YSQL: Add {active_ssts,wals}_size to yb_tablet_metadata

Author: keisku

src/postgres/src/backend/utils/misc/pg_yb_utils.c

@@ -8396,6 +8396,17 @@ YbUseMinimalCatalogCachesPreload()
 	return false;
 }
 
+/* Sort replica indices lexicographically while keeping parallel arrays aligned. */
+static int
+replica_index_cmp(const void *a, const void *b, void *arg)
+{
+	const char **replicas = (const char **) arg;
+	int			ia = *(const int *) a;
+	int			ib = *(const int *) b;
+
+	return strcmp(replicas[ia], replicas[ib]);
+}
+
 /*
  * Returns the metadata for all tablets in the cluster.
  * The returned data structure is a row type with the following columns:
@@ -8416,16 +8427,6 @@ YbUseMinimalCatalogCachesPreload()
  * column for simpler querying and self-explanatory access. The size arrays are
  * parallel to replicas (same index refers to the same replica).
  */
-static int
-replica_index_cmp(const void *a, const void *b, void *arg)
-{
-	const char **replicas = (const char **) arg;
-	int			ia = *(const int *) a;
-	int			ib = *(const int *) b;
-
-	return strcmp(replicas[ia], replicas[ib]);
-}
-
 Datum
 yb_get_tablet_metadata(PG_FUNCTION_ARGS)
 {

src/yb/yql/pgwrapper/pg_mini-test.cc

@@ -3307,20 +3307,50 @@ TEST_F(PgMiniTest, TabletMetadataOidMatchesPgClass) {
 TEST_F(PgMiniTest, TabletMetadataSizeColumns) {
   auto pg_conn = ASSERT_RESULT(Connect());
   ASSERT_OK(pg_conn.Execute(
-      "CREATE TABLE size_test (id INT PRIMARY KEY, data TEXT)"));
-  ASSERT_OK(pg_conn.Execute(
-      "INSERT INTO size_test SELECT g, repeat('x', 100) FROM generate_series(1, 100) g"));
-
-  // Verify that the size columns exist and are non-null arrays whose length
-  // matches the replicas array length.
-  auto result = ASSERT_RESULT(pg_conn.FetchRow<bool>(
-      "SELECT bool_and("
-      "  active_ssts_size IS NOT NULL AND"
-      "  wals_size IS NOT NULL AND"
-      "  array_length(active_ssts_size, 1) = array_length(replicas, 1) AND"
-      "  array_length(wals_size, 1) = array_length(replicas, 1)"
-      ") FROM yb_tablet_metadata WHERE relname = 'size_test'"));
-  ASSERT_TRUE(result) << "Size array columns must be non-null and parallel to replicas";
+      "CREATE TABLE size_test (id INT PRIMARY KEY, data TEXT) SPLIT INTO 1 TABLETS"));
+
+  // All three arrays must exist and have one element per replica.
+  auto [replicas_len, ssts_len, wals_len] = ASSERT_RESULT(
+      (pg_conn.FetchRow<int32_t, int32_t, int32_t>(
+          "SELECT array_length(replicas, 1),"
+          "       array_length(active_ssts_size, 1),"
+          "       array_length(wals_size, 1) "
+          "FROM yb_tablet_metadata WHERE relname = 'size_test'")));
+  ASSERT_EQ(replicas_len, ssts_len);
+  ASSERT_EQ(replicas_len, wals_len);
+  ASSERT_EQ(static_cast<size_t>(replicas_len), NumTabletServers());
+
+  // Unnest all three arrays in parallel to verify ordering and alignment.
+  // Uses WITH ORDINALITY to join corresponding elements in a single snapshot.
+  auto result = ASSERT_RESULT(pg_conn.Fetch(
+      "SELECT r.val, s.val, w.val "
+      "FROM yb_tablet_metadata tm, "
+      "     unnest(tm.replicas)          WITH ORDINALITY AS r(val, ord), "
+      "     unnest(tm.active_ssts_size)  WITH ORDINALITY AS s(val, ord), "
+      "     unnest(tm.wals_size)         WITH ORDINALITY AS w(val, ord) "
+      "WHERE tm.relname = 'size_test' "
+      "  AND r.ord = s.ord AND r.ord = w.ord "
+      "ORDER BY r.ord"));
+
+  auto num_rows = PQntuples(result.get());
+  ASSERT_EQ(static_cast<size_t>(num_rows), NumTabletServers());
+
+  for (int i = 0; i < num_rows; ++i) {
+    auto replica  = ASSERT_RESULT(GetValue<std::string>(result.get(), i, 0));
+    auto sst_size = ASSERT_RESULT(GetValue<int64_t>(result.get(), i, 1));
+    auto wal_size = ASSERT_RESULT(GetValue<int64_t>(result.get(), i, 2));
+    ASSERT_FALSE(replica.empty());
+    ASSERT_GE(sst_size, 0) << "replica " << replica;
+    ASSERT_GE(wal_size, 0) << "replica " << replica;
+  }
+
+  // Every replica address must correspond to a live tserver.
+  auto valid_count = ASSERT_RESULT(pg_conn.FetchRow<int64_t>(
+      "SELECT count(*) FROM yb_servers() s "
+      "WHERE s.host || ':' || s.port IN ("
+      "  SELECT unnest(replicas) FROM yb_tablet_metadata WHERE relname = 'size_test'"
+      ")"));
+  ASSERT_EQ(static_cast<size_t>(valid_count), NumTabletServers());
 }
 
 TEST_F(PgMiniTest, TestYbGetLocalTserverUuid) {