Fix calculation of which GENERATED columns need to be updated.

We were identifying the updatable generated columns of inheritance
children by transposing the calculation made for their parent.
However, there's nothing that says a traditional-inheritance child
can't have generated columns that aren't there in its parent, or that
have different dependencies than are in the parent's expression.
(At present it seems that we don't enforce that for partitioning
either, which is likely wrong to some degree or other; but the case
clearly needs to be handled with traditional inheritance.)

Hence, drop the very-klugy-anyway "extraUpdatedCols" RTE field
in favor of identifying which generated columns depend on updated
columns during executor startup.  In HEAD we can remove
extraUpdatedCols altogether; in back branches, it's still there but
always empty.  Another difference between the HEAD and back-branch
versions of this patch is that in HEAD we can add the new bitmap field
to ResultRelInfo, but that would cause an ABI break in back branches.
Like 4b3e37993, add a List field at the end of struct EState instead.

Back-patch to v13.  The bogus calculation is also being made in v12,
but it doesn't have the same visible effect because we don't use it
to decide which generated columns to recalculate; as a consequence of
which the patch doesn't apply easily.  I think that there might still
be a demonstrable bug associated with trigger firing conditions, but
that's such a weird corner-case usage that I'm content to leave it
unfixed in v12.

Amit Langote and Tom Lane

Discussion: https://postgr.es/m/CA+HiwqFshLKNvQUd1DgwJ-7tsTp=dwv7KZqXC4j2wYBV1aCDUA@mail.gmail.com
Discussion: https://postgr.es/m/2793383.1672944799@sss.pgh.pa.us

1 files changed, 89 insertions, 8 deletions

diff --git a/src/backend/optimizer/util/inherit.c b/src/backend/optimizer/util/inherit.c
index 992ef87b9da..7ea758049ed 100644
--- a/src/backend/optimizer/util/inherit.c
+++ b/src/backend/optimizer/util/inherit.c
@@ -25,6 +25,7 @@
 #include "optimizer/inherit.h"
 #include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/plancat.h"
 #include "optimizer/planmain.h"
 #include "optimizer/planner.h"
 #include "optimizer/prep.h"
@@ -47,6 +48,10 @@ static void expand_single_inheritance_child(PlannerInfo *root,
 											Index *childRTindex_p);
 static Bitmapset *translate_col_privs(const Bitmapset *parent_privs,
 									  List *translated_vars);
+static Bitmapset *translate_col_privs_multilevel(PlannerInfo *root,
+												 RelOptInfo *rel,
+												 RelOptInfo *parent_rel,
+												 Bitmapset *parent_cols);
 static void expand_appendrel_subquery(PlannerInfo *root, RelOptInfo *rel,
 									  RangeTblEntry *rte, Index rti);
 
@@ -333,11 +338,6 @@ expand_partitioned_rtentry(PlannerInfo *root, RelOptInfo *relinfo,
 		root->partColsUpdated =
 			has_partition_attrs(parentrel, parentrte->updatedCols, NULL);
 
-	/*
-	 * There shouldn't be any generated columns in the partition key.
-	 */
-	Assert(!has_partition_attrs(parentrel, parentrte->extraUpdatedCols, NULL));
-
 	/* Nothing further to do here if there are no partitions. */
 	if (partdesc->nparts == 0)
 		return;
@@ -556,15 +556,12 @@ expand_single_inheritance_child(PlannerInfo *root, RangeTblEntry *parentrte,
 													 appinfo->translated_vars);
 		childrte->updatedCols = translate_col_privs(parentrte->updatedCols,
 													appinfo->translated_vars);
-		childrte->extraUpdatedCols = translate_col_privs(parentrte->extraUpdatedCols,
-														 appinfo->translated_vars);
 	}
 	else
 	{
 		childrte->selectedCols = bms_copy(parentrte->selectedCols);
 		childrte->insertedCols = bms_copy(parentrte->insertedCols);
 		childrte->updatedCols = bms_copy(parentrte->updatedCols);
-		childrte->extraUpdatedCols = bms_copy(parentrte->extraUpdatedCols);
 	}
 
 	/*
@@ -649,6 +646,52 @@ expand_single_inheritance_child(PlannerInfo *root, RangeTblEntry *parentrte,
 }
 
 /*
+ * get_rel_all_updated_cols
+ * 		Returns the set of columns of a given "simple" relation that are
+ * 		updated by this query.
+ */
+Bitmapset *
+get_rel_all_updated_cols(PlannerInfo *root, RelOptInfo *rel)
+{
+	Index		relid;
+	RangeTblEntry *rte;
+	Bitmapset  *updatedCols,
+			   *extraUpdatedCols;
+
+	Assert(root->parse->commandType == CMD_UPDATE);
+	Assert(IS_SIMPLE_REL(rel));
+
+	/*
+	 * We obtain updatedCols for the query's result relation.  Then, if
+	 * necessary, we map it to the column numbers of the relation for which
+	 * they were requested.
+	 */
+	relid = root->parse->resultRelation;
+	rte = planner_rt_fetch(relid, root);
+
+	updatedCols = rte->updatedCols;
+
+	if (rel->relid != relid)
+	{
+		RelOptInfo *top_parent_rel = find_base_rel(root, relid);
+
+		Assert(IS_OTHER_REL(rel));
+
+		updatedCols = translate_col_privs_multilevel(root, rel, top_parent_rel,
+													 updatedCols);
+	}
+
+	/*
+	 * Now we must check to see if there are any generated columns that depend
+	 * on the updatedCols, and add them to the result.
+	 */
+	extraUpdatedCols = get_dependent_generated_columns(root, rel->relid,
+													   updatedCols);
+
+	return bms_union(updatedCols, extraUpdatedCols);
+}
+
+/*
  * translate_col_privs
  *	  Translate a bitmapset representing per-column privileges from the
  *	  parent rel's attribute numbering to the child's.
@@ -701,6 +744,44 @@ translate_col_privs(const Bitmapset *parent_privs,
 }
 
 /*
+ * translate_col_privs_multilevel
+ *		Recursively translates the column numbers contained in 'parent_cols'
+ *		to the column numbers of a descendant relation given by 'rel'
+ *
+ * Note that because this is based on translate_col_privs, it will expand
+ * a whole-row reference into all inherited columns.  This is not an issue
+ * for current usages, but beware.
+ */
+static Bitmapset *
+translate_col_privs_multilevel(PlannerInfo *root, RelOptInfo *rel,
+							   RelOptInfo *parent_rel,
+							   Bitmapset *parent_cols)
+{
+	AppendRelInfo *appinfo;
+
+	/* Fast path for easy case. */
+	if (parent_cols == NULL)
+		return NULL;
+
+	Assert(root->append_rel_array != NULL);
+	appinfo = root->append_rel_array[rel->relid];
+	Assert(appinfo != NULL);
+
+	/* Recurse if immediate parent is not the top parent. */
+	if (appinfo->parent_relid != parent_rel->relid)
+	{
+		RelOptInfo *next_parent = find_base_rel(root, appinfo->parent_relid);
+
+		parent_cols = translate_col_privs_multilevel(root, next_parent,
+													 parent_rel,
+													 parent_cols);
+	}
+
+	/* Now translate for this child. */
+	return translate_col_privs(parent_cols, appinfo->translated_vars);
+}
+
+/*
  * expand_appendrel_subquery
  *		Add "other rel" RelOptInfos for the children of an appendrel baserel
  *