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
|
// Test that even when the execution of a query fails, explain reports query
// planner information.
var t = db.explain_execution_error;
t.drop();
var result;
/**
* Asserts that explain reports an error in its execution stats section.
*/
function assertExecError(explain) {
var errorObj;
var execStats = explain.executionStats;
if (execStats.executionStages.stage == "SINGLE_SHARD") {
errorObj = execStats.executionStages.shards[0];
} else {
errorObj = execStats;
}
assert.eq(false, errorObj.executionSuccess);
assert("errorMessage" in errorObj);
assert("errorCode" in errorObj);
}
/**
* Asserts that explain reports success in its execution stats section.
*/
function assertExecSuccess(explain) {
var errorObj;
var execStats = explain.executionStats;
if (execStats.executionStages.stage == "SINGLE_SHARD") {
errorObj = execStats.executionStages.shards[0];
} else {
errorObj = execStats;
}
assert.eq(true, errorObj.executionSuccess);
assert(!("errorMessage" in errorObj));
assert(!("errorCode" in errorObj));
}
// Make a string that exceeds 1 MB.
var bigStr = "x";
while (bigStr.length < (1024 * 1024)) {
bigStr += bigStr;
}
// Make a collection that is about 40 MB.
for (var i = 0; i < 40; i++) {
assert.writeOK(t.insert({a: bigStr, b: 1, c: i}));
}
// A query which sorts the whole collection by "b" should throw an error due to hitting the
// memory limit for sort.
assert.throws(function() {
t.find({a: {$exists: true}}).sort({b: 1}).itcount();
});
// Explain of this query should succeed at query planner verbosity.
result = db.runCommand({
explain: {find: t.getName(), filter: {a: {$exists: true}}, sort: {b: 1}},
verbosity: "queryPlanner"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
// Explaining the same query at execution stats verbosity should succeed, but indicate that the
// underlying operation failed.
result = db.runCommand({
explain: {find: t.getName(), filter: {a: {$exists: true}}, sort: {b: 1}},
verbosity: "executionStats"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
assert("executionStats" in result);
assertExecError(result);
// The underlying operation should also report a failure at allPlansExecution verbosity.
result = db.runCommand({
explain: {find: t.getName(), filter: {a: {$exists: true}}, sort: {b: 1}},
verbosity: "allPlansExecution"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
assert("executionStats" in result);
assert("allPlansExecution" in result.executionStats);
assertExecError(result);
// Now we introduce two indices. One provides the requested sort order, and
// the other does not.
t.ensureIndex({b: 1});
t.ensureIndex({c: 1});
// The query should no longer fail with a memory limit error because the planner can obtain
// the sort by scanning an index.
assert.eq(40, t.find({c: {$lt: 40}}).sort({b: 1}).itcount());
// The explain should succeed at all verbosity levels because the query itself succeeds.
// First test "queryPlanner" verbosity.
result = db.runCommand({
explain: {find: t.getName(), filter: {c: {$lt: 40}}, sort: {b: 1}},
verbosity: "queryPlanner"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
result = db.runCommand({
explain: {find: t.getName(), filter: {c: {$lt: 40}}, sort: {b: 1}},
verbosity: "executionStats"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
assert("executionStats" in result);
assertExecSuccess(result);
// We expect allPlansExecution verbosity to show execution stats for both candidate plans.
result = db.runCommand({
explain: {find: t.getName(), filter: {c: {$lt: 40}}, sort: {b: 1}},
verbosity: "allPlansExecution"
});
assert.commandWorked(result);
assert("queryPlanner" in result);
assert("executionStats" in result);
assert("allPlansExecution" in result.executionStats);
assertExecSuccess(result);
|
