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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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4
src/backend/nodes/readfuncs.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.123 2002/06/20 20:29:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.124 2002/07/04 15:23:54 thomas Exp $
*
* NOTES
* Most of the read functions for plan nodes are tested. (In fact, they
@ -804,6 +804,8 @@ _readExpr(void)
token = pg_strtok(&length); /* get opType */
if (strncmp(token, "op", 2) == 0)
local_node->opType = OP_EXPR;
else if (strncmp(token, "distinct", 8) == 0)
local_node->opType = DISTINCT_EXPR;
else if (strncmp(token, "func", 4) == 0)
local_node->opType = FUNC_EXPR;
else if (strncmp(token, "or", 2) == 0)