diff --git a/mysql-test/r/bug41756.result b/mysql-test/r/bug41756.result new file mode 100644 index 00000000000..7c97b2ac690 --- /dev/null +++ b/mysql-test/r/bug41756.result @@ -0,0 +1,277 @@ +# +# Bug#41756 Strange error messages about locks from InnoDB +# +drop table if exists t1; +# In the default transaction isolation mode, and/or with +# innodb_locks_unsafe_for_binlog=OFF, handler::unlock_row() +# in InnoDB does nothing. +# Thus in order to reproduce the condition that led to the +# warning, one needs to relax isolation by either +# setting a weaker tx_isolation value, or by turning on +# the unsafe replication switch. +# For testing purposes, choose to tweak the isolation level, +# since it's settable at runtime, unlike +# innodb_locks_unsafe_for_binlog, which is +# only a command-line switch. +# +set @@session.tx_isolation="read-committed"; +# Prepare data. We need a table with a unique index, +# for join_read_key to be used. The other column +# allows to control what passes WHERE clause filter. +create table t1 (a int primary key, b int) engine=innodb; +# Let's make sure t1 has sufficient amount of rows +# to exclude JT_ALL access method when reading it, +# i.e. make sure that JT_EQ_REF(a) is always preferred. +insert into t1 values (1,1), (2,null), (3,1), (4,1), +(5,1), (6,1), (7,1), (8,1), (9,1), (10,1), +(11,1), (12,1); +# +# Demonstrate that for the SELECT statement +# used later in the test JT_EQ_REF access method is used. +# +explain +select 1 from t1 natural join (select 2 as a, 1 as b union all +select 2 as a, 2 as b) as t2 for update; +id 1 +select_type PRIMARY +table +type ALL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows 2 +Extra +id 1 +select_type PRIMARY +table t1 +type eq_ref +possible_keys PRIMARY +key PRIMARY +key_len 4 +ref t2.a +rows 1 +Extra Using where +id 2 +select_type DERIVED +table NULL +type NULL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra No tables used +id 3 +select_type UNION +table NULL +type NULL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra No tables used +id NULL +select_type UNION RESULT +table +type ALL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra +# +# Demonstrate that the reported SELECT statement +# no longer produces warnings. +# +select 1 from t1 natural join (select 2 as a, 1 as b union all +select 2 as a, 2 as b) as t2 for update; +1 +commit; +# +# Demonstrate that due to lack of inter-sweep "reset" function, +# we keep some non-matching records locked, even though we know +# we could unlock them. +# To do that, show that if there is only one distinct value +# for a in t2 (a=2), we will keep record (2,null) in t1 locked. +# But if we add another value for "a" to t2, say 6, +# join_read_key cache will be pruned at least once, +# and thus record (2, null) in t1 will get unlocked. +# +begin; +select 1 from t1 natural join (select 2 as a, 1 as b union all +select 2 as a, 2 as b) as t2 for update; +1 +# +# Switching to connection con1 +# We should be able to delete all records from t1 except (2, null), +# since they were not locked. +begin; +delete from t1 where a in (1,3,4); +delete from t1 where a in (5,6,7); +delete from t1 where a in (8,9,10); +delete from t1 where a in (11,12); +# +# Record (2, null) is locked. This is actually unnecessary, +# because the previous select returned no rows. +# Just demonstrate the effect. +# +delete from t1; +ERROR HY000: Lock wait timeout exceeded; try restarting transaction +rollback; +# +# Switching to connection default +# +# Show that the original contents of t1 is intact: +select * from t1; +a b +1 1 +2 NULL +3 1 +4 1 +5 1 +6 1 +7 1 +8 1 +9 1 +10 1 +11 1 +12 1 +commit; +# +# Have a one more record in t2 to show that +# if join_read_key cache is purned, the current +# row under the cursor is unlocked (provided, this row didn't +# match the partial WHERE clause, of course). +# Sic: the result of this test dependent on the order of retrieval +# of records --echo # from the derived table, if ! +# We use DELETE to disable the JOIN CACHE. This DELETE modifies no +# records. It also should leave no InnoDB row locks. +# +begin; +delete t1.* from t1 natural join (select 2 as a, 2 as b union all +select 0 as a, 0 as b) as t2; +# Demonstrate that nothing was deleted form t1 +select * from t1; +a b +1 1 +2 NULL +3 1 +4 1 +5 1 +6 1 +7 1 +8 1 +9 1 +10 1 +11 1 +12 1 +# +# Switching to connection con1 +begin; +# Since there is another distinct record in the derived table +# the previous matching record in t1 -- (2,null) -- was unlocked. +delete from t1; +# We will need the contents of the table again. +rollback; +select * from t1; +a b +1 1 +2 NULL +3 1 +4 1 +5 1 +6 1 +7 1 +8 1 +9 1 +10 1 +11 1 +12 1 +commit; +# +# Switching to connection default +commit; +begin; +# +# Before this patch, we could wrongly unlock a record +# that was cached and later used in a join. Demonstrate that +# this is no longer the case. +# Sic: this test is also order-dependent (i.e. the +# the bug would show up only if the first record in the union +# is retreived and processed first. +# +# Verify that JT_EQ_REF is used. +explain +select 1 from t1 natural join (select 3 as a, 3 as b union all +select 3 as a, 1 as b) as t2 for update; +id 1 +select_type PRIMARY +table t1 +type ALL +possible_keys PRIMARY +key NULL +key_len NULL +ref NULL +rows 1 +Extra +id 1 +select_type PRIMARY +table +type ALL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows 2 +Extra Using where +id 2 +select_type DERIVED +table NULL +type NULL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra No tables used +id 3 +select_type UNION +table NULL +type NULL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra No tables used +id NULL +select_type UNION RESULT +table +type ALL +possible_keys NULL +key NULL +key_len NULL +ref NULL +rows NULL +Extra +# Lock the record. +select 1 from t1 natural join (select 3 as a, 3 as b union all +select 3 as a, 2 as b) as t2 for update; +1 +# Switching to connection con1 +# +# We should not be able to delete record (3,1) from t1, +# (previously it was possible). +# +delete from t1 where a=3; +ERROR HY000: Lock wait timeout exceeded; try restarting transaction +# Switching to connection default +commit; +set @@session.tx_isolation=default; +drop table t1; +# +# End of 5.0 tests +# diff --git a/mysql-test/t/bug41756-master.opt b/mysql-test/t/bug41756-master.opt new file mode 100644 index 00000000000..50c7c0e0ffa --- /dev/null +++ b/mysql-test/t/bug41756-master.opt @@ -0,0 +1,2 @@ +--innodb_lock_wait_timeout=1 +--innodb-locks-unsafe-for-binlog diff --git a/mysql-test/t/bug41756.test b/mysql-test/t/bug41756.test new file mode 100644 index 00000000000..0d635a6a9f6 --- /dev/null +++ b/mysql-test/t/bug41756.test @@ -0,0 +1,153 @@ +--source include/have_innodb.inc +--echo # +--echo # Bug#41756 Strange error messages about locks from InnoDB +--echo # +--disable_warnings +drop table if exists t1; +--enable_warnings +--echo # In the default transaction isolation mode, and/or with +--echo # innodb_locks_unsafe_for_binlog=OFF, handler::unlock_row() +--echo # in InnoDB does nothing. +--echo # Thus in order to reproduce the condition that led to the +--echo # warning, one needs to relax isolation by either +--echo # setting a weaker tx_isolation value, or by turning on +--echo # the unsafe replication switch. +--echo # For testing purposes, choose to tweak the isolation level, +--echo # since it's settable at runtime, unlike +--echo # innodb_locks_unsafe_for_binlog, which is +--echo # only a command-line switch. +--echo # +set @@session.tx_isolation="read-committed"; + +--echo # Prepare data. We need a table with a unique index, +--echo # for join_read_key to be used. The other column +--echo # allows to control what passes WHERE clause filter. +create table t1 (a int primary key, b int) engine=innodb; +--echo # Let's make sure t1 has sufficient amount of rows +--echo # to exclude JT_ALL access method when reading it, +--echo # i.e. make sure that JT_EQ_REF(a) is always preferred. +insert into t1 values (1,1), (2,null), (3,1), (4,1), + (5,1), (6,1), (7,1), (8,1), (9,1), (10,1), + (11,1), (12,1); +--echo # +--echo # Demonstrate that for the SELECT statement +--echo # used later in the test JT_EQ_REF access method is used. +--echo # +--vertical_results +explain +select 1 from t1 natural join (select 2 as a, 1 as b union all + select 2 as a, 2 as b) as t2 for update; +--horizontal_results +--echo # +--echo # Demonstrate that the reported SELECT statement +--echo # no longer produces warnings. +--echo # +select 1 from t1 natural join (select 2 as a, 1 as b union all + select 2 as a, 2 as b) as t2 for update; +commit; +--echo # +--echo # Demonstrate that due to lack of inter-sweep "reset" function, +--echo # we keep some non-matching records locked, even though we know +--echo # we could unlock them. +--echo # To do that, show that if there is only one distinct value +--echo # for a in t2 (a=2), we will keep record (2,null) in t1 locked. +--echo # But if we add another value for "a" to t2, say 6, +--echo # join_read_key cache will be pruned at least once, +--echo # and thus record (2, null) in t1 will get unlocked. +--echo # +begin; +select 1 from t1 natural join (select 2 as a, 1 as b union all + select 2 as a, 2 as b) as t2 for update; +connect (con1,localhost,root,,); +--echo # +--echo # Switching to connection con1 +connection con1; +--echo # We should be able to delete all records from t1 except (2, null), +--echo # since they were not locked. +begin; +delete from t1 where a in (1,3,4); +delete from t1 where a in (5,6,7); +delete from t1 where a in (8,9,10); +delete from t1 where a in (11,12); +--echo # +--echo # Record (2, null) is locked. This is actually unnecessary, +--echo # because the previous select returned no rows. +--echo # Just demonstrate the effect. +--echo # +--error ER_LOCK_WAIT_TIMEOUT +delete from t1; +rollback; +--echo # +--echo # Switching to connection default +connection default; +--echo # +--echo # Show that the original contents of t1 is intact: +select * from t1; +commit; +--echo # +--echo # Have a one more record in t2 to show that +--echo # if join_read_key cache is purned, the current +--echo # row under the cursor is unlocked (provided, this row didn't +--echo # match the partial WHERE clause, of course). +--echo # Sic: the result of this test dependent on the order of retrieval +--echo # of records --echo # from the derived table, if ! +--echo # We use DELETE to disable the JOIN CACHE. This DELETE modifies no +--echo # records. It also should leave no InnoDB row locks. +--echo # +begin; +delete t1.* from t1 natural join (select 2 as a, 2 as b union all + select 0 as a, 0 as b) as t2; +--echo # Demonstrate that nothing was deleted form t1 +select * from t1; +--echo # +--echo # Switching to connection con1 +connection con1; +begin; +--echo # Since there is another distinct record in the derived table +--echo # the previous matching record in t1 -- (2,null) -- was unlocked. +delete from t1; +--echo # We will need the contents of the table again. +rollback; +select * from t1; +commit; +--echo # +--echo # Switching to connection default +connection default; +commit; +begin; +--echo # +--echo # Before this patch, we could wrongly unlock a record +--echo # that was cached and later used in a join. Demonstrate that +--echo # this is no longer the case. +--echo # Sic: this test is also order-dependent (i.e. the +--echo # the bug would show up only if the first record in the union +--echo # is retreived and processed first. +--echo # +--echo # Verify that JT_EQ_REF is used. +--vertical_results +explain +select 1 from t1 natural join (select 3 as a, 3 as b union all + select 3 as a, 1 as b) as t2 for update; +--horizontal_results +--echo # Lock the record. +select 1 from t1 natural join (select 3 as a, 3 as b union all + select 3 as a, 2 as b) as t2 for update; +--echo # Switching to connection con1 +connection con1; +--echo # +--echo # We should not be able to delete record (3,1) from t1, +--echo # (previously it was possible). +--echo # +--error ER_LOCK_WAIT_TIMEOUT +delete from t1 where a=3; +--echo # Switching to connection default +connection default; +commit; + +disconnect con1; +set @@session.tx_isolation=default; +drop table t1; + +--echo # +--echo # End of 5.0 tests +--echo # diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc index 805669b3cfa..80fbc2c74d3 100644 --- a/sql/item_subselect.cc +++ b/sql/item_subselect.cc @@ -1869,6 +1869,7 @@ int subselect_single_select_engine::exec() tab->read_record.record= tab->table->record[0]; tab->read_record.thd= join->thd; tab->read_record.ref_length= tab->table->file->ref_length; + tab->read_record.unlock_row= rr_unlock_row; *(last_changed_tab++)= tab; break; } diff --git a/sql/records.cc b/sql/records.cc index d564533ae7a..26f4fd4aa23 100644 --- a/sql/records.cc +++ b/sql/records.cc @@ -61,6 +61,7 @@ void init_read_record_idx(READ_RECORD *info, THD *thd, TABLE *table, info->file= table->file; info->record= table->record[0]; info->print_error= print_error; + info->unlock_row= rr_unlock_row; table->status=0; /* And it's always found */ if (!table->file->inited) @@ -135,6 +136,7 @@ void init_read_record(READ_RECORD *info,THD *thd, TABLE *table, } info->select=select; info->print_error=print_error; + info->unlock_row= rr_unlock_row; info->ignore_not_found_rows= 0; table->status=0; /* And it's always found */ diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 0014504a52f..51794c1f158 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -140,6 +140,7 @@ static int join_read_const_table(JOIN_TAB *tab, POSITION *pos); static int join_read_system(JOIN_TAB *tab); static int join_read_const(JOIN_TAB *tab); static int join_read_key(JOIN_TAB *tab); +static void join_read_key_unlock_row(st_join_table *tab); static int join_read_always_key(JOIN_TAB *tab); static int join_read_last_key(JOIN_TAB *tab); static int join_no_more_records(READ_RECORD *info); @@ -5376,7 +5377,9 @@ static bool create_ref_for_key(JOIN *join, JOIN_TAB *j, KEYUSE *org_keyuse, } j->ref.key_buff2=j->ref.key_buff+ALIGN_SIZE(length); j->ref.key_err=1; + j->ref.has_record= FALSE; j->ref.null_rejecting= 0; + j->ref.use_count= 0; keyuse=org_keyuse; store_key **ref_key= j->ref.key_copy; @@ -6176,6 +6179,20 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond) DBUG_RETURN(0); } + +/** + The default implementation of unlock-row method of READ_RECORD, + used in all access methods. +*/ + +void rr_unlock_row(st_join_table *tab) +{ + READ_RECORD *info= &tab->read_record; + info->file->unlock_row(); +} + + + static void make_join_readinfo(JOIN *join, ulonglong options) { @@ -6191,6 +6208,7 @@ make_join_readinfo(JOIN *join, ulonglong options) TABLE *table=tab->table; tab->read_record.table= table; tab->read_record.file=table->file; + tab->read_record.unlock_row= rr_unlock_row; tab->next_select=sub_select; /* normal select */ /* @@ -6234,6 +6252,7 @@ make_join_readinfo(JOIN *join, ulonglong options) delete tab->quick; tab->quick=0; tab->read_first_record= join_read_key; + tab->read_record.unlock_row= join_read_key_unlock_row; tab->read_record.read_record= join_no_more_records; if (table->used_keys.is_set(tab->ref.key) && !table->no_keyread) @@ -10936,7 +10955,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab, return NESTED_LOOP_NO_MORE_ROWS; } else - join_tab->read_record.file->unlock_row(); + join_tab->read_record.unlock_row(join_tab); } else { @@ -10946,7 +10965,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab, */ join->examined_rows++; join->thd->row_count++; - join_tab->read_record.file->unlock_row(); + join_tab->read_record.unlock_row(join_tab); } return NESTED_LOOP_OK; } @@ -11299,17 +11318,55 @@ join_read_key(JOIN_TAB *tab) table->status=STATUS_NOT_FOUND; return -1; } + /* + Moving away from the current record. Unlock the row + in the handler if it did not match the partial WHERE. + */ + if (tab->ref.has_record && tab->ref.use_count == 0) + { + tab->read_record.file->unlock_row(); + tab->ref.has_record= FALSE; + } + error=table->file->index_read(table->record[0], tab->ref.key_buff, tab->ref.key_length,HA_READ_KEY_EXACT); if (error && error != HA_ERR_KEY_NOT_FOUND) return report_error(table, error); + + if (! error) + { + tab->ref.has_record= TRUE; + tab->ref.use_count= 1; + } + } + else if (table->status == 0) + { + DBUG_ASSERT(tab->ref.has_record); + tab->ref.use_count++; } table->null_row=0; return table->status ? -1 : 0; } +/** + Since join_read_key may buffer a record, do not unlock + it if it was not used in this invocation of join_read_key(). + Only count locks, thus remembering if the record was left unused, + and unlock already when pruning the current value of + TABLE_REF buffer. + @sa join_read_key() +*/ + +static void +join_read_key_unlock_row(st_join_table *tab) +{ + DBUG_ASSERT(tab->ref.use_count); + if (tab->ref.use_count) + tab->ref.use_count--; +} + /* ref access method implementation: "read_first" function diff --git a/sql/sql_select.h b/sql/sql_select.h index a217d199a30..346d98aae58 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -53,6 +53,8 @@ class store_key; typedef struct st_table_ref { bool key_err; + /** True if something was read into buffer in join_read_key. */ + bool has_record; uint key_parts; // num of ... uint key_length; // length of key_buff int key; // key no @@ -79,7 +81,11 @@ typedef struct st_table_ref key_part_map null_rejecting; table_map depend_map; // Table depends on these tables. byte *null_ref_key; // null byte position in the key_buf. - // used for REF_OR_NULL optimization. + /* + The number of times the record associated with this key was used + in the join. + */ + ha_rows use_count; } TABLE_REF; /* diff --git a/sql/structs.h b/sql/structs.h index be55527eaa0..3a7b2f49b2a 100644 --- a/sql/structs.h +++ b/sql/structs.h @@ -117,16 +117,22 @@ typedef struct st_reginfo { /* Extra info about reg */ } REGINFO; -struct st_read_record; /* For referense later */ class SQL_SELECT; class THD; class handler; +struct st_join_table; -typedef struct st_read_record { /* Parameter to read_record */ +void rr_unlock_row(st_join_table *tab); + +struct READ_RECORD { /* Parameter to read_record */ + typedef int (*Read_func)(READ_RECORD*); + typedef void (*Unlock_row_func)(st_join_table *); struct st_table *table; /* Head-form */ handler *file; struct st_table **forms; /* head and ref forms */ - int (*read_record)(struct st_read_record *); + + Read_func read_record; + Unlock_row_func unlock_row; THD *thd; SQL_SELECT *select; uint cache_records; @@ -138,7 +144,7 @@ typedef struct st_read_record { /* Parameter to read_record */ byte *cache,*cache_pos,*cache_end,*read_positions; IO_CACHE *io_cache; bool print_error, ignore_not_found_rows; -} READ_RECORD; +}; /*