mirror of
https://github.com/MariaDB/server.git
synced 2025-01-16 20:12:31 +01:00
7b988e5ceb
Added:
1) estimated_join_cardinality
2) best_chosen_access_method for a table
3) best_join_order
755 lines
27 KiB
Text
755 lines
27 KiB
Text
set @tmp_opt_switch= @@optimizer_switch;
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set optimizer_switch='index_merge_sort_intersection=on';
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set optimizer_trace='enabled=on';
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create table t0 (a int);
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insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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create table t1 (a int, b int, c int, filler char(100),
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key(a), key(b), key(c));
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insert into t1 select
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A.a * B.a*10 + C.a*100,
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A.a * B.a*10 + C.a*100,
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A.a,
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'filler'
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from t0 A, t0 B, t0 C;
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This should use union:
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explain select * from t1 where a=1 or b=1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index_merge a,b a,b 5,5 NULL 2 Using union(a,b); Using where
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select * from information_schema.OPTIMIZER_TRACE;
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QUERY TRACE MISSING_BYTES_BEYOND_MAX_MEM_SIZE INSUFFICIENT_PRIVILEGES
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explain select * from t1 where a=1 or b=1 {
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"steps": [
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{
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"join_preparation": {
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"select_id": 1,
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"steps": [
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{
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"expanded_query": "select t1.a AS a,t1.b AS b,t1.c AS c,t1.filler AS filler from t1 where t1.a = 1 or t1.b = 1"
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}
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]
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}
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},
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{
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"join_optimization": {
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"select_id": 1,
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"steps": [
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{
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"condition_processing": {
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"condition": "WHERE",
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"original_condition": "t1.a = 1 or t1.b = 1",
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"steps": [
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{
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"transformation": "equality_propagation",
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"resulting_condition": "multiple equal(1, t1.a) or multiple equal(1, t1.b)"
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},
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{
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"transformation": "constant_propagation",
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"resulting_condition": "multiple equal(1, t1.a) or multiple equal(1, t1.b)"
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},
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{
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"transformation": "trivial_condition_removal",
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"resulting_condition": "multiple equal(1, t1.a) or multiple equal(1, t1.b)"
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}
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]
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}
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},
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{
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"table_dependencies": [
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{
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"table": "t1",
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"row_may_be_null": false,
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"map_bit": 0,
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"depends_on_map_bits": []
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}
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]
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},
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{
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"ref_optimizer_key_uses": []
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},
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{
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"rows_estimation": [
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{
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"table": "t1",
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"range_analysis": {
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"table_scan": {
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"rows": 1000,
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"cost": 231.69
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},
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"potential_range_indexes": [
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{
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"index": "a",
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"usable": true,
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"key_parts": ["a"]
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},
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{
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"index": "b",
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"usable": true,
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"key_parts": ["b"]
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},
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{
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"index": "c",
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"usable": false,
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"cause": "not applicable"
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}
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],
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"setup_range_conditions": [],
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"group_index_range": {
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"chosen": false,
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"cause": "no group by or distinct"
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},
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"analyzing_range_alternatives": {
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"range_scan_alternatives": [],
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"analyzing_roworder_intersect": {
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"cause": "too few roworder scans"
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},
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"analyzing_sort_intersect": {},
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"analyzing_index_merge_union": [
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{
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"indexes_to_merge": [
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{
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"range_scan_alternatives": [
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{
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"index": "a",
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"ranges": ["(1) <= (a) <= (1)"],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": true,
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"rows": 1,
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"cost": 1.1773,
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"chosen": true
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}
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],
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"index_to_merge": "a",
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"cumulated_cost": 1.1773
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},
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{
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"range_scan_alternatives": [
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{
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"index": "b",
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"ranges": ["(1) <= (b) <= (1)"],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": true,
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"rows": 1,
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"cost": 1.1773,
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"chosen": true
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}
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],
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"index_to_merge": "b",
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"cumulated_cost": 2.3547
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}
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],
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"cost_of_reading_ranges": 2.3547,
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"use_roworder_union": true,
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"cause": "always cheaper than non roworder retrieval",
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"analyzing_roworder_scans": [
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{
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"type": "range_scan",
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"index": "a",
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"rows": 1,
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"ranges": ["(1) <= (a) <= (1)"],
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"analyzing_roworder_intersect": {
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"cause": "too few roworder scans"
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}
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},
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{
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"type": "range_scan",
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"index": "b",
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"rows": 1,
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"ranges": ["(1) <= (b) <= (1)"],
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"analyzing_roworder_intersect": {
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"cause": "too few roworder scans"
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}
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}
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],
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"index_roworder_union_cost": 4.1484,
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"members": 2,
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"chosen": true
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}
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]
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},
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"chosen_range_access_summary": {
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"range_access_plan": {
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"type": "index_roworder_union",
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"union_of": [
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{
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"type": "range_scan",
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"index": "a",
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"rows": 1,
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"ranges": ["(1) <= (a) <= (1)"]
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},
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{
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"type": "range_scan",
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"index": "b",
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"rows": 1,
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"ranges": ["(1) <= (b) <= (1)"]
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}
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]
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},
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"rows_for_plan": 2,
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"cost_for_plan": 4.1484,
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"chosen": true
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}
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}
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},
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{
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"selectivity_for_indexes": [],
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"selectivity_for_columns": [],
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"cond_selectivity": 0.002
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}
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]
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},
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{
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"considered_execution_plans": [
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{
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"plan_prefix": [],
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"table": "t1",
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"best_access_path": {
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"considered_access_paths": [
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{
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"access_type": "index_merge",
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"resulting_rows": 2,
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"cost": 4.1484,
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"chosen": true
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}
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],
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"chosen_access_method": {
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"type": "index_merge",
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"records": 2,
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"cost": 4.1484,
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"uses_join_buffering": false,
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"filter_used": false
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}
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},
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"rows_for_plan": 2,
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"cost_for_plan": 4.5484,
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"estimated_join_cardinality": 2
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}
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]
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},
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{
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"best_join_order": ["t1"]
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},
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{
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"attaching_conditions_to_tables": {
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"original_condition": "t1.a = 1 or t1.b = 1",
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"attached_conditions_computation": [],
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"attached_conditions_summary": [
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{
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"table": "t1",
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"attached": "t1.a = 1 or t1.b = 1"
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}
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]
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}
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}
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]
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}
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},
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{
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"join_execution": {
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"select_id": 1,
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"steps": []
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}
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}
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]
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} 0 0
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drop table t0,t1;
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set optimizer_trace="enabled=off";
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set @@optimizer_switch= @tmp_opt_switch;
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# More tests added index_merge access
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create table t1
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(
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/* Field names reflect value(rowid) distribution, st=STairs, swt= SaWTooth */
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st_a int not null default 0,
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swt1a int not null default 0,
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swt2a int not null default 0,
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st_b int not null default 0,
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swt1b int not null default 0,
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swt2b int not null default 0,
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/* fields/keys for row retrieval tests */
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key1 int,
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key2 int,
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key3 int,
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key4 int,
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/* make rows much bigger then keys */
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filler1 char (200),
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filler2 char (200),
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filler3 char (200),
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filler4 char (200),
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filler5 char (200),
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filler6 char (200),
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/* order of keys is important */
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key sta_swt12a(st_a,swt1a,swt2a),
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key sta_swt1a(st_a,swt1a),
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key sta_swt2a(st_a,swt2a),
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key sta_swt21a(st_a,swt2a,swt1a),
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key st_a(st_a),
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key stb_swt1a_2b(st_b,swt1b,swt2a),
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key stb_swt1b(st_b,swt1b),
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key st_b(st_b),
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key(key1),
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key(key2),
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key(key3),
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key(key4)
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) ;
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create table t0 as select * from t1;
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# Printing of many insert into t0 values (....) disabled.
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alter table t1 disable keys;
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# Printing of many insert into t1 select .... from t0 disabled.
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# Printing of many insert into t1 (...) values (....) disabled.
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alter table t1 enable keys;
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insert into t1 (key1, key2, key3, key4, filler1) values (100, 100, -1, -1, 'key1-key2');
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insert into t1 (key1, key2, key3, key4, filler1) values (-1, -1, 100, 100, 'key4-key3');
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set optimizer_trace='enabled=on';
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# 3-way ROR-intersection
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explain select key1,key2,key3 from t1 where key1=100 and key2=100 and key3=100;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index_merge key1,key2,key3 key1,key2,key3 5,5,5 NULL 2 Using intersect(key1,key2,key3); Using where; Using index
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select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
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JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives'))
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[
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{
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"range_scan_alternatives":
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[
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{
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"index": "key1",
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"ranges":
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[
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"(100) <= (key1) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": false,
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"rows": 2243,
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"cost": 2862.1,
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"chosen": true
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},
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{
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"index": "key2",
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"ranges":
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[
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"(100) <= (key2) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": false,
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"rows": 2243,
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"cost": 2862.1,
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"chosen": false,
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"cause": "cost"
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},
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{
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"index": "key3",
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"ranges":
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[
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"(100) <= (key3) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": false,
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"rows": 2243,
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"cost": 2862.1,
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"chosen": false,
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"cause": "cost"
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}
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],
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"analyzing_roworder_intersect":
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{
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"intersecting_indexes":
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[
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{
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"index": "key1",
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"index_scan_cost": 58.252,
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"cumulated_index_scan_cost": 58.252,
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"disk_sweep_cost": 1923.1,
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"cumulative_total_cost": 1981.4,
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"usable": true,
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"matching_rows_now": 2243,
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"intersect_covering_with_this_index": false,
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"chosen": true
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},
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{
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"index": "key2",
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"index_scan_cost": 58.252,
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"cumulated_index_scan_cost": 116.5,
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"disk_sweep_cost": 84.518,
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"cumulative_total_cost": 201.02,
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"usable": true,
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"matching_rows_now": 77.636,
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"intersect_covering_with_this_index": false,
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"chosen": true
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},
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{
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"index": "key3",
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"index_scan_cost": 58.252,
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"cumulated_index_scan_cost": 174.76,
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"disk_sweep_cost": 0,
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"cumulative_total_cost": 174.76,
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"usable": true,
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"matching_rows_now": 2.6872,
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"intersect_covering_with_this_index": true,
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"chosen": true
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}
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],
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"clustered_pk":
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{
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"clustered_pk_added_to_intersect": false,
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"cause": "no clustered pk index"
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},
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"rows": 2,
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"cost": 174.76,
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"covering": true,
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"chosen": true
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},
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"analyzing_index_merge_union":
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[
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]
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}
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]
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select JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
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JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary'))
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[
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{
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"range_access_plan":
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{
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"type": "index_roworder_intersect",
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"rows": 2,
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"cost": 174.76,
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"covering": true,
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"clustered_pk_scan": false,
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"intersect_of":
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[
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{
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"type": "range_scan",
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"index": "key1",
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"rows": 2243,
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"ranges":
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[
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"(100) <= (key1) <= (100)"
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]
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},
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{
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"type": "range_scan",
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"index": "key2",
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"rows": 2243,
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"ranges":
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[
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"(100) <= (key2) <= (100)"
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]
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},
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{
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"type": "range_scan",
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"index": "key3",
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"rows": 2243,
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"ranges":
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[
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"(100) <= (key3) <= (100)"
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]
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}
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]
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},
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"rows_for_plan": 2,
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"cost_for_plan": 174.76,
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"chosen": true
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}
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]
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# ROR-union(ROR-intersection, ROR-range)
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explain select key1,key2,key3,key4 from t1 where key1=100 and key2=100 or key3=100 and key4=100;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index_merge key1,key2,key3,key4 key1,key2,key3,key4 5,5,5,5 NULL 154 Using union(intersect(key1,key2),intersect(key3,key4)); Using where
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select JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
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JSON_DETAILED(JSON_EXTRACT(trace, '$**.analyzing_range_alternatives'))
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[
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{
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"range_scan_alternatives":
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[
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],
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"analyzing_roworder_intersect":
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{
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"cause": "too few roworder scans"
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},
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"analyzing_index_merge_union":
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[
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{
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"indexes_to_merge":
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[
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{
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"range_scan_alternatives":
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[
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{
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"index": "key1",
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"ranges":
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[
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"(100) <= (key1) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": true,
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"rows": 2243,
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"cost": 170.53,
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"chosen": true
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},
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{
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"index": "key2",
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"ranges":
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[
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"(100) <= (key2) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": true,
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"rows": 2243,
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"cost": 170.53,
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"chosen": false,
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"cause": "cost"
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}
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],
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"index_to_merge": "key1",
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"cumulated_cost": 170.53
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},
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{
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"range_scan_alternatives":
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[
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{
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"index": "key3",
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"ranges":
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[
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"(100) <= (key3) <= (100)"
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],
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"rowid_ordered": true,
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"using_mrr": false,
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"index_only": true,
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"rows": 2243,
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"cost": 170.53,
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"chosen": true
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},
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|
|
{
|
|
"index": "key4",
|
|
"ranges":
|
|
[
|
|
"(100) <= (key4) <= (100)"
|
|
],
|
|
"rowid_ordered": true,
|
|
"using_mrr": false,
|
|
"index_only": true,
|
|
"rows": 2243,
|
|
"cost": 170.53,
|
|
"chosen": false,
|
|
"cause": "cost"
|
|
}
|
|
],
|
|
"index_to_merge": "key3",
|
|
"cumulated_cost": 341.05
|
|
}
|
|
],
|
|
"cost_of_reading_ranges": 341.05,
|
|
"use_roworder_union": true,
|
|
"cause": "always cheaper than non roworder retrieval",
|
|
"analyzing_roworder_scans":
|
|
[
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key1",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key1) <= (100)"
|
|
],
|
|
"analyzing_roworder_intersect":
|
|
{
|
|
"intersecting_indexes":
|
|
[
|
|
|
|
{
|
|
"index": "key1",
|
|
"index_scan_cost": 58.252,
|
|
"cumulated_index_scan_cost": 58.252,
|
|
"disk_sweep_cost": 1923.1,
|
|
"cumulative_total_cost": 1981.4,
|
|
"usable": true,
|
|
"matching_rows_now": 2243,
|
|
"intersect_covering_with_this_index": false,
|
|
"chosen": true
|
|
},
|
|
|
|
{
|
|
"index": "key2",
|
|
"index_scan_cost": 58.252,
|
|
"cumulated_index_scan_cost": 116.5,
|
|
"disk_sweep_cost": 84.518,
|
|
"cumulative_total_cost": 201.02,
|
|
"usable": true,
|
|
"matching_rows_now": 77.636,
|
|
"intersect_covering_with_this_index": false,
|
|
"chosen": true
|
|
}
|
|
],
|
|
"clustered_pk":
|
|
{
|
|
"clustered_pk_added_to_intersect": false,
|
|
"cause": "no clustered pk index"
|
|
},
|
|
"rows": 77,
|
|
"cost": 201.02,
|
|
"covering": false,
|
|
"chosen": true
|
|
}
|
|
},
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key3",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key3) <= (100)"
|
|
],
|
|
"analyzing_roworder_intersect":
|
|
{
|
|
"intersecting_indexes":
|
|
[
|
|
|
|
{
|
|
"index": "key3",
|
|
"index_scan_cost": 58.252,
|
|
"cumulated_index_scan_cost": 58.252,
|
|
"disk_sweep_cost": 1923.1,
|
|
"cumulative_total_cost": 1981.4,
|
|
"usable": true,
|
|
"matching_rows_now": 2243,
|
|
"intersect_covering_with_this_index": false,
|
|
"chosen": true
|
|
},
|
|
|
|
{
|
|
"index": "key4",
|
|
"index_scan_cost": 58.252,
|
|
"cumulated_index_scan_cost": 116.5,
|
|
"disk_sweep_cost": 84.518,
|
|
"cumulative_total_cost": 201.02,
|
|
"usable": true,
|
|
"matching_rows_now": 77.636,
|
|
"intersect_covering_with_this_index": false,
|
|
"chosen": true
|
|
}
|
|
],
|
|
"clustered_pk":
|
|
{
|
|
"clustered_pk_added_to_intersect": false,
|
|
"cause": "no clustered pk index"
|
|
},
|
|
"rows": 77,
|
|
"cost": 201.02,
|
|
"covering": false,
|
|
"chosen": true
|
|
}
|
|
}
|
|
],
|
|
"index_roworder_union_cost": 386.73,
|
|
"members": 2,
|
|
"chosen": true
|
|
}
|
|
]
|
|
}
|
|
]
|
|
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
|
|
JSON_DETAILED(JSON_EXTRACT(trace, '$**.chosen_range_access_summary'))
|
|
[
|
|
|
|
{
|
|
"range_access_plan":
|
|
{
|
|
"type": "index_roworder_union",
|
|
"union_of":
|
|
[
|
|
|
|
{
|
|
"type": "index_roworder_intersect",
|
|
"rows": 77,
|
|
"cost": 201.02,
|
|
"covering": false,
|
|
"clustered_pk_scan": false,
|
|
"intersect_of":
|
|
[
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key1",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key1) <= (100)"
|
|
]
|
|
},
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key2",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key2) <= (100)"
|
|
]
|
|
}
|
|
]
|
|
},
|
|
|
|
{
|
|
"type": "index_roworder_intersect",
|
|
"rows": 77,
|
|
"cost": 201.02,
|
|
"covering": false,
|
|
"clustered_pk_scan": false,
|
|
"intersect_of":
|
|
[
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key3",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key3) <= (100)"
|
|
]
|
|
},
|
|
|
|
{
|
|
"type": "range_scan",
|
|
"index": "key4",
|
|
"rows": 2243,
|
|
"ranges":
|
|
[
|
|
"(100) <= (key4) <= (100)"
|
|
]
|
|
}
|
|
]
|
|
}
|
|
]
|
|
},
|
|
"rows_for_plan": 154,
|
|
"cost_for_plan": 386.73,
|
|
"chosen": true
|
|
}
|
|
]
|
|
drop table t0,t1;
|
|
set optimizer_trace="enabled=off";
|