I have a S3 bucket with 500,000+ json records, eg.
{
"userId": "00000000001",
"profile": {
"created": 1539469486,
"userId": "00000000001",
"primaryApplicant": {
"totalSavings": 65000,
"incomes": [
{ "amount": 5000, "incomeType": "SALARY", "frequency": "FORTNIGHTLY" },
{ "amount": 2000, "incomeType": "OTHER", "frequency": "MONTHLY" }
]
}
}
}
I created a new table in Athena
CREATE EXTERNAL TABLE profiles (
userId string,
profile struct<
created:int,
userId:string,
primaryApplicant:struct<
totalSavings:int,
incomes:array<struct<amount:int,incomeType:string,frequency:string>>,
>
>
)
ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe'
WITH SERDEPROPERTIES ( 'ignore.malformed.json' = 'true')
LOCATION 's3://profile-data'
I am interested in the incomeTypes, eg. "SALARY", "PENSIONS", "OTHER", etc.. and ran this query changing jsonData.incometype each time:
SELECT jsonData
FROM "sampledb"."profiles"
CROSS JOIN UNNEST(sampledb.profiles.profile.primaryApplicant.incomes) AS la(jsonData)
WHERE jsonData.incometype='SALARY'
This worked fine with CROSS JOIN UNNEST which flattened the incomes array so that the data example above would span across 2 rows. The only idiosyncratic thing was that CROSS JOIN UNNEST made all the field names lowercase, eg. a row looked like this:
{amount=1520, incometype=SALARY, frequency=FORTNIGHTLY}
Now I have been asked how many users have two or more "SALARY" entries, eg.
"incomes": [
{ "amount": 3000, "incomeType": "SALARY", "frequency": "FORTNIGHTLY" },
{ "amount": 4000, "incomeType": "SALARY", "frequency": "MONTHLY" }
],
I'm not sure how to go about this.
How do I query the array of structures to look for duplicate incomeTypes of "SALARY"?
Do I have to iterate over the array?
What should the result look like?
UNNEST is a very powerful feature, and it's possible to solve this problem using it. However, I think using Presto's Lambda functions is more straight forward:
SELECT COUNT(*)
FROM sampledb.profiles
WHERE CARDINALITY(FILTER(profile.primaryApplicant.incomes, income -> income.incomeType = 'SALARY')) > 1
This solution uses FILTER on the profile.primaryApplicant.incomes array to get only those with an incomeType of SALARY, and then CARDINALITY to extract the length of that result.
Case sensitivity is never easy with SQL engines. In general I think you should not expect them to respect case, and many don't. Athena in particular explicitly converts column names to lower case.
You can combine filter with cardinality to filter array elements having incomeType = 'SALARY' more than once.
This can be further improve so that intermediate array is not materialized by using reduce (see examples in the docs; I'm not quoting them here, since they do not directly answer your question).
Related
I have a posts table with few columns including a liked_by column which's type is an int array.
As I can't post the table here I'll post a single post's JSON structure which comes as below
"post": {
"ID": 1,
"CreatedAt": "2022-08-15T11:06:44.386954+05:30",
"UpdatedAt": "2022-08-15T11:06:44.386954+05:30",
"DeletedAt": null,
"title": "Pofst1131",
"postText": "yyhfgwegfewgewwegwegwegweg",
"img": "fegjegwegwg.com",
"userName": "AthfanFasee",
"likedBy": [
3,
1,
4
],
"createdBy": 1,
}
I'm trying to send posts in the order they are liked (Most Liked Posts). Which should order the posts according to the number of values inside the liked_by array. How can I achieve this in Postgres?
For a side note, I'm using Go lang with GORM ORM but I'm using raw SQL builder instead of ORM tools. I'll be fine with solving this problem using go lang as well. The way I achieved this in MongoDB and NodeJS is to group by the size of liked by array and add a total like count field and sort using that field as below
if(sort === 'likesCount') {
data = Post.aggregate([
{
$addFields: {
totalLikesCount: { $size: "$likedBy" }
}
}
])
data = data.sort('-totalLikesCount');
} else {
data = data.sort('-createdAt') ;
}
Use a native query.
Provided that the table column that contains the sample data is called post, then
select <list of expressions> from the_table
order by json_array_length(post->'likedBy') desc;
Unrelated but why don't you try a normalized data design?
Edit
Now that I know your table structure here is the updated query. Use array_length.
select <list of expressions> from public.posts
order by array_length(liked_by, 1) desc nulls last;
You may also wish to add a where clause too.
There are a lot of posts on unnesting repeated fields in BigQuery -- but, being new to this environment, I have tried almost every code variation I found to flatten a data file. But, I cannot seem to produce one without creating blanks in the id field. It seem like I need to unflatten a nested variable?
I'm using a COVID Dimensions data set that is part of the public collection. Here is some minimal code that produces my problem:
SELECT
id,
authors
FROM
`covid-19-dimensions-ai.data.publications`
CROSS JOIN
UNNEST(authors)
LIMIT 1000
And, here is the JSON structure after running this query. Everything is flattened with the structure I want, but I don't know how to fill in / avoid the blank id variables.
{
"id": "pub.1130234899",
"authors": {
"first_name": "Eric M",
"last_name": "Yoshida",
"initials": null,
"researcher_id": "ur.01071531321.03",
"grid_ids": [
"grid.17091.3e"
],
"corresponding": false,
"raw_affiliations": [
"Division of Gastroenterology, University of British Columbia, Vancouver, British Columbia, Canada"
],
"affiliations_address": [
{
"grid_id": "grid.17091.3e",
"city_id": "6173331",
"state_code": "CA-BC",
"country_code": "CA",
"raw_affiliation": "Division of Gastroenterology, University of British Columbia, Vancouver, British Columbia, Canada"
}
]
}
}
See small correction to your original query
SELECT
id,
author
FROM
`covid-19-dimensions-ai.data.publications`
CROSS JOIN
UNNEST(authors) author
LIMIT 1000
I am new to couchbase and to non-relational DB.
I have a bucket with players and teams(2 types of documents).
each player has type, playedFor(an array with all the teams he played) and a name for example:
{
"type":"player"
"name":"player1"
"playedFor": [
"England/Manchester/United"
"England/Manchester/City"
]
}
each team has type, name and category for example:
{
"type": "team"
"name": "England/Manchester/City"
"category": "FC"
}
I want to know how many players played for each team of category FC.
I made this query to calc for specific team:
SELECT COUNT(1) AS total
FROM bucket AS a
WHERE a.type='player'
AND (any r in a.playedFor satisfies r in ["England/Manchester/United"] end)
but how can i make this query for all teams?
The wrinkle in the way you've modeled this data is that player can play for 1 or more teams (hence the array).
One way to approach this is to use Couchbase's UNNEST clause to "flatten" these arrays (it's basically joining the document to each of the items in the array).
At that point, it becomes as easy as a standard GROUP BY. Here's an example:
SELECT team, count(1) AS totalPlayers
FROM `bucket` AS a
UNNEST a.playedFor team
WHERE a.type='player'
GROUP BY team
This query would generate output like:
[
{
"team": "Pittsburgh/Pirates",
"totalPlayers": 8
},
{
"team": "England/Manchester/United",
"totalPlayers": 10
},
{
"team": "England/Manchester/City",
"totalPlayers": 15
},
{
"team": "Cincinnati/Reds",
"totalPlayers": 21
}
]
(Sorry, I used MLB teams to augment your sample, since I don't know much about soccer teams).
Notice that the separate team documents don't figure into this query, but you could also JOIN to them if you need information from them for your quer(ies).
I am new to Couchbase and kind a stuck with the following problem.
This query works just fine in the Couchbase Query Editor:
SELECT
p.countryCode,
SUM(c.total) AS total
FROM bucket p
USE KEYS (
SELECT RAW "p::" || ca.token
FROM bucket ca USE INDEX (idx_cr)
WHERE ca._class = 'backend.db.p.ContactsDo'
AND ca.total IS NOT MISSING
AND ca.date IS NOT MISSING
AND ca.token IS NOT MISSING
AND ca.id = 288
ORDER BY ca.total DESC, ca.date ASC
LIMIT 20 OFFSET 0
)
LEFT OUTER JOIN bucket finished_contacts
ON KEYS ["finishedContacts::" || p.token]
GROUP BY p.countryCode ORDER BY total DESC
I get this:
[
{
"countryCode": "en",
"total": 145
},
{
"countryCode": "at",
"total": 133
},
{
"countryCode": "de",
"total": 53
},
{
"countryCode": "fr",
"total": 6
}
]
Now, using this query in a spring-boot application i end up with this error:
Unable to retrieve enough metadata for N1QL to entity mapping, have you selected _ID and _CAS?
adding metadata,
SELECT
meta(p).id AS _ID,
meta(p).cas AS _CAS,
p.countryCode,
SUM(c.total) AS total
FROM bucket p
trying to map it to the following object:
data class CountryIntermediateRankDo(
#Id
#Field
val id: String,
#Field
#NotNull
val countryCode: String,
#Field
#NotNull
val total: Long
)
results in:
Unable to execute query due to the following n1ql errors:
{“msg”:“Expression must be a group key or aggregate: (meta(p).id)“,”code”:4210}
Using Map as return value results in:
org.springframework.data.couchbase.core.CouchbaseQueryExecutionException: Query returning a primitive type are expected to return exactly 1 result, got 0
Clearly i missed something important here in terms of how to write proper Couchbase queries. I am stuck between needing metadata and getting this key/aggregate error that relates to the GROUP BY clause. I'd be very thankful for any help.
When you have a GROUP BY query, everything in the SELECT clause should be either a field used for grouping or a group aggregate. You need to add the new fields into the GROUP by statement, sort of like this:
SELECT
_ID,
_CAS,
p.countryCode,
SUM(p.c.total) AS total
FROM testBucket p
USE KEYS ["foo", "bar"]
LEFT OUTER JOIN testBucket finished_contacts
ON KEYS ["finishedContacts::" || p.token]
GROUP BY p.countryCode, meta(p).id AS _ID, meta(p).cas AS _CAS
ORDER BY total DESC
(I had to make some changes to your query to work with it effectively. You'll need to retrofit the advice to your specific case.)
If you need more detailed advice, let me suggest the N1QL forum https://forums.couchbase.com/c/n1ql . StackOverflow is great for one-and-done questions, but the forum is better for extended interactions.
I'm trying to flatten data from repeated fields in Big Query. I have had a look at this Querying multiple repeated fields in BigQuery, however I can't seem to get this to work.
My data looks like the following:
[
{
"visitorId": null,
"visitNumber": "15",
"device": {
"browser": "Safari (in-app)",
"browserVersion": "(not set)",
"browserSize": "380x670",
"operatingSystem": "iOS",
},
"hits": [
{
"isEntrance": "true",
"isExit": "true",
"referer": null,
"page": {
"pagePath": "/news/bla-bla-bla",
"hostname": "www.example.com",
"pageTitle": "Win tickets!!",
"searchKeyword": null,
"searchCategory": null,
"pagePathLevel1": "/news/",
"pagePathLevel2": "/bla-bla-bla",
"pagePathLevel3": "",
"pagePathLevel4": ""
},
"transaction": null
}
]
}
]
What I want is the fields in the hits-page repeated fields.
For instance i want to fetch the hits.page.pagePath (with the value "/news/bla-bla-bla")
I have tried with the following query, but i get an error:
SELECT
visitorId,
visitNumber,
device.browser,
hits.page.pagePath
FROM
`Project.Page`
LIMIT 1000
The error i'm getting is this
Error: Cannot access field page on a value with type ARRAY<STRUCT<hitNumber INT64, time INT64, hour INT64, ...>>
In ga_sessions schema, the field hits is represented as an ARRAY type.
Usually when working with this type field you need to apply the UNNEST operation in order to open the array.
Specifically, in the FROM clause, you can apply a CROSS JOIN (you unnest arrays by applying a cross join operation, which can be represented as a comma followed by the UNNEST function) like so:
SELECT
visitorId,
visitNumber,
device.browser,
hits.page.pagePath
FROM `Project.Page`,
UNNEST(hits) hits
LIMIT 1000
If you want specific pagePaths, you can filter them out like so:
SELECT
visitorId,
visitNumber,
device.browser,
hits.page.pagePath
FROM `Project.Page`,
UNNEST(hits) hits
WHERE regexp_contains(hits.page.pagePath, r'/news/bla-bla-bla')
LIMIT 1000
Make sure to follow through BigQuery documentation on this topic, it's really well written and you'll learn a lot on new techniques to process big data.