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Don't convert to and from floats in pg_dump.

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Commit 8f427187db 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 00d61a08c5.

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
This commit is contained in:
Jeff Davis
2025-03-08 11:25:36 -08:00
parent 7fb8801021
commit 1852aea3f5
2 changed files with 10 additions and 14 deletions
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22
src/bin/pg_dump/pg_dump.c
View File

@ -525,9 +525,6 @@ 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.
@ -6816,10 +6813,12 @@ getFuncs(Archive *fout)
* 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)
@ -6846,7 +6845,7 @@ 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;
@ -7149,7 +7148,6 @@ 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;
@ -7252,8 +7250,8 @@ 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
@ -7762,7 +7760,6 @@ 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;
@ -7805,7 +7802,8 @@ 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));
@ -10493,7 +10491,6 @@ 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;
@ -10568,8 +10565,7 @@ 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);

2
src/bin/pg_dump/pg_dump.h
View File

@ -439,7 +439,7 @@ typedef struct _relStatsInfo
{
DumpableObject dobj;
int32 relpages;
float reltuples;
char *reltuples;
int32 relallvisible;
char relkind; /* 'r', 'm', 'i', etc */