From c1b1be47ba4a3b43a0d96141fb73f9cfb16ecc5e Mon Sep 17 00:00:00 2001
From: "Lei, HUANG" <6406592+v0y4g3r@users.noreply.github.com>
Date: Wed, 14 Aug 2024 17:01:42 +0800
Subject: [PATCH] fix: append table stats (#4561)

* fix: append table stats

* fix: clippy
---
 src/table/src/table/scan.rs                   |  1 +
 .../explain/analyze_append_table_count.result | 34 +++++++++++++++++++
 .../explain/analyze_append_table_count.sql    | 21 ++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 tests/cases/distributed/explain/analyze_append_table_count.result
 create mode 100644 tests/cases/distributed/explain/analyze_append_table_count.sql

diff --git a/src/table/src/table/scan.rs b/src/table/src/table/scan.rs
index c7d4fe98a2..83c348d6d9 100644
--- a/src/table/src/table/scan.rs
+++ b/src/table/src/table/scan.rs
@@ -168,6 +168,7 @@ impl ExecutionPlan for RegionScanExec {
                 .iter()
                 .map(|_| ColumnStatistics {
                     distinct_count: Precision::Exact(self.total_rows),
+                    null_count: Precision::Exact(0), // all null rows are counted for append-only table
                     ..Default::default()
                 })
                 .collect();
diff --git a/tests/cases/distributed/explain/analyze_append_table_count.result b/tests/cases/distributed/explain/analyze_append_table_count.result
new file mode 100644
index 0000000000..7a2a1603f2
--- /dev/null
+++ b/tests/cases/distributed/explain/analyze_append_table_count.result
@@ -0,0 +1,34 @@
+CREATE TABLE IF NOT EXISTS `test_table` (
+  `bytes` BIGINT NULL,
+  `http_version` STRING NULL,
+  `ip` STRING NULL,
+  `method` STRING NULL,
+  `path` STRING NULL,
+  `status` SMALLINT UNSIGNED NULL,
+  `user` STRING NULL,
+  `timestamp` TIMESTAMP(3) NOT NULL,
+  TIME INDEX (`timestamp`),
+  PRIMARY KEY (`user`, `path`, `status`)
+)
+ENGINE=mito
+WITH(
+  append_mode = 'true'
+);
+
+Affected Rows: 0
+
+-- SQLNESS REPLACE (metrics.*) REDACTED
+-- SQLNESS REPLACE (peers.*) REDACTED
+EXPLAIN ANALYZE SELECT count(*) FROM test_table;
+
++-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+| stage | node | plan                                                                                                                                                                               |
++-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+| 0     | 0    |  MergeScanExec: REDACTED
+|       |      |                                                                                                                                                                                    |
+| 1     | 0    |  ProjectionExec: expr=[0 as COUNT(test_table.timestamp)] REDACTED
+|       |      |   common_recordbatch::adapter::MetricCollector REDACTED
+|       |      |                                                                                                                                                                                    |
+|       |      | Total rows: 1                                                                                                                                                                      |
++-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+
diff --git a/tests/cases/distributed/explain/analyze_append_table_count.sql b/tests/cases/distributed/explain/analyze_append_table_count.sql
new file mode 100644
index 0000000000..fedf18dfa8
--- /dev/null
+++ b/tests/cases/distributed/explain/analyze_append_table_count.sql
@@ -0,0 +1,21 @@
+CREATE TABLE IF NOT EXISTS `test_table` (
+  `bytes` BIGINT NULL,
+  `http_version` STRING NULL,
+  `ip` STRING NULL,
+  `method` STRING NULL,
+  `path` STRING NULL,
+  `status` SMALLINT UNSIGNED NULL,
+  `user` STRING NULL,
+  `timestamp` TIMESTAMP(3) NOT NULL,
+  TIME INDEX (`timestamp`),
+  PRIMARY KEY (`user`, `path`, `status`)
+)
+
+ENGINE=mito
+WITH(
+  append_mode = 'true'
+);
+
+-- SQLNESS REPLACE (metrics.*) REDACTED
+-- SQLNESS REPLACE (peers.*) REDACTED
+EXPLAIN ANALYZE SELECT count(*) FROM test_table;