domain: stop schema validator to prohibit DML executing when tidb lost session of etcd #8441
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…t session of etcd
winkyao
added
type/bugfix
A schema change should meet either of the two conditions:
If none of the condition is satisfied, how could it change to a newer version 3 ?
We do not need to stop the schema validator, instead, we should stop the version change in the owner. @winkyao |
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@winkyao Please add a test case. |
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I'll add test cases. |
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@tiancaiamao It is another issue, we can fix the issue you mentioned later, but not his PR. |
tiancaiamao
reviewed
Nov 26, 2018
…into fix_schema_validator
…ffects the schema reloading.
tiancaiamao
reviewed
Nov 26, 2018
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LGTM |
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@crazycs520 @zimulala PTAL |
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/run-all-tests |
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/run-common-test tidb-test=pr/668 |
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/run-integration-common-test tidb-test=pr/668 |
crazycs520
added
status/LGT2
winkyao
added
require-LGT3
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What problem does this PR solve?
The etcd is responsible for schema synchronization, we should ensure there is at most two diffrent schema version in the TiDB cluster, to make the data/schema be consistent.
If we lost connection/session to etcd, the cluster will treats this TiDB as a down instance, and etcd will remove the key of
/tidb/ddl/all_schema_versions/tidb-id.Say the schema version now is 1, the owner is changing the schema version to 2, it will not wait for this down TiDB syncing the schema, then continue to change the TiDB schema to version 3. Unfortunately, this down TiDB schema version will still be version 1. And version 1 is not consistent to version 3.
So we need to stop the schema validator to prohibit the DML executing when we lost session of etcd.
This PR revert partial changes of #7810
This change is