<para>

<programlisting>

RefetchForeignRow(EState *estate,

ExecRowMark *erm,

Datum rowid,

TupleTableSlot *slot,

bool *updated);

</programlisting>

Re-fetch one tuple from the foreign table, after locking it if required.

Re-fetch one tupleslotfrom the foreign table, after locking it if required.

<literal>estate</literal> is global execution state for the query.

<literal>erm</literal> is the <structname>ExecRowMark</structname> struct describing

the target foreign table and the row lock type (if any) to acquire.

<literal>rowid</literal> identifies the tuple to be fetched.

<literal>updated</literal> is an output parameter.

<literal>slot</literal> contains nothing useful upon call, but can be used to

hold the returned tuple. <literal>updated</literal> is an output parameter.

</para>

<para>

This function shouldreturn a palloc'ed copy ofthefetched tuple,

or <literal>NULL</literal> ifthe row lock couldn't be obtained. The row lock

type to acquire isdefined by <literal>erm-&gt;markType</literal>, which is the

valuepreviously returned by <function>GetForeignRowMarkType</function>.

(<literal>ROW_MARK_REFERENCE</literal> means to just re-fetch the tuple without

acquiring any lock, and <literal>ROW_MARK_COPY</literal> will never be seen by

this routine.)

This function shouldstore the tuple intotheprovided, or clear it if if

the row lock couldn't be obtained. The row lock type to acquire is

defined by <literal>erm-&gt;markType</literal>, which is the value

previously returned by <function>GetForeignRowMarkType</function>.

(<literal>ROW_MARK_REFERENCE</literal> means to just re-fetch the tuple

withoutacquiring any lock, and <literal>ROW_MARK_COPY</literal> will

never be seen bythis routine.)

</para>

<para>

<para>

Note that by default, failure to acquire a row lock should result in

raising an error;a <literal>NULL</literal> return is only appropriate if

raising an error;returning with an empty slot is only appropriate if

the <literal>SKIP LOCKED</literal> option is specified

by <literal>erm-&gt;waitPolicy</literal>.

</para>