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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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56
src/backend/rewrite/rewriteManip.c
View File

@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.103 2007/01/05 22:19:36 momjian Exp $
* $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.104 2007/06/11 01:16:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -151,6 +151,14 @@ OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
}
return false;
}
if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
if (context->sublevels_up == 0)
cexpr->cvarno += context->offset;
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
@@ -302,6 +310,15 @@ ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
}
return false;
}
if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
if (context->sublevels_up == 0 &&
cexpr->cvarno == context->rt_index)
cexpr->cvarno = context->new_index;
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
@@ -466,6 +483,13 @@ IncrementVarSublevelsUp_walker(Node *node,
var->varlevelsup += context->delta_sublevels_up;
return false; /* done here */
}
if (IsA(node, CurrentOfExpr))
{
/* this should not happen */
if (context->min_sublevels_up == 0)
elog(ERROR, "cannot push down CurrentOfExpr");
return false;
}
if (IsA(node, Aggref))
{
Aggref *agg = (Aggref *) node;
@@ -536,6 +560,15 @@ rangeTableEntry_used_walker(Node *node,
return true;
return false;
}
if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
if (context->sublevels_up == 0 &&
cexpr->cvarno == context->rt_index)
return true;
return false;
}
if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
@@ -932,8 +965,27 @@ ResolveNew_mutator(Node *node, ResolveNew_context *context)
}
/* otherwise fall through to copy the var normally */
}
else if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
int this_varno = (int) cexpr->cvarno;
if (IsA(node, Query))
if (this_varno == context->target_varno &&
context->sublevels_up == 0)
{
/*
* We get here if a WHERE CURRENT OF expression turns out to
* apply to a view. Someday we might be able to translate
* the expression to apply to an underlying table of the view,
* but right now it's not implemented.
*/
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("WHERE CURRENT OF on a view is not implemented")));
}
/* otherwise fall through to copy the expr normally */
}
else if (IsA(node, Query))
{
/* Recurse into RTE subquery or not-yet-planned sublink subquery */
Query *newnode;