Don't convert to and from floats in pg_dump.

Commit 8f42718 improved performance by remembering relation stats
as native types rather than issuing a new query for each relation.

Using native types is fine for integers like relpages; but reltuples
is floating point. The commit controllled for that complexity by using
setlocale(LC_NUMERIC, "C"). After that, Alexander Lakhin found a
problem in pg_strtof(), fixed in 00d61a0.

While we aren't aware of any more problems with that approach, it
seems wise to just use a string the whole way for floating point
values, as Corey's original patch did, and get rid of the
setlocale(). Integers are still converted to native types to avoid
wasting memory.

Co-authored-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/3049348.1740855411@sss.pgh.pa.us
Discussion: https://postgr.es/m/560cca3781740bd69881bb07e26eb8f65b09792c.camel%40j-davis.com
(cherry picked from commit 1852aea)

Author: 2 people

src/bin/pg_dump/pg_dump.c

@@ -433,9 +433,6 @@ main(int argc, char **argv)
 	pg_logging_set_level(PG_LOG_WARNING);
 	set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_dump"));
 
-	/* ensure that locale does not affect floating point interpretation */
-	setlocale(LC_NUMERIC, "C");
-
 	/*
 	 * Initialize what we need for parallel execution, especially for thread
 	 * support on Windows.
@@ -6291,10 +6288,12 @@ getFuncs(Archive *fout, int *numFuncs)
  * getRelationStatistics
  *    register the statistics object as a dependent of the relation.
  *
+ * reltuples is passed as a string to avoid complexities in converting from/to
+ * floating point.
  */
 static RelStatsInfo *
 getRelationStatistics(Archive *fout, DumpableObject *rel, int32 relpages,
-					  float reltuples, int32 relallvisible, char relkind,
+					  char *reltuples, int32 relallvisible, char relkind,
 					  char **indAttNames, int nindAttNames)
 {
 	if (!fout->dopt->dumpStatistics)
@@ -6321,7 +6320,7 @@ getRelationStatistics(Archive *fout, DumpableObject *rel, int32 relpages,
 		dobj->name = pg_strdup(rel->name);
 		dobj->namespace = rel->namespace;
 		info->relpages = relpages;
-		info->reltuples = reltuples;
+		info->reltuples = pstrdup(reltuples);
 		info->relallvisible = relallvisible;
 		info->relkind = relkind;
 		info->indAttNames = indAttNames;
@@ -6622,7 +6621,6 @@ getTables(Archive *fout, int *numTables)
 
 	for (i = 0; i < ntups; i++)
 	{
-		float		reltuples = strtof(PQgetvalue(res, i, i_reltuples), NULL);
 		int32		relallvisible = atoi(PQgetvalue(res, i, i_relallvisible));
 
 		tblinfo[i].dobj.objType = DO_TABLE;
@@ -6725,8 +6723,8 @@ getTables(Archive *fout, int *numTables)
 		/* Add statistics */
 		if (tblinfo[i].interesting)
 			getRelationStatistics(fout, &tblinfo[i].dobj, tblinfo[i].relpages,
-								  reltuples, relallvisible, tblinfo[i].relkind,
-								  NULL, 0);
+								  PQgetvalue(res, i, i_reltuples),
+								  relallvisible, tblinfo[i].relkind, NULL, 0);
 
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
@@ -7202,7 +7200,6 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 			char		indexkind;
 			RelStatsInfo *relstats;
 			int32		relpages = atoi(PQgetvalue(res, j, i_relpages));
-			float		reltuples = strtof(PQgetvalue(res, j, i_reltuples), NULL);
 			int32		relallvisible = atoi(PQgetvalue(res, j, i_relallvisible));
 
 			indxinfo[j].dobj.objType = DO_INDEX;
@@ -7245,7 +7242,8 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 			}
 
 			relstats = getRelationStatistics(fout, &indxinfo[j].dobj, relpages,
-											 reltuples, relallvisible, indexkind,
+											 PQgetvalue(res, j, i_reltuples),
+											 relallvisible, indexkind,
 											 indAttNames, nindAttNames);
 
 			contype = *(PQgetvalue(res, j, i_contype));
@@ -9936,7 +9934,6 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
 	DumpId	   *deps = NULL;
 	int			ndeps = 0;
 	char	   *qualified_name;
-	char		reltuples_str[FLOAT_SHORTEST_DECIMAL_LEN];
 	int			i_attname;
 	int			i_inherited;
 	int			i_null_frac;
@@ -10011,8 +10008,7 @@ dumpRelationStats(Archive *fout, const RelStatsInfo *rsinfo)
 	appendStringLiteralAH(out, qualified_name, fout);
 	appendPQExpBufferStr(out, "::regclass,\n");
 	appendPQExpBuffer(out, "\t'relpages', '%d'::integer,\n", rsinfo->relpages);
-	float_to_shortest_decimal_buf(rsinfo->reltuples, reltuples_str);
-	appendPQExpBuffer(out, "\t'reltuples', '%s'::real,\n", reltuples_str);
+	appendPQExpBuffer(out, "\t'reltuples', '%s'::real,\n", rsinfo->reltuples);
 	appendPQExpBuffer(out, "\t'relallvisible', '%d'::integer\n);\n",
 					  rsinfo->relallvisible);
 

src/bin/pg_dump/pg_dump.h

@@ -432,7 +432,7 @@ typedef struct _relStatsInfo
 {
 	DumpableObject dobj;
 	int32		relpages;
-	float		reltuples;
+	char	   *reltuples;
 	int32		relallvisible;
 	char		relkind;		/* 'r', 'm', 'i', etc */