diff options
Diffstat (limited to 'doc/src/sgml/ref/create_index.sgml')
| -rw-r--r-- | doc/src/sgml/ref/create_index.sgml | 37 |
1 files changed, 2 insertions, 35 deletions
diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml index 4df3d756de7..ad619cdcfe4 100644 --- a/doc/src/sgml/ref/create_index.sgml +++ b/doc/src/sgml/ref/create_index.sgml @@ -356,41 +356,8 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] <replaceable class= <para> The optional <literal>WITH</literal> clause specifies <firstterm>storage parameters</firstterm> for the index. Each index method has its own set of allowed - storage parameters. All indexes accept the following parameter: - </para> - - <variablelist> - <varlistentry> - <term><literal>recheck_on_update</literal></term> - <listitem> - <para> - Specifies whether to recheck a functional index value to see whether - we can use a HOT update or not. The default value is on for functional - indexes with an total expression cost less than 1000, otherwise off. - You might decide to turn this off if you knew that a function used in - an index is unlikely to return the same value when one of the input - columns is updated and so the recheck is not worth the additional cost - of executing the function. - </para> - - <para> - Functional indexes are used frequently for the case where the function - returns a subset of the argument. Examples of this would be accessing - part of a string with <literal>SUBSTR()</literal> or accessing a single - field in a JSON document using an expression such as - <literal>(bookinfo->>'isbn')</literal>. In this example, the JSON - document might be updated frequently, yet it is uncommon for the ISBN - field for a book to change so we would keep the parameter set to on - for that index. A more frequently changing field might have an index - with this parameter turned off, while very frequently changing fields - might be better to avoid indexing at all under high load. - </para> - </listitem> - </varlistentry> - </variablelist> - - <para> - The B-tree, hash, GiST and SP-GiST index methods all accept this parameter: + storage parameters. The B-tree, hash, GiST and SP-GiST index methods all + accept this parameter: </para> <variablelist> |