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Support UPDATE/DELETE WHERE CURRENT OF cursor_name, per SQL standard.

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Along the way, allow FOR UPDATE in non-WITH-HOLD cursors; there may once
have been a reason to disallow that, but it seems to work now, and it's
really rather necessary if you want to select a row via a cursor and then
update it in a concurrent-safe fashion.

Original patch by Arul Shaji, rather heavily editorialized by Tom Lane.
This commit is contained in:
Tom Lane
2007-06-11 01:16:30 +00:00
parent 85d72f0516
commit 6808f1b1de
30 changed files with 940 additions and 127 deletions
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17
src/include/nodes/primnodes.h
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@@ -10,7 +10,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.130 2007/06/05 21:31:08 tgl Exp $
* $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.131 2007/06/11 01:16:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -915,6 +915,21 @@ typedef struct SetToDefault
int32 typeMod; /* typemod for substituted value */
} SetToDefault;
/*
* Node representing [WHERE] CURRENT OF cursor_name
*
* CURRENT OF is a bit like a Var, in that it carries the rangetable index
* of the target relation being constrained; this aids placing the expression
* correctly during planning. We can assume however that its "levelsup" is
* always zero, due to the syntactic constraints on where it can appear.
*/
typedef struct CurrentOfExpr
{
Expr xpr;
Index cvarno; /* RT index of target relation */
char *cursor_name; /* name of referenced cursor */
} CurrentOfExpr;
/*--------------------
* TargetEntry -
* a target entry (used in query target lists)