diff options
Diffstat (limited to 'src/include/nodes/primnodes.h')
| -rw-r--r-- | src/include/nodes/primnodes.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h index cb09df9e745..59e7bb26bbd 100644 --- a/src/include/nodes/primnodes.h +++ b/src/include/nodes/primnodes.h @@ -223,6 +223,11 @@ typedef struct Expr * Note that it affects the meaning of all of varno, varnullingrels, and * varnosyn, all of which refer to the range table of that query level. * + * varreturningtype is used for Vars that refer to the target relation in the + * RETURNING list of data-modifying queries. The default behavior is to + * return old values for DELETE and new values for INSERT and UPDATE, but it + * is also possible to explicitly request old or new values. + * * In the parser, varnosyn and varattnosyn are either identical to * varno/varattno, or they specify the column's position in an aliased JOIN * RTE that hides the semantic referent RTE's refname. This is a syntactic @@ -244,6 +249,14 @@ typedef struct Expr #define PRS2_OLD_VARNO 1 #define PRS2_NEW_VARNO 2 +/* Returning behavior for Vars in RETURNING list */ +typedef enum VarReturningType +{ + VAR_RETURNING_DEFAULT, /* return OLD for DELETE, else return NEW */ + VAR_RETURNING_OLD, /* return OLD for DELETE/UPDATE, else NULL */ + VAR_RETURNING_NEW, /* return NEW for INSERT/UPDATE, else NULL */ +} VarReturningType; + typedef struct Var { Expr xpr; @@ -279,6 +292,9 @@ typedef struct Var */ Index varlevelsup; + /* returning type of this var (see above) */ + VarReturningType varreturningtype; + /* * varnosyn/varattnosyn are ignored for equality, because Vars with * different syntactic identifiers are semantically the same as long as @@ -2143,6 +2159,30 @@ typedef struct InferenceElem Oid inferopclass; /* OID of att opclass, or InvalidOid */ } InferenceElem; +/* + * ReturningExpr - return OLD/NEW.(expression) in RETURNING list + * + * This is used when updating an auto-updatable view and returning a view + * column that is not simply a Var referring to the base relation. In such + * cases, OLD/NEW.viewcol can expand to an arbitrary expression, but the + * result is required to be NULL if the OLD/NEW row doesn't exist. To handle + * this, the rewriter wraps the expanded expression in a ReturningExpr, which + * is equivalent to "CASE WHEN (OLD/NEW row exists) THEN (expr) ELSE NULL". + * + * A similar situation can arise when rewriting the RETURNING clause of a + * rule, which may also contain arbitrary expressions. + * + * ReturningExpr nodes never appear in a parsed Query --- they are only ever + * inserted by the rewriter. + */ +typedef struct ReturningExpr +{ + Expr xpr; + int retlevelsup; /* > 0 if it belongs to outer query */ + bool retold; /* true for OLD, false for NEW */ + Expr *retexpr; /* expression to be returned */ +} ReturningExpr; + /*-------------------- * TargetEntry - * a target entry (used in query target lists) |