PostgreSQL TODO List
====================
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
-Last updated: Thu Dec 1 17:12:27 EST 2005
+Last updated: Thu Dec 1 17:30:23 EST 2005
The most recent version of this document can be viewed at
http://www.postgresql.org/docs/faqs.TODO.html.
Currently indexes do not have enough tuple visibility information
to allow data to be pulled from the index without also accessing
- the heap. One way to allow this is to set a bit to index tuples
+ the heap. One way to allow this is to set a bit on index tuples
to indicate if a tuple is currently visible to all transactions
when the first valid heap lookup happens. This bit would have to
- be cleared when a heap tuple is expired.
-
+ be cleared when a heap tuple is expired. Another idea is to maintain
+ a bitmap of heap pages where all rows are visible to all backends,
+ and allow index lookups to reference that bitmap to avoid heap
+ lookups, perhaps the same bitmap we might add someday to determine
+ which heap pages need vacuuming.
* Consider automatic caching of queries at various levels:
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<h1><a name="section_1">PostgreSQL TODO List</a></h1>
<p>Current maintainer: Bruce Momjian (<a href="mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</a>)<br/>
-Last updated: Thu Dec 1 17:12:27 EST 2005
+Last updated: Thu Dec 1 17:30:23 EST 2005
</p>
<p>The most recent version of this document can be viewed at<br/>
<a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
</li><li>Allow data to be pulled directly from indexes
<p> Currently indexes do not have enough tuple visibility information
to allow data to be pulled from the index without also accessing
- the heap. One way to allow this is to set a bit to index tuples
+ the heap. One way to allow this is to set a bit on index tuples
to indicate if a tuple is currently visible to all transactions
when the first valid heap lookup happens. This bit would have to
- be cleared when a heap tuple is expired.
+ be cleared when a heap tuple is expired. Another idea is to maintain
+ a bitmap of heap pages where all rows are visible to all backends,
+ and allow index lookups to reference that bitmap to avoid heap
+ lookups, perhaps the same bitmap we might add someday to determine
+ which heap pages need vacuuming.
</p>
</li><li>Consider automatic caching of queries at various levels:
<ul>
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