diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index fa628cd8eef..07a80bf9365 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -349,25 +349,6 @@ typedef struct
List *already_used; /* expressions already dealt with */
} ec_member_foreign_arg;
-/* Pairs of remote columns with local columns */
-typedef struct
-{
- AttrNumber local_attnum;
- char *local_attname;
- char *remote_attname;
- int res_index;
-} RemoteAttributeMapping;
-
-/* Result sets that are returned from a foreign statistics scan */
-typedef struct
-{
- PGresult *rel;
- PGresult *att;
- double livetuples;
- double deadtuples;
- int version;
-} RemoteStatsResults;
-
/* Column order in relation stats query */
enum RelStatsColumns
{
@@ -397,6 +378,25 @@ enum AttStatsColumns
ATTSTATS_NUM_FIELDS,
};
+/* Result sets that are returned from a foreign statistics scan */
+typedef struct
+{
+ PGresult *rel; /* result for relation stats query */
+ PGresult *att; /* result for attribute stats query */
+ double livetuples; /* livetuples estimates, for pgstat report */
+ double deadtuples; /* deadtuples estimates, for pgstat report */
+ int version; /* version of remote server */
+} RemoteStatsResults;
+
+/* Pairs of remote columns with local columns */
+typedef struct
+{
+ AttrNumber local_attnum; /* attribute number of local column */
+ char *local_attname; /* attribute name of local column */
+ char *remote_attname; /* attribute name of remote column */
+ int res_index; /* index of row in attribute stats result */
+} RemoteAttributeMapping;
+
/*
* SQL functions
*/
@@ -592,12 +592,12 @@ static void analyze_row_processor(PGresult *res, int row,
PgFdwAnalyzeState *astate);
static bool fetch_remote_statistics(Relation relation,
List *va_cols,
- ForeignTable *table,
const char *local_schemaname,
const char *local_relname,
- int *p_attrcnt,
+ ForeignTable *table,
+ RemoteStatsResults *remstats,
RemoteAttributeMapping **p_remattrmap,
- RemoteStatsResults *remstats);
+ int *p_attrcnt);
static PGresult *fetch_relstats(PGconn *conn, Relation relation);
static PGresult *fetch_attstats(PGconn *conn, int server_version_num,
const char *remote_schemaname, const char *remote_relname,
@@ -612,14 +612,14 @@ static bool match_attrmap(PGresult *res,
const char *local_relname,
const char *remote_schemaname,
const char *remote_relname,
- int attrcnt,
- RemoteAttributeMapping *remattrmap);
+ RemoteAttributeMapping *remattrmap,
+ int attrcnt);
static bool import_fetched_statistics(Relation relation,
const char *schemaname,
const char *relname,
- int attrcnt,
+ RemoteStatsResults *remstats,
const RemoteAttributeMapping *remattrmap,
- RemoteStatsResults *remstats);
+ int attrcnt);
static char *get_opt_value(PGresult *res, int row, int col);
static void set_text_arg(NullableDatum *arg, const char *s);
static void set_int32_arg(NullableDatum *arg, const char *s);
@@ -5763,12 +5763,12 @@ postgresImportForeignStatistics(Relation relation, List *va_cols, int elevel)
starttime = GetCurrentTimestamp();
ok = fetch_remote_statistics(relation, va_cols,
- table, schemaname, relname,
- &attrcnt, &remattrmap, &remstats);
+ schemaname, relname, table,
+ &remstats, &remattrmap, &attrcnt);
if (ok)
ok = import_fetched_statistics(relation, schemaname, relname,
- attrcnt, remattrmap, &remstats);
+ &remstats, remattrmap, attrcnt);
if (ok)
{
@@ -5794,12 +5794,12 @@ postgresImportForeignStatistics(Relation relation, List *va_cols, int elevel)
static bool
fetch_remote_statistics(Relation relation,
List *va_cols,
- ForeignTable *table,
const char *local_schemaname,
const char *local_relname,
- int *p_attrcnt,
+ ForeignTable *table,
+ RemoteStatsResults *remstats,
RemoteAttributeMapping **p_remattrmap,
- RemoteStatsResults *remstats)
+ int *p_attrcnt)
{
const char *remote_schemaname = NULL;
const char *remote_relname = NULL;
@@ -5816,7 +5816,7 @@ fetch_remote_statistics(Relation relation,
ListCell *lc;
/*
- * Assume the remote schema/relation names are the same as the local name
+ * Assume the remote schema/table names are the same as the local name
* unless the foreign table's options tell us otherwise.
*/
remote_schemaname = local_schemaname;
@@ -5834,6 +5834,9 @@ fetch_remote_statistics(Relation relation,
/*
* Get connection to the foreign server. Connection manager will
* establish new connection if necessary.
+ *
+ * Note that unlike the sampling case, we only query pg_class and
+ * pg_stats, so we do the remote access as the current user.
*/
user = GetUserMapping(GetUserId(), table->serverid);
conn = GetConnection(user, false, NULL);
@@ -5870,36 +5873,26 @@ fetch_remote_statistics(Relation relation,
* If the reltuples value > 0, then we can expect to find attribute stats
* for the remote table.
*
- * In v14 or later, if a reltuples value is -1, it means the table has
- * never been analyzed, so we wouldn't expect to find the stats for the
- * table; fallback to sampling in that case. If the value is 0, it means
- * it was empty; in which case skip the stats and import relation stats
- * only.
+ * In v14 or later, if the value is -1, it means the table had never been
+ * analyzed, so we wouldn't expect to find the stats; fallback to sampling
+ * in that case. If the value is 0, it means it was empty, in which case
+ * we don't need the stats, so import relation stats only.
*
* In versions prior to v14, a value of 0 was ambiguous; it could mean
- * that the table had never been analyzed, or that it was empty. Either
- * way, we wouldn't expect to find the stats for the table, so we fallback
- * to sampling.
+ * that the table had never been analyzed, or that it was empty. Assuming
+ * the former, fallback to sampling.
*/
reltuples = strtod(PQgetvalue(relstats, 0, RELSTATS_RELTUPLES), NULL);
- if (((server_version_num < 140000) && (reltuples == 0)) ||
- ((server_version_num >= 140000) && (reltuples == -1)))
- {
- ereport(WARNING,
- errmsg("could not import statistics for foreign table \"%s.%s\" --- remote table \"%s.%s\" has no relation statistics to import",
- local_schemaname, local_relname,
- remote_schemaname, remote_relname));
- goto fetch_cleanup;
- }
-
if (reltuples > 0)
{
StringInfoData column_list;
+ /* Create mappings of local/remote columns. */
*p_remattrmap = remattrmap = build_remattrmap(relation, va_cols,
&attrcnt, &column_list);
*p_attrcnt = attrcnt;
+ /* Try to get attribute stats if needed. */
if (attrcnt > 0)
{
/* Fetch attribute stats. */
@@ -5913,10 +5906,19 @@ fetch_remote_statistics(Relation relation,
if (!match_attrmap(attstats,
local_schemaname, local_relname,
remote_schemaname, remote_relname,
- attrcnt, remattrmap))
+ remattrmap, attrcnt))
goto fetch_cleanup;
}
}
+ else if (((server_version_num < 140000) && (reltuples == 0)) ||
+ ((server_version_num >= 140000) && (reltuples == -1)))
+ {
+ ereport(WARNING,
+ errmsg("could not import statistics for foreign table \"%s.%s\" --- remote table \"%s.%s\" has no relation statistics to import",
+ local_schemaname, local_relname,
+ remote_schemaname, remote_relname));
+ goto fetch_cleanup;
+ }
/* We assume that we have no dead tuple. */
remstats->deadtuples = 0.0;
@@ -6042,7 +6044,7 @@ build_remattrmap(Relation relation, List *va_cols,
Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
char *attname = NameStr(attr->attname);
AttrNumber attnum = attr->attnum;
- char *remote_attname;
+ char *colname;
List *fc_options;
ListCell *lc;
@@ -6054,7 +6056,7 @@ build_remattrmap(Relation relation, List *va_cols,
continue;
/* If the column_name option is not specified, go with attname. */
- remote_attname = attname;
+ colname = attname;
fc_options = GetForeignColumnOptions(RelationGetRelid(relation), attnum);
foreach(lc, fc_options)
{
@@ -6062,24 +6064,24 @@ build_remattrmap(Relation relation, List *va_cols,
if (strcmp(def->defname, "column_name") == 0)
{
- remote_attname = defGetString(def);
+ colname = defGetString(def);
break;
}
}
if (attrcnt > 0)
appendStringInfoString(column_list, ", ");
- deparseStringLiteral(column_list, remote_attname);
+ deparseStringLiteral(column_list, colname);
remattrmap[attrcnt].local_attnum = attnum;
remattrmap[attrcnt].local_attname = pstrdup(attname);
- remattrmap[attrcnt].remote_attname = pstrdup(remote_attname);
+ remattrmap[attrcnt].remote_attname = pstrdup(colname);
remattrmap[attrcnt].res_index = -1;
attrcnt++;
}
appendStringInfoChar(column_list, ']');
- /* Sort mappings by remote attribute name if needed. */
+ /* Sort the mappings by remote_attname if needed. */
if (attrcnt > 1)
qsort(remattrmap, attrcnt, sizeof(RemoteAttributeMapping), remattrmap_cmp);
@@ -6158,8 +6160,8 @@ match_attrmap(PGresult *res,
const char *local_relname,
const char *remote_schemaname,
const char *remote_relname,
- int attrcnt,
- RemoteAttributeMapping *remattrmap)
+ RemoteAttributeMapping *remattrmap,
+ int attrcnt)
{
int numrows = PQntuples(res);
int row = -1;
@@ -6246,9 +6248,9 @@ static bool
import_fetched_statistics(Relation relation,
const char *schemaname,
const char *relname,
- int attrcnt,
+ RemoteStatsResults *remstats,
const RemoteAttributeMapping *remattrmap,
- RemoteStatsResults *remstats)
+ int attrcnt)
{
PGresult *res;
NullableDatum args[ATTSTATS_NUM_FIELDS];
@@ -6340,6 +6342,7 @@ import_fetched_statistics(Relation relation,
Assert(!args[1].isnull);
set_float_arg(&args[2], get_opt_value(res, 0, RELSTATS_RELTUPLES));
Assert(!args[2].isnull);
+ /* We don't import relallvisible/relallfrozen. */
args[3].value = (Datum) 0;
args[3].isnull = true;
args[4].value = (Datum) 0;
diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml
index 0103fdacfdf..502441fefcb 100644
--- a/doc/src/sgml/fdwhandler.sgml
+++ b/doc/src/sgml/fdwhandler.sgml
@@ -1430,7 +1430,7 @@ ImportForeignStatistics(Relation relation,
If the function imports the statistics successfully, it should return
true. Otherwise, return false, in
which case AnalyzeForeignTable callback function is
- called on the foreign table to collect statistics locally, if supported.
+ called on the foreign table to generate statistics locally, if supported.
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 15beb8150de..c05f9f50e43 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -1171,6 +1171,11 @@ examine_attribute(Relation onerel, int attnum, Node *index_expr)
return stats;
}
+/*
+ * Determine whether the column is analyzable.
+ *
+ * If the column is analyzable, return its attstattarget value, if asked to.
+ */
bool
attribute_is_analyzable(Relation onerel, int attnum, Form_pg_attribute attr,
int *p_attstattarget)