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Add select_common_typmod()

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This accompanies select_common_type() and select_common_collation().
Typmods were previously combined using hand-coded logic in several
places.  The logic in select_common_typmod() isn't very exciting, but
it makes the code more compact and readable in a few locations, and in
the future we can perhaps do more complicated things if desired.

As a small enhancement, the type unification of the direct and
aggregate arguments of hypothetical-set aggregates now unifies the
typmod as well using this new function, instead of just dropping it.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://www.postgresql.org/message-id/flat/97df3af9-8b5e-fb7f-a029-3eb7e80d7af9@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2020-10-27 17:39:23 +01:00
parent 59ab4ac324
commit f893e68d76
5 changed files with 57 additions and 39 deletions
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26
src/backend/parser/analyze.c
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@@ -1434,9 +1434,8 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
for (i = 0; i < sublist_length; i++)
{
Oid coltype;
int32 coltypmod = -1;
int32 coltypmod;
Oid colcoll;
bool first = true;
coltype = select_common_type(pstate, colexprs[i], "VALUES", NULL);
@@ -1446,19 +1445,9 @@ 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;
}
}
coltypmod = select_common_typmod(pstate, colexprs[i], coltype);
colcoll = select_common_collation(pstate, colexprs[i], true);
coltypes = lappend_oid(coltypes, coltype);
@@ -2020,8 +2009,6 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
Node *rcolnode = (Node *) rtle->expr;
Oid lcoltype = exprType(lcolnode);
Oid rcoltype = exprType(rcolnode);
int32 lcoltypmod = exprTypmod(lcolnode);
int32 rcoltypmod = exprTypmod(rcolnode);
Node *bestexpr;
int bestlocation;
Oid rescoltype;
@@ -2034,11 +2021,6 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
context,
&bestexpr);
bestlocation = exprLocation(bestexpr);
/* if same type and same typmod, use typmod; else default */
if (lcoltype == rcoltype && lcoltypmod == rcoltypmod)
rescoltypmod = lcoltypmod;
else
rescoltypmod = -1;
/*
* Verify the coercions are actually possible. If not, we'd fail
@@ -2089,6 +2071,10 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
rtle->expr = (Expr *) rcolnode;
}
rescoltypmod = select_common_typmod(pstate,
list_make2(lcolnode, rcolnode),
rescoltype);
/*
* Select common collation. A common collation is required for
* all set operators except UNION ALL; see SQL:2008 7.13 <query