implemented proper limitation and error reporting in case of truncation for term and query expansions

src/doc/user/usermanual.sgml

@@ -569,9 +569,9 @@ recoll
 
 
       <sect2 id="rcl.indexing.config.gui">
-        <title>The indexing configuration GUI</title>
+        <title>The index configuration GUI</title>
 
-        <para>Most parameters for a given indexing configuration can
+        <para>Most parameters for a given index configuration can
         be set from a <command>recoll</command> GUI running on this
         configuration (either as default, or by setting
         <envar>RECOLL_CONFDIR</envar> or the <option>-c</option>
@@ -4219,6 +4219,24 @@ skippedPaths = ~/somedir/&lowast;.txt
             </listitem>
           </varlistentry>
 
+          <varlistentry><term><varname>maxTermExpand</varname></term>
+            <listitem><para>Maximum expansion count for a single term (e.g.:
+                when using wildcards). The default of 10000 is reasonable and
+                will avoid queries that appear frozen while the engine is
+                walking the term list.</para>
+            </listitem>
+         </varlistentry>
+
+          <varlistentry><term><varname>maxXapianClauses</varname></term>
+            <listitem><para>Maximum number of elementary clauses we can add
+                to a single Xapian query. In some cases, the result of term
+                expansion can be multiplicative, and we want to avoid using
+                excessive memory. The default of 100 000 should be both
+                high enough in most cases and compatible with current
+                typical hardware configurations.</para>
+            </listitem>
+         </varlistentry>
+
           <varlistentry><term><varname>nonumbers</varname></term>
             <listitem><para>If this set to true, no terms will be generated
             for numbers. For example "123", "1.5e6", 192.168.1.4, would not

src/qtgui/confgui/confguiindex.cpp

@@ -195,6 +195,34 @@ ConfSearchPanelW::ConfSearchPanelW(QWidget *parent, ConfNull *config)
 			       ));
     vboxLayout->addWidget(cp2);
 
+    ConfLink lnk3(new ConfLinkRclRep(config, "maxTermExpand"));
+    ConfParamIntW* cp3 = 
+        new ConfParamIntW(this, lnk3, 
+			   tr("Maximum term expansion count"),
+			   tr("<p>Maximum expansion count for a single term "
+			      "(e.g.: when using wildcards). The default "
+			      "of 10 000 is reasonable and will avoid "
+			      "queries that appear frozen while the engine is "
+			      "walking the term list."
+			       ));
+    vboxLayout->addWidget(cp3);
+
+
+    ConfLink lnk4(new ConfLinkRclRep(config, "maxXapianClauses"));
+    ConfParamIntW* cp4 = 
+        new ConfParamIntW(this, lnk4, 
+			   tr("Maximum Xapian clauses count"),
+			   tr("<p>Maximum number of elementary clauses we "
+			      "add to a single Xapian query. In some cases, "
+			      "the result of term expansion can be "
+			      "multiplicative, and we want to avoid using "
+			      "excessive memory. The default of 100 000 "
+			      "should be both high enough in most cases "
+			      "and compatible with current typical hardware "
+			      "configurations."
+			       ));
+    vboxLayout->addWidget(cp4);
+
     vboxLayout->insertStretch(-1);
 }
 

src/query/docseq.h

@@ -138,7 +138,10 @@ class DocSequence {
     {
 	return std::list<std::string>();
     }
-
+    virtual std::string getReason() 
+    {
+	return m_reason;
+    }
     /** Optional functionality. */
     virtual bool canFilter() {return false;}
     virtual bool canSort() {return false;}
@@ -154,6 +157,7 @@ class DocSequence {
 protected:
     static std::string o_sort_trans;
     static std::string o_filt_trans;
+    std::string          m_reason;
  private:
     std::string          m_title;
 };
@@ -206,6 +210,12 @@ public:
 	    return false;
 	return m_seq->getEnclosing(doc, pdoc);
     }
+    virtual std::string getReason() 
+    {
+	if (m_seq.isNull())
+	    return false;
+	return m_seq->getReason();
+    }
     virtual std::string title() {return m_seq->title();}
     virtual RefCntr<DocSequence> getSourceSeq() {return m_seq;}
 

src/query/docseqdb.cpp

@@ -51,14 +51,16 @@ string DocSequenceDb::getDescription()
 
 bool DocSequenceDb::getDoc(int num, Rcl::Doc &doc, string *sh)
 {
-    setQuery();
+    if (!setQuery())
+	return false;
     if (sh) sh->erase();
     return m_q->getDoc(num, doc);
 }
 
 int DocSequenceDb::getResCnt()
 {
-    setQuery();
+    if (!setQuery())
+	return false;
     if (m_rescnt < 0) {
 	m_rescnt= m_q->getResCnt();
     }
@@ -71,7 +73,8 @@ static const string cstr_mre("[...]");
 bool DocSequenceDb::getAbstract(Rcl::Doc &doc, vector<Rcl::Snippet>& vpabs)
 {
     LOGDEB(("DocSequenceDb::getAbstract/pair\n"));
-    setQuery();
+    if (!setQuery())
+	return false;
 
     // Have to put the limit somewhere. 
     int maxoccs = 500;
@@ -93,7 +96,8 @@ bool DocSequenceDb::getAbstract(Rcl::Doc &doc, vector<Rcl::Snippet>& vpabs)
 
 bool DocSequenceDb::getAbstract(Rcl::Doc &doc, vector<string>& vabs)
 {
-    setQuery();
+    if (!setQuery())
+	return false;
     if (m_q->whatDb() &&
 	m_queryBuildAbstract && (doc.syntabs || m_queryReplaceAbstract)) {
 	m_q->makeDocAbstract(doc, vabs);
@@ -105,7 +109,8 @@ bool DocSequenceDb::getAbstract(Rcl::Doc &doc, vector<string>& vabs)
 
 int DocSequenceDb::getFirstMatchPage(Rcl::Doc &doc, string& term)
 {
-    setQuery();
+    if (!setQuery())
+	return false;
     if (m_q->whatDb()) {
 	return m_q->getFirstMatchPage(doc, term);
     }
@@ -114,7 +119,8 @@ int DocSequenceDb::getFirstMatchPage(Rcl::Doc &doc, string& term)
 
 bool DocSequenceDb::getEnclosing(Rcl::Doc& doc, Rcl::Doc& pdoc) 
 {
-    setQuery();
+    if (!setQuery())
+	return false;
     string udi;
     if (!FileInterner::getEnclosing(doc.url, doc.ipath, pdoc.url, pdoc.ipath,
                                     udi))
@@ -124,7 +130,8 @@ bool DocSequenceDb::getEnclosing(Rcl::Doc& doc, Rcl::Doc& pdoc)
 
 list<string> DocSequenceDb::expand(Rcl::Doc &doc)
 {
-    setQuery();
+    if (!setQuery())
+	return list<string>();
     vector<string> v = m_q->expand(doc);
     return list<string>(v.begin(), v.end());
 }
@@ -209,13 +216,10 @@ bool DocSequenceDb::setQuery()
 	return true;
     m_rescnt = -1;
     m_needSetQuery = !m_q->setQuery(m_fsdata);
-
+    if (m_needSetQuery) {
-#if 0
+	m_reason = m_q->getReason();
-	HighlightData hld;
+	LOGERR(("DocSequenceDb::setQuery: rclquery::setQuery failed: %s\n",
-	m_fsdata->getTerms(hld);
+		m_reason.c_str()));
-	string str; 
+    }
-	hld.toString(str);
-	fprintf(stderr, "DocSequenceDb::setQuery: terms: %s\n", str.c_str());
-#endif
     return !m_needSetQuery;
 }

src/query/docseqdb.h

@@ -67,6 +67,7 @@ class DocSequenceDb : public DocSequence {
     bool                     m_isFiltered;
     bool                     m_isSorted;
     bool   m_needSetQuery; // search data changed, need to reapply before fetch
+
     bool setQuery();
 };
 

src/query/recollq.cpp

@@ -319,7 +319,10 @@ int recollq(RclConfig **cfp, int argc, char **argv)
 	query.setSortBy(sortfield, (op_flags & OPT_D) ? false : true);
     }
     Chrono chron;
-    query.setQuery(rq);
+    if (!query.setQuery(rq)) {
+	cerr << "Query setup failed: " << query.getReason() << endl;
+	return(1);
+    }
     int cnt = query.getResCnt();
     if (!(op_flags & OPT_b)) {
 	cout << "Recoll query: " << rq->getDescription() << endl;

src/query/reslistpager.cpp

@@ -337,37 +337,43 @@ void ResListPager::displayPage(RclConfig *config)
 
     if (pageEmpty()) {
 	chunk << trans("<p><b>No results found</b><br>");
-	HighlightData hldata;
+	string reason = m_docSource->getReason();
-        m_docSource->getTerms(hldata);
+	if (!reason.empty()) {
-        vector<string> uterms(hldata.uterms.begin(), hldata.uterms.end());
+	    chunk << "<blockquote>" << escapeHtml(reason) << 
-        if (!uterms.empty()) {
+		"</blockquote></p>";
-            map<string, vector<string> > spellings;
+	} else {
-            suggest(uterms, spellings);
+	    HighlightData hldata;
-            if (!spellings.empty()) {
+	    m_docSource->getTerms(hldata);
-		if (o_index_stripchars) {
+	    vector<string> uterms(hldata.uterms.begin(), hldata.uterms.end());
-		    chunk << 
+	    if (!uterms.empty()) {
-		trans("<p><i>Alternate spellings (accents suppressed): </i>")
+		map<string, vector<string> > spellings;
-			  << "<br /><blockquote>";
+		suggest(uterms, spellings);
-		} else {
+		if (!spellings.empty()) {
-		    chunk << 
+		    if (o_index_stripchars) {
-			trans("<p><i>Alternate spellings: </i>")
+			chunk << 
-			  << "<br /><blockquote>";
+			    trans("<p><i>Alternate spellings (accents suppressed): </i>")
+			      << "<br /><blockquote>";
+		    } else {
+			chunk << 
+			    trans("<p><i>Alternate spellings: </i>")
+			      << "<br /><blockquote>";
 		    
-		}
-
-		for (map<string, vector<string> >::const_iterator it0 =
-			 spellings.begin(); it0 != spellings.end(); it0++) {
-		    chunk << "<b>" << it0->first << "</b> : ";
-		    for (vector<string>::const_iterator it = 
-			     it0->second.begin();
-			 it != it0->second.end(); it++) {
-			chunk << *it << " ";
 		    }
-		    chunk << "<br />";
+
+		    for (map<string, vector<string> >::const_iterator it0 =
+			     spellings.begin(); it0 != spellings.end(); it0++) {
+			chunk << "<b>" << it0->first << "</b> : ";
+			for (vector<string>::const_iterator it = 
+				 it0->second.begin();
+			     it != it0->second.end(); it++) {
+			    chunk << *it << " ";
+			}
+			chunk << "<br />";
+		    }
+		    chunk << "</blockquote></p>";
 		}
-                chunk << "</blockquote></p>";
+	    }
-            }
+	}
-        }
     } else {
 	unsigned int resCnt = m_docSource->getResCnt();
 	if (m_winfirst + m_respage.size() < resCnt) {

src/rcldb/rcldb.cpp

@@ -1431,7 +1431,7 @@ bool Db::purgeFile(const string &udi, bool *existed)
 }
 
 // File name wild card expansion. This is a specialisation ot termMatch
-bool Db::filenameWildExp(const string& fnexp, vector<string>& names)
+bool Db::filenameWildExp(const string& fnexp, vector<string>& names, int max)
 {
     string pattern = fnexp;
     names.clear();
@@ -1449,7 +1449,7 @@ bool Db::filenameWildExp(const string& fnexp, vector<string>& names)
     LOGDEB(("Rcl::Db::filenameWildExp: pattern: [%s]\n", pattern.c_str()));
 
     TermMatchResult result;
-    if (!termMatch(ET_WILD, string(), pattern, result, -1,
+    if (!termMatch(ET_WILD, string(), pattern, result, max,
 		   unsplitFilenameFieldName))
 	return false;
     for (vector<TermMatchEntry>::const_iterator it = result.entries.begin();
@@ -1459,7 +1459,7 @@ bool Db::filenameWildExp(const string& fnexp, vector<string>& names)
     if (names.empty()) {
 	// Build an impossible query: we know its impossible because we
 	// control the prefixes!
-	names.push_back("XNONENoMatchingTerms");
+	names.push_back(wrap_prefix("XNONE") + "NoMatchingTerms");
     }
     return true;
 }

src/rcldb/rcldb.h

@@ -315,7 +315,7 @@ class Db {
     bool maxYearSpan(int *minyear, int *maxyear);
 
     /** Wildcard expansion specific to file names. Internal/sdata use only */
-    bool filenameWildExp(const string& exp, vector<string>& names);
+    bool filenameWildExp(const string& exp, vector<string>& names, int max);
 
     /** Set parameters for synthetic abstract generation */
     void setAbstractParams(int idxTrunc, int synthLen, int syntCtxLen);

src/rcldb/rclquery.cpp

@@ -193,8 +193,13 @@ bool Query::setQuery(RefCntr<SearchData> sdata)
     m_nq->clear();
     m_sd = sdata;
     
+    int maxexp = 10000;
+    m_db->getConf()->getConfParam("maxTermExpand", &maxexp);
+    int maxcl = 100000;
+    m_db->getConf()->getConfParam("maxXapianClauses", &maxcl);
+
     Xapian::Query xq;
-    if (!sdata->toNativeQuery(*m_db, &xq)) {
+    if (!sdata->toNativeQuery(*m_db, &xq, maxexp, maxcl)) {
 	m_reason += sdata->getReason();
 	return false;
     }

src/rcldb/searchdata.cpp

@@ -201,14 +201,16 @@ bool SearchData::expandFileTypes(RclConfig *cfg, vector<string>& tps)
 
 bool SearchData::clausesToQuery(Rcl::Db &db, SClType tp, 
 				vector<SearchDataClause*>& query, 
-				string& reason, void *d)
+				string& reason, void *d, 
+				int maxexp, int maxcl)
 {
     Xapian::Query xq;
     for (qlist_it_t it = query.begin(); it != query.end(); it++) {
 	Xapian::Query nq;
-	if (!(*it)->toNativeQuery(db, &nq)) {
+	if (!(*it)->toNativeQuery(db, &nq, maxexp, maxcl)) {
-	    LOGERR(("SearchData::clausesToQuery: toNativeQuery failed\n"));
+	    LOGERR(("SearchData::clausesToQuery: toNativeQuery failed: %s\n",
-	    reason = (*it)->getReason();
+		    (*it)->getReason().c_str()));
+	    reason += (*it)->getReason() + " ";
 	    return false;
 	}	    
         if (nq.empty()) {
@@ -236,6 +238,13 @@ bool SearchData::clausesToQuery(Rcl::Db &db, SClType tp,
         } else {
             xq = Xapian::Query(op, xq, nq);
         }
+	if (int(xq.get_length()) >= maxcl) {
+	    LOGERR(("Maximum Xapian query size exceeded."
+		    " Maybe increase maxXapianClauses."));
+	    m_reason += "Maximum Xapian query size exceeded."
+		" Maybe increase maxXapianClauses.";
+	    return false;
+	}
     }
     if (xq.empty())
 	xq = Xapian::Query::MatchAll;
@@ -244,7 +253,7 @@ bool SearchData::clausesToQuery(Rcl::Db &db, SClType tp,
     return true;
 }
 
-bool SearchData::toNativeQuery(Rcl::Db &db, void *d)
+bool SearchData::toNativeQuery(Rcl::Db &db, void *d, int maxexp, int maxcl)
 {
     LOGDEB(("SearchData::toNativeQuery: stemlang [%s]\n", m_stemlang.c_str()));
     m_reason.erase();
@@ -252,8 +261,9 @@ bool SearchData::toNativeQuery(Rcl::Db &db, void *d)
     // Walk the clause list translating each in turn and building the 
     // Xapian query tree
     Xapian::Query xq;
-    if (!clausesToQuery(db, m_tp, m_query, m_reason, &xq)) {
+    if (!clausesToQuery(db, m_tp, m_query, m_reason, &xq, maxexp, maxcl)) {
-	LOGERR(("SearchData::toNativeQuery: clausesToQuery failed\n"));
+	LOGERR(("SearchData::toNativeQuery: clausesToQuery failed. reason: %s\n", 
+		m_reason.c_str()));
 	return false;
     }
 
@@ -620,10 +630,10 @@ private:
 class StringToXapianQ {
 public:
     StringToXapianQ(Db& db, HighlightData& hld, const string& field, 
-		    const string &stmlng, bool boostUser)
+		    const string &stmlng, bool boostUser, int maxexp, int maxcl)
 	: m_db(db), m_field(field), m_stemlang(stmlng),
 	  m_doBoostUserTerms(boostUser), m_hld(hld), m_autodiacsens(false),
-	  m_autocasesens(true)
+	  m_autocasesens(true), m_maxexp(maxexp), m_maxcl(maxcl), m_curcl(0)
     { 
 	m_db.getConf()->getConfParam("autodiacsens", &m_autodiacsens);
 	m_db.getConf()->getConfParam("autocasesens", &m_autocasesens);
@@ -635,15 +645,15 @@ public:
 			   vector<Xapian::Query> &pqueries, 
 			   int slack = 0, bool useNear = false);
 private:
-    void expandTerm(int mods, 
+    bool expandTerm(string& ermsg, int mods, 
 		    const string& term, vector<string>& exp, 
                     string& sterm, const string& prefix);
     // After splitting entry on whitespace: process non-phrase element
-    void processSimpleSpan(const string& span, 
+    void processSimpleSpan(string& ermsg, const string& span, 
 			   int mods,
 			   vector<Xapian::Query> &pqueries);
     // Process phrase/near element
-    void processPhraseOrNear(TextSplitQ *splitData, 
+    void processPhraseOrNear(string& ermsg, TextSplitQ *splitData, 
 			     int mods,
 			     vector<Xapian::Query> &pqueries,
 			     bool useNear, int slack);
@@ -655,6 +665,9 @@ private:
     HighlightData& m_hld;
     bool m_autodiacsens;
     bool m_autocasesens;
+    int  m_maxexp;
+    int  m_maxcl;
+    int  m_curcl;
 };
 
 #if 1
@@ -679,7 +692,7 @@ static void listVector(const string& what, const vector<string>&l)
  *  has it already. Used in the simple case where there is nothing to expand, 
  *  and we just return the prefixed term (else Db::termMatch deals with it).
  */
-void StringToXapianQ::expandTerm(int mods, 
+bool StringToXapianQ::expandTerm(string& ermsg, int mods, 
 				 const string& term, 
                                  vector<string>& oexp, string &sterm,
 				 const string& prefix)
@@ -689,7 +702,7 @@ void StringToXapianQ::expandTerm(int mods,
     sterm.clear();
     oexp.clear();
     if (term.empty())
-	return;
+	return true;
 
     bool haswild = term.find_first_of(cstr_minwilds) != string::npos;
 
@@ -753,7 +766,7 @@ void StringToXapianQ::expandTerm(int mods,
 	oexp.push_back(prefix + term);
 	m_hld.terms[term] = m_hld.uterms.size() - 1;
 	LOGDEB(("ExpandTerm: final: %s\n", stringsToString(oexp).c_str()));
-	return;
+	return true;
     } 
 
     // Make objects before the goto jungle to avoid compiler complaints
@@ -770,7 +783,7 @@ void StringToXapianQ::expandTerm(int mods,
 	// expansion, which means that we are casediac-sensitive. There
 	// would be nothing to prevent us to expand from the casediac
 	// synonyms first. To be done later
-	m_db.termMatch(Rcl::Db::ET_WILD, m_stemlang, term, res, -1, m_field);
+	m_db.termMatch(Rcl::Db::ET_WILD, m_stemlang,term,res,m_maxexp,m_field);
 	goto termmatchtoresult;
     }
 
@@ -778,14 +791,14 @@ void StringToXapianQ::expandTerm(int mods,
 
 #ifdef RCL_INDEX_STRIPCHARS
 
-    m_db.termMatch(Rcl::Db::ET_STEM, m_stemlang, term, res, -1, m_field);
+    m_db.termMatch(Rcl::Db::ET_STEM, m_stemlang, term, res, m_maxexp, m_field);
 
 #else
 
     if (o_index_stripchars) {
 	// If the index is raw, we can only come here if nostemexp is unset
 	// and we just need stem expansion.
-	m_db.termMatch(Rcl::Db::ET_STEM, m_stemlang, term, res, -1, m_field);
+	m_db.termMatch(Rcl::Db::ET_STEM, m_stemlang,term,res,m_maxexp,m_field);
 	goto termmatchtoresult;
     } 
 
@@ -854,12 +867,17 @@ exptotermatch:
     LOGDEB(("ExpandTerm:TM: lexp: %s\n", stringsToString(lexp).c_str()));
     for (vector<string>::const_iterator it = lexp.begin();
 	 it != lexp.end(); it++) {
-	m_db.termMatch(Rcl::Db::ET_WILD, m_stemlang, *it,  res, -1, m_field);
+	m_db.termMatch(Rcl::Db::ET_WILD, m_stemlang, *it, res,m_maxexp,m_field);
     }
 #endif
 
     // Term match entries to vector of terms
 termmatchtoresult:
+    if (int(res.entries.size()) >= m_maxexp) {
+	ermsg = "Maximum term expansion size exceeded."
+	    " Maybe increase maxTermExpand.";
+	return false;
+    }
     for (vector<TermMatchEntry>::const_iterator it = res.entries.begin(); 
 	 it != res.entries.end(); it++) {
 	oexp.push_back(it->term);
@@ -876,6 +894,7 @@ termmatchtoresult:
 	m_hld.terms[strip_prefix(*it)] = term;
     }
     LOGDEB(("ExpandTerm: final: %s\n", stringsToString(oexp).c_str()));
+    return true;
 }
 
 // Do distribution of string vectors: a,b c,d -> a,c a,d b,c b,d
@@ -912,7 +931,7 @@ void multiply_groups(vector<vector<string> >::const_iterator vvit,
     }
 }
 
-void StringToXapianQ::processSimpleSpan(const string& span, 
+void StringToXapianQ::processSimpleSpan(string& ermsg, const string& span, 
 					int mods,
 					vector<Xapian::Query> &pqueries)
 {
@@ -927,7 +946,8 @@ void StringToXapianQ::processSimpleSpan(const string& span,
 	prefix = wrap_prefix(ftp->pfx);
     }
 
-    expandTerm(mods, span, exp, sterm, prefix);
+    if (!expandTerm(ermsg, mods, span, exp, sterm, prefix))
+	return;
     
     // Set up the highlight data. No prefix should go in there
     for (vector<string>::const_iterator it = exp.begin(); 
@@ -939,6 +959,7 @@ void StringToXapianQ::processSimpleSpan(const string& span,
 
     // Push either term or OR of stem-expanded set
     Xapian::Query xq(Xapian::Query::OP_OR, exp.begin(), exp.end());
+    m_curcl += exp.size();
 
     // If sterm (simplified original user term) is not null, give it a
     // relevance boost. We do this even if no expansion occurred (else
@@ -957,7 +978,7 @@ void StringToXapianQ::processSimpleSpan(const string& span,
 // NEAR xapian query, the elements of which can themselves be OR
 // queries if the terms get expanded by stemming or wildcards (we
 // don't do stemming for PHRASE though)
-void StringToXapianQ::processPhraseOrNear(TextSplitQ *splitData, 
+void StringToXapianQ::processPhraseOrNear(string& ermsg, TextSplitQ *splitData, 
 					  int mods,
 					  vector<Xapian::Query> &pqueries,
 					  bool useNear, int slack)
@@ -999,7 +1020,8 @@ void StringToXapianQ::processPhraseOrNear(TextSplitQ *splitData,
 	    lmods |= SearchDataClause::SDCM_NOSTEMMING;
 	string sterm;
 	vector<string> exp;
-	expandTerm(lmods, *it, exp, sterm, prefix);
+	if (!expandTerm(ermsg, lmods, *it, exp, sterm, prefix))
+	    return;
 	LOGDEB0(("ProcessPhraseOrNear: exp size %d\n", exp.size()));
 	listVector("", exp);
 	// groups is used for highlighting, we don't want prefixes in there.
@@ -1011,6 +1033,9 @@ void StringToXapianQ::processPhraseOrNear(TextSplitQ *splitData,
 	groups.push_back(noprefs);
 	orqueries.push_back(Xapian::Query(Xapian::Query::OP_OR, 
 					  exp.begin(), exp.end()));
+	m_curcl += exp.size();
+	if (m_curcl >= m_maxcl)
+	    return;
 #ifdef XAPIAN_NEAR_EXPAND_SINGLE_BUF
 	if (exp.size() > 1) 
 	    hadmultiple = true;
@@ -1099,7 +1124,7 @@ bool StringToXapianQ::processUserString(const string &iq,
 	    "slack %d near %d\n", 
 	    iq.c_str(), m_field.c_str(), mods, slack, useNear));
     ermsg.erase();
-
+    m_curcl = 0;
     const StopList stops = m_db.getStopList();
 
     // Simple whitespace-split input into user-level words and
@@ -1165,12 +1190,18 @@ bool StringToXapianQ::processUserString(const string &iq,
 		if (splitter.nostemexps.front())
 		    lmods |= SearchDataClause::SDCM_NOSTEMMING;
 		m_hld.ugroups.push_back(vector<string>(1, *it));
-		processSimpleSpan(splitter.terms.front(), lmods, pqueries);
+		processSimpleSpan(ermsg,splitter.terms.front(),lmods, pqueries);
 	    }
 		break;
 	    default:
 		m_hld.ugroups.push_back(vector<string>(1, *it));
-		processPhraseOrNear(&splitter, mods, pqueries, useNear, slack);
+		processPhraseOrNear(ermsg, &splitter, mods, pqueries,
+				    useNear, slack);
+	    }
+	    if (m_curcl >= m_maxcl) {
+		ermsg = "Maximum Xapian query size exceeded."
+		    " Maybe increase maxXapianClauses.";
+		break;
 	    }
 	}
     } catch (const Xapian::Error &e) {
@@ -1190,7 +1221,8 @@ bool StringToXapianQ::processUserString(const string &iq,
 }
 
 // Translate a simple OR, AND, or EXCL search clause. 
-bool SearchDataClauseSimple::toNativeQuery(Rcl::Db &db, void *p)
+bool SearchDataClauseSimple::toNativeQuery(Rcl::Db &db, void *p, 
+					   int maxexp, int maxcl)
 {
     LOGDEB2(("SearchDataClauseSimple::toNativeQuery: stemlang [%s]\n",
 	     getStemLang().c_str()));
@@ -1216,7 +1248,8 @@ bool SearchDataClauseSimple::toNativeQuery(Rcl::Db &db, void *p)
 	(m_parentSearch && !m_parentSearch->haveWildCards()) || 
 	(m_parentSearch == 0 && !m_haveWildCards);
 
-    StringToXapianQ tr(db, m_hldata, m_field, getStemLang(), doBoostUserTerm);
+    StringToXapianQ tr(db, m_hldata, m_field, getStemLang(), doBoostUserTerm,
+		       maxexp, maxcl);
     if (!tr.processUserString(m_text, getModifiers(), m_reason, pqueries))
 	return false;
     if (pqueries.empty()) {
@@ -1240,13 +1273,14 @@ bool SearchDataClauseSimple::toNativeQuery(Rcl::Db &db, void *p)
 // about expanding multiple fragments in the past. We just take the
 // value blanks and all and expand this against the indexed unsplit
 // file names
-bool SearchDataClauseFilename::toNativeQuery(Rcl::Db &db, void *p)
+bool SearchDataClauseFilename::toNativeQuery(Rcl::Db &db, void *p, 
+					     int maxexp, int)
 {
     Xapian::Query *qp = (Xapian::Query *)p;
     *qp = Xapian::Query();
 
     vector<string> names;
-    db.filenameWildExp(m_text, names);
+    db.filenameWildExp(m_text, names, maxexp);
     *qp = Xapian::Query(Xapian::Query::OP_OR, names.begin(), names.end());
 
     if (m_weight != 1.0) {
@@ -1256,7 +1290,8 @@ bool SearchDataClauseFilename::toNativeQuery(Rcl::Db &db, void *p)
 }
 
 // Translate NEAR or PHRASE clause. 
-bool SearchDataClauseDist::toNativeQuery(Rcl::Db &db, void *p)
+bool SearchDataClauseDist::toNativeQuery(Rcl::Db &db, void *p, 
+					 int maxexp, int maxcl)
 {
     LOGDEB(("SearchDataClauseDist::toNativeQuery\n"));
 
@@ -1281,7 +1316,8 @@ bool SearchDataClauseDist::toNativeQuery(Rcl::Db &db, void *p)
     }
     string s = cstr_dquote + m_text + cstr_dquote;
     bool useNear = (m_tp == SCLT_NEAR);
-    StringToXapianQ tr(db, m_hldata, m_field, getStemLang(), doBoostUserTerm);
+    StringToXapianQ tr(db, m_hldata, m_field, getStemLang(), doBoostUserTerm,
+		       maxexp, maxcl);
     if (!tr.processUserString(s, getModifiers(), m_reason, pqueries, 
 			      m_slack, useNear))
 	return false;

src/rcldb/searchdata.h

@@ -89,8 +89,7 @@ public:
     bool haveWildCards() {return m_haveWildCards;}
 
     /** Translate to Xapian query. rcldb knows about the void*  */
-    bool toNativeQuery(Rcl::Db &db, void *);
+    bool toNativeQuery(Rcl::Db &db, void *, int maxexp, int maxcl);
-
 
     /** We become the owner of cl and will delete it */
     bool addClause(SearchDataClause *cl);
@@ -175,7 +174,7 @@ private:
     bool expandFileTypes(RclConfig *cfg, std::vector<std::string>& exptps);
     bool clausesToQuery(Rcl::Db &db, SClType tp,     
 			std::vector<SearchDataClause*>& query,
-			string& reason, void *d);
+			string& reason, void *d, int, int);
 
     /* Copyconst and assignment private and forbidden */
     SearchData(const SearchData &) {}
@@ -192,7 +191,7 @@ public:
       m_modifiers(SDCM_NONE), m_weight(1.0)
     {}
     virtual ~SearchDataClause() {}
-    virtual bool toNativeQuery(Rcl::Db &db, void *) = 0;
+    virtual bool toNativeQuery(Rcl::Db &db, void *, int maxexp, int maxcl) = 0;
     bool isFileName() const {return m_tp == SCLT_FILENAME ? true: false;}
     virtual std::string getReason() const {return m_reason;}
     virtual void getTerms(HighlightData & hldata) const = 0;
@@ -266,7 +265,7 @@ public:
     }
 
     /** Translate to Xapian query */
-    virtual bool toNativeQuery(Rcl::Db &, void *);
+    virtual bool toNativeQuery(Rcl::Db &, void *, int maxexp, int maxcl);
 
     virtual void getTerms(HighlightData& hldata) const
     {
@@ -307,7 +306,7 @@ public:
     {
     }
 
-    virtual bool toNativeQuery(Rcl::Db &, void *);
+    virtual bool toNativeQuery(Rcl::Db &, void *, int maxexp, int maxcl);
 };
 
 /** 
@@ -326,7 +325,7 @@ public:
     {
     }
 
-    virtual bool toNativeQuery(Rcl::Db &, void *);
+    virtual bool toNativeQuery(Rcl::Db &, void *, int maxexp, int maxcl);
 private:
     int m_slack;
 };
@@ -338,9 +337,12 @@ public:
 	: SearchDataClause(tp), m_sub(sub) 
     {
     }
-    virtual bool toNativeQuery(Rcl::Db &db, void *p)
+    virtual bool toNativeQuery(Rcl::Db &db, void *p, int maxexp, int maxcl)
     {
-	return m_sub->toNativeQuery(db, p);
+	bool ret = m_sub->toNativeQuery(db, p, maxexp, maxcl);
+	if (!ret) 
+	    m_reason = m_sub->getReason();
+	return ret;
     }
 
     virtual void getTerms(HighlightData& hldata) const

src/sampleconf/recoll.conf.in

@@ -103,6 +103,17 @@ indexstemminglanguages = english
 # Actually, this seems a reasonable default for all until someone protests.
 unac_except_trans = åå Åå ää Ää öö Öö üü Üü ßss œoe Œoe æae ÆAE fifi flfl
 
+# Maximum expansion count for a single term (ie: when using wildcards).
+# We used to not limit this at all (except for filenames where the limit
+# was too low at 1000), but it is unreasonable with a big index. 
+# Default 10 000
+maxTermExpand = 10000
+
+# Maximum number of clauses we add to a single Xapian query. In some cases,
+# the result of term expansion can be multiplicative, and we want to avoid
+# eating all the memory. Default 100 000
+maxXapianClauses = 100000
+
 # Where to store the database (directory). This may be an absolute path,
 # else it is taken as relative to the configuration directory (-c argument
 # or $RECOLL_CONFDIR). 
@@ -132,18 +143,6 @@ filtersdir = @prefix@/share/recoll/filters
 # want to change the icons displayed in the result list
 iconsdir = @prefix@/share/recoll/images
 
-# A list of characters, encoded in UTF-8, which should be handled specially
-# when converting text to unaccented lowercase. For example, in Swedish,
-# the letter a with diaeresis has full alphabet citizenship and should not
-# be turned into an a.  Each element in the space-separated list has the
-# special character as first element and the translation following
-# (multiple chars allowed.  The handling of both the lowercase and
-# upper-case versions of a character should be specified, as appartenance
-# to the list will turn-off both standard accent and case
-# processing. ** Changing the list implies a full reindex **
-# Example for Swedish:
-# unac_except_trans =  åå Åå ää Ää öö Öö
-
 # Should we use the system's 'file -i' command as a final step in file type
 # identification ? This may be useful, but will usually cause the
 # indexation of many bogus 'text' files