feat: persist AlterSchema and AlterOptions to data WAL
#166
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Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
waynexia
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feature
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
chunshao90
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May 15, 2023
* feat: move schema out from manifest Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * change the AlterSchema persist destination to Wal Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * AlterSchema decodeing Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * impl alter options; store update to Manifest as well Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * update mod doc Signed-off-by: Ruihang Xia <waynestxia@gmail.com> * fix decoding header Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
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Which issue does this PR close?
Closes #82
Rationale for this change
quote from #82:
This PR focus on the second target -- put DDL (altering schema and options) together with data WAL.
A more detailed reason is that in distributed mode, we have a writer node and serval reader nodes. Where the writer serves all the related write requests, including writing data and altering schema/options. And readers sync new data from their writer. They communicate with data WAL. However, the data WAL used only contains the data logs. This is problematic when for example, the schema is changing. Readers don't know at which point the schema has changed, and therefore cannot handle their memory status correctly.
After this patch readers can know when to update their schema and/or options. Those DDL records are associated with data records.
Besides this, those DDL records still exist in the Manifest. I.e. this PR doesn't touch the Manifest. I haven't found a better place to put those metadata. This kind of data changes frequently thus OSS is not a good choice.
What changes are included in this PR?
Duplicate
AlterSchemaandAlterOptionsto data WALAre there any user-facing changes?
No, all changes are internal.
How does this change test
Unit test