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revert: Transform OR clauses to ANY expression

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This commit reverts 72bd38cc99 due to implementation and design issues.

Reported-by: Tom Lane
Discussion: https://postgr.es/m/3604469.1712628736%40sss.pgh.pa.us
This commit is contained in:
Alexander Korotkov
2024-04-10 02:07:34 +03:00
parent 5a15bdea3b
commit ff9f72c68f
14 changed files with 20 additions and 786 deletions
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27
src/backend/nodes/queryjumblefuncs.c
View File

@ -141,33 +141,6 @@ JumbleQuery(Query *query)
return jstate;
}
JumbleState *
JumbleExpr(Expr *expr, uint64 *exprId)
{
JumbleState *jstate = NULL;
Assert(exprId != NULL);
jstate = (JumbleState *) palloc(sizeof(JumbleState));
/* Set up workspace for query jumbling */
jstate->jumble = (unsigned char *) palloc(JUMBLE_SIZE);
jstate->jumble_len = 0;
jstate->clocations_buf_size = 32;
jstate->clocations = (LocationLen *)
palloc(jstate->clocations_buf_size * sizeof(LocationLen));
jstate->clocations_count = 0;
jstate->highest_extern_param_id = 0;
/* Compute query ID */
_jumbleNode(jstate, (Node *) expr);
*exprId = DatumGetUInt64(hash_any_extended(jstate->jumble,
jstate->jumble_len,
0));
return jstate;
}
/*
* Enables query identifier computation.
*

400
src/backend/optimizer/prep/prepqual.c
View File

@ -31,25 +31,16 @@
#include "postgres.h"
#include "catalog/namespace.h"
#include "catalog/pg_operator.h"
#include "common/hashfn.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/queryjumble.h"
#include "optimizer/optimizer.h"
#include "parser/parse_coerce.h"
#include "parser/parse_oper.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
int or_to_any_transform_limit = 5;
static List *pull_ands(List *andlist);
static List *pull_ors(List *orlist);
static Expr *find_duplicate_ors(Expr *qual, bool is_check);
static Expr *process_duplicate_ors(List *orlist);
static List *transform_or_to_any(List *orlist);
/*
@ -275,376 +266,6 @@ negate_clause(Node *node)
return (Node *) make_notclause((Expr *) node);
}
/*
* The key for grouping similar operator expressions in transform_or_to_any().
*/
typedef struct OrClauseGroupKey
{
/* We need this to put this structure into list together with other nodes */
NodeTag type;
/* The expression of the variable side of operator */
Expr *expr;
/* The operator of the operator expression */
Oid opno;
/* The collation of the operator expression */
Oid inputcollid;
/* The type of constant side of operator */
Oid consttype;
} OrClauseGroupKey;
/*
* The group of similar operator expressions in transform_or_to_any().
*/
typedef struct OrClauseGroupEntry
{
OrClauseGroupKey key;
/* The list of constant sides of operators */
List *consts;
/*
* List of source expressions. We need this for convenience in case we
* will give up on transformation.
*/
List *exprs;
} OrClauseGroupEntry;
/*
* The hash function for OrClauseGroupKey.
*/
static uint32
orclause_hash(const void *data, Size keysize)
{
OrClauseGroupKey *key = (OrClauseGroupKey *) data;
uint64 exprHash;
Assert(keysize == sizeof(OrClauseGroupKey));
Assert(IsA(data, Invalid));
(void) JumbleExpr(key->expr, &exprHash);
return hash_combine((uint32) exprHash,
hash_combine((uint32) key->opno,
hash_combine((uint32) key->consttype,
(uint32) key->inputcollid)));
}
/*
* The copy function for OrClauseGroupKey.
*/
static void *
orclause_keycopy(void *dest, const void *src, Size keysize)
{
OrClauseGroupKey *src_key = (OrClauseGroupKey *) src;
OrClauseGroupKey *dst_key = (OrClauseGroupKey *) dest;
Assert(sizeof(OrClauseGroupKey) == keysize);
Assert(IsA(src, Invalid));
dst_key->type = T_Invalid;
dst_key->expr = src_key->expr;
dst_key->opno = src_key->opno;
dst_key->consttype = src_key->consttype;
dst_key->inputcollid = src_key->inputcollid;
return dst_key;
}
/*
* The equality function for OrClauseGroupKey.
*/
static int
orclause_match(const void *data1, const void *data2, Size keysize)
{
OrClauseGroupKey *key1 = (OrClauseGroupKey *) data1;
OrClauseGroupKey *key2 = (OrClauseGroupKey *) data2;
Assert(sizeof(OrClauseGroupKey) == keysize);
Assert(IsA(key1, Invalid));
Assert(IsA(key2, Invalid));
if (key1->opno == key2->opno &&
key1->consttype == key2->consttype &&
key1->inputcollid == key2->inputcollid &&
equal(key1->expr, key2->expr))
return 0;
return 1;
}
/*
* transform_or_to_any -
* Discover the args of an OR expression and try to group similar OR
* expressions to SAOP expressions.
*
* This transformation groups two-sided equality expression. One side of
* such an expression must be a plain constant or constant expression. The
* other side must be a variable expression without volatile functions.
* To group quals, opno, inputcollid of variable expression, and type of
* constant expression must be equal too.
*
* The grouping technique is based on the equivalence of variable sides of
* the expression: using exprId and equal() routine, it groups constant sides
* of similar clauses into an array. After the grouping procedure, each
* couple ('variable expression' and 'constant array') forms a new SAOP
* operation, which is added to the args list of the returning expression.
*/
static List *
transform_or_to_any(List *orlist)
{
List *neworlist = NIL;
List *entries = NIL;
ListCell *lc;
HASHCTL info;
HTAB *or_group_htab = NULL;
int len_ors = list_length(orlist);
OrClauseGroupEntry *entry = NULL;
Assert(or_to_any_transform_limit >= 0 &&
len_ors >= or_to_any_transform_limit);
MemSet(&info, 0, sizeof(info));
info.keysize = sizeof(OrClauseGroupKey);
info.entrysize = sizeof(OrClauseGroupEntry);
info.hash = orclause_hash;
info.keycopy = orclause_keycopy;
info.match = orclause_match;
or_group_htab = hash_create("OR Groups",
len_ors,
&info,
HASH_ELEM | HASH_FUNCTION | HASH_COMPARE | HASH_KEYCOPY);
foreach(lc, orlist)
{
Node *orqual = lfirst(lc);
Node *const_expr;
Node *nconst_expr;
OrClauseGroupKey hashkey;
bool found;
Oid opno;
Oid consttype;
Node *leftop,
*rightop;
if (!IsA(orqual, OpExpr))
{
entries = lappend(entries, orqual);
continue;
}
opno = ((OpExpr *) orqual)->opno;
if (get_op_rettype(opno) != BOOLOID)
{
/* Only operator returning boolean suits OR -> ANY transformation */
entries = lappend(entries, orqual);
continue;
}
/*
* Detect the constant side of the clause. Recall non-constant
* expression can be made not only with Vars, but also with Params,
* which is not bonded with any relation. Thus, we detect the const
* side - if another side is constant too, the orqual couldn't be an
* OpExpr. Get pointers to constant and expression sides of the qual.
*/
leftop = get_leftop(orqual);
if (IsA(leftop, RelabelType))
leftop = (Node *) ((RelabelType *) leftop)->arg;
rightop = get_rightop(orqual);
if (IsA(rightop, RelabelType))
rightop = (Node *) ((RelabelType *) rightop)->arg;
if (IsA(leftop, Const))
{
opno = get_commutator(opno);
if (!OidIsValid(opno))
{
/* commutator doesn't exist, we can't reverse the order */
entries = lappend(entries, orqual);
continue;
}
nconst_expr = get_rightop(orqual);
const_expr = get_leftop(orqual);
}
else if (IsA(rightop, Const))
{
const_expr = get_rightop(orqual);
nconst_expr = get_leftop(orqual);
}
else
{
entries = lappend(entries, orqual);
continue;
}
/*
* Forbid transformation for composite types, records, and volatile
* expressions.
*/
consttype = exprType(const_expr);
if (type_is_rowtype(exprType(const_expr)) ||
type_is_rowtype(consttype) ||
contain_volatile_functions((Node *) nconst_expr))
{
entries = lappend(entries, orqual);
continue;
}
/*
* At this point we definitely have a transformable clause. Classify
* it and add into specific group of clauses, or create new group.
*/
hashkey.type = T_Invalid;
hashkey.expr = (Expr *) nconst_expr;
hashkey.opno = opno;
hashkey.consttype = consttype;
hashkey.inputcollid = exprCollation(const_expr);
entry = hash_search(or_group_htab, &hashkey, HASH_ENTER, &found);
if (unlikely(found))
{
entry->consts = lappend(entry->consts, const_expr);
entry->exprs = lappend(entry->exprs, orqual);
}
else
{
entry->consts = list_make1(const_expr);
entry->exprs = list_make1(orqual);
/*
* Add the entry to the list. It is needed exclusively to manage
* the problem with the order of transformed clauses in explain.
* Hash value can depend on the platform and version. Hence,
* sequental scan of the hash table would prone to change the
* order of clauses in lists and, as a result, break regression
* tests accidentially.
*/
entries = lappend(entries, entry);
}
}
/* Let's convert each group of clauses to an ANY expression. */
/*
* Go through the list of groups and convert each, where number of consts
* more than 1. trivial groups move to OR-list again
*/
foreach(lc, entries)
{
Oid scalar_type;
Oid array_type;
if (!IsA(lfirst(lc), Invalid))
{
neworlist = lappend(neworlist, lfirst(lc));
continue;
}
entry = (OrClauseGroupEntry *) lfirst(lc);
Assert(list_length(entry->consts) > 0);
Assert(list_length(entry->exprs) == list_length(entry->consts));
if (list_length(entry->consts) == 1)
{
/*
* Only one element returns origin expression into the BoolExpr
* args list unchanged.
*/
list_free(entry->consts);
neworlist = list_concat(neworlist, entry->exprs);
continue;
}
/*
* Do the transformation.
*/
scalar_type = entry->key.consttype;
array_type = OidIsValid(scalar_type) ? get_array_type(scalar_type) :
InvalidOid;
if (OidIsValid(array_type))
{
/*
* OK: coerce all the right-hand non-Var inputs to the common type
* and build an ArrayExpr for them.
*/
List *aexprs = NIL;
ArrayExpr *newa = NULL;
ScalarArrayOpExpr *saopexpr = NULL;
HeapTuple opertup;
Form_pg_operator operform;
List *namelist = NIL;
ListCell *lc2;
foreach(lc2, entry->consts)
{
Node *node = (Node *) lfirst(lc2);
node = coerce_to_common_type(NULL, node, scalar_type,
"OR ANY Transformation");
aexprs = lappend(aexprs, node);
}
newa = makeNode(ArrayExpr);
/* array_collid will be set by parse_collate.c */
newa->element_typeid = scalar_type;
newa->array_typeid = array_type;
newa->multidims = false;
newa->elements = aexprs;
newa->location = -1;
/*
* Try to cast this expression to Const. Due to current strict
* transformation rules it should be done [almost] every time.
*/
newa = (ArrayExpr *) eval_const_expressions(NULL, (Node *) newa);
opertup = SearchSysCache1(OPEROID,
ObjectIdGetDatum(entry->key.opno));
if (!HeapTupleIsValid(opertup))
elog(ERROR, "cache lookup failed for operator %u",
entry->key.opno);
operform = (Form_pg_operator) GETSTRUCT(opertup);
if (!OperatorIsVisible(entry->key.opno))
namelist = lappend(namelist, makeString(get_namespace_name(operform->oprnamespace)));
namelist = lappend(namelist, makeString(pstrdup(NameStr(operform->oprname))));
ReleaseSysCache(opertup);
saopexpr =
(ScalarArrayOpExpr *)
make_scalar_array_op(NULL,
namelist,
true,
(Node *) entry->key.expr,
(Node *) newa,
-1);
saopexpr->inputcollid = entry->key.inputcollid;
neworlist = lappend(neworlist, (void *) saopexpr);
}
else
{
/*
* If the const node's (right side of operator expression) type
* don't have “true” array type, then we cannnot do the
* transformation. We simply concatenate the expression node.
*/
list_free(entry->consts);
neworlist = list_concat(neworlist, entry->exprs);
}
}
hash_destroy(or_group_htab);
list_free(entries);
/* One more trick: assemble correct clause */
return neworlist;
}
/*
* canonicalize_qual
@ -980,22 +601,10 @@ process_duplicate_ors(List *orlist)
}
/*
* If no winners, we can't do OR-to-ANY transformation.
* If no winners, we can't transform the OR
*/
if (winners == NIL)
{
/*
* Make an attempt to group similar OR clauses into SAOP if the list
* is lengthy enough.
*/
if (or_to_any_transform_limit >= 0 &&
list_length(orlist) >= or_to_any_transform_limit)
orlist = transform_or_to_any(orlist);
/* Transformation could group all OR clauses to a single SAOP */
return (list_length(orlist) == 1) ?
(Expr *) linitial(orlist) : make_orclause(orlist);
}
return make_orclause(orlist);
/*
* Generate new OR list consisting of the remaining sub-clauses.
@ -1042,11 +651,6 @@ process_duplicate_ors(List *orlist)
}
}
/* Make an attempt to group similar OR clauses into ANY operation */
if (or_to_any_transform_limit >= 0 &&
list_length(neworlist) >= or_to_any_transform_limit)
neworlist = transform_or_to_any(neworlist);
/*
* Append reduced OR to the winners list, if it's not degenerate, handling
* the special case of one element correctly (can that really happen?).

12
src/backend/utils/misc/guc_tables.c
View File

@ -3668,18 +3668,6 @@ struct config_int ConfigureNamesInt[] =
NULL, NULL, NULL
},
{
{"or_to_any_transform_limit", PGC_USERSET, QUERY_TUNING_OTHER,
gettext_noop("Sets the minimum length of the list of OR clauses to attempt the OR-to-ANY transformation."),
gettext_noop("Once the limit is reached, the planner will try to replace expression like "
"'x=c1 OR x=c2 ..' to the expression 'x = ANY(ARRAY[c1,c2,..])'"),
GUC_EXPLAIN
},
&or_to_any_transform_limit,
5, -1, INT_MAX,
NULL, NULL, NULL
},
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL

1
src/backend/utils/misc/postgresql.conf.sample
View File

@ -392,7 +392,6 @@
# - Planner Method Configuration -
#enable_async_append = on
#or_to_any_transform_limit = 5
#enable_bitmapscan = on
#enable_gathermerge = on
#enable_hashagg = on