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< could only see committed rows from another transaction. However, > could only see rows from another completed transaction. However, 981c981 < proper visibility of the row, for example, for cursors. > proper visibility of the row's cmin, for example, for cursors.
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doc/TODO
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doc/TODO
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PostgreSQL TODO List
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====================
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Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
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Last updated: Fri Sep 2 15:39:11 EDT 2005
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Last updated: Fri Sep 2 15:51:34 EDT 2005
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The most recent version of this document can be viewed at
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http://www.postgresql.org/docs/faqs.TODO.html.
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@ -972,13 +972,13 @@ Miscellaneous Performance
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xmax), cmin, cmax, and if the transaction was expiring a row from a
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another transaction, the fields stored were xmin (cmin was not
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needed), xmax, and cmax. Such a system worked because a transaction
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could only see committed rows from another transaction. However,
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could only see rows from another completed transaction. However,
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subtransactions can see rows from outer transactions, and once the
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subtransaction completes, the outer transaction continues, requiring
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the storage of all four fields. With subtransactions, an outer
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transaction can create a row, a subtransaction expire it, and when the
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subtransaction completes, the outer transaction still has to have
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proper visibility of the row, for example, for cursors.
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proper visibility of the row's cmin, for example, for cursors.
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One possible solution is to create a phantom cid which represents a
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cmin/cmax pair and is stored in local memory.
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@ -8,7 +8,7 @@
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<body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF">
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<h1><a name="section_1">PostgreSQL TODO List</a></h1>
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<p>Current maintainer: Bruce Momjian (<a href="mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</a>)<br/>
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Last updated: Fri Sep 2 15:39:11 EDT 2005
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Last updated: Fri Sep 2 15:51:34 EDT 2005
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</p>
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<p>The most recent version of this document can be viewed at<br/>
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<a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
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@ -876,13 +876,13 @@ first.
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xmax), cmin, cmax, and if the transaction was expiring a row from a
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another transaction, the fields stored were xmin (cmin was not
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needed), xmax, and cmax. Such a system worked because a transaction
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could only see committed rows from another transaction. However,
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could only see rows from another completed transaction. However,
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subtransactions can see rows from outer transactions, and once the
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subtransaction completes, the outer transaction continues, requiring
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the storage of all four fields. With subtransactions, an outer
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transaction can create a row, a subtransaction expire it, and when the
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subtransaction completes, the outer transaction still has to have
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proper visibility of the row, for example, for cursors.
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proper visibility of the row's cmin, for example, for cursors.
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</p>
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<p> One possible solution is to create a phantom cid which represents a
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cmin/cmax pair and is stored in local memory.
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