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Comment: Published by Scroll Versions from space ML1 and version 9.1

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Transaction Lifespan
xidTransaction start id. Marks the logical beginning of the transaction.
iidInvocation 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
Isolation_Levels
Isolation_Levels
Isolation Levels

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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.