Doc: Refer to line pointers as item identifiers.

An upcoming HEAD-only patch will standardize the terminology around
ItemIdData variables/line pointers, ending the practice of referring to
them as "item pointers".  Make the "Database Page Layout" docs
consistent with the new policy.  The term "item identifier" is already
used in the same section, so stick with that.

Discussion: https://postgr.es/m/CAH2-Wz=c=MZQjUzde3o9+2PLAPuHTpVZPPdYxN=E4ndQ2--8ew@mail.gmail.com
Backpatch: All supported branches.

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 8ef2ac80106052423a2323b1d31822006b2162f2..ea9640f76d9c9d3dca86a4a935d899358457a69d 100644 (file)
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -750,14 +750,14 @@ free space pointers.</entry>
 
 <row>
 <entry>ItemIdData</entry>
-<entry>Array of (offset,length) pairs pointing to the actual items.
-4 bytes per item.</entry>
+<entry>Array of item identifiers pointing to the actual items. Each
+entry is an (offset,length) pair. 4 bytes per item.</entry>
 </row>
 
 <row>
 <entry>Free space</entry>
-<entry>The unallocated space. New item pointers are allocated from the start
-of this area, new items from the end.</entry>
+<entry>The unallocated space. New item identifiers are allocated from
+the start of this area, new items from the end.</entry>
 </row>
 
 <row>