enable select for update in autocommit mode#3265
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demmer wants to merge 1 commit intovitessio:masterfrom
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enable select for update in autocommit mode#3265demmer wants to merge 1 commit intovitessio:masterfrom
demmer wants to merge 1 commit intovitessio:masterfrom
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Add support for autocommit mode and select for update transactions which is needed in cases where a DML is issued on a table with an owned secondary vindex, since the vtgate will first issue a query to get the index value from the primary row before trying to delete it.
sougou
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Sep 30, 2017
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autocommit at vttablet level is deprecated (and highly discouraged). We introduced it to support certain v2 operations, but this totally fails for v3 operations that may have lookup updates, etc.
The v3 autocommit happens through the session object. Also, it's a common misunderstanding that select for update locks the row. In reality, no lock is obtained because the statement is immediately 'commited': https://dev.mysql.com/doc/refman/5.7/en/innodb-locking-reads.html,
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Ah -- this makes much more sense and exposes a design flaw in the current vtexplain implementation. Will replace with a better approach. |
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Add support for autocommit mode and select for update transactions
which is needed in cases where a DML is issued on a table with an
owned secondary vindex, since the vtgate will first issue a query
to get the index value from the primary row before trying to delete
it.