BUG#22385442 - INNODB: DIFFICULT TO FIND FREE BLOCKS IN THE BUFFER POOL

Problem:
We keep pinning pages in dict_stats_analyze_index_below_cur(),
but doesn't release these pages. When we have a relative small
buffer pool size, and big innodb_stats_persistent_sample_pages,
there will be no free pages for use.

Solution:
Use a separate mtr in dict_stats_analyze_index_below_cur(),
and commit mtr before return.

Reviewed-by: Jimmy Yang <[email protected]>
RB: 11362

Author: Shaohua Wang

mysql-test/suite/innodb/r/analyze_table.result

@@ -0,0 +1,25 @@
+CREATE PROCEDURE populate_t1()
+BEGIN
+DECLARE i int DEFAULT 1;
+START TRANSACTION;
+WHILE (i <= 1000000) DO
+INSERT INTO t1 VALUES (i, i, CONCAT('a', i));
+SET i = i + 1;
+END WHILE;
+COMMIT;
+END|
+CREATE TABLE t1(
+class   INT,
+id      INT,
+title   VARCHAR(100)
+) ENGINE=InnoDB;
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+1000000
+SET GLOBAL innodb_stats_persistent_sample_pages=2000;
+ANALYZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+DROP TABLE t1;
+DROP PROCEDURE populate_t1;
+SET GLOBAL innodb_stats_persistent_sample_pages=default;

mysql-test/suite/innodb/t/analyze_table.test

@@ -0,0 +1,42 @@
+#
+# BUG#22385442 - INNODB: DIFFICULT TO FIND FREE BLOCKS IN THE BUFFER POOL
+#
+
+--source include/have_innodb.inc
+--source include/big_test.inc
+
+DELIMITER |;
+CREATE PROCEDURE populate_t1()
+BEGIN
+        DECLARE i int DEFAULT 1;
+
+        START TRANSACTION;
+        WHILE (i <= 1000000) DO
+                INSERT INTO t1 VALUES (i, i, CONCAT('a', i));
+                SET i = i + 1;
+        END WHILE;
+        COMMIT;
+END|
+DELIMITER ;|
+
+CREATE TABLE t1(
+        class   INT,
+        id      INT,
+        title   VARCHAR(100)
+) ENGINE=InnoDB;
+
+-- disable_query_log
+CALL populate_t1();
+-- enable_query_log
+
+SELECT COUNT(*) FROM t1;
+
+SET GLOBAL innodb_stats_persistent_sample_pages=2000;
+
+ANALYZE TABLE t1;
+
+DROP TABLE t1;
+
+DROP PROCEDURE populate_t1;
+
+SET GLOBAL innodb_stats_persistent_sample_pages=default;

storage/innobase/dict/dict0stats.cc

@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 2009, 2014, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2009, 2015, Oracle and/or its affiliates. All Rights Reserved.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -1434,16 +1434,14 @@ on the leaf page.
 when comparing records
 @param[out]	n_diff			number of distinct records
 @param[out]	n_external_pages	number of external pages
-@param[in,out]	mtr			mini-transaction
 @return number of distinct records on the leaf page */
 static
 void
 dict_stats_analyze_index_below_cur(
 	const btr_cur_t*	cur,
 	ulint			n_prefix,
 	ib_uint64_t*		n_diff,
-	ib_uint64_t*		n_external_pages,
-	mtr_t*			mtr)
+	ib_uint64_t*		n_external_pages)
 {
 	dict_index_t*	index;
 	ulint		space;
@@ -1457,6 +1455,7 @@ dict_stats_analyze_index_below_cur(
 	ulint*		offsets2;
 	ulint*		offsets_rec;
 	ulint		size;
+	mtr_t		mtr;
 
 	index = btr_cur_get_index(cur);
 
@@ -1495,12 +1494,14 @@ dict_stats_analyze_index_below_cur(
 	function without analyzing any leaf pages */
 	*n_external_pages = 0;
 
+	mtr_start(&mtr);
+
 	/* descend to the leaf level on the B-tree */
 	for (;;) {
 
 		block = buf_page_get_gen(space, zip_size, page_no, RW_S_LATCH,
 					 NULL /* no guessed block */,
-					 BUF_GET, __FILE__, __LINE__, mtr);
+					 BUF_GET, __FILE__, __LINE__, &mtr);
 
 		page = buf_block_get_frame(block);
 
@@ -1522,6 +1523,8 @@ dict_stats_analyze_index_below_cur(
 		ut_a(*n_diff > 0);
 
 		if (*n_diff == 1) {
+			mtr_commit(&mtr);
+
 			/* page has all keys equal and the end of the page
 			was reached by dict_stats_scan_page(), no need to
 			descend to the leaf level */
@@ -1546,7 +1549,7 @@ dict_stats_analyze_index_below_cur(
 	}
 
 	/* make sure we got a leaf page as a result from the above loop */
-	ut_ad(btr_page_get_level(page, mtr) == 0);
+	ut_ad(btr_page_get_level(page, &mtr) == 0);
 
 	/* scan the leaf page and find the number of distinct keys,
 	when looking only at the first n_prefix columns; also estimate
@@ -1563,6 +1566,7 @@ dict_stats_analyze_index_below_cur(
 		     __func__, page_no, n_diff);
 #endif
 
+	mtr_commit(&mtr);
 	mem_heap_free(heap);
 }
 
@@ -1772,8 +1776,7 @@ dict_stats_analyze_index_for_n_prefix(
 		dict_stats_analyze_index_below_cur(btr_pcur_get_btr_cur(&pcur),
 						   n_prefix,
 						   &n_diff_on_leaf_page,
-						   &n_external_pages,
-						   mtr);
+						   &n_external_pages);
 
 		/* We adjust n_diff_on_leaf_page here to avoid counting
 		one record twice - once as the last on some page and once