Graph/4378233f-ddca-4242-958f-a7503ef81b07

Domainunvalidated

Aggregations

4378233f-ddca-4242-958f-a7503ef81b07

Aggregations

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Updated5/1/2026

PageRank0.0000

Effectiveness0.000

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45 linked nodes

RELATES_TOProblem

I'm trying in a single query to get the avg value of a given field and the average value of the top 5 values of that same field — using django ORM. Tension: I've found two different ways to achieve this in SQL, but I'm having trouble implementing those queries using django ORM.

PERTAIN_TOProblem

as long as the `realm_id` has a name which status is neither `closed` nor `denied`, it'll be marked as `active`, otherwise, it's `inactive` — aggregate based on `realm_id` first;. Tension: I've tried to use aggregate and left outer join, but no luck thus far. Outcome: You can use `bool_or()` aggregation function.

PERTAIN_TOSolution

on 2M rows it takes `575ms` on average, having to run a sequential scan. Tension: Unfortunately, it can't use an index which is why on 2M rows it takes `575ms` on average. Outcome: The skip scan runs 56x faster, under `11ms` using index-onlies.

PERTAIN_TORootCause

The following is the method I use. It is very bloated and the execution time is too long. — Especially if there are more score columns(score8, score9...), more `UNION ALL` will be piled up. Tension: more `UNION ALL` will be piled up. Outcome: Use `GREATEST()` and `LEAST()`.

PERTAIN_TOSolution

You can use `GREATEST()` and `LEAST()`, it's simple and executes faster: — SELECT id, ( score1 +score2 +score3 +score4 +score5 +score6 +score7 -GREATEST(score1,score2,score3,score4,score5,score6,score7) -LEAST(score1,score2,score3,score4,score5,score6,score7) )/ 5 AS average_score. Tension: it's simple and executes faster. Outcome: average_score.

PERTAIN_TOProblem

The following is the method I use. It is very bloated and the execution time is too long. — especially if there are more score columns(score8, score9...), more `UNION ALL` will be piled up.

PERTAIN_TOProblem

how to get cumulative count? — In postgresql. Tension: I wanted to get a cumulative count of customers enrolled between 01-01 and 02-01, 01-01 and 03-01, 01-01 and 04-01 etc. Outcome: ideally the output should be like.

PERTAIN_TOSolution

You need a window function to do a running sum over the normal aggregation. — select count(distinct mt.customer) as count. Outcome: sum(count(distinct mt.customer)) over (order by mt.enrollment_dt rows unbounded preceding) as running_count.

PERTAIN_TOProblem

No built-in shorthand for null-safe addition in PostgreSQL

PERTAIN_TOSolution

Other than `coalesce(col1, 0) + coalesce(col2, 0)` — do null safe addition. Tension: is there any built in shorthand function, like `least`, that will let me do null safe addition? Outcome: There is nothing built in, but you can create your own:.

PERTAIN_TOProblem

I want to pivot this datasets from rows to columns. — timeseries data. Tension: This means in each row one complete dataset.

PERTAIN_TOSolution

select "timestamp", const, array_agg(distinct "value") as names — group by "timestamp", const. Outcome: Then it's simple as that.

PERTAIN_TOSolution

You may use `jsonb_agg` instead of `array_agg` — have the list as a JSON array. Tension: if this is more relevant to your case.

PERTAIN_TOSolution

select "timestamp", const, jsonb_agg(jsonb_build_object(name, "value")) as names — If you need the contents of column "name" in the result. Outcome: the result may be a JSON array of objects.

PERTAIN_TOProblem

more than one row returned by a subquery used as an expression.

PERTAIN_TOSolution

LEFT JOIN kyc ON kyc.created_date>= thang.start_date AND kyc.created_date < thang.end_date.

PERTAIN_TOProblem

java.io.InvalidClassException: tls.other.app.package.SomeClass; local class incompatible: stream classdesc serialVersionUID = 1, local class serialVersionUID = 2 — deserializing the older streams. Tension: some (older) streams seem to have been serialized using classes with different serial version IDs. Outcome: I want to deserialize both versions of the Java object streams with the same application.

PERTAIN_TORootCause

`accumulator` is a perfectly valid combiner and is used as such. — On parallel streams, the stream may be broken into chunks. Tension: with those constraints, that implementation is valid. Outcome: `fold` drops the restrictions that the combiner function must be associative.

PERTAIN_TOProblem

When should one use the new `fold`-Gatherer over the classic `reduce`-method? — Java 24 introduced Stream Gatherers as a full-fledged feature. Tension: But reduction on a sequential Stream is already ordered:.

PERTAIN_TOSolution

I would generally consider it appropriate to use in that circumstance. Tension: when there is no associative combining operation. Outcome: works on arbitrary streams (sequential or parallel) in that context.

PERTAIN_TOAnswer

so-79759297

PERTAIN_TOProblem

java.lang.IllegalStateException: Duplicate key a (attempted merging values 1 and 1) — I'm trying to convert a list of objects to a `Map` using Java Streams. Tension: I expected it to just create a map with unique keys, but I forgot that my list has duplicates.

PERTAIN_TOSolution

tell it with a merge function what to do in case of a duplicate — To handle it. Tension: or just keep the first one? Outcome: collect(Collectors.toMap( s -> s, String::length, (a1, a2) -> a1 )).

PERTAIN_TOAnswer

so-79642599

PERTAIN_TOSolution

Make sure you have 'distinct' values: — List.of("a", "b", "a"); Map map = list.stream(). Outcome: Map map = list.stream() .distinct() .collect(Collectors.toMap(s -> s, String::length));.

PERTAIN_TOAnswer

so-79642591

PERTAIN_TORootCause

I can do the grouping — going over the map via streamed entry set I can apply the "hammer" logic. Tension: I can do the grouping. Outcome: need to keep a list of the grouped values so you can access the nail index later.

PERTAIN_TOProblem

I'm now loo. Tension: Most of the answers are not using the collectors, which I think is a valid solution. Outcome: return a map with the nail length, and the number of nails with that lengt.

PERTAIN_TOSolution

You can use `Collectors.collectingAndThen`, but then you need to keep a list of the grouped values so you can access the nail index later — Collectors.collectingAndThen. Tension: you need to keep a list of the grouped values so you can access the nail index later.

I'm trying in a single query to get the avg value of a given field and the average value of the top 5 values of that same field — using django ORM. Tension: I've found two different ways to achieve this in SQL, but I'm having trouble implementing those queries using django ORM.

PERTAIN_TOAnswer

so-77925537

PERTAIN_TOProblem

Iterating through a Review QuerySet associated to an Album QuerySet to gather the total amount of ratings

PERTAIN_TOSolution

Use album.review_set.all() in a nested loop, or use aggregate database functions instead

PERTAIN_TOAnswer

so-76754475

PERTAIN_TOSolution

filter the FooBar instances with the same Foo and Bar instances as relations.

PERTAIN_TOAnswer

so-75989481

PERTAIN_TOProblem

find duplicates of django model on two fields. Outcome: here's a hint.

PERTAIN_TOSolution

Use Django ORM aggregation to group by the two fields and filter groups with count greater than one

IMPLEMENTATION_OFComponent

django

IMPLEMENTATION_OFPackage

django

IMPLEMENTATION_OFLanguage

django

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