Fix MERGE with DO NOTHING actions into a partitioned table.

ExecInitPartitionInfo() duplicates much of the logic in
ExecInitMerge(), except that it failed to handle DO NOTHING
actions. This would cause an "unknown action in MERGE WHEN clause"
error if a MERGE with any DO NOTHING actions attempted to insert into
a partition not already initialised by ExecInitModifyTable().

Bug: #18871
Reported-by: Alexander Lakhin <[email protected]>
Author: Tender Wang <[email protected]>
Reviewed-by: Gurjeet Singh <[email protected]>
Discussion: https://postgr.es/m/18871-b44e3c96de3bd2e8%40postgresql.org
Backpatch-through: 15

1 files changed, 1 insertions, 1 deletions

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 87c820276a8..309e27f8b5f 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3784,7 +3784,7 @@ ExecInitMerge(ModifyTableState *mtstate, EState *estate)
 				case CMD_NOTHING:
 					break;
 				default:
-					elog(ERROR, "unknown operation");
+					elog(ERROR, "unknown action in MERGE WHEN clause");
 					break;
 			}
 		}