Details
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Bug
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Status: Closed (View Workflow)
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Blocker
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Resolution: Fixed
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10.2(EOL), 10.3(EOL), 10.4(EOL), 10.5, 10.6, 10.7(EOL), 10.8(EOL)
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None
Description
CREATE TABLE t1 ( a char(25), b text); |
INSERT INTO t1 VALUES ('foo','bar'); |
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SELECT SUM(b) OVER (PARTITION BY a), ROW_NUMBER() OVER (PARTITION BY b) |
FROM t1 |
GROUP BY LEFT((SYSDATE()), 'foo') WITH ROLLUP; |
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10.2 54d0a55adf6fbfc92c5473b |
mysqld: /10.2/sql/sql_window.cc:322: int compare_order_elements(ORDER*, ORDER*): Assertion `item1->type() == Item::FIELD_ITEM && item2->type() == Item::FIELD_ITEM' failed.
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190506 10:48:00 [ERROR] mysqld got signal 6 ;
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linux/raise.c:54(__GI_raise)[0x7f70751d2428]
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stdlib/abort.c:91(__GI_abort)[0x7f70751d402a]
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assert/assert.c:92(__assert_fail_base)[0x7f70751cabd7]
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/lib/x86_64-linux-gnu/libc.so.6(+0x2dc82)[0x7f70751cac82]
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sql/sql_window.cc:323(compare_order_elements(st_order*, st_order*))[0x558ae3b19362]
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sql/sql_window.cc:361(compare_order_lists(SQL_I_List<st_order>*, SQL_I_List<st_order>*))[0x558ae3b19924]
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sql/sql_window.cc:474(compare_window_funcs_by_window_specs(Item_window_func*, Item_window_func*, void*))[0x558ae3b1a0b5]
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sql/sql_list.h:626(void bubble_sort<Item_window_func>(List<Item_window_func>*, int (*)(Item_window_func*, Item_window_func*, void*), void*))[0x558ae3b2719b]
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sql/sql_window.cc:561(order_window_funcs_by_window_specs(List<Item_window_func>*))[0x558ae3b1a830]
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sql/sql_window.cc:2897(Window_funcs_computation::setup(THD*, List<Item_window_func>*, st_join_table*))[0x558ae3b1ed34]
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sql/sql_select.cc:2914(JOIN::make_aggr_tables_info())[0x558ae379498c]
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sql/sql_select.cc:2233(JOIN::optimize_inner())[0x558ae378dd41]
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sql/sql_select.cc:1116(JOIN::optimize())[0x558ae3783103]
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sql/sql_select.cc:3806(mysql_select(THD*, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*))[0x558ae379c66b]
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sql/sql_select.cc:376(handle_select(THD*, LEX*, select_result*, unsigned long))[0x558ae377bf4b]
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sql/sql_parse.cc:6486(execute_sqlcom_select(THD*, TABLE_LIST*))[0x558ae37039e7]
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sql/sql_parse.cc:3534(mysql_execute_command(THD*))[0x558ae36f0ddc]
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sql/sql_parse.cc:8020(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x558ae370c14b]
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sql/sql_parse.cc:1835(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x558ae36e77d5]
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sql/sql_parse.cc:1387(do_command(THD*))[0x558ae36e4952]
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sql/sql_connect.cc:1335(do_handle_one_connection(CONNECT*))[0x558ae3a0e146]
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sql/sql_connect.cc:1242(handle_one_connection)[0x558ae3a0db4e]
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perfschema/pfs.cc:1864(pfs_spawn_thread)[0x558ae4bbc1c8]
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/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7f7075e0f6ba]
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x86_64/clone.S:111(clone)[0x7f70752a441d]
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Attachments
Issue Links
- is duplicated by
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- Closed
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- Closed
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- relates to
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- Closed
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- Closed
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Activity
In the above case (avg(1) + 3 is not stored as a field in any temporary table.
Suggestion: can we get rid of the crash by adjusting the comparison function to
- compare Item_field objects like it does now
- any item that's not an Item_field is greater than any Item_field
- two non-Item-field items are compared as their pointers.
This is "compatible" with the current ordering for Item_field objects.
It may miss some optimization opportunities when multiple window functions use the same PARTITION/ORDER BY expressions.
Comparing Item* pointers means the ordering will vary across executions. (What is the effect of this? Window Function step will run sorts in different order?)
... yes, implementing the above will have an issue that window_functions_computation.sorts will list the sorts in arbitrary order:
{
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"query_block": {
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"select_id": 1,
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"filesort": {
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"sort_key": "nullif(t1.`id`,15532)",
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"window_functions_computation": {
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"sorts": {
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"filesort": {
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"sort_key": "avg(1) + 3"
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},
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"filesort": {
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"sort_key": "avg(1)"
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}
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},
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"temporary_table": {
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"table": {
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"table_name": "t1",
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"access_type": "ALL",
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"rows": 3,
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"filtered": 100
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}
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}
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}
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}
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}
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Ok, the new fix is here https://github.com/MariaDB/server/commit/85cc56875e9ddb7f5f56013bac22e36805288c16
and it fixes MDEV-26614 , too.
Note that this is not limited to Item_copy or Item_sum_field-derived items.
Slightly modified Alice's testcase:
This crashes compare_order_elements, too, and we have:
(gdb) p item1$8 = (Item_func_plus *) 0x7fff74013ad8(gdb) p item2$9 = (Item_avg_field_decimal *) 0x7fff740178d0... so the ORDER BY list can have an arbitrary item.
I don't see this causing any problems in window function computation code btw. Only compare_order_elements has an issue.