diff options
Diffstat (limited to 'doc/src')
-rw-r--r-- | doc/src/sgml/bloom.sgml | 19 |
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 — col16</></term> + <term><literal>col1 — 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> |