Fix incorrect comment in JsonTablePlanJoinNextRow()

The comment on the return-false path when both UNION siblings are
exhausted said "there are more rows," which is the opposite of what
the code does. The code itself is correct, returning false to signal
no more rows, but the misleading comment could tempt a reader into
"fixing" the return value, which would cause UNION plans to loop
indefinitely.

Back-patch to 17, where JSON_TABLE was introduced.

Author: Chuanwen Hu <463945512@qq.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/tencent_4CC6316F02DECA61ACCF22F933FEA5C12806@qq.com
Backpatch-through: 17

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 770840a06118bd763503818050e397b23368717c..0ec9b4df2efe470f1b5e6401ce2f5a5b34bb6973 100644 (file)
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -4729,7 +4729,7 @@ JsonTablePlanJoinNextRow(JsonTablePlanState *planstate)
                 */
                if (!JsonTablePlanNextRow(planstate->right))
                {
-                       /* Right sibling ran out of row, so there are more rows. */
+                       /* Right sibling ran out of rows too, so there are no more rows. */
                        return false;
                }
        }