Gather used column from baserestrictinfo and reltargetlist of RelOptInfo.

diff --git a/contrib/postgresql_fdw/postgresql_fdw.c b/contrib/postgresql_fdw/postgresql_fdw.c
index 70e7500b06c063cf98b4c3f2adb09818bf8025fe..940ff1f8d0e2d5c1ba1d3c8bbd3f2e984c4477d0 100644 (file)
--- a/contrib/postgresql_fdw/postgresql_fdw.c
+++ b/contrib/postgresql_fdw/postgresql_fdw.c
@@ -27,6 +27,7 @@
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/plancat.h"
+#include "optimizer/var.h"
 #include "parser/parsetree.h"
 #include "parser/scansup.h"
 #include "utils/builtins.h"
@@ -332,6 +333,8 @@ is_foreign_qual(PlannerInfo *root, RelOptInfo *baserel, Expr *expr)
 static char *
 deparseSql(Oid foreigntableid, PlannerInfo *root, RelOptInfo *baserel)
 {
+   AttrNumber      attr;
+   List           *attr_used = NIL;
    List           *context;
    StringInfoData  sql;
    ForeignTable   *table = GetForeignTable(foreigntableid);
@@ -347,24 +350,52 @@ deparseSql(Oid foreigntableid, PlannerInfo *root, RelOptInfo *baserel)
 
    context = deparse_context_for("foreigntable", foreigntableid);
 
+   /* Collect used columns from restrict information and target list */
+   foreach (lc, baserel->baserestrictinfo)
+   {
+       List           *l;
+       RestrictInfo   *ri = lfirst(lc);
+
+       l = pull_var_clause((Node *) ri->clause, PVC_RECURSE_PLACEHOLDERS);
+       attr_used = list_union(attr_used, l);
+   }
+   attr_used = list_union(attr_used, baserel->reltargetlist);
+
    /* deparse SELECT target list */
    appendStringInfoString(&sql, "SELECT ");
    first = true;
-   foreach (lc, baserel->reltargetlist)
+   for (attr = baserel->min_attr; attr < baserel->max_attr; attr++)
    {
-       Var *var = lfirst(lc);
+       Var *var;
 
-       /* system columns cannot be retrieved from remote */
-       if (var->varattno < 0)
+       /* System columns cannot be retrieved from remote. */
+       if (attr < 0)
            continue;
 
+       /* Separete columns with comma. */
        if (!first)
            appendStringInfoString(&sql, ", ");
        first = false;
-       deparse_var(root, &sql, var);
+
+       /* Use "NULL" for column which isn't in reltargetlist. */
+       foreach (lc, attr_used)
+       {
+           var = lfirst(lc);
+           if (var->varattno == attr)
+               break;
+           var = NULL;
+       }
+
+       if (var != NULL)
+           deparse_var(root, &sql, var);
+       else
+           appendStringInfo(&sql, "NULL");
    }
    if (strcmp(sql.data, "SELECT ") == 0)
+   {
+       ereport(DEBUG1, (errmsg("targetlist is empty, retrieve all columns")));
        appendStringInfo(&sql, "*");
+   }
 
    /*
     * Deparse FROM