diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/fdwhandler.sgml | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml index 77038f53f9a..81c12e36cd4 100644 --- a/doc/src/sgml/fdwhandler.sgml +++ b/doc/src/sgml/fdwhandler.sgml @@ -992,29 +992,31 @@ GetForeignRowMarkType(RangeTblEntry *rte, <para> <programlisting> -HeapTuple +void 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 tuple slot from 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 should return a palloc'ed copy of the fetched tuple, - or <literal>NULL</literal> if the row lock couldn't be obtained. The row lock - type to acquire is defined by <literal>erm->markType</literal>, which is the - value previously 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 should store the tuple into the provided, or clear it if if + the row lock couldn't be obtained. The row lock type to acquire is + defined by <literal>erm->markType</literal>, which is the value + previously 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.) </para> <para> @@ -1026,7 +1028,7 @@ RefetchForeignRow(EState *estate, <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->waitPolicy</literal>. </para> |