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Graph/missing-composite-unique-constraint

AntiPattern

Composite Uniqueness Gaps

missing-composite-unique-constraint

Duplicate records slip through because uniqueness is enforced only on single fields (or not at all), and detection is done via ad-hoc grouping or serialization workarounds instead of a composite unique constraint.

Node Details

Public graph metadata

Updated7/22/2026

Connections

30 linked nodes

MATCHESSolution

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.

MATCHESSolution

per-deployment provider EXCLUSIVITY as the operating rule — one provider per vector index population. Tension: mixing spaces silently corrupts similarity. Outcome: an embeddingVersion string stamped onto every node at write time so drift is detectable after the fact.

MATCHESSolution

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

MATCHESSolution

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.

MATCHESSolution

More complex, multi-statement queries, or things like `insert..on conflict` and `merge`.

MATCHESSolution

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.

MATCHESSolution

create table t1( id uuid primary key default gen_random_uuid() ,created_at timestamptz default now() ); — You can also side-step the problem entirely. Tension: it doesn't matter where the identifier is generated, removing the need for clients to share the sequence object.

MATCHESSolution

without using reWriteBatchedInserts inserts will not be merged — set batch_size > 1. Tension: Hibernate send multiple statement in the same time and not merging them into multi-valued INSERT. Outcome: without using reWriteBatchedInserts inserts will not be merged.

MATCHESSolution

annotate fields(ex: id) with `sequenceGenerator` not the Entity or class — @Entity @Table(name = "ENTITY") public class ENTITY extends PanacheEntityBase. Tension: those values are inconsistent. Outcome: @Id @SequenceGenerator(name = "ID_SEQ", sequenceName = "ID_SEQ", allocationSize =100) public Integer id;.

MATCHESSolution

Avoiding duplicates requires a table constraint like: — Concurrency. Tension: you run the risk of getting duplicates. Outcome: UNIQUE (auction_id, max_bid).

MATCHESSolution

I want to retain the discrete event scoring, but also rank the racer in the series. Tension: if there are legitimate ties across different racers, I want there to be gaps in the rank. Outcome: The easiest way to solve this I think would be to issue two queries, one with the "duplicate" racers eliminated, and then a second one where I can retain the individual race data.

MATCHESSolution

Depending on which DBMS you're actually using, you could use window functions and exist expressions. — SELECT * FROM ( SELECT *, COUNT(*) OVER (PARTITION BY col2) AS occurences FROM table1 ). Tension: where col2 = t1.col2. Outcome: WHERE occurrences > 1 AND NOT EXISTS ( SELECT * FROM table2 WHERE col2 = t1.col2 ).

MATCHESSolution

Enforce/optimize uniqueness on storage_time_series by creating a UNIQUE INDEX on (akd, ii, value), then replace the NOT EXISTS pattern with INSERT ... ON CONFLICT DO NOTHING to avoid slow existence checks.

MATCHESSolution

Define a composite type (e.g., with bigint fields) and cast/select the scalar subquery results into that type to return a single composite row.

MATCHESSolution

a workaround for this — when directly fetching objects using findById. Tension: the bug is still there. Outcome: There is an existing bug in Hibernate 6.2.

MATCHESSolution

Use separate entities with one-to-one relations instead of trying to create PersonExtra and PersonBasic with the same primary key

MATCHESSolution

Execute the jOOQ DELETE/UPDATE and use the returned affected-row count: treat 0 as not found (404), 1 as success, and >1 as a primary-key/invariant problem. Optionally, to reduce rollback/transaction footprint, select the target row with `SELECT .. FOR UPDATE` (or otherwise enforce uniqueness) before deleting when multiple rows could otherwise occur.

MATCHESSolution

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 )).

MATCHESSolution

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));.

MATCHESSolution

Removing `orderId(UUID.randomUUID())` from order Builder works like a charm. — The error occurs because the `@Id` field (`orderId`) is annotated with `@GeneratedValue(strategy = GenerationType.AUTO)`. Tension: Hibernate automatically generates the value for this field. Outcome: Removing `orderId(UUID.randomUUID())` from order Builder works like a charm.

MATCHESSolution

you can use subqueries like this: — if you plan to remove that to support non-unique names. Tension: Although this can be a bit slow, so make sure you have the indexes setup.

MATCHESSolution

Pre-check duplicator spawns as a batch — before any objects are created. Outcome: before any objects are created.

MATCHESSolution

CREATE CONSTRAINT domain_normalized_label IF NOT EXISTS FOR (n:Domain) REQUIRE n.normalizedLabel IS UNIQUE — Added. Tension: Makes the MERGE atomic — concurrent transactions serialize on the constraint. Outcome: (and same for Algorithm).

MATCHESSolution

Combined the renormalize + merge phases into a single pass — that groups all nodes by canonical label in memory first. Tension: This avoids a chicken-and-egg problem where renormalizing before merging hits the new unique constraint. Outcome: merges duplicates (keeping the most-connected node, redirecting edges via APOC), then updates the survivor's label.

MATCHESSolution

In server-to-server callers of signUpEmail, do an explicit pre-flight email + username uniqueness check against the `user` table before invoking signUpEmail — server-to-server callers of signUpEmail. Tension: Bypassing the enumeration mitigation is correct on internal-secret-gated routes because there is no untrusted caller to defend against. Outcome: return a clean 409 on collision. Add a belt-and-braces post-call check: SELECT user.id WHERE id = result.user.id — if the row doesn't exist, refuse to use the id.

MATCHESSolution

Use a two-layer dedup strategy: first run a fast synchronous PostgreSQL full-text/BM25 (tsvector/ts_rank) pre-insert check to catch obvious duplicates, then perform embedding + pgvector similarity asynchronously after insertion. For the knowledge graph, add a unique constraint on `normalizedLabel` (e.g., `Domain.normalizedLabel`) so MERGE is serialized and concurrent jobs cannot create duplicate entities.

MATCHESSolution

Content-hash dedup against existing entries — before inserting. Tension: For our case (ChromaDB 1845 → Chronicle), 1238/1845 were already present from a prior graph migration. Outcome: Only 607 net-new.

MATCHESSolution

UNION ALL is the right call. — Unified activity feeds. Tension: Materialized views are tempting but stale instantly on a write-heavy platform. Outcome: Performance tip: add a composite index on `(author_type, author_id, created_at DESC)` on each content table.

MATCHESSolution

How to find similar latent FKs before they bite — grep migrations for `REFERENCES <parent>(id)` lines without `ON DELETE`. Tension: Tables created with default RESTRICT but written only from rarely-fired code paths are time bombs. Outcome: audit each.

MATCHESSolution

backwards compatibility with persisted legacy data. Tension: indexes are positions; positions are not identity.

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