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BUG#670417: Diverging results in maria-5.3-mwl128-dsmrr-cpk with join buffer, attempt 4
- Disable identical key handling optimization when IndexConditionPushdown is used
This commit is contained in:
Sergey Petrunya
parent
197c99427d
commit
0fb342ba56
4 changed files with 138 additions and 1 deletions
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@ -462,3 +462,48 @@ FROM t1
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WHERE `key1` LIKE CONCAT( LEFT( '1' , 7 ) , '%' )
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ORDER BY col1 LIMIT 7;
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drop table t0, t1, t2;
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#
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# BUG#670417: Diverging results in maria-5.3-mwl128-dsmrr-cpk with join buffer (incremental, BKA join)
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#
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set @save_join_cache_level = @@join_cache_level;
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set join_cache_level = 6;
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set @save_join_buffer_size=@@join_buffer_size;
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set join_buffer_size = 136;
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CREATE TABLE t1 (
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pk int(11) NOT NULL AUTO_INCREMENT,
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col_int_key int(11) NOT NULL,
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col_varchar_key varchar(1) NOT NULL,
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col_varchar_nokey varchar(1) NOT NULL,
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PRIMARY KEY (pk),
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KEY col_varchar_key (col_varchar_key,col_int_key)
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);
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INSERT INTO t1 VALUES
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(10,8,'v','v'),(11,8,'f','f'), (12,5,'v','v'),
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(13,8,'s','s'),(14,8,'a','a'),(15,6,'p','p'),
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(16,7,'z','z'),(17,2,'a','a'),(18,5,'h','h'),
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(19,7,'h','h'),(20,2,'v','v'),(21,9,'v','v'),
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(22,142,'b','b'),(23,3,'y','y'),(24,0,'v','v'),
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(25,3,'m','m'),(26,5,'z','z'),(27,9,'n','n'),
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(28,1,'d','d'),(29,107,'a','a');
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SELECT COUNT(*)
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FROM
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t1 AS table2, t1 AS table3
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where
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table3.col_varchar_key = table2.col_varchar_key AND
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table3.col_varchar_key = table2.col_varchar_nokey AND
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table3.pk<>0;
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COUNT(*)
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50
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EXPLAIN SELECT COUNT(*)
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FROM
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t1 AS table2, t1 AS table3
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where
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table3.col_varchar_key = table2.col_varchar_key AND
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table3.col_varchar_key = table2.col_varchar_nokey AND
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table3.pk<>0;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE table2 ALL col_varchar_key NULL NULL NULL 20 Using where
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1 SIMPLE table3 ref PRIMARY,col_varchar_key col_varchar_key 3 test.table2.col_varchar_key 3 Using index condition(BKA); Using where; Using join buffer (flat, BKA join)
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set join_cache_level= @save_join_cache_level;
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set join_buffer_size= @save_join_buffer_size;
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drop table t1;
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@ -169,3 +169,52 @@ FROM t1
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WHERE `key1` LIKE CONCAT( LEFT( '1' , 7 ) , '%' )
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ORDER BY col1 LIMIT 7;
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drop table t0, t1, t2;
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--echo #
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--echo # BUG#670417: Diverging results in maria-5.3-mwl128-dsmrr-cpk with join buffer (incremental, BKA join)
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--echo #
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set @save_join_cache_level = @@join_cache_level;
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set join_cache_level = 6;
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set @save_join_buffer_size=@@join_buffer_size;
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--disable_warnings
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set join_buffer_size = 136;
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--enable_warnings
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CREATE TABLE t1 (
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pk int(11) NOT NULL AUTO_INCREMENT,
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col_int_key int(11) NOT NULL,
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col_varchar_key varchar(1) NOT NULL,
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col_varchar_nokey varchar(1) NOT NULL,
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PRIMARY KEY (pk),
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KEY col_varchar_key (col_varchar_key,col_int_key)
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);
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INSERT INTO t1 VALUES
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(10,8,'v','v'),(11,8,'f','f'), (12,5,'v','v'),
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(13,8,'s','s'),(14,8,'a','a'),(15,6,'p','p'),
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(16,7,'z','z'),(17,2,'a','a'),(18,5,'h','h'),
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(19,7,'h','h'),(20,2,'v','v'),(21,9,'v','v'),
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(22,142,'b','b'),(23,3,'y','y'),(24,0,'v','v'),
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(25,3,'m','m'),(26,5,'z','z'),(27,9,'n','n'),
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(28,1,'d','d'),(29,107,'a','a');
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SELECT COUNT(*)
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FROM
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t1 AS table2, t1 AS table3
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where
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table3.col_varchar_key = table2.col_varchar_key AND
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table3.col_varchar_key = table2.col_varchar_nokey AND
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table3.pk<>0;
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EXPLAIN SELECT COUNT(*)
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FROM
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t1 AS table2, t1 AS table3
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where
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table3.col_varchar_key = table2.col_varchar_key AND
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table3.col_varchar_key = table2.col_varchar_nokey AND
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table3.pk<>0;
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set join_cache_level= @save_join_cache_level;
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set join_buffer_size= @save_join_buffer_size;
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drop table t1;
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@ -472,6 +472,42 @@ int Mrr_ordered_index_reader::init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
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mrr_funcs= *seq_funcs;
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know_key_tuple_params= FALSE;
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buf_manager= buf_manager_arg;
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/*
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Short: don't do identical key handling when we have a pushed index
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condition.
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Long: In order to check pushed index condition, we need to have both
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index tuple table->record[0] and range_id.
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Key_value_records_iterator has special handling for case when we have
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multiple (key_value, range_id) pairs with the same key_value. In that
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case it will make an index lookup only for the first such element,
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for subsequent elements it will only return the new range_id.
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The problem here is that h->table->record[0] is shared with the part that
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does full record retrieval with rnd_pos() calls, and if we have the
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following scenario:
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1. We scan ranges {(key_value, range_id1), (key_value, range_id2)}
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2. Iterator makes a lookup with key_value, produces the (index_tuple,
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range_id1) pair. Index tuple is read into table->record[0], which
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allows us to check index condition.
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3. At this point, we figure that key buffer is full, so we sort it,
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and return control to Mrr_ordered_rndpos_reader.
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3.1 Mrr_ordered_rndpos_reader gets rowids and makes rnd_pos() calls, which
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puts some arbitrary data into table->record[0] in the process.
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3.2 We ask the iterator for the next (rowid, range_id) pair. The iterator
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puts in range_id2, and that shuld be sufficient (this is identical key
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handling at work)
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However, index tuple in table->record[0] has been destroyed and we
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can't check index conditon for (index_tuple, range_id2) now.
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TODO: It is possible to support identical key handling and index condition
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pushdown, working together (one possible solution is to save/restore the
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contents of table->record[0]). We will probably implement that.
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*/
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disallow_identical_key_handling= test(mrr_funcs.skip_index_tuple);
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return 0;
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}
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@ -1123,7 +1159,8 @@ int Key_value_records_iterator::init(Mrr_ordered_index_reader *owner_arg)
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uchar *save_cur_index_tuple= cur_index_tuple;
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while (!identical_key_it.read())
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{
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if (Mrr_ordered_index_reader::key_tuple_cmp(owner, key_in_buf,
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if (owner->disallow_identical_key_handling ||
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Mrr_ordered_index_reader::key_tuple_cmp(owner, key_in_buf,
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cur_index_tuple))
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break;
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last_identical_key_ptr= cur_index_tuple;
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@ -289,6 +289,12 @@ private:
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/* TRUE <=> need range association, buffers hold {rowid, range_id} pairs */
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bool is_mrr_assoc;
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/*
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TRUE <=> Don't do optimizations for identical key value (see comment in
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Mrr_ordered_index_reader::init for details)
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*/
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bool disallow_identical_key_handling;
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/* Range sequence iteration members */
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RANGE_SEQ_IF mrr_funcs;
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range_seq_t mrr_iter;
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