DBZ-7293 Fallback to old schema in case of race condition between ROW and FIELD #175
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Hi @s-gelazevicius, thanks for your contribution. Please prefix the commit message(s) with the DBZ-xxx JIRA issue key. |
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Welcome as a new contributor to Debezium, @s-gelazevicius. Reviewers, please add missing author name(s) and alias name(s) to the COPYRIGHT.txt and Aliases.txt respectively. |
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Thanks for the PR. It looks good as a start.
Please make sure the code is properly formatted (run the mvn install locally).
I recommend to change the naming - instead of backup it should be delayed.
Also I belive the schema instance should be passed so it is visible that there migh be discrepancy in the schema processing.
Also please make sure the followinf scenarios are tested
- field added
- field removed
- field type changed
| * the old schema version in case row length mismatches between Row and Table in schema cache. | ||
| * <a href="https://vitess.io/docs/18.0/reference/vreplication/internal/tracker/#caveat">...</a> | ||
| */ | ||
| private List<Column> resolveColumns(Row row, Table table, Boolean fromBackup) { |
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| private List<Column> resolveColumns(Row row, Table table, Boolean fromBackup) { | |
| private List<Column> resolveColumns(Row row, Table table, boolean fromBackup) { |
| public VStreamOutputMessageDecoder(VitessDatabaseSchema schema) { | ||
| this.schema = schema; | ||
| // Schema can be null. See: VitessConnector.validateConnection | ||
| if (schema != null) this.schemaBackup = schema.clone(); |
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There should be no cloning, both schema and delayedSchema should be passed from the constructor so it is apparent outside that two instances are needed.
| @@ -47,8 +45,13 @@ public class VStreamOutputMessageDecoder implements MessageDecoder { | |||
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| private final VitessDatabaseSchema schema; | |||
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| private final VitessDatabaseSchema schemaBackup; | |||
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| private final VitessDatabaseSchema schemaBackup; | |
| private final VitessDatabaseSchema delayedSchema; |
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This doesn't fix race condition fully, it's still not handled in |
Sometimes due to race condition in Vitess, ROW and TYPE messages can be mixed up. Adding a fallback to the old schema version in case row length mismatches between Row and Table in schema cache.
https://vitess.io/docs/18.0/reference/vreplication/internal/tracker/#caveat
Only best-effort versioning can be provided due to races between DDLs and DMLs