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Rewriter and planner should use only resno, not resname, to identify

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target columns in INSERT and UPDATE targetlists.  Don't rely on resname
to be accurate in ruleutils, either.  This fixes bug reported by
Donald Fraser, in which renaming a column referenced in a rule did not
work very well.
This commit is contained in:
Tom Lane
2003-08-11 23:04:50 +00:00
parent 730b3a1502
commit 302f1a86dc
15 changed files with 144 additions and 115 deletions
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37
src/include/nodes/primnodes.h
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@@ -10,7 +10,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: primnodes.h,v 1.90 2003/08/08 21:42:48 momjian Exp $
* $Id: primnodes.h,v 1.91 2003/08/11 23:04:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -31,13 +31,29 @@
*
* Notes:
*
* resno will normally be equal to the item's position in a targetlist,
* but the code generally tries to avoid relying on that (eg, we avoid
* using "nth()" rather than a search to find an item by resno).
* In a SELECT's targetlist, resno should always be equal to the item's
* ordinal position (counting from 1). However, in an INSERT or UPDATE
* targetlist, resno represents the attribute number of the destination
* column for the item; so there may be missing or out-of-order resnos.
* In an UPDATE, it is even legal to have duplicated resnos; consider
* UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
* The two meanings come together in the executor, because the planner
* transforms INSERT/UPDATE tlists into a normalized form with exactly
* one entry for each column of the destination table. Before that's
* happened, however, it is risky to assume that resno == position.
* Generally get_tle_by_resno() should be used rather than nth() to fetch
* tlist entries by resno.
*
* resname will be null if no name can easily be assigned to the column.
* But it should never be null for user-visible columns (i.e., non-junk
* columns in a toplevel targetlist).
* resname is required to represent the correct column name in non-resjunk
* entries of top-level SELECT targetlists, since it will be used as the
* column title sent to the frontend. In most other contexts it is only
* a debugging aid, and may be wrong or even NULL. (In particular, it may
* be wrong in a tlist from a stored rule, if the referenced column has been
* renamed by ALTER TABLE since the rule was made. Also, the planner tends
* to store NULL rather than look up a valid name for tlist entries in
* non-toplevel plan nodes.) In resjunk entries, resname should be either
* a specific system-generated name (such as "ctid") or NULL; anything else
* risks confusing ExecGetJunkAttribute!
*
* ressortgroupref is used in the representation of ORDER BY and
* GROUP BY items. Targetlist entries with ressortgroupref=0 are not
@@ -53,13 +69,16 @@
* a simple reference, these fields are zeroes.
*
* If resjunk is true then the column is a working column (such as a sort key)
* that should be removed from the final output of the query.
* that should be removed from the final output of the query. Resjunk columns
* must have resnos that cannot duplicate any regular column's resno. Also
* note that there are places that assume resjunk columns come after non-junk
* columns.
*--------------------
*/
typedef struct Resdom
{
NodeTag type;
AttrNumber resno; /* attribute number (1..N) */
AttrNumber resno; /* attribute number (see notes above) */
Oid restype; /* type of the value */
int32 restypmod; /* type-specific modifier of the value */
char *resname; /* name of the column (could be NULL) */