fix last row cache

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

src/mito2/src/read/last_row.rs

@@ -515,6 +515,13 @@ impl FlatRowGroupLastRowReader {
         if self.yielded_batches.is_empty() {
             return;
         }
+
+        // Filtered flat last-row scans only contain the subset of series that matched the
+        // encoded primary-key prefilter, so they cannot be published under the shared
+        // selector cache key.
+        if self.primary_key_filter.is_some() {
+            return;
+        }
         let batches = std::mem::take(&mut self.yielded_batches);
         let value = Arc::new(SelectorResultValue::new_flat(
             batches,

tests/cases/standalone/common/aggregate/last_row_selector_cache_filter.result

@@ -0,0 +1,53 @@
+CREATE TABLE last_row_selector_cache_filter (
+  host STRING,
+  cpu DOUBLE,
+  ts TIMESTAMP TIME INDEX,
+  PRIMARY KEY (host)
+) WITH ('sst_format' = 'flat');
+
+Affected Rows: 0
+
+INSERT INTO last_row_selector_cache_filter VALUES
+  ('a', 1.0, 1000),
+  ('a', 2.0, 2000),
+  ('b', 3.0, 1000),
+  ('b', 4.0, 2000);
+
+Affected Rows: 4
+
+ADMIN FLUSH_TABLE('last_row_selector_cache_filter');
+
++-----------------------------------------------------+
+| ADMIN FLUSH_TABLE('last_row_selector_cache_filter') |
++-----------------------------------------------------+
+| 0                                                   |
++-----------------------------------------------------+
+
+SELECT host, last_value(cpu ORDER BY ts) AS last_cpu
+FROM last_row_selector_cache_filter
+WHERE host = 'a'
+GROUP BY host
+ORDER BY host;
+
++------+----------+
+| host | last_cpu |
++------+----------+
+| a    | 2.0      |
++------+----------+
+
+SELECT host, last_value(cpu ORDER BY ts) AS last_cpu
+FROM last_row_selector_cache_filter
+GROUP BY host
+ORDER BY host;
+
++------+----------+
+| host | last_cpu |
++------+----------+
+| a    | 2.0      |
+| b    | 4.0      |
++------+----------+
+
+DROP TABLE last_row_selector_cache_filter;
+
+Affected Rows: 0
+

tests/cases/standalone/common/aggregate/last_row_selector_cache_filter.sql

@@ -0,0 +1,27 @@
+CREATE TABLE last_row_selector_cache_filter (
+  host STRING,
+  cpu DOUBLE,
+  ts TIMESTAMP TIME INDEX,
+  PRIMARY KEY (host)
+) WITH ('sst_format' = 'flat');
+
+INSERT INTO last_row_selector_cache_filter VALUES
+  ('a', 1.0, 1000),
+  ('a', 2.0, 2000),
+  ('b', 3.0, 1000),
+  ('b', 4.0, 2000);
+
+ADMIN FLUSH_TABLE('last_row_selector_cache_filter');
+
+SELECT host, last_value(cpu ORDER BY ts) AS last_cpu
+FROM last_row_selector_cache_filter
+WHERE host = 'a'
+GROUP BY host
+ORDER BY host;
+
+SELECT host, last_value(cpu ORDER BY ts) AS last_cpu
+FROM last_row_selector_cache_filter
+GROUP BY host
+ORDER BY host;
+
+DROP TABLE last_row_selector_cache_filter;