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Fix incorrect hash equality operator bug in Memoize

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In v14, because we don't have a field in RestrictInfo to cache both the
left and right type's hash equality operator, we just restrict the scope
of Memoize to only when the left and right types of a RestrictInfo are the
same.

In master we add another field to RestrictInfo and cache both hash
equality operators.

Reported-by: Jaime Casanova
Author: David Rowley
Discussion: https://postgr.es/m/20210929185544.GB24346%40ahch-to
Backpatch-through: 14
This commit is contained in:
David Rowley
2021-11-08 14:40:33 +13:00
parent e2fbb88372
commit 39a3105678
6 changed files with 54 additions and 22 deletions
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31
src/backend/optimizer/path/joinpath.c
View File

@@ -394,9 +394,15 @@ paraminfo_get_equal_hashops(PlannerInfo *root, ParamPathInfo *param_info,
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
OpExpr *opexpr;
Node *expr;
Oid hasheqoperator;
/* can't use a memoize node without a valid hash equals operator */
if (!OidIsValid(rinfo->hasheqoperator) ||
opexpr = (OpExpr *) rinfo->clause;
/*
* Bail if the rinfo is not compatible. We need a join OpExpr
* with 2 args.
*/
if (!IsA(opexpr, OpExpr) || list_length(opexpr->args) != 2 ||
!clause_sides_match_join(rinfo, outerrel, innerrel))
{
list_free(*operators);
@@ -404,17 +410,26 @@ paraminfo_get_equal_hashops(PlannerInfo *root, ParamPathInfo *param_info,
return false;
}
/*
* We already checked that this is an OpExpr with 2 args when
* setting hasheqoperator.
*/
opexpr = (OpExpr *) rinfo->clause;
if (rinfo->outer_is_left)
{
expr = (Node *) linitial(opexpr->args);
hasheqoperator = rinfo->left_hasheqoperator;
}
else
{
expr = (Node *) lsecond(opexpr->args);
hasheqoperator = rinfo->right_hasheqoperator;
}
*operators = lappend_oid(*operators, rinfo->hasheqoperator);
/* can't do memoize if we can't hash the outer type */
if (!OidIsValid(hasheqoperator))
{
list_free(*operators);
list_free(*param_exprs);
return false;
}
*operators = lappend_oid(*operators, hasheqoperator);
*param_exprs = lappend(*param_exprs, expr);
}
}

28
src/backend/optimizer/plan/initsplan.c
View File

@@ -2711,15 +2711,16 @@ check_hashjoinable(RestrictInfo *restrictinfo)
/*
* check_memoizable
* If the restrictinfo's clause is suitable to be used for a Memoize node,
* set the hasheqoperator to the hash equality operator that will be needed
* during caching.
* set the lefthasheqoperator and righthasheqoperator to the hash equality
* operator that will be needed during caching.
*/
static void
check_memoizable(RestrictInfo *restrictinfo)
{
TypeCacheEntry *typentry;
Expr *clause = restrictinfo->clause;
Node *leftarg;
Oid lefttype;
Oid righttype;
if (restrictinfo->pseudoconstant)
return;
@@ -2728,13 +2729,24 @@ check_memoizable(RestrictInfo *restrictinfo)
if (list_length(((OpExpr *) clause)->args) != 2)
return;
leftarg = linitial(((OpExpr *) clause)->args);
lefttype = exprType(linitial(((OpExpr *) clause)->args));
typentry = lookup_type_cache(exprType(leftarg), TYPECACHE_HASH_PROC |
typentry = lookup_type_cache(lefttype, TYPECACHE_HASH_PROC |
TYPECACHE_EQ_OPR);
if (!OidIsValid(typentry->hash_proc) || !OidIsValid(typentry->eq_opr))
return;
if (OidIsValid(typentry->hash_proc) && OidIsValid(typentry->eq_opr))
restrictinfo->left_hasheqoperator = typentry->eq_opr;
restrictinfo->hasheqoperator = typentry->eq_opr;
righttype = exprType(lsecond(((OpExpr *) clause)->args));
/*
* Lookup the right type, unless it's the same as the left type, in which
* case typentry is already pointing to the required TypeCacheEntry.
*/
if (lefttype != righttype)
typentry = lookup_type_cache(righttype, TYPECACHE_HASH_PROC |
TYPECACHE_EQ_OPR);
if (OidIsValid(typentry->hash_proc) && OidIsValid(typentry->eq_opr))
restrictinfo->right_hasheqoperator = typentry->eq_opr;
}

6
src/backend/optimizer/util/restrictinfo.c
View File

@@ -217,7 +217,8 @@ make_restrictinfo_internal(PlannerInfo *root,
restrictinfo->left_mcvfreq = -1;
restrictinfo->right_mcvfreq = -1;
restrictinfo->hasheqoperator = InvalidOid;
restrictinfo->left_hasheqoperator = InvalidOid;
restrictinfo->right_hasheqoperator = InvalidOid;
return restrictinfo;
}
@@ -368,7 +369,8 @@ commute_restrictinfo(RestrictInfo *rinfo, Oid comm_op)
result->right_bucketsize = rinfo->left_bucketsize;
result->left_mcvfreq = rinfo->right_mcvfreq;
result->right_mcvfreq = rinfo->left_mcvfreq;
result->hasheqoperator = InvalidOid;
result->left_hasheqoperator = InvalidOid;
result->right_hasheqoperator = InvalidOid;
return result;
}