Fix bug in the tsvector stats collection function, which caused a crash if

the sample contains just a one tsvector, containing only one lexeme.

diff --git a/src/backend/tsearch/ts_typanalyze.c b/src/backend/tsearch/ts_typanalyze.c
index a284360a922bff19c860dc14e80718038feeb3f6..199432097bc969b53e327357a841d316253b26ea 100644 (file)
--- a/src/backend/tsearch/ts_typanalyze.c
+++ b/src/backend/tsearch/ts_typanalyze.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/tsearch/ts_typanalyze.c,v 1.2 2008/09/19 19:03:40 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/tsearch/ts_typanalyze.c,v 1.3 2008/11/27 21:17:39 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -290,26 +290,6 @@ compute_tsvector_stats(VacAttrStats *stats,
                if (num_mcelem > track_len)
                        num_mcelem = track_len;
 
-               /* Grab the minimal and maximal frequencies that will get stored */
-               minfreq = sort_table[num_mcelem - 1]->frequency;
-               maxfreq = sort_table[0]->frequency;
-
-               /*
-                * We want to store statistics sorted on the lexeme value using first
-                * length, then byte-for-byte comparison. The reason for doing length
-                * comparison first is that we don't care about the ordering so long
-                * as it's consistent, and comparing lengths first gives us a chance
-                * to avoid a strncmp() call.
-                *
-                * This is different from what we do with scalar statistics -- they get
-                * sorted on frequencies. The rationale is that we usually search
-                * through most common elements looking for a specific value, so we can
-                * grab its frequency.  When values are presorted we can employ binary
-                * search for that.  See ts_selfuncs.c for a real usage scenario.
-                */
-               qsort(sort_table, num_mcelem, sizeof(TrackItem *),
-                         trackitem_compare_lexemes);
-
                /* Generate MCELEM slot entry */
                if (num_mcelem > 0)
                {
@@ -317,6 +297,27 @@ compute_tsvector_stats(VacAttrStats *stats,
                        Datum                   *mcelem_values;
                        float4                  *mcelem_freqs;
 
+                       /* Grab the minimal and maximal frequencies that will get stored */
+                       minfreq = sort_table[num_mcelem - 1]->frequency;
+                       maxfreq = sort_table[0]->frequency;
+
+                       /*
+                        * We want to store statistics sorted on the lexeme value using
+                        * first length, then byte-for-byte comparison. The reason for
+                        * doing length comparison first is that we don't care about the
+                        * ordering so long as it's consistent, and comparing lengths first
+                        * gives us a chance to avoid a strncmp() call.
+                        *
+                        * This is different from what we do with scalar statistics -- they
+                        * get sorted on frequencies. The rationale is that we usually
+                        * search through most common elements looking for a specific
+                        * value, so we can grab its frequency.  When values are presorted
+                        * we can employ binary search for that.  See ts_selfuncs.c for a
+                        * real usage scenario.
+                        */
+                       qsort(sort_table, num_mcelem, sizeof(TrackItem *),
+                                 trackitem_compare_lexemes);
+
                        /* Must copy the target values into anl_context */
                        old_context = MemoryContextSwitchTo(stats->anl_context);