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<!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 9.2.24 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="2017-11-06T22:43:11"></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" ><A HREF="index.html" >PostgreSQL 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="psql Support" HREF="textsearch-psql.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="textsearch.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 12. Full Text Search</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="Migration from Pre-8.3 Text Search" 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 — 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 >