mariadb/mysql-test/suite/heap/heap_memory_used.result
Monty 52c29f3bdc MDEV-35469 Heap tables are calling mallocs to often
Heap tables are allocated blocks to store rows according to
my_default_record_cache (mapped to the server global variable
 read_buffer_size).
This causes performance issues when the record length is big
(> 1000 bytes) and the my_default_record_cache is small.

Changed to instead split the default heap allocation to 1/16 of the
allowed space and not use my_default_record_cache anymore when creating
the heap. The allocation is also aligned to be just under a power of 2.

For some test that I have been running, which was using record length=633,
the speed of the query doubled thanks to this change.

Other things:
- Fixed calculation of max_records passed to hp_create() to take
  into account padding between records.
- Updated calculation of memory needed by heap tables. Before we
  did not take into account internal structures needed to access rows.
- Changed block sized for memory_table from 1 to 16384 to get less
  fragmentation. This also avoids a problem where we need 1K
  to manage index and row storage which was not counted for before.
- Moved heap memory usage to a separate test for 32 bit.
- Allocate all data blocks in heap in powers of 2. Change reported
  memory usage for heap to reflect this.

Reviewed-by: Sergei Golubchik <serg@mariadb.org>
2025-01-05 16:40:11 +02:00

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#
# Test of heap table memory usage
#
CREATE TABLE t1 (a int, index(a)) engine=heap min_rows=10 max_rows=100;
insert into t1 values(1);
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
16352 16352
drop table t1;
CREATE TABLE t1 (a int, index(a)) engine=heap min_rows=10 max_rows=10000;
insert into t1 values(1);
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
16352 16352
drop table t1;
CREATE TABLE t1 (a int, index(a)) engine=heap min_rows=3000 max_rows=3000;
insert into t1 values(1);
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
65504 131040
drop table t1;
CREATE TABLE t1 (a int, index(a)) engine=heap max_rows=15000;
insert into t1 values(1);
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
16352 32736
drop table t1;
create table t1 (c1 int, index(c1)) engine=heap max_rows=10000;
insert into t1 select rand(100000000);
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1;
insert into t1 select rand(100000000) from t1 limit 488;
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
32704 32704
insert into t1 select rand(100000000) from t1 limit 1;
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
32704 32704
insert into t1 select rand(100000000) from t1 limit 1000;
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
49056 65408
insert into t1 select rand(100000000) from t1;
select data_length,index_length from information_schema.tables where table_schema="test" and table_name="t1";
data_length index_length
81760 114464
drop table t1;