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Transaction Lifespan | |
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xid | Transaction start id. Marks the logical beginning of the transaction. |
iid | Invocation id. Marks the beginning of a statement within a transaction. |
cid | Commit id. Marks the id at which transaction changes are visible to other transactions. |
The following table describes MVCC visibility rules in different isolation levels. Note that ClustrixDB does not support the read uncommitted level.
Anchor | ||||
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ClustrixDB implements row level locks for transactions which touch a few rows at a time (a runtime configurable variable). For statements which affect a signification significant portion of a table, the query optimizer will promote row level locks to a table lock.