Graph/9353aefd-3bb4-47e1-a2f5-02403d528a7b

Domainunvalidated

Query Optimization

9353aefd-3bb4-47e1-a2f5-02403d528a7b

Query Optimization

Node Details

Public graph metadata

Updated4/30/2026

PageRank0.0008

Effectiveness0.000

Connections

50 linked nodes

When I try do drop the column it times out after 20 mins. — I have a very large table (over a TB space) in a postgres db and it has a text column which is also large causing TOASTING in the db. Outcome: I am getting an error stating the statement is canceled due to timeout.

RELATES_TOProblem

in which the query above is nested. Tension: why is it a must to alias in the second query and not the first ?

RELATES_TORootCause

the `UNION` will cause an implicit distinct on the sub-select — you don't really need as te `MAX()` and `GROUP BY` later on. Tension: which you don't really need. Outcome: you better remove then again off course.

RELATES_TOProblem

canceling statement due to statement timeout — the below query is timing out due to large data set. Tension: I appreciate any suggestions on how to increase the below query performance.

RELATES_TOSolution

Personally I would go for this: — the below query is timing out due to large data set. Tension: you really should provide the full EXPLAIN ANALYZE result otherwise we're just flying blind and guessing here.

RELATES_TOProblem

I am not able to get certain results from Java client side. — uses java HLRC client fetching results from Elasticsearch cluster. Tension: when i am firing the underlying query of Java client in kibana devtools I am getting valid results. Outcome: This issue is just happening for a particular [KNOWN error — represented by RootCause "Spring Data JPA does not automatically map native query result columns to Java r" (anchor id=866c5bc6-e8c4-4b07-825c-daa708d304ec)].

RELATES_TOSolution

To better investigate The explain api. Tension: Text field vs Keyword Field ? Outcome: There is the explain api that can help you understand why or why not documents are matching.

PERTAIN_TOProblem

I can get the same performance issues with either a select or a delete — they join two tables, and none of the join conditions compares using `=`. Tension: `IS NOT DISTINCT FROM` is not supported by indexes, and `OR` is usually a performance problem anyway. Outcome: the root of your problem are the NULL values.

PERTAIN_TOProblem

sqlc always generates a struct with an `interface — I’ve tried several approaches. Tension: I need to aggregate more complex data into a slice. Outcome: Composite and record types aren't yet supported by `sqlc`.

PERTAIN_TOProblem

TanStack Query cache is not being leveraged for Firestore data fetched manually

PERTAIN_TOSolution

The statements that use `coalesce()` join using `=` — they join two tables, and none of the join conditions compares using `=`. Tension: you can get a hash or a merge join, depending on the size of the tables. Outcome: That is most likely the reason for the observed performance difference.

PERTAIN_TOProblem

that will give me 3 levels deep of nodes in my json output — I have a many to many self referential relationship. Tension: is there a way to do that so it goes as many levels deep as needed until nodes = [] ? Outcome: Do I need to use something like marshmallow-sqlalchemy ?

PERTAIN_TOSolution

select_options=[ selectinload(Parent.child) .selectinload(Node.nodes) ] — possible workaround if there's a way to do this dynamically. Outcome: for option in select_options: query = query.options(option).

PERTAIN_TORootCause

So the above allows me to dynamically add as many options. Tension: Editing to add a possible workaround if there's a way to do this dynamically.

PERTAIN_TOSolution

Tension: this eliminates the need for a loop. Outcome: this eliminates the need for a loop.

PERTAIN_TOProblem

does not populate by query — retrieve via query results from two related tables via a third mid table. Tension: It's a relationship between Product - Category via ProductCategory join.

PERTAIN_TOSolution

call one off the other and not list them separately with a comma.

PERTAIN_TOSolution

you can use following — joined tables. Tension: Any other columns you need from joined tables.

PERTAIN_TOProblem

datetime arithmetic using intervals is not directly supported on MySQL

PERTAIN_TOSolution

Use manual transformation of both sides of the expression, such as conversion to integer epoch values first via expression.func

PERTAIN_TOProblem

these requests do not show any header information that I can use to get that tier category — use a command-line query to learn if an object is in the "Frequent Access", "Infrequent Access", or "Archive Instant Access" tier. Tension: Is there another CLI option for getting this information? Outcome: It is currently only possible to view an object's S3 Intelligent Tiering access tier through an S3 Inventory report.

PERTAIN_TOSolution

view an object's S3 Intelligent Tiering access tier through an S3 Inventory report — Configure S3 Inventory. Tension: This can be enabled on a bucket or prefix level and is generated on a daily or weekly frequency. Outcome: download the file from the S3 Inventory output location and parse if locally or query it via Athena.

PERTAIN_TOProblem

Finding duplicate objects in an S3 bucket by metadata values requires a way to search matching objects

PERTAIN_TOSolution

Use S3 Metadata tables and query e_tag with Athena or another Iceberg-compatible tool to locate duplicate objects

PERTAIN_TOProblem

does not produce such a `query_profile.json` file — If you run an `EXPLAIN` or `EXPLAIN ANALYZE` query. Tension: profiling/timing stats to a `query_profile.json`, which I should be able to use to generate an html file. Outcome: the profiling information will not be written to the desired file, but will rather show up in the result.

PERTAIN_TOSolution

If you run a straight `SELECT/UPDATE/DELETE` query, then the profiling information is written to the file. Tension: If you run an `EXPLAIN` or `EXPLAIN ANALYZE` query, the profiling information will not be written to the desired file. Outcome: and the result is the result of the query.

PERTAIN_TOProblem

there is no option for "key" in the method I'm using , only "prefix" — rollback an S3 object to a specific version. Tension: in this example i will end up delete all versions of objects named "questions copy". So as you see, I had to filter in python, which seems less efficient.

PERTAIN_TOSolution

it is necessary to use `.object_versions` (or `list_object_versions()` for client calls) — since your code is written to only roll-back a single object. Tension: it's not really possible to reduce the number of API calls to AWS. Outcome: An alternative approach that could be considered 'more efficient' would be to copy the desired previous version to the same Key.

PERTAIN_TOProblem

Athena is making separate calls to read footer, column data and separate calls to each partition if the file is large — using Athena to query an S3 bucket and using Athena partition projection as well. Tension: I use node, date and effective_time_start in query. Outcome: Apparently, this is how parquet works.

PERTAIN_TOSolution

for CSV file and run the same queries and see that it is only doing one GET per file — I have setup the same table for CSV file and run the same queries. Tension: Athena is making separate calls to read footer, column data and separate calls to each partition if the file is large. Outcome: it is only doing one GET per file.

PERTAIN_TOSolution

you can use type overrides as suggested in related issue #309 — Composite and record types aren't yet supported by `sqlc`. Outcome: you can aggregate the table record types directly into an `item[]` field.

PERTAIN_TOProblem

indexes by Seq Scan — Tried to set db_index=True, HashIndex and BrinIndex. Tension: there are 1000 records in the database. Outcome: 1000 records is very small amount of records.

PERTAIN_TOSolution

1000 records is very small amount of records. — At this scale Postgres might decide that sequential scan will be faster. Outcome: sequential scan will be faster.

PERTAIN_TOSolution

If you want to use jOOQ API for these two things, use the above functions. — `->>` which translates to `jsonGetAttributeAsText`. Tension: If anything isn't supported in jOOQ, or in an older version of jOOQ, or if you prefer to use the simpler `jsonb_array_elements` function over the more verbose `JSON_TABLE` function. Outcome: just use plain SQL templates, as always.

PERTAIN_TOProblem

Selecting a more optimal index for a PostgreSQL query that filters on multiple fields inside a JSONB column

PERTAIN_TOSolution

It works but this is not optimal since the `created_at` column is duplicated. — I created three indexes for each `data_discriminator`, JSONB columns and `created_at`. Tension: Is there a way to create one index for this query and with two columns from JSONB for one of the discriminators (`B`)? Outcome: Or is there a more optimal approach to indexing this case?

PERTAIN_TOProblem

A PostgreSQL query uses a CTE to select the old session_id and then performs an INSERT ... ON CONFLICT DO UPDATE, returning the CTE’s result as the previous value. The user needs to know whether PostgreSQL guarantees the CTE is evaluated before the INSERT/UPDATE so the returned value is correct.

PERTAIN_TOSolution

Use RETURNING to capture the previous value from the row being updated instead (e.g., compute the old value directly from the target row during the UPDATE/ON CONFLICT path). If you rely on the CTE output, ensure the query shape forces dependency on the CTE (as in the current example), but be aware the CTE may be discarded in cases where a conflict can be proven not to occur.

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_TOProblem

none of the three queries you showed ended up using it — Select * from users where Type = 'SomeType' and First = 'SomeName1' Order by CreatedAt DESC;. Tension: The fact that you're selecting and ordering by `CreatedAt` doesn't mean it's needed as an index key. Outcome: If you simply remove `createdat` from the index, they're happy to use it for a Bitmap Index Scan taking below `5ms`.

PERTAIN_TOSolution

first, middle, and last varies. Tension: You can add more tweaks depending on how much input latency you're ready to tolerate and how much space you're willing to spend. Outcome: Thorsten Kettner.

PERTAIN_TOSolution

`(Type) incl. Tension: first, middle, and last varies.

PERTAIN_TOSolution

So, an index for the first query would look like this: — For the first query. Tension: all those matches would already be sorted. Outcome: create index idx_1 on users (first, type, createdat desc);.

PERTAIN_TOSolution

If you only wanted to provide a single index for all queries instead — all three queries have in common. Tension: I doubt the DBMS would use the index. Outcome: then you'd index the type.

PERTAIN_TORootCause

duplicate key value violates unique constraint "orders_pkey" — using a LEFT JOIN with WHERE o.order_id IS NULL. Tension: The `LEFT JOIN` with `WHERE o.order_id IS NULL` should filter out existing `order_id`s. Outcome: Use NOT EXISTS Instead of LEFT JOIN.

PERTAIN_TOProblem

ERROR: duplicate key value violates unique constraint "orders_pkey" — using a LEFT JOIN with WHERE o.order_id IS NULL. Tension: This query should only insert `order_id`s that do not already exist in `orders`. Outcome: Use ON CONFLICT DO NOTHING.

PERTAIN_TOSolution

Use ON CONFLICT DO NOTHING — INSERT INTO orders (order_id, customer_id, order_date). Tension: despite using a LEFT JOIN with WHERE o.order_id IS NULL, I still get the following error. Outcome: Use NOT EXISTS Instead of LEFT JOIN.

[inerrata]Tags Knowledge Graph Docs About Team Pricing Contact Report a Bug Privacy Terms Cookie Settings Do Not Sell or Share My Info