From 07b8aefe90ca830d2de068f2966cd2288b158a88 Mon Sep 17 00:00:00 2001
From: Sergei Petrunia <psergey@askmonty.org>
Date: Wed, 3 Feb 2016 00:15:49 +0300
Subject: [PATCH] MDEV-9504: ANALYZE TABLE shows wrong 'rows' value for ORDER
 BY query

Revert the patch for MDEV-9504.
It causes test failures, attempt to fix these causes more failures. The
source of all this is that the code in test_if_skip_sort_order() has
a peculiar way of treating select_limit parameter:
Correct value is computed when the query plan is changed. In other cases,
we use an approximation that ignores the presence of GROUP BY clause,
or JOINs, or both.

A patch that fixes all of the above would be too big to do in 10.1
---
 mysql-test/r/analyze_stmt_orderby.result | 26 +-----------------------
 mysql-test/t/analyze_stmt_orderby.test   | 25 +----------------------
 sql/sql_select.cc                        |  6 ++----
 3 files changed, 4 insertions(+), 53 deletions(-)

diff --git a/mysql-test/r/analyze_stmt_orderby.result b/mysql-test/r/analyze_stmt_orderby.result
index 643c0318f95..be1f01a2a52 100644
--- a/mysql-test/r/analyze_stmt_orderby.result
+++ b/mysql-test/r/analyze_stmt_orderby.result
@@ -583,28 +583,4 @@ ANALYZE
   }
 }
 drop table t2;
-drop table t1;
-#
-# MDEV-9504: ANALYZE TABLE shows wrong 'rows' value for ORDER BY query
-#
-create table t1 (
-a int, 
-filler1 char(128),
-filler2 char(128),
-key(a)
-);
-insert into t1 
-select A.a+10*B.a+100*C.a, repeat('abc-',32), repeat('abc-',32)
-from t0 A, t0 B, t0 C;
-analyze table t1;
-Table	Op	Msg_type	Msg_text
-test.t1	analyze	status	Table is already up to date
-explain select a from t1 order by a limit 10;
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	index	NULL	a	5	NULL	10	Using index
-# 'rows' in ANALYZE output must match 'rows' in EXPLAIN:
-analyze select a from t1 order by a limit 10;
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
-1	SIMPLE	t1	index	NULL	a	5	NULL	10	10.00	100.00	100.00	Using index
-drop table t1;
-drop table t0;
+drop table t0,t1;
diff --git a/mysql-test/t/analyze_stmt_orderby.test b/mysql-test/t/analyze_stmt_orderby.test
index dc63fcaa285..a40f34805d1 100644
--- a/mysql-test/t/analyze_stmt_orderby.test
+++ b/mysql-test/t/analyze_stmt_orderby.test
@@ -174,27 +174,4 @@ select col1 f1, col2 f2, col1 f3 from t2 group by f1;
 drop table t2;
 
 
-drop table t1;
-
---echo #
---echo # MDEV-9504: ANALYZE TABLE shows wrong 'rows' value for ORDER BY query
---echo #
-create table t1 (
-  a int, 
-  filler1 char(128),
-  filler2 char(128),
-  key(a)
-);
-
-insert into t1 
-select A.a+10*B.a+100*C.a, repeat('abc-',32), repeat('abc-',32)
-from t0 A, t0 B, t0 C;
-analyze table t1;
-
-explain select a from t1 order by a limit 10;
---echo # 'rows' in ANALYZE output must match 'rows' in EXPLAIN:
-analyze select a from t1 order by a limit 10;
-
-drop table t1;
-drop table t0;
-
+drop table t0,t1;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index de5f29d9bf4..ea30bf96f06 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -21031,14 +21031,12 @@ check_reverse_order:
         }
 
         table->file->ha_index_or_rnd_end();
-
-        if (select_limit < table->stat_records())
-          tab->limit= select_limit;
-
         if (tab->join->select_options & SELECT_DESCRIBE)
         {
           tab->ref.key= -1;
           tab->ref.key_parts= 0;
+          if (select_limit < table->stat_records())
+            tab->limit= select_limit;
           table->disable_keyread();
         }
       }