Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.5, 10.6
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None
Description
As of now MDB doesn't use Select Handler for queries like:
INSERT INTO t1 SELECT * FROM (SELECT * FROM mcs1) d;
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but Select Handler works for the SELECT part of the query.
The reason why this happens is that join->tables_list doesn't have TABLE_LIST* for a real table but for a derived one. Here is the gdb snippet taken in the first iteration of the loop in SELECT_LEX::find_select_handler():
(gdb) p tbl->table_name
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$2 = {
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str = 0x55907a9f76c8 <internal_table_name> "*",
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length = 1
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}
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It doesn't matter if derived_merged is on or off.
(gdb) p thd->variables->optimizer_switch & OPTIMIZER_SWITCH_DERIVED_MERGE
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$8 = 128
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(gdb) p join->tables_list->table_name
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$9 = {
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str = 0x55bee4acaa28 <internal_table_name> "*",
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length = 1
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}
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(gdb) p join->tables_list->next_global
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$10 = (TABLE_LIST *) 0x0
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(gdb)
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Here is the code of the mentioned find_select_handler():
select_handler *SELECT_LEX::find_select_handler(THD *thd)
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{
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if (next_select()) |
return 0; |
if (master_unit()->outer_select()) |
return 0; |
for (TABLE_LIST *tbl= join->tables_list; tbl; tbl= tbl->next_global) |
{
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if (!tbl->table) |
continue; |
handlerton *ht= tbl->table->file->partition_ht();
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if (!ht->create_select) |
continue; |
select_handler *sh= ht->create_select(thd, this); |
return sh; |
}
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return 0; |
}
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