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MDEV-14907 FEDERATEDX doesn't respect DISTINCT

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Federated and Federatex cannot be used with ROR scans

Federated::position() and Federatex::position() is storing in 'ref' a
pointer into a local result set buffer. This means that one cannot
compare 'ref' from different handler instances to see if they point to the
same physical record.

This bug caused federated.federatedx to return wrong results when the
optimizer tried to use index_merge to resolve some queries.

Fixed by introducing table flag HA_NON_COMPARABLE_ROWID and using this
with the above handlers.

Todo:
- Fix multi_delete(), multi_update and read_records() to use primary key
  instead of 'ref' if case HA_NON_COMPARABLE_ROWID is set. The current
  code only works if we have only one range (like table scan) for the
  tables that will be updated in the second pass.
- Enable DBUG_ASSERT() in ha_federated::cmp_ref() and
  ha_federatedx::cmp_ref().
This commit is contained in:
Monty 2021-12-27 18:51:00 +02:00
parent a48d2ec866
commit c18896f9c1
7 changed files with 138 additions and 3 deletions
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52
mysql-test/suite/federated/optimizer.result Normal file
View file

@ -0,0 +1,52 @@
connect master,127.0.0.1,root,,test,$MASTER_MYPORT,;
connect slave,127.0.0.1,root,,test,$SLAVE_MYPORT,;
connection master;
CREATE DATABASE federated;
connection slave;
CREATE DATABASE federated;
connection default;
#
# MDEV-14907 FEDERATEDX doesn't respect DISTINCT
#
CREATE TABLE t1 (
`foo_id` bigint(20) unsigned NOT NULL,
`foo_name` varchar(255) DEFAULT NULL,
`parent_foo_id` bigint(20) unsigned DEFAULT NULL,
PRIMARY KEY (`foo_id`),
KEY `foo_name` (`foo_name`),
KEY `parent_foo_id` (`parent_foo_id`)
) DEFAULT CHARSET=utf8;
CREATE TABLE `fed_t1` ENGINE=FEDERATED DEFAULT CHARSET=utf8 CONNECTION='mysql://root@127.0.0.1:MASTER_PORT/test/t1';
INSERT INTO t1 VALUES (968903, 'STRING - 0', 822857);
INSERT INTO t1 VALUES (968953, 'STRING - 1', 822857);
INSERT INTO t1 VALUES (971603, 'STRING - 2', 822857);
INSERT INTO t1 VALUES (971803, 'STRING - 3', 822857);
INSERT INTO t1 VALUES (975103, 'STRING - 4', 822857);
INSERT INTO t1 VALUES (822857, 'STRING', NULL);
select foo_id,parent_foo_id,foo_name from t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
foo_id parent_foo_id foo_name
968903 822857 STRING - 0
968953 822857 STRING - 1
971603 822857 STRING - 2
971803 822857 STRING - 3
975103 822857 STRING - 4
822857 NULL STRING
explain
select foo_id,parent_foo_id,foo_name from fed_t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE fed_t1 ALL foo_name,parent_foo_id NULL NULL NULL 6 Using where
select foo_id,parent_foo_id,foo_name from fed_t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
foo_id parent_foo_id foo_name
968903 822857 STRING - 0
968953 822857 STRING - 1
971603 822857 STRING - 2
971803 822857 STRING - 3
975103 822857 STRING - 4
822857 NULL STRING
DROP TABLE fed_t1, t1;
connection master;
DROP TABLE IF EXISTS federated.t1;
DROP DATABASE IF EXISTS federated;
connection slave;
DROP TABLE IF EXISTS federated.t1;
DROP DATABASE IF EXISTS federated;

39
mysql-test/suite/federated/optimizer.test Normal file
View file

@ -0,0 +1,39 @@
#
#Test optimizer flags related to federated tables
#
--source have_federatedx.inc
--source include/federated.inc
connection default;
--echo #
--echo # MDEV-14907 FEDERATEDX doesn't respect DISTINCT
--echo #
CREATE TABLE t1 (
`foo_id` bigint(20) unsigned NOT NULL,
`foo_name` varchar(255) DEFAULT NULL,
`parent_foo_id` bigint(20) unsigned DEFAULT NULL,
PRIMARY KEY (`foo_id`),
KEY `foo_name` (`foo_name`),
KEY `parent_foo_id` (`parent_foo_id`)
) DEFAULT CHARSET=utf8;
--replace_result $MASTER_MYPORT MASTER_PORT
eval CREATE TABLE `fed_t1` ENGINE=FEDERATED DEFAULT CHARSET=utf8 CONNECTION='mysql://root@127.0.0.1:$MASTER_MYPORT/test/t1';
INSERT INTO t1 VALUES (968903, 'STRING - 0', 822857);
INSERT INTO t1 VALUES (968953, 'STRING - 1', 822857);
INSERT INTO t1 VALUES (971603, 'STRING - 2', 822857);
INSERT INTO t1 VALUES (971803, 'STRING - 3', 822857);
INSERT INTO t1 VALUES (975103, 'STRING - 4', 822857);
INSERT INTO t1 VALUES (822857, 'STRING', NULL);
select foo_id,parent_foo_id,foo_name from t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
explain
select foo_id,parent_foo_id,foo_name from fed_t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
select foo_id,parent_foo_id,foo_name from fed_t1 where parent_foo_id = 822857 or foo_name like 'STRING%';
DROP TABLE fed_t1, t1;
source include/federated_cleanup.inc;

12
sql/handler.h
View file

@ -329,7 +329,17 @@ enum enum_alter_inplace_result {
/* Support native hash index */
#define HA_CAN_HASH_KEYS (1ULL << 58)
#define HA_LAST_TABLE_FLAG HA_CAN_HASH_KEYS
/*
Rowid's are not comparable. This is set if the rowid is unique to the
current open handler, like it is with federated where the rowid is a
pointer to a local result set buffer. The effect of having this set is
that the optimizer will not consirer the following optimizations for
the table:
ror scans or filtering
*/
#define HA_NON_COMPARABLE_ROWID (1ULL << 59)
#define HA_LAST_TABLE_FLAG HA_NON_COMPARABLE_ROWID
/* bits in index_flags(index_number) for what you can do with index */
#define HA_READ_NEXT 1 /* TODO really use this flag */

5
sql/opt_range.cc
View file

@ -2678,6 +2678,8 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
records= head->stat_records();
if (!records)
records++; /* purecov: inspected */
if (head->file->ha_table_flags() & HA_NON_COMPARABLE_ROWID)
only_single_index_range_scan= 1;
if (head->force_index || force_quick_range)
scan_time= read_time= DBL_MAX;
@ -11312,6 +11314,9 @@ static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts)
table_key->user_defined_key_parts);
uint pk_number;
if (param->table->file->ha_table_flags() & HA_NON_COMPARABLE_ROWID)
return false;
for (KEY_PART_INFO *kp= table_key->key_part; kp < key_part; kp++)
{
uint16 fieldnr= param->table->key_info[keynr].

3
sql/rowid_filter.cc
View file

@ -347,6 +347,9 @@ void TABLE::init_cost_info_for_usable_range_rowid_filters(THD *thd)
usable_range_filter_keys.clear_all();
key_map::Iterator it(quick_keys);
if (file->ha_table_flags() & HA_NON_COMPARABLE_ROWID)
return; // Cannot create filtering
/*
From all indexes that can be used for range accesses select only such that
- range filter pushdown is supported by the engine for them (1)

15
storage/federated/ha_federated.h
View file

@ -146,7 +146,7 @@ public:
HA_NO_PREFIX_CHAR_KEYS | HA_PRIMARY_KEY_REQUIRED_FOR_DELETE |
HA_NO_TRANSACTIONS /* until fixed by WL#2952 */ |
HA_PARTIAL_COLUMN_READ | HA_NULL_IN_KEY |
HA_CAN_ONLINE_BACKUPS |
HA_CAN_ONLINE_BACKUPS | HA_NON_COMPARABLE_ROWID |
HA_CAN_REPAIR);
}
/*
@ -238,6 +238,19 @@ public:
int rnd_next_int(uchar *buf);
int rnd_pos(uchar *buf, uchar *pos); //required
void position(const uchar *record); //required
/*
A ref is a pointer inside a local buffer. It is not comparable to
other ref's. This is never called as HA_NON_COMPARABLE_ROWID is set.
*/
int cmp_ref(const uchar *ref1, const uchar *ref2)
{
#ifdef NOT_YET
DBUG_ASSERT(0);
return 0;
#else
return handler::cmp_ref(ref1,ref2); /* Works if table scan is used */
#endif
}
int info(uint); //required
int extra(ha_extra_function operation);

15
storage/federatedx/ha_federatedx.h
View file

@ -338,7 +338,7 @@ public:
| HA_REC_NOT_IN_SEQ | HA_AUTO_PART_KEY | HA_CAN_INDEX_BLOBS |
HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE | HA_CAN_REPAIR |
HA_PRIMARY_KEY_REQUIRED_FOR_DELETE | HA_CAN_ONLINE_BACKUPS |
HA_PARTIAL_COLUMN_READ | HA_NULL_IN_KEY);
HA_PARTIAL_COLUMN_READ | HA_NULL_IN_KEY | HA_NON_COMPARABLE_ROWID);
}
/*
This is a bitmap of flags that says how the storage engine
@ -428,6 +428,19 @@ public:
int rnd_next(uchar *buf); //required
int rnd_pos(uchar *buf, uchar *pos); //required
void position(const uchar *record); //required
/*
A ref is a pointer inside a local buffer. It is not comparable to
other ref's. This is never called as HA_NON_COMPARABLE_ROWID is set.
*/
int cmp_ref(const uchar *ref1, const uchar *ref2)
{
#ifdef NOT_YET
DBUG_ASSERT(0);
return 0;
#else
return handler::cmp_ref(ref1,ref2); /* Works if table scan is used */
#endif
}
int info(uint); //required
int extra(ha_extra_function operation);