tidb panic when processing insert select query #39611
Comments
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/cc @ekexium |
ti-chi-bot
added
may-affects-4.0
ekexium
added
affects-6.5
and removed
may-affects-4.0
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The sequence of events that leads to the panic is: When reverting to last checkpoint, memdb iterates over the nodes backwards, here is why it panics: |
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can reproduce it with the case after the fix pr, reopen. drop table if exists t;
create table t(a int, index idx(a));
insert into t values (1), (2), (3);
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
insert into t select * from t;
set tidb_mem_quota_query=1073741824;
insert /*+ memory_quota(1 MB) */ into t (select * from t);
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It's directly caused by the panicking leaving memdb in an inconsistent state. I've filed a PR to fix it. |
Bug Report
Please answer these questions before submitting your issue. Thanks!
1. Minimal reproduce step (Required)
Use TPC-H 100 database.
Create a table
lineitem1whose schema is the same as the lineitem table.Run
explain analyze insert into lineitem1 select * from lineitem limit 10000000;By the way, when I ran
explain analyze insert into lineitem1 select * from lineitem limit 1000000;, the result is ok.2. What did you expect to see? (Required)
A result of
explain analyze.3. What did you see instead (Required)
ERROR 1105 (HY000): runtime error: slice bounds out of range [-20:]The panic log in TiDB log is:
And the tidb log said this query exceeded memory quota.
4. What is your TiDB version? (Required)
The latest master.
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