Documentation corrections for opclass parameters

Discussion: https://postgr.es/m/20200331024419.GB14618%40telsasoft.com
Author: Justin Pryzby

doc/src/sgml/hstore.sgml

@@ -468,13 +468,13 @@ CREATE INDEX hidx ON testhstore USING GIN (h);
 </programlisting>
 
   <para>
-   <literal>gist_hstore_ops</literal> GiST opclass approximates set of
-   key/value pairs as a bitmap signature.  Optional integer parameter
-   <literal>siglen</literal> of <literal>gist_hstore_ops</literal> determines
-   signature length in bytes.  Default signature length is 16 bytes.
+   <literal>gist_hstore_ops</literal> GiST opclass approximates a set of
+   key/value pairs as a bitmap signature.  Its optional integer parameter
+   <literal>siglen</literal> determines the
+   signature length in bytes.  The default length is 16 bytes.
    Valid values of signature length are between 1 and 2024 bytes.  Longer
-   signatures leads to more precise search (scan less fraction of index, scan
-   less heap pages), but larger index.
+   signatures lead to a more precise search (scanning a smaller fraction of the index and
+   fewer heap pages), at the cost of a larger index.
   </para>
 
   <para>

doc/src/sgml/intarray.sgml

@@ -265,7 +265,7 @@
   </para>
 
   <para>
-   Two parametrized GiST index operator classes are provided:
+   Two parameterized GiST index operator classes are provided:
    <literal>gist__int_ops</literal> (used by default) is suitable for
    small- to medium-size data sets, while
    <literal>gist__intbig_ops</literal> uses a larger signature and is more
@@ -276,22 +276,23 @@
   </para>
    
   <para>
-   <literal>gist__int_ops</literal> approximates integer set as an array of
-   integer ranges.  Optional integer parameter <literal>numranges</literal> of
-   <literal>gist__int_ops</literal> determines maximum number of ranges in
-   one index key.  Default value of <literal>numranges</literal> is 100.
+   <literal>gist__int_ops</literal> approximates an integer set as an array of
+   integer ranges.  Its optional integer parameter <literal>numranges</literal>
+   determines the maximum number of ranges in
+   one index key.  The default value of <literal>numranges</literal> is 100.
    Valid values are between 1 and 253.  Using larger arrays as GiST index
-   keys leads to more precise search (scan less fraction of index, scan less
-   heap pages), but larger index.
+   keys leads to a more precise search (scaning a smaller fraction of the index and
+   fewer heap pages), at the cost of a larger index.
   </para>
    
   <para>
-   <literal>gist__intbig_ops</literal> approximates integer set as a bitmap
-   signature.  Optional integer parameter <literal>siglen</literal> of
-   <literal>gist__intbig_ops</literal> determines signature length in bytes.
-   Default signature length is 16 bytes.  Valid values of signature length
-   are between 1 and 2024 bytes.  Longer signatures leads to more precise
-   search (scan less fraction of index, scan less heap pages), but larger index.
+   <literal>gist__intbig_ops</literal> approximates an integer set as a bitmap
+   signature.  Its optional integer parameter <literal>siglen</literal>
+   determines the signature length in bytes.
+   The default signature length is 16 bytes.  Valid values of signature length
+   are between 1 and 2024 bytes.  Longer signatures lead to a more precise
+   search (scanning a smaller fraction of the index and fewer heap pages), at
+   the cost of a larger index.
   </para>
 
   <para>

doc/src/sgml/ltree.sgml

@@ -516,16 +516,16 @@ Europe & Russia*@ & !Transportation
      <literal>@</literal>, <literal>~</literal>, <literal>?</literal>
     </para>
     <para>
-     <literal>gist_ltree_ops</literal> GiST opclass approximates set of
-     path labels as a bitmap signature.  Optional integer parameter
-     <literal>siglen</literal> of <literal>gist_ltree_ops</literal> determines
-     signature length in bytes.  Default signature length is 8 bytes.
+     <literal>gist_ltree_ops</literal> GiST opclass approximates a set of
+     path labels as a bitmap signature.  Its optional integer parameter
+     <literal>siglen</literal> determines the
+     signature length in bytes.  The default signature length is 8 bytes.
      Valid values of signature length are between 1 and 2024 bytes.  Longer
-     signatures leads to more precise search (scan less fraction of index, scan
-     less heap pages), but larger index.
+     signatures lead to a more precise search (scanning a smaller fraction of the index and
+     fewer heap pages), at the cost of a larger index.
     </para>
     <para>
-     Example of creating such an index with a default signature length of 8 bytes:
+     Example of creating such an index with the default signature length of 8 bytes:
     </para>
 <programlisting>
 CREATE INDEX path_gist_idx ON test USING GIST (path);
@@ -545,13 +545,13 @@ CREATE INDEX path_gist_idx ON test USING GIST (path gist_ltree_ops(siglen=100));
      <literal>@</literal>, <literal>~</literal>, <literal>?</literal>
     </para>
     <para>
-     <literal>gist__ltree_ops</literal> GiST opclass works similar to
+     <literal>gist__ltree_ops</literal> GiST opclass works similarly to
      <literal>gist_ltree_ops</literal> and also takes signature length as
-     a parameter.  Default value of <literal>siglen</literal> in
+     a parameter.  The default value of <literal>siglen</literal> in
       <literal>gist__ltree_ops</literal> is 28 bytes.
     </para>
     <para>
-     Example of creating such an index with a default signature length of 28 bytes:
+     Example of creating such an index with the default signature length of 28 bytes:
     </para>
 <programlisting>
 CREATE INDEX path_gist_idx ON test USING GIST (array_path);

doc/src/sgml/pgtrgm.sgml

@@ -391,13 +391,13 @@ CREATE INDEX trgm_idx ON test_trgm USING GIN (t gin_trgm_ops);
   </para>
 
   <para>
-   <literal>gist_trgm_ops</literal> GiST opclass approximates set of
-   trigrams as a bitmap signature.  Optional integer parameter
-   <literal>siglen</literal> of <literal>gist_trgm_ops</literal> determines
-   signature length in bytes.  Default signature length is 12 bytes.
+   <literal>gist_trgm_ops</literal> GiST opclass approximates a set of
+   trigrams as a bitmap signature.  Its optional integer parameter
+   <literal>siglen</literal> determines the
+   signature length in bytes.  The default length is 12 bytes.
    Valid values of signature length are between 1 and 2024 bytes.  Longer
-   signatures leads to more precise search (scan less fraction of index, scan
-   less heap pages), but larger index.
+   signatures lead to a more precise search (scanning a smaller fraction of the index and
+   fewer heap pages), at the cost of a larger index.
   </para>
 
   <para>

doc/src/sgml/textsearch.sgml

@@ -3670,17 +3670,17 @@ SELECT plainto_tsquery('supernovae stars');
    to check the actual table row to eliminate such false matches.
    (<productname>PostgreSQL</productname> does this automatically when needed.)
    GiST indexes are lossy because each document is represented in the
-   index by a fixed-length signature.  Signature length in bytes is determined
+   index by a fixed-length signature.  The signature length in bytes is determined
    by the value of the optional integer parameter <literal>siglen</literal>.
-   Default signature length (when <literal>siglen</literal> is not specied) is
-   124 bytes, maximal length is 2024 bytes. The signature is generated by hashing
+   The default signature length (when <literal>siglen</literal> is not specified) is
+   124 bytes, the maximum signature length is 2024 bytes. The signature is generated by hashing
    each word into a single bit in an n-bit string, with all these bits OR-ed
    together to produce an n-bit document signature.  When two words hash to
    the same bit position there will be a false match.  If all words in
    the query have matches (real or false) then the table row must be
-   retrieved to see if the match is correct.  Longer signatures leads to more
-   precise search (scan less fraction of index, scan less heap pages), but
-   larger index.
+   retrieved to see if the match is correct.  Longer signatures lead to a more
+   precise search (scanning a smaller fraction of the index and fewer heap
+   pages), at the cost of a larger index.
   </para>
 
   <para>