Minor editorial improvements to txid functions' documentation: put back

some text that got dropped, improve markup, improve descriptions of
snapshot components.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index cb278afb2466bc8e03a49e402c554fa0c92ffeb5..993c8fe38045e9cf2c2d1f2ffebe3ade04850ffd 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-
+
 
  
   Functions and Operators
@@ -11514,6 +11514,13 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
     txid_visible_in_snapshot
    
 
+   
+    The functions shown in 
+    export server internal transaction information to user level.  The main
+    use of these functions is to determine which transactions were committed
+    between two snapshots.
+   
+
    
     Transaction IDs and snapshots
     
@@ -11557,27 +11564,22 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
    
 
    
-    The internal transaction ID type (xid) is 32 bits wide and
-    so it wraps around every 4 billion transactions.  However, these
-    functions export a 64-bit format that is extended with an
-    epoch counter so that it will not wrap around for the life
-    of an installation.  The main use of these functions is to determine
-    which transactions were committed between two snapshots.
+    The internal transaction ID type (xid) is 32 bits wide and so
+    it wraps around every 4 billion transactions.  However, these functions
+    export a 64-bit format that is extended with an epoch counter
+    so that it will not wrap around for the life of an installation.
+    The data type used by these functions, txid_snapshot,
+    stores information about transaction ID
+    visibility at a particular moment in time.  Its components are
+    described in .
    
 
-   
-    The data type txid_snapshot stores info about transaction ID
-    visibility at a particular moment in time. The components are
-    described in .
-   
-
-   
+   
     Snapshot components
     
      
       
        Name
-       Query Function
        Description
       
      
@@ -11586,9 +11588,8 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
 
       
        xmin
-       txid_snapshot_xmin()
        
-         Earliest transaction ID that is still active.  All earlier
+         Earliest transaction ID (txid) that is still active.  All earlier
          transactions will either be committed and visible, or rolled
          back and dead.
        
@@ -11596,20 +11597,20 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
 
       
        xmax
-       txid_snapshot_xmax()
        
-        Next unassigned txid.  All txids later than this one are
-        unassigned, and thus invisible.
+        First as-yet-unassigned txid.  All txids later than this one are
+        not yet started as of the time of the snapshot, and thus invisible.
        
       
 
       
        xip_list
-       txid_snapshot_xip()
        
-        Active txids at the time of snapshot.  All of them are between
-        xmin and xmax.  A txid that is xmin <= txid <
-        xmax and not in this list is visible.
+        Active txids at the time of the snapshot.  All of them are between
+        xmin and xmax.  A txid that is
+        xmin <= txid < xmax and not in this list was
+        already completed at the time of the snapshot, and thus either visible
+        or dead according to its commit status.
        
       
 
@@ -11618,11 +11619,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
    
 
    
-    Snapshot's textual representation is [xmin]:[xmax]:[xip_list]
-    for example 10:20:10,14,15 means
-    xmin=10 xmax=20 xip_list=10,14,15.
+    txid_snapshot's textual representation is
+    xmin:xmax:xip_list.
+    For example 10:20:10,14,15 means
+    xmin=10, xmax=20, xip_list=10, 14, 15.
    
-