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

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the sample contains just a one tsvector, containing only one lexeme.
This commit is contained in:
Heikki Linnakangas 2008-11-27 21:17:39 +00:00
parent fb645f6426
commit a93b3b98cd
1 changed files with 22 additions and 21 deletions
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43
src/backend/tsearch/ts_typanalyze.c
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@ -7,7 +7,7 @@
* *
* *
* IDENTIFICATION * 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) if (num_mcelem > track_len)
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 */ /* Generate MCELEM slot entry */
if (num_mcelem > 0) if (num_mcelem > 0)
{ {
@ -317,6 +297,27 @@ compute_tsvector_stats(VacAttrStats *stats,
Datum *mcelem_values; Datum *mcelem_values;
float4 *mcelem_freqs; 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 */ /* Must copy the target values into anl_context */
old_context = MemoryContextSwitchTo(stats->anl_context); old_context = MemoryContextSwitchTo(stats->anl_context);