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* Add AUTO RELEASE TEMP BLOBID transaction option It makes the transaction release temporary ID of user BLOB just after its materialization. It's useful for massive insertions of records with user-defined BLOBs because it eliminates the memory overhead caused by creating and keeping temporary IDs until the transaction ends. This option is used during the database restore. * Place tokens in the correct sections * Avoid repeated attempts to start a transaction with options that are not supported by the target server * Correct AUTO RELEASE TEMP BLOBID description * Check bad_tpb_form error for more reliable detection of unsupported transaction options * Do not use unsupported options for transactions of parallel workers performing RestoreRelationTask
55 lines
2.1 KiB
Plaintext
55 lines
2.1 KiB
Plaintext
More options exposed in the SET TRANSACTION command.
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Syntax
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========
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SET TRANSACTION option_list
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The command is used in DSQL to start a transaction without using the specialized
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API call to create a new transaction. To the already existing options, the following
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have been added. Notice this is not new functionality: it's available through the
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TPB since years ago (they appear in ibase.h as items for TPBs). This extension
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only makes those options available to clients that want to start a transaction by
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executing a DSQL command, like isql's command prompt.
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The new options exposed are:
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NO AUTO UNDO: prevents the transaction from keeping an undo log that would be used
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to undo its changes if it's rolled back. The net effect is undoing the changes, then
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marking the transaction as committed. Without the undo logs, other transactions
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reading the affected record will collect the garbage. This option is useful for
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massive insertions when there's no need to roll back.
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IGNORE LIMBO: ignores the records created by transactions in limbo. Typically a
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transaction is in limbo when it's a multi-database transaction and the two phase
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commit fails. This option is mostly used by gfix.
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LOCK TIMEOUT nonneg_short_integer: it's the time (measured in seconds) that a
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transaction waits for a lock in a record before giving up and reporting an error.
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AUTO RELEASE TEMP BLOBID: makes the transaction release a temporary ID of a user
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BLOB just after its materialization. It's useful for massive insertions of records
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with user-defined BLOBs because it eliminates the memory overhead caused by creating
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and keeping temporary IDs until the transaction ends. This option should be used
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with care and only if there is no need to access a materialized BLOB via a temporary
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ID obtained after its creation. It's used during the database restore.
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Author:
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Claudio Valderrama C.
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N O T E S
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=========
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1. Lock timeout has to be zero or positive and will be rejected if the NO WAIT
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option is specified.
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2.- For transactions that only read data, no auto undo has zero impact.
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Example
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=======
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Using an isql session:
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set transaction no auto undo lock timeout 10;
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