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Implement the IS DISTINCT FROM operator per SQL99.

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Reused the Expr node to hold DISTINCT which strongly resembles
 the existing OP info. Define DISTINCT_EXPR which strongly resembles
 the existing OPER_EXPR opType, but with handling for NULLs required
 by SQL99.
We have explicit support for single-element DISTINCT comparisons
 all the way through to the executor. But, multi-element DISTINCTs
 are handled by expanding into a comparison tree in gram.y as is done for
 other row comparisons. Per discussions, it might be desirable to move
 this into one or more purpose-built nodes to be handled in the backend.
Define the optional ROW keyword and token per SQL99.
 This allows single-element row constructs, which were formerly disallowed
 due to shift/reduce conflicts with parenthesized a_expr clauses.
Define the SQL99 TREAT() function. Currently, use as a synonym for CAST().
This commit is contained in:
Thomas G. Lockhart
2002-07-04 15:24:11 +00:00
parent c7eea66c39
commit 68d9fbeb55
10 changed files with 438 additions and 100 deletions
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5
src/include/nodes/primnodes.h
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@@ -10,7 +10,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: primnodes.h,v 1.64 2002/06/20 20:29:51 momjian Exp $
* $Id: primnodes.h,v 1.65 2002/07/04 15:24:11 thomas Exp $
*
*-------------------------------------------------------------------------
*/
@@ -144,7 +144,8 @@ typedef struct RangeVar
*/
typedef enum OpType
{
OP_EXPR, FUNC_EXPR, OR_EXPR, AND_EXPR, NOT_EXPR, SUBPLAN_EXPR
OP_EXPR, DISTINCT_EXPR, FUNC_EXPR,
OR_EXPR, AND_EXPR, NOT_EXPR, SUBPLAN_EXPR
} OpType;
typedef struct Expr