/*
* Executes default values for columns for which we can't map to remote
* relation columns.
*
* This allows us to support tables which have more columns on the downstream
* than on the upstream.
*/
static void
slot_fill_defaults(LogicalRepRelMapEntry *rel, EState *estate,
TupleTableSlot *slot)
{
TupleDesc desc = RelationGetDescr(rel->localrel);
int num_phys_attrs = desc->natts;
int i;
int attnum,
num_defaults = 0;
int *defmap;
ExprState **defexprs;
ExprContext *econtext;
econtext = GetPerTupleExprContext(estate);
/* We got all the data via replication, no need to evaluate anything. */
if (num_phys_attrs == rel->remoterel.natts)
return;
defmap = (int *) palloc(num_phys_attrs * sizeof(int));
defexprs = (ExprState **) palloc(num_phys_attrs * sizeof(ExprState *));
for (attnum = 0; attnum < num_phys_attrs; attnum++)
{
Expr *defexpr;
if (TupleDescAttr(desc, attnum)->attisdropped)
continue;
if (rel->attrmap[attnum] >= 0)
continue;
defexpr = (Expr *) build_column_default(rel->localrel, attnum + 1);
if (defexpr != NULL)
{
/* Run the expression through planner */
defexpr = expression_planner(defexpr);
/* Initialize executable expression in copycontext */
defexprs[num_defaults] = ExecInitExpr(defexpr, NULL);
defmap[num_defaults] = attnum;
num_defaults++;
}
}
for (i = 0; i < num_defaults; i++)
slot->tts_values[defmap[i]] =
ExecEvalExpr(defexprs[i], econtext, &slot->tts_isnull[defmap[i]]);
}
/*
* Copied from src/backend/commands/indexcmds.c, not exported.
* CheckMutability
* Test whether given expression is mutable
*/
bool
CheckMutability(Expr *expr)
{
/*
* First run the expression through the planner. This has a couple of
* important consequences. First, function default arguments will get
* inserted, which may affect volatility (consider "default now()").
* Second, inline-able functions will get inlined, which may allow us to
* conclude that the function is really less volatile than it's marked. As
* an example, polymorphic functions must be marked with the most volatile
* behavior that they have for any input type, but once we inline the
* function we may be able to conclude that it's not so volatile for the
* particular input type we're dealing with.
*
* We assume here that expression_planner() won't scribble on its input.
*/
expr = expression_planner(expr);
/* Now we can search for non-immutable functions */
return contain_mutable_functions((Node *) expr);
}
/*
* GetStreamScanPlan
*/
ForeignScan *
GetStreamScanPlan(PlannerInfo *root, RelOptInfo *baserel,
Oid relid, ForeignPath *best_path, List *tlist, List *scan_clauses, Plan *outer_plan)
{
StreamFdwInfo *sinfo = (StreamFdwInfo *) baserel->fdw_private;
List *physical_tlist = build_physical_tlist(root, baserel);
RangeTblEntry *rte = NULL;
int i;
TableSampleClause *sample;
Value *sample_cutoff = NULL;
/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
scan_clauses = extract_actual_clauses(scan_clauses, false);
for (i = 1; i <= root->simple_rel_array_size; i++)
{
rte = root->simple_rte_array[i];
if (rte && rte->relid == relid)
break;
}
if (!rte || rte->relid != relid)
elog(ERROR, "stream RTE missing");
sample = rte->tablesample;
if (sample)
{
double dcutoff;
Datum d;
ExprContext *econtext;
bool isnull;
Node *node;
Expr *expr;
ExprState *estate;
ParseState *ps = make_parsestate(NULL);
float4 percent;
if (sample->tsmhandler != BERNOULLI_OID)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("tablesample method %s is not supported by streams", get_func_name(sample->tsmhandler)),
errhint("Only bernoulli tablesample method can be used with streams.")));
if (sample->repeatable)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("streams don't support the REPEATABLE clause for tablesample")));
econtext = CreateStandaloneExprContext();
ps = make_parsestate(NULL);
node = (Node *) linitial(sample->args);
node = transformExpr(ps, node, EXPR_KIND_OTHER);
expr = expression_planner((Expr *) node);
estate = ExecInitExpr(expr, NULL);
d = ExecEvalExpr(estate, econtext, &isnull, NULL);
free_parsestate(ps);
FreeExprContext(econtext, false);
percent = DatumGetFloat4(d);
if (percent < 0 || percent > 100 || isnan(percent))
ereport(ERROR,
(errcode(ERRCODE_INVALID_TABLESAMPLE_ARGUMENT),
errmsg("sample percentage must be between 0 and 100")));
dcutoff = rint(((double) RAND_MAX + 1) * percent / 100);
sample_cutoff = makeInteger((int) dcutoff);
}
return make_foreignscan(tlist, scan_clauses, baserel->relid,
NIL, list_make3(sinfo->colnames, physical_tlist, sample_cutoff), NIL, NIL, outer_plan);
}
