Issue percona#67: Inefficient index condition pushdown

Summary:
Inside index_next_same() call, we should
1. first check whether the record matches the index
   lookup prefix,
2. then check pushed index condition.

If we try to check percona#2 without checking percona#1 first, we may walk
off the index lookup prefix and scan till the end of the index.

Test Plan: Run mtr

Reviewers: hermanlee4, maykov, jtolmer, yoshinorim

Reviewed By: yoshinorim

Differential Revision: https://reviews.facebook.net/D38769

mysql-test/suite/rocksdb/r/rocksdb_icp.result

@@ -191,3 +191,37 @@ ROWS_INDEX_NEXT-@rin	0
 drop table t4;
 drop procedure save_read_stats;
 drop procedure get_read_stats;
+#
+# Issue #67: Inefficient index condition pushdown
+#
+create table t0 (a int);
+insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+create table t1 (
+pk int not null primary key,
+key1 bigint(20) unsigned,
+col1 int,
+key (key1)
+) engine=rocksdb;
+insert into t1 
+select 
+A.a+10*B.a+100*C.a,
+A.a+10*B.a+100*C.a,
+1234
+from t0 A, t0 B, t0 C;
+set @count=0;
+explain 
+select * from t1 where key1=1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ref	key1	key1	9	const	10	Using index condition
+set @count_diff =(select (value - @count) from information_schema.rocksdb_perf_context 
+where table_schema=database() and table_name='t1' and stat_type='INTERNAL_KEY_SKIPPED_COUNT');
+select * from t1 where key1=1;
+pk	key1	col1
+1	1	1234
+set @count_diff =(select (value - @count) from information_schema.rocksdb_perf_context 
+where table_schema=database() and table_name='t1' and stat_type='INTERNAL_KEY_SKIPPED_COUNT');
+# The following must be =1, or in any case not 999:
+select @count_diff as "INTERNAL_KEY_SKIPPED_COUNT increment";
+INTERNAL_KEY_SKIPPED_COUNT increment
+1
+drop table t0,t1;

mysql-test/suite/rocksdb/t/rocksdb_icp.test

@@ -3,3 +3,39 @@ let $cf_name=cf1;
 
 --source suite/rocksdb/t/rocksdb_icp.inc
 
+--echo #
+--echo # Issue #67: Inefficient index condition pushdown
+--echo #
+create table t0 (a int);
+insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+
+create table t1 (
+  pk int not null primary key,
+  key1 bigint(20) unsigned,
+  col1 int,
+  key (key1)
+) engine=rocksdb;
+
+insert into t1 
+select 
+  A.a+10*B.a+100*C.a,
+  A.a+10*B.a+100*C.a,
+  1234
+from t0 A, t0 B, t0 C;
+
+set @count=0;
+let $save_query= 
+set @count_diff =(select (value - @count) from information_schema.rocksdb_perf_context 
+     where table_schema=database() and table_name='t1' and stat_type='INTERNAL_KEY_SKIPPED_COUNT');
+
+explain 
+select * from t1 where key1=1;
+
+eval $save_query;
+select * from t1 where key1=1;
+eval $save_query;
+--echo # The following must be =1, or in any case not 999:
+select @count_diff as "INTERNAL_KEY_SKIPPED_COUNT increment";
+
+drop table t0,t1;
+