted</structfield>

column is true on success, and false if the buffer wasn't valid, if it

couldn't be evicted because it was pinned, or if it became dirty again

after an attempt to write it out. The buffer_flushed column is true if the

after an attempt to write it out.

The <structfield>buffer_flushed</structfield> column is true if the

buffer was flushed. This does not necessarily mean that buffer was flushed

by us, it might be flushed by someone else. The result is immediately out

of date upon return, as the buffer might become valid again at any time due