Add all heap page rows visible bitmap idea:

bmomjian · bmomjian · commit 113ece8f3d70 · 2005-12-01T22:30:43.000Z
&lt;   the heap.  One way to allow this is to set a bit to index tuples
&gt;   the heap.  One way to allow this is to set a bit on index tuples
&lt;   be cleared when a heap tuple is expired.
&lt;
&gt;   be cleared when a heap tuple is expired.  Another idea is to maintain
&gt;   a bitmap of heap pages where all rows are visible to all backends,
&gt;   and allow index lookups to reference that bitmap to avoid heap
&gt;   lookups, perhaps the same bitmap we might add someday to determine
&gt;   which heap pages need vacuuming.
diff --git a/doc/TODO b/doc/TODO
@@ -2,7 +2,7 @@
 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.
@@ -859,11 +859,14 @@ Cache Usage
 
   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:
 
diff --git a/doc/src/FAQ/TODO.html b/doc/src/FAQ/TODO.html
@@ -8,7 +8,7 @@
 <body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF">
 <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>.
@@ -778,10 +778,14 @@ <h1><a name="section_15">Cache Usage</a></h1>
   </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>
