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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>
14 lines
606 B
Plaintext
14 lines
606 B
Plaintext
SET SESSION aria_repair_threads=128;
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SET SESSION aria_sort_buffer_size=CAST(-1 AS UNSIGNED INT);
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Warnings:
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Note 1105 Cast to unsigned converted negative integer to it's positive complement
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Note 1105 Cast to unsigned converted negative integer to it's positive complement
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Warning 1292 Truncated incorrect aria_sort_buffer_size value: '18446744073709551615'
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SET SESSION tmp_table_size=65535;
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Warnings:
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Warning 1292 Truncated incorrect tmp_table_size value: '65535'
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CREATE TABLE t1 (a VARCHAR(255));
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insert into t1 (a) select seq from seq_1_to_1000;
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UPDATE t1 SET a=( (SELECT MAX(a) FROM t1));
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DROP TABLE t1;
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