</para>

<para>

When the <structname>pg_buffercache</structname> view is accessed, internal buffer

manager locks are taken for long enough to copy all the buffer state

data that the view will display.

This ensures that the view produces a consistent set of results, while not

blocking normal buffer activity longer than necessary. Nonetheless there

could be some impact on database performance if this view is read often.

Since buffer manager locks are not taken to copy the buffer state data that

the view will display, accessing <structname>pg_buffercache</structname> view

has less impact on normal buffer activity but it doesn't provide a consistent

set of results across all buffers. However, we ensure that the information of

each buffer is self-consistent.

</para>

</sect2>