diff options
Diffstat (limited to 'src/include/nodes/primnodes.h')
| -rw-r--r-- | src/include/nodes/primnodes.h | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h index 8f2c64847e2..f10ae4efa88 100644 --- a/src/include/nodes/primnodes.h +++ b/src/include/nodes/primnodes.h @@ -127,9 +127,13 @@ typedef struct Expr * upper-level plan nodes are reassigned to point to the outputs of their * subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR * and varattno becomes the index of the proper element of that subplan's - * target list. But varnoold/varoattno continue to hold the original values. - * The code doesn't really need varnoold/varoattno, but they are very useful - * for debugging and interpreting completed plans, so we keep them around. + * target list. Similarly, INDEX_VAR is used to identify Vars that reference + * an index column rather than a heap column. (In ForeignScan and CustomScan + * plan nodes, INDEX_VAR is abused to signify references to columns of a + * custom scan tuple type.) In all these cases, varnoold/varoattno hold the + * original values. The code doesn't really need varnoold/varoattno, but they + * are very useful for debugging and interpreting completed plans, so we keep + * them around. */ #define INNER_VAR 65000 /* reference to inner subplan */ #define OUTER_VAR 65001 /* reference to outer subplan */ |