1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
--
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements. See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License. You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-- Very basic single user testing of read locks in "set" queries on heap tables.
-- This ".subsql" test is
-- meant to be run from another test such that it gets run under multiple
-- isolation levels. This is important as they behave
-- differently, depending on isolation levels.
--
-- assume's caller has already done: run 'LockTableQuery.subsql'; to get
-- easy access to the lock VTI.
-- TEST 0: heap scan.
-- TEST 1: heap scan, some rows deleted.
-- TEST 2: heap scan, (scan with "<" qualifier)
-- TEST 3: heap scan, (scan with equals qualifier)
-- TEST 4: heap scan, (equals qualifier, no rows return)
autocommit off;
--------------------------------------------------------------------------------
-- Assumes that calling routine has set up the following simple dataset,
-- a heap, no indexes with following initial values:
-- create table (a int, b int, c somesortofchar);
-- 1, 10, 'one'
-- 2, 20, 'two'
-- 3, 30, 'three'
-- 4, 40, 'four'
-- 5, 50, 'five'
-- 6, 60, 'six'
-- 7, 70, 'seven'
--------------------------------------------------------------------------------
select * from a;
commit;
--------------------------------------------------------------------------------
-- TEST 0: heap scan.
-- Test full cursor scan which does no updates.
-- SERIALIZABLE - will get table level S lock, held to end of xact.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones). held to end of xact.
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release. No
-- locks held when statement completes.
-- READ UNCOMMITTED - TABLE IS, no row locks. No locks after statement ends.
--------------------------------------------------------------------------------
select a, b, c from a;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
--------------------------------------------------------------------------------
-- TEST 1: heap scan, some rows deleted.
-- Test full cursor scan on a data set with some deleted rows (the "even" ones).
-- SERIALIZABLE - will get table level S lock.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones).
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release
-- READ UNCOMMITTED - TABLE IS, no row locks.
-- SERIALIZABLE - will get table level S lock, held to end of xact.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones). held to end of xact.
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release. No
-- locks held when statement completes.
-- READ UNCOMMITTED - TABLE IS, no row locks. No locks after statement ends.
--
-- After the delete the table should look like:
-- 1, 10, 'one'
-- 3, 30, 'three'
-- 5, 50, 'five'
-- 7, 70, 'seven'
--------------------------------------------------------------------------------
delete from a where a = 2 or a = 4 or a = 6;
commit;
-- The above delete and commit can allow post commit processing to run before
-- the subsequent select is run, most likely if this run is on a table where
-- there is one row per page. To get reproducible results from the subsequent
-- lock calls, wait for post commit to finish before running the select.
-- Without this wait "extra" locks sometimes might show up - these are locks
-- on the committed deleted rows which have not been cleaned yet depending
-- on timing.
CALL WAIT_FOR_POST_COMMIT();
select a, b, c from a;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
--------------------------------------------------------------------------------
-- TEST 2: heap scan, (scan with "<" qualifier)
-- Test "less than" qualified cursor scan on a data set.
-- SERIALIZABLE - will get table level S lock, held to end of xact.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones). held to end of xact.
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release. No
-- locks held when statement completes.
-- READ UNCOMMITTED - TABLE IS, no row locks. No locks after statement ends.
--
-- At this point the table should look like:
-- 1, 10, 'one'
-- 3, 30, 'three'
-- 5, 50, 'five'
-- 7, 70, 'seven'
--------------------------------------------------------------------------------
select a, b, c from a;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
--------------------------------------------------------------------------------
-- TEST 3: heap scan, (scan with equals qualifier)
-- Test "equals" qualified cursor scan on a data set.
-- SERIALIZABLE - will get table level S lock, held to end of xact.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones). held to end of xact.
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release. No
-- locks held when statement completes.
-- READ UNCOMMITTED - TABLE IS, no row locks. No locks after statement ends.
--
-- At this point the table should look like:
-- 1, 10, 'one'
-- 3, 30, 'three'
-- 5, 50, 'five'
-- 7, 70, 'seven'
--------------------------------------------------------------------------------
select a, b, c from a where a = 5;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
--------------------------------------------------------------------------------
-- TEST 4: heap scan, (equals qualifier, no rows return)
-- Test "equals" qualified cursor scan on a data set, no rows returned.
-- SERIALIZABLE - will get table level S lock, held to end of xact.
-- REPEATABLE READ - TABLE IS, will get row S locks as it visits each row
-- (including deleted ones). held to end of xact.
-- READ COMMITTED - TABLE IS, will get instantaneous locks and release. No
-- locks held when statement completes.
-- READ UNCOMMITTED - TABLE IS, no row locks. No locks after statement ends.
--
-- At this point the table should look like:
-- 1, 10, 'one'
-- 3, 30, 'three'
-- 5, 50, 'five'
-- 7, 70, 'seven'
--------------------------------------------------------------------------------
select a, b, c from a where a = 7;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
select * from lock_table order by tabname, type desc, mode, cnt, lockname;
commit;
drop table a;
|
