If I want to update the "amount" field within a particular element inside "f_units" collection in the below resource (protocol buffer), how will the FieldMask look like to update the amount field? Does the field mask operate on array index for collections?
{
"f_sel": {
"f_units": [
{
"id": "1",
"amount": {
"coefficient": 1000,
"exponent": -2
}
},
{
"id": "2",
"amount": {
"coefficient": 2000,
"exponent": -2
}
}
]
}
}
Will it be "f_sel.f_units.0.amount" ? How can I update the amount using FieldMask?
As far as I know, there is no way to replace individual elements of a repeated field with an index in a FieldMask.
Instead, you'd update the amount field for the element within f_units you wish to change and set the FieldMask to
"f_sel.f_units"
It would be slightly more efficient to only have to send a delta to the original list, but it would be hard to prevent bugs. For example, what if the proto was modified in the meantime and the specified index (presuming there was a way to specify one) for the repeated field was no longer in range?
As an aside, Google does propose the concept of MergeOptions which defines semantics for how repeated fields are to be handled when merging. Currently, it appears they intend for you either to replace the repeated field in its entirety or append to the end of the destination field. Both of these merging strategies avoid the aforementioned bug that could be caused by specifying an invalid index.
Related
I am trying to use the metricbeat http module to monitor F5 pools.
I make a request to the f5 api and bring back json, which is saved to kibana. But the json contains an array of pool members and I want to count the number which are up.
The advice seems to be that this can be done with a scripted field. However, I can't get the script to retrieve the array. eg
doc['http.f5pools.items.monitor'].value.length()
returns in the preview results with the same 'Additional Field' added for comparison:
[
{
"_id": "rT7wdGsBXQSGm_pQoH6Y",
"http": {
"f5pools": {
"items": [
{
"monitor": "default"
},
{
"monitor": "default"
}
]
}
},
"pool.MemberCount": [
7
]
},
If I try
doc['http.f5pools.items']
Or similar I just get an error:
"reason": "No field found for [http.f5pools.items] in mapping with types []"
Googling suggests that the doc construct does not contain arrays?
Is it possible to make a scripted field which can access the set of values? ie is my code or the way I'm indexing the data wrong.
If not is there an alternative approach within metricbeats? I don't want to have to make a whole new api to do the calculation and add a separate field
-- update.
Weirdly it seems that the number values in the array do return the expected results. ie.
doc['http.f5pools.items.ratio']
returns
{
"_id": "BT6WdWsBXQSGm_pQBbCa",
"pool.MemberCount": [
1,
1
]
},
-- update 2
Ok, so if the strings in the field have different values then you get all the values. if they are the same you just get one. wtf?
I'm adding another answer instead of deleting my previous one which is not the actual question but still may be helpful for someone else in future.
I found a hint in the same documentation:
Doc values are a columnar field value store
Upon googling this further I found this Doc Value Intro which says that the doc values are essentially "uninverted index" useful for operations like sorting; my hypotheses is while sorting you essentially dont want same values repeated and hence the data structure they use removes those duplicates. That still did not answer as to why it works different for string than number. Numbers are preserved but strings are filters into unique.
This “uninverted” structure is often called a “column-store” in other
systems. Essentially, it stores all the values for a single field
together in a single column of data, which makes it very efficient for
operations like sorting.
In Elasticsearch, this column-store is known as doc values, and is
enabled by default. Doc values are created at index-time: when a field
is indexed, Elasticsearch adds the tokens to the inverted index for
search. But it also extracts the terms and adds them to the columnar
doc values.
Some more deep-dive into doc values revealed it a compression technique which actually de-deuplicates the values for efficient and memory-friendly operations.
Here's a NOTE given on the link above which answers the question:
You may be thinking "Well that’s great for numbers, but what about
strings?" Strings are encoded similarly, with the help of an ordinal
table. The strings are de-duplicated and sorted into a table, assigned
an ID, and then those ID’s are used as numeric doc values. Which means
strings enjoy many of the same compression benefits that numerics do.
The ordinal table itself has some compression tricks, such as using
fixed, variable or prefix-encoded strings.
Also, if you dont want this behavior then you can disable doc-values
OK, solved it.
https://discuss.elastic.co/t/problem-looping-through-array-in-each-doc-with-painless/90648
So as I discovered arrays are prefiltered to only return distinct values (except in the case of ints apparently?)
The solution is to use params._source instead of doc[]
The answer for why doc doesnt work
Quoting below:
Doc values are a columnar field value store, enabled by default on all
fields except for analyzed text fields.
Doc-values can only return "simple" field values like numbers, dates,
geo- points, terms, etc, or arrays of these values if the field is
multi-valued. It cannot return JSON objects
Also, important to add a null check as mentioned below:
Missing fields
The doc['field'] will throw an error if field is
missing from the mappings. In painless, a check can first be done with
doc.containsKey('field')* to guard accessing the doc map.
Unfortunately, there is no way to check for the existence of the field
in mappings in an expression script.
Also, here is why _source works
Quoting below:
The document _source, which is really just a special stored field, can
be accessed using the _source.field_name syntax. The _source is loaded
as a map-of-maps, so properties within object fields can be accessed
as, for example, _source.name.first.
.
Responding to your comment with an example:
The kyeword here is: It cannot return JSON objects. The field doc['http.f5pools.items'] is a JSON object
Try running below and see the mapping it creates:
PUT t5/doc/2
{
"items": [
{
"monitor": "default"
},
{
"monitor": "default"
}
]
}
GET t5/_mapping
{
"t5" : {
"mappings" : {
"doc" : {
"properties" : {
"items" : {
"properties" : {
"monitor" : { <-- monitor is a property of items property(Object)
"type" : "text",
"fields" : {
"keyword" : {
"type" : "keyword",
"ignore_above" : 256
}
}
}
}
}
}
}
}
}
}
I can't decide which way to save event information to elasticsearch. The information is stored in mysql, and since I want to make them filterable, I've decided to use elasticsearch to index the events. Each of the fields have a limited number of options, but multiple options are allowed. Should I store the information directly like this:
{
"id":"1",
"name":"Event A",
"type":"Training,Workshop,Meeting",
"industrialSector":"Energy,Transport",
"country":"China"
// + 80 fields alike
}
Or use some backend work to turn the string values into numeric tokens before saving to elasticsearch:
{
"id":"1",
"name":"Event A",
"type":"1 3 5",
"industrialSector":"2 3",
"country":"7"
// + 80 fields alike
}
There will be a map object to reference the field options before saved or after fetched:
let options =
{
type:{
Training:1,
Fair:2
Workshop:3,
Brokerage:4
Meeting:5
},
industrialSector:{
Tech:1
Energy:2
Transport:3
}
}
The first one requires less work, but does it perform slower and require more diskspaces than the second one?
I think your second solution has no benefits. I would just store the options as an array:
{
"id":"1",
"name":"Event A",
"type":["Training","Workshop","Meeting"]
"industrialSector":["Energy","Transport"]
"country":"China"
// + 80 fields alike
}
I'm parsing log files which for simplicity's sake let's say will have the following format :
{"message": "hello world", "size": 100, "forward-to": 127.0.0.1}
I'm indexing these lines into an Elasticsearch index, where I've defined a custom mapping such that message, size, and forward-to are of type text, integer, and ip respectively. However, some log lines will look like this :
{"message": "hello world", "size": "-", "forward-to": ""}
This leads to parsing errors when Elasticsearch tries to index these documents. For technical reasons, it's very much untrivial for me to pre-process these documents and change "-" and "" to null. Is there anyway to define which values my mapping should treat as null ? Is there perhaps an analyzer I can write which works on any field type whatsoever that I can add to all entries in my mapping ?
Basically I'm looking for somewhat of the opposite of the null_value option. Instead of telling Elasticsearch what to turn a null_value into, I'd like to tell it what it should turn into a null_value. Also acceptable would be a way to tell Elasticsearch to simply ignore fields that look a certain way but still parse the other fields in the document.
So this one's easy apparently. Add the following to your mapping settings :
{
"settings": {
"index": {
"mapping": {
"ignore_malformed": "true"
}
}
}
}
This will still index the field (contrary to what I've understood from the documentation...) but it will be ignored during aggregations (so if you have 3 entries in an integer field that are "1", 3, and "hello world", an averaging aggregation will yield 2).
Keep in mind that because of the way the option was implemented (and I would say this is a bug) this still fails for and object that is entered as a concrete value and vice versa. If you'd like to get around that you can set the field's enabled value to false like this :
{
"mappings": {
"my_mapping_name": {
"properties": {
"my_unpredictable_field": {
"enabled": false
}
}
}
}
}
This comes at a price though, since this means the field won't be indexed, but the values entered will be still be stored so you can still accessing them by searching for that document through another field. This usually shouldn't be an issue as you likely won't be filtering documents based on the value of such an unpredictable field, but that depends on your specific case use. See here for the official discussion of this issue.
I need a auto increment integer field across two index.
Can Elasticsearch do it automatically like MySQL "auto increment" field in a table?
Eg. when puts some documents in two different index:
POST /my_index_1/blogpost/
{
"title": "Foo Bar"
}
POST /my_index_2/blogpost/
{
"title": "Baz quux"
}
On retrieve it, i want:
GET /my_index_*/blogpost/
{
"uid" : 1,
"title": "Foo Bar"
},
{
"uid" : 2,
"title": "Baz quux"
}
No, ES does not have any auto increment feature since it is a distributed system, figuring out the correct value for the counter is non trivial. Especially since (bulk) indexing tends to be heavily concurrent. You can typically max out CPUs on all nodes if you throw enough documents at it.
So, your best option is to do this outside of ES before you send the documents to ES. Or even better, don't do this. If you need some kind of order of insertion, a better option is to simply use a timestamp. They are actually stored as a number internally. You still might get duplicates of course if two documents get indexed the same millisecond. A trick we've used to work around that is to offset documents indexed at the same time by 1 ms. to ensure we keep the insertion order.
All other things being equal, including indexing, I'm wondering if it is more performant to search on fields closer to the root of the document.
For example, lets say we have a document with a customer ID. Two ways to store this:
{
"customer_id": "xyz"
}
and
{
"customer": {
"id": "xyz"
}
}
Will it be any slower to search for documents where "customer.id = 'xyq'" than to search for documents where "customer_id = 'xyz'" ?
That's pure syntactic sugar. The second form, i.e. using object type, will be flattened out and internally stored as
"customer.id": "xyz"
Hence, both forms you described are semantically equivalent as far as what gets indexed into ES, i.e.:
"customer_id": "xyz"
"customer.id": "xyz"