Sophie

Sophie

distrib > Mandriva > 2008.1 > x86_64 > media > main-testing > by-pkgid > bab02a23fa9f3df8d66a9a3231b50245 > files > 847

postgresql8.3-docs-8.3.6-2mdv2008.1.x86_64.rpm

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Limitations</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 8.3.6 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Full Text Search"
HREF="textsearch.html"><LINK
REL="PREVIOUS"
TITLE="psql Support"
HREF="textsearch-psql.html"><LINK
REL="NEXT"
TITLE="Migration from Pre-8.3 Text Search"
HREF="textsearch-migration.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2009-02-03T04:34:16"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
>PostgreSQL 8.3.6 Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="textsearch-psql.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="textsearch.html"
>Fast Backward</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 12. Full Text Search</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="textsearch.html"
>Fast Forward</A
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="top"
><A
HREF="textsearch-migration.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="TEXTSEARCH-LIMITATIONS"
>12.11. Limitations</A
></H1
><P
>   The current limitations of <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>'s
   text search features are:
   <P
></P
></P><UL
COMPACT="COMPACT"
><LI
STYLE="list-style-type: disc"
><P
>The length of each lexeme must be less than 2K bytes</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>The length of a <TT
CLASS="TYPE"
>tsvector</TT
> (lexemes + positions) must be
     less than 1 megabyte</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>The number of lexemes must be less than
     2<SUP
>64</SUP
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Position values in <TT
CLASS="TYPE"
>tsvector</TT
> must be greater than 0 and
     no more than 16,383</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>No more than 256 positions per lexeme</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>The number of nodes (lexemes + operators) in a <TT
CLASS="TYPE"
>tsquery</TT
>
     must be less than 32,768</P
></LI
></UL
><P>
  </P
><P
>   For comparison, the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 8.1 documentation
   contained 10,441 unique words, a total of 335,420 words, and the most
   frequent word <SPAN
CLASS="QUOTE"
>"postgresql"</SPAN
> was mentioned 6,127 times in 655
   documents.
  </P
><P
>   Another example &mdash; the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> mailing
   list archives contained 910,989 unique words with 57,491,343 lexemes in
   461,020 messages.
  </P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="textsearch-psql.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="textsearch-migration.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><SPAN
CLASS="APPLICATION"
>psql</SPAN
> Support</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="textsearch.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Migration from Pre-8.3 Text Search</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>