database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-09-02 04:21:28 +03:00
Code Activity

Fix reporting of column typmods for multi-row VALUES constructs.

Browse Source 
expandRTE() and get_rte_attribute_type() reported the exprType() and
exprTypmod() values of the expressions in the first row of the VALUES as
being the column type/typmod returned by the VALUES RTE.  That's fine for
the data type, since we coerce all expressions in a column to have the same
common type.  But we don't coerce them to have a common typmod, so it was
possible for rows after the first one to return values that violate the
claimed column typmod.  This leads to the incorrect result seen in bug
#14448 from Hassan Mahmood, as well as some other corner-case misbehaviors.

The desired behavior is the same as we use in other type-unification
cases: report the common typmod if there is one, but otherwise return -1
indicating no particular constraint.  It's cheap for transformValuesClause
to determine the common typmod while transforming a multi-row VALUES, but
it'd be less cheap for expandRTE() and get_rte_attribute_type() to
re-determine that info every time they're asked --- possibly a lot less
cheap, if the VALUES has many rows.  Therefore, the best fix is to record
the common typmods explicitly in a list in the VALUES RTE, as we were
already doing for column collations.  This looks quite a bit like what
we're doing for CTE RTEs, so we can save a little bit of space and code by
unifying the representation for those two RTE types.  They both now share
coltypes/coltypmods/colcollations fields.  (At some point it might seem
desirable to populate those fields for all RTE types; but right now it
looks like constructing them for other RTE types would add more code and
cycles than it would save.)

The RTE change requires a catversion bump, so this fix is only usable
in HEAD.  If we fix this at all in the back branches, the patch will
need to look quite different.

Report: https://postgr.es/m/20161205143037.4377.60754@wrigleys.postgresql.org
Discussion: https://postgr.es/m/27429.1480968538@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2016-12-08 11:40:02 -05:00
parent 2560d244b4
commit 0b78106cd4
12 changed files with 151 additions and 109 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
src/backend/parser/analyze.c
View File

@@ -633,10 +633,11 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
* RTE.
*/
List *exprsLists = NIL;
List *collations = NIL;
List *coltypes = NIL;
List *coltypmods = NIL;
List *colcollations = NIL;
int sublist_length = -1;
bool lateral = false;
int i;
Assert(selectStmt->intoClause == NULL);
@@ -703,11 +704,20 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
}
/*
* Although we don't really need collation info, let's just make sure
* we provide a correctly-sized list in the VALUES RTE.
* Construct column type/typmod/collation lists for the VALUES RTE.
* Every expression in each column has been coerced to the type/typmod
* of the corresponding target column or subfield, so it's sufficient
* to look at the exprType/exprTypmod of the first row. We don't care
* about the collation labeling, so just fill in InvalidOid for that.
*/
for (i = 0; i < sublist_length; i++)
collations = lappend_oid(collations, InvalidOid);
foreach(lc, (List *) linitial(exprsLists))
{
Node *val = (Node *) lfirst(lc);
coltypes = lappend_oid(coltypes, exprType(val));
coltypmods = lappend_int(coltypmods, exprTypmod(val));
colcollations = lappend_oid(colcollations, InvalidOid);
}
/*
* Ordinarily there can't be any current-level Vars in the expression
@@ -722,7 +732,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
/*
* Generate the VALUES RTE
*/
rte = addRangeTableEntryForValues(pstate, exprsLists, collations,
rte = addRangeTableEntryForValues(pstate, exprsLists,
coltypes, coltypmods, colcollations,
NULL, lateral, true);
rtr = makeNode(RangeTblRef);
/* assume new rte is at end */
@@ -1274,7 +1285,9 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
{
Query *qry = makeNode(Query);
List *exprsLists;
List *collations;
List *coltypes = NIL;
List *coltypmods = NIL;
List *colcollations = NIL;
List **colexprs = NULL;
int sublist_length = -1;
bool lateral = false;
@@ -1360,8 +1373,8 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
/*
* Now resolve the common types of the columns, and coerce everything to
* those types. Then identify the common collation, if any, of each
* column.
* those types. Then identify the common typmod and common collation, if
* any, of each column.
*
* We must do collation processing now because (1) assign_query_collations
* doesn't process rangetable entries, and (2) we need to label the VALUES
@@ -1372,11 +1385,12 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
*
* Note we modify the per-column expression lists in-place.
*/
collations = NIL;
for (i = 0; i < sublist_length; i++)
{
Oid coltype;
int32 coltypmod = -1;
Oid colcoll;
bool first = true;
coltype = select_common_type(pstate, colexprs[i], "VALUES", NULL);
@@ -1386,11 +1400,24 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
col = coerce_to_common_type(pstate, col, coltype, "VALUES");
lfirst(lc) = (void *) col;
if (first)
{
coltypmod = exprTypmod(col);
first = false;
}
else
{
/* As soon as we see a non-matching typmod, fall back to -1 */
if (coltypmod >= 0 && coltypmod != exprTypmod(col))
coltypmod = -1;
}
}
colcoll = select_common_collation(pstate, colexprs[i], true);
collations = lappend_oid(collations, colcoll);
coltypes = lappend_oid(coltypes, coltype);
coltypmods = lappend_int(coltypmods, coltypmod);
colcollations = lappend_oid(colcollations, colcoll);
}
/*
@@ -1432,7 +1459,8 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
/*
* Generate the VALUES RTE
*/
rte = addRangeTableEntryForValues(pstate, exprsLists, collations,
rte = addRangeTableEntryForValues(pstate, exprsLists,
coltypes, coltypmods, colcollations,
NULL, lateral, true);
addRTEtoQuery(pstate, rte, true, true, true);