<para>

If <productname>systemd</productname> is in use, some care must be taken

that IPC resources (shared memory and semaphores) are not prematurely

that IPC resources (includingshared memory) are not prematurely

removed by the operating system. This is especially of concern when

installing PostgreSQL from source. Users of distribution packages of

PostgreSQL are less likely to be affected, as

</para>

<para>

A typical observed effect when this setting is on is that the semaphore

objects used by a PostgreSQL server are removed at apparently random

times, leading to the server crashing with log messages like

A typical observed effect when this setting is on is that shared memory

objects used for parallel query execution are removed at apparently random

times, leading to errors and warnings while attempting to open and remove

them, like

<screen>

</screen>

Different types of IPC objects (shared memory vs. semaphores, System V

vs. POSIX) are treated slightly differently