summaryrefslogtreecommitdiff
path: root/doc/src
diff options
context:
space:
mode:
Diffstat (limited to 'doc/src')
-rw-r--r--doc/src/sgml/bloom.sgml19
1 files changed, 10 insertions, 9 deletions
diff --git a/doc/src/sgml/bloom.sgml b/doc/src/sgml/bloom.sgml
index 49cb066144c..8667763c43c 100644
--- a/doc/src/sgml/bloom.sgml
+++ b/doc/src/sgml/bloom.sgml
@@ -8,8 +8,8 @@
</indexterm>
<para>
- <literal>bloom</> is a module which implements an index access method. It comes
- as an example of custom access methods and generic WAL records usage. But it
+ <literal>bloom</> is a module that implements an index access method. It comes
+ as an example of custom access methods and generic WAL record usage. But it
is also useful in itself.
</para>
@@ -22,8 +22,9 @@
allows fast exclusion of non-candidate tuples via signatures.
Since a signature is a lossy representation of all indexed attributes,
search results must be rechecked using heap information.
- The user can specify signature length (in uint16, default is 5) and the
- number of bits, which can be set per attribute (1 < colN < 2048).
+ The user can specify signature length in bits (default 80, maximum 4096)
+ and the number of bits generated for each index column (default 2,
+ maximum 4095).
</para>
<para>
@@ -51,17 +52,17 @@
<term><literal>length</></term>
<listitem>
<para>
- Length of signature in uint16 type values
+ Length of signature in bits
</para>
</listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
- <term><literal>col1 &mdash; col16</></term>
+ <term><literal>col1 &mdash; col32</></term>
<listitem>
<para>
- Number of bits for corresponding column
+ Number of bits generated for each index column
</para>
</listitem>
</varlistentry>
@@ -77,12 +78,12 @@
<programlisting>
CREATE INDEX bloomidx ON tbloom USING bloom (i1,i2,i3)
- WITH (length=5, col1=2, col2=2, col3=4);
+ WITH (length=80, col1=2, col2=2, col3=4);
</programlisting>
<para>
Here, we created a bloom index with a signature length of 80 bits,
- and attributes i1 and i2 mapped to 2 bits, and attribute i3 to 4 bits.
+ and attributes i1 and i2 mapped to 2 bits, and attribute i3 mapped to 4 bits.
</para>
<para>