debug_io_direct

doc html

<p>
        Ask the kernel to minimize caching effects for relation data and WAL
        files using <code class="literal">O_DIRECT</code> (most Unix-like systems),
        <code class="literal">F_NOCACHE</code> (macOS) or
        <code class="literal">FILE_FLAG_NO_BUFFERING</code> (Windows).
       </p><p>
        May be set to an empty string (the default) to disable use of direct
        I/O, or a comma-separated list of operations that should use direct I/O.
        The valid options are <code class="literal">data</code> for
        main data files, <code class="literal">wal</code> for WAL files, and
        <code class="literal">wal_init</code> for WAL files when being initially
        allocated.
        This parameter can only be set at server start.
       </p><p>
        Some operating systems and file systems do not support direct I/O, so
        non-default settings may be rejected at startup or cause errors.
       </p><p>
        Currently this feature reduces performance, and is intended for
        developer testing only.
       </p>

documentation revision

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