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Splunk Advanced Power User > Advanced Searching and Reporting > Flashcards

Advanced Searching and Reporting Flashcards

1
Q

What kind of searches are prime candidates for optimization

A

Searched that run often or query broad amounts of data

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2
Q

What is stored in a journal.gz file and a .tsidx file on the buckets within indexers?

A

Compressed raw event data is stored in journal

Reference to journals raw events is stored in .tsidx

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3
Q

What are the components of the .tsidx file?

A

Lexicon with unique terms from event data
Posting list provides reference to values array Values Array is has posting value and a seek address as reference into the journal.gz

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4
Q

What is a bloom filter?

A

A bit array associated with each bucket and search string used to predict if a lexicon term is likely to be found in the bucket

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5
Q

Are false positives and negatives possible with a bloom filters?

A

False positive are possible,

False negatives are not possible

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6
Q

What is the series of events for retrieving event data with a bloom filter?

A
  1. Searchstring bloom filter created
  2. Find buckets in index within timerange
  3. Compare search bloom to bucket bloom
  4. If a match, find search terms in .tsidx
  5. Use .tsidx to get events from journal.gz
  6. Do search time extractions for final filter
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7
Q

What does the job inspector command.search.index inform you of?

A

The time to get location info in .tsidx

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8
Q

What does the job inspector command.search.rawdata inform you of?

A

Time to extract event data from journal.gz

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9
Q

What does the job inspector command.search.kv inform you of?

A

Time to perform search time field extractions

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10
Q

What do you use to calculate performance with the job inspector?

A

scanCount/time to get events per second including the time to read all events from disk

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11
Q

In a distributed environment will the search execute faster if commands are on the SH or the indexer?

A

Execute faster on the indexer

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12
Q

Where are transforming commands executed?

A

Operate on the entire results set on the Search head

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13
Q

Does order of events matter when running a transforming command?

A

no

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14
Q

What are the two types of streaming command?

A

Distributable - could be run on indexer

centralized - always run on search head

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15
Q

Is the event order important for streaming commands?

A

Distributable - No

Centralized - Yes

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16
Q

When is a distributable command run on the search head vs the indexer?

A

Search head if any preceding commands are executed on search head
Indexer if all preceding commands execute on indexer

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17
Q

Do streaming commands need the entire event result set prior to executing?

A

Distributable - no

Centralized - yes

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18
Q

Do streaming commands operate on the entire results set of event data?

A

No they operate on each event returned by a search

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19
Q

How does having more disk reads affect search execution?

A

More disk reads leads to longer search execution time

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20
Q

How does splunk decide which events to read after determining which buckets match bloom filters?

A

Tokens (or terms) from search string are compared to tokens in events and match results in event being read from disk

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21
Q

How are event tokens derived?

A

Derived by breaking up searches and event data using segmenters

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22
Q

What are segmenters?

A

Major or minor breakers that separate searches and events into smaller pieces

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23
Q

What are major breakers?

A

Character set used to divide words, phrases, terms into large tokens: space, newline, carriage return, tab, [] () {} ! ? ; , ‘ “ &

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24
Q

What are minor breakers?

A

Used to divide large tokens into smaller tokens: / : = @ . - $ # % \ \ _

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25
Q

Where are tokens created from event data stored?

A

.tsidx files

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26
Q

Where can you see how the base search was tokenized?

A

Use the job inspector and look for the token after ‘base lispy’

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27
Q

In prefix notation where does the operator appear?

A

Before the operands. Ex with search index=web 21.12: lispy: [ AND 12 21 index::web]

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28
Q

What is a directive?

A

An instruction for how part of a search should be processed

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29
Q

What does the case sensitive ‘TERM’ directive do?

A

Forces Splunk to only look for a complete value by searching only based on major breakers and skip minor breakers - term must be bound by major breakers

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30
Q

Can key value pairs be passed into the TERM() directive?

A

Yes because key=value only has a minor breaker in it

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31
Q

Does negation in a search yield negation in a lispy?

A

Works for negating single terms but not for terms that include minor breakers UNLESS you use TERM()
Ex that will work: NOT TERM(example.1)
Ex does not work: NOT example.1

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32
Q

Do wildcards in a search work in a lispy?

A

Only when they are at the middle or end of a string and have no major or minor breakers

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33
Q

How do index time fields appear in lispy?

A

Appear as field::value instead of field=value like they do in a search

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34
Q

As more fields are extracted at index time what happens to the size of .tsidx files and resource usage at indexer?

A

Both are increased

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35
Q

What type of data can have indexed field extraction to a specific source type>?

A

Sourcetypes with certain types of structured data (JSON, CSV, W3C)

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36
Q

Do comparisons against fields extracted at search time result in filtering events returned from the disk?

A

No, all events from a sourcetype will still be read from the disk (except for an equals operator).

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37
Q

What would the lispy be for a search: index=web sourcetype=a_c status>400

A

Lispy: [ AND index::web sourcetype::a_c ]

Comparisons are not included when filtering what is read from disk

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38
Q

Does the TERM() directive work with aliases?

A

No

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39
Q

When are lookups completed while using a lispy?

A

In the search itself, lookup can be done before the lispy is created.
Lookups done for transformations or other pipe commands can be done post lispy

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40
Q

What does a subsearch do?

A

Takes the results from an inner search and using boolean AND, combines the results with the outer search - an OR boolean is inserted between each inner search result

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41
Q

What command do subsearches typically begin with?

A

[ search search_criteria… ]

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42
Q

Is an inner search or outer search completed first?

A

Inner subsearch completed first

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43
Q

How do you send only specific fields of a subsearch to the outer search?

A

Using fields or results command

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44
Q

What is returned by default when using the results command in a subsearch?

A

First value of each specified field is returned with the field name and the field value

45
Q

How do you adjust the defaults for the |return command in a subsearch?

A

Specify a number with ‘count’ and omit a field name with $before field name:
|return 5 $ip_address => returns first 5 values of ip_address

46
Q

Can you return subsearch results as an alias?

A

Yes, use |return alias_name=field

47
Q

What is the time and event count limit on a subsearch?

A

60 seconds and 10,000 events

48
Q

Over what time range will a subsearch execute if the root search is run in real-time?

A

Run over all time by default unless setting earliest and latest restriction in subsearch

49
Q

Should you use stats and/or eval over using subsearch?

A

Yes, whenever possible especially if searches are executed often

50
Q

What does the append command do?

A

Using only historical data, appends results of subsearch to the current results

51
Q

Does the |append command overlay primary and subsearch results?

A

No, they will appear one after another in a graph (when used with both stats and timechart as main search)

52
Q

How do you get appended results to overlay primary search results?

A

Use | stats first(*) as *

Or | timechart first(*) as *

53
Q

What command will overlay search and subsearch results in one step?

A

|appendcols

54
Q

When should you take caution using the appendcols command?

A

When used with stats because if there is a null value in the data, the empty values get pushed up and values may not be aligned to fields appropriately

55
Q

For larger amounts of data, should you use append and appendcols?

A

No, they should be avoided as more efficient searches should be used

56
Q

If a search can be done with stats or join/union which is usually more efficient?

A

stats command is usually more efficient

57
Q

What does the join command do?

A

Combines results from two searches with a default of inner join - results only include events from first search that match the second search

58
Q

What does the left, or outer join argument of the join command define?

A

Includes results from only the first search and those events matching in the second search

59
Q

How do you define which fields to use for the join command?

A

Define after the |join command:

| join fields_to_use

60
Q

What search combines two or more result sets into a single search?

A

union

61
Q

What can be used to specify a result search when using the union command?

A

Use a regular search, subsearch or a data model(defined with datamodel command)

62
Q

Does the union command execute on the search head or indexer?

A

As a distributable streaming command it executes in parallel on indexers if all searches are distributable otherwise on search head

63
Q

What is the union syntax?

A

union datamodel:name1.dataset datamodel:name2.dataset …
Search1 |union [search2]
Search1 |union datamodel:search2 …

64
Q

What command puts numerical values into discrete sets?

A

| where binoptions is optional

bin binoptions field

65
Q

How are bin sizes set?

A

Through the span=size option

| bin fieldname span=size

66
Q

What happens if span created more buckets than the max specified by bins?

A

bins is ignored

67
Q

What command reformats chartable, tabular output as a stats-like output?

A

| xfield:x-axis yfield:data labels datafield:fields with the charted data

untable xfield yfield datafield

68
Q

What command reformats stats-like output as chartable, tabular output?

A

xyseries xfield yfield datafield

69
Q

What does the forearch command do?

A

foreach replaces the <> token with field names that match: |foreach www* [eval <> = round(<>/2)]

70
Q

What are multivalue eval functions used for?

A

Used to analyze and format multivalue data

71
Q

What command do you use to convert a single value into a multivalue field /

A

|makemv command

72
Q

What do JSON array contents become when auto extracted by Splunk?

A

Contents become multivalue fields

73
Q

In JSON data, what to the {} and [] indicate?

A

{} is an object, a grouping of field value pairs

[] is an array of objects

74
Q

How are fields nested within a JSON event represented when extracted into Splunk?

A

Event_name{}.field1

Event_name{}.field2 …

75
Q

Which commands can you use with multivalue functions?

A

eval where and fieldformat commands

76
Q

What does the mvsort() function do?

A

Intakes a multivalue field and returns the values sorted lexicographically

77
Q

How are numbers sorted in lexicographical order?

A

Numbers are sorted before letters and are sorted based on the first digit not the number as a whole: 100 200 70 9 is in order

78
Q

Are uppercase or lowercase letters first in lexicographical order?

A

Uppercase is first

79
Q

Can functions and commands process fields that contain a {}

A

No, so mv fields extracted from JSON will have to be renamed

80
Q

What does the mvfilter function do?

A

Filters(refines) one mvfield based on a boolean expression

81
Q

How do you remove null values returned from mvfilter function?

A

Use mvfilter(isnotnull(x))

82
Q

What function concatenates individual values from a mvfield and uses a delimiter as a separator?

A

mvjoin(fieldname, “delimiter”)

83
Q

What function takes 2 mvfields and concatenates the first values of each, the second values of each etc. with a delimiter to separate?

A

mvzip(mvfield1,mvfield2,”delimiter”)

84
Q

What does the mvcount function do?

A

Returns count of values in the specified mvfield returning null if no field values or field does not exist: mvcount(fieldname)

85
Q

What does the split function do?

A

Takes a single value field and a delimiter to split by and creates a new mvfield: split(fieldname, “delim”)

86
Q

What does the mvindex function do?

A

Take an mvfield and an integer to return a value at the specified integer index in the mv array - indexing starts at 0 NOT 1 : mvindex(fieldname, indexnum)

87
Q

What command converts an existing single value field to a mvfield based on delimiter or regex(referred to as a tokenizer)

A

makemv (delim=string | tokenizer=regex) fieldname

88
Q

What does the mvexpand command do?

A

Takes mvfield and creates separate event for each value in the mvfield:
|mvexpand fieldname

89
Q

Does mvexpand command create new events on disk/in index?

A

No, only created in memory for purposes of search at hand

90
Q

What is referred to as any group of conceptually related events?

A

A transaction via the | transaction command

91
Q

What does the |transaction command enable?

A

Enables you to specify criteria used to determine how to group events via ranges of time, # of events, text contained in events

92
Q

Is stats or transaction faster ?

A

Stats, as transaction is resource intensive and should be used only when stats is insufficient

93
Q

In what order do events need to be ingested for transactions to work?

A

Reverse chronological order

94
Q

In order to use |transaction, how do you correct events that are not coming in reverse cron order?

A

Use | sort -_time

Use right before |transaction

95
Q

How do you find events that occur before or after a specific event?

A

Use |transaction fieldname (endswith=() | startswith=() )

96
Q

What function is used to normalize field names by taking a number of arguments and returning first one that is not null and storing it as new field?

A

coalesce(field1,field2,…)

97
Q

What does the keepevicted=1 argument used for when dealing with transactions?

A

It is a setting used to retain any transactions where one or both of beginning/ending criteria are not satisfied (transaction did not complete successfully)

98
Q

What field is used to determine if a transaction is complete or incomplete?

A

closed_txn = 1 if transaction is a success or closed_txn = 0 if transaction is not a success

99
Q

What has to be met for a transaction to be closed?

A

One or more of these criteria are met: maxevents, maxpause, maxspan, startswith, endswith

100
Q

Where does |transaction execute?

A

Executes on the SH as it is a centralized streaming command

101
Q

Does |transaction require access to all the _raw data?

A

Yes, because search is forced to send all _raw data back from indexers to search head as transactions require all event data

102
Q

Can the timepicker be overridden during a search?

A

Yes through the earliest= & latest= time modifiers

103
Q

When snapping to a time, does the time round up or down?

A

Always rounds down (backward to a previous time)

104
Q

How do you define a search for the past 24 hours using earliest and latest modifiers?

A

Mainsearch earliest=-24h@h latest=@h

105
Q

What are default time fields?

A

date_* fields (time/date) stamps taken directly from raw events providing extra info for searching but these are not representative of time zone conversions or time value changes

106
Q

How would you exclude events from the current day?

A

latest=@d

107
Q

How would you include data beginning at the start of the day, 2 days ago?

A

earliest=-2d@d

108
Q

What does date_hour.=2 AND date_hour<5 represent?

A

Find events between 2am and 5am

109
Q

What function can be used to create a new field with adjusted time zones?

A

|eval new_time_field =strftime(_time, “%H”)

will get the hour from the event and convert the hour to you local time based on time zone setting

Splunk Advanced Power User (3 decks)

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