Github user Librago commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1384#discussion_r208439468
--- Diff: src/backend/commands/analyze.c ---
@@ -3266,3 +3298,380 @@ static void
gp_statistics_estimate_reltuples_relpages_parquet(Relation rel, floa
pfree(fstotal);
return;
}
+
+/**
+ * This method estimates the number of tuples and pages in an extern
relation. We can not get accurate tuple counts
+ * and pages counts in the catalog. Therefore, we have to get reltuples
and relpages manually.
+ *
+ * Input:
+ * rel - Relation. Must be an external table.
+ *
+ * Output:
+ * reltuples - exact number of tuples in relation.
+ * relpages - exact number of pages.
+ */
+static void gp_statistics_estimate_reltuples_relpages_external(Relation
rel, float4 *relTuples, float4 *relPages){
+ Oid extRelationOid = RelationGetRelid(rel);
+ getExternalRelTuples(extRelationOid, relTuples);
+ getExternalRelPages(extRelationOid, relPages, rel);
+}
+
+/**
+ * This method called by analyzeExternalEstimateReltuplesRelpages,
+ * to get External Relation reltuple counts, we run count(*) sql manually
+ *
+ * Input:
+ * extRelationOid - External Table Relation Oid
+ * Output:
+ * relTuples - exact number of tuples in relation.
+ */
+static void getExternalRelTuples(Oid extRelationOid, float4 *relTuples){
+ const char *schemaName = NULL;
+ const char *tableName = NULL;
+ schemaName = get_namespace_name(get_rel_namespace(extRelationOid)); /*
must be pfreed */
+ tableName = get_rel_name(extRelationOid); /* must be pfreed */
+
+ StringInfoData str;
+ initStringInfo(&str);
+ appendStringInfo(&str, "select count(*)::float4 from %s.%s as Ta",
+ quote_identifier(schemaName),
+ quote_identifier(tableName));
+
+ spiExecuteWithCallback(str.data, false /*readonly*/, 0 /*tcount */,
+
spiCallback_getSingleResultRowColumnAsFloat4, relTuples);
+ pfree((void *) tableName);
--- End diff --
no need (void *), and does it need to be free?
---
