/*
* tuplestore_markpos - saves current position in the tuple sequence
*/
void
tuplestore_markpos_pos(Tuplestorestate *state, TuplestorePos *pos)
{
Assert(state->eflags & EXEC_FLAG_MARK);
switch (state->status)
{
case TSS_INMEM:
pos->markpos_current = pos->current;
/*
* We can truncate the tuplestore if neither backward scan nor
* rewind capability are required by the caller. There will never
* be a need to back up past the mark point.
*
* Note: you might think we could remove all the tuples before
* "current", since that one is the next to be returned. However,
* since tuplestore_gettuple returns a direct pointer to our
* internal copy of the tuple, it's likely that the caller has
* still got the tuple just before "current" referenced in a slot.
* Don't free it yet.
*/
if (!(state->eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_REWIND)))
tuplestore_trim(state, 1);
break;
case TSS_WRITEFILE:
if (pos->eof_reached)
{
/* Need to record the implicit read position */
BufFileTell(state->myfile,
&pos->markpos_offset);
}
else
{
pos->markpos_offset = pos->readpos_offset;
}
break;
case TSS_READFILE:
BufFileTell(state->myfile,
&pos->markpos_offset);
break;
default:
elog(ERROR, "invalid tuplestore state");
break;
}
}
/* ----------------------------------------------------------------
* ExecMaterialMarkPos
*
* Calls tuplestore to save the current position in the stored file.
* ----------------------------------------------------------------
*/
void
ExecMaterialMarkPos(MaterialState *node)
{
Assert(node->eflags & EXEC_FLAG_MARK);
/*
* if we haven't materialized yet, just return.
*/
if (!node->tuplestorestate)
return;
/*
* copy the active read pointer to the mark.
*/
tuplestore_copy_read_pointer(node->tuplestorestate, 0, 1);
/*
* since we may have advanced the mark, try to truncate the tuplestore.
*/
tuplestore_trim(node->tuplestorestate);
}
