Relational icons

The 50 relational icons in Data Engineering, described

Auto incrementauto-increment

Auto-increment — the column that fills its own id, one higher each time.

Cardinalitycardinality

Cardinality — how many distinct values a column actually holds.

Cascade deletecascade-delete

Cascade delete — the children go when the parent does.

Check constraintcheck-constraint

A check constraint — a rule every row has to satisfy to be stored.

Collationcollation

Collation — the rule that decides how text sorts and compares.

Composite keycomposite-key

A composite key — a key made of more than one column together.

Connection poolconnection-pool

A connection pool — a handful of connections handed round instead of opened each time.

Cross joincross-join

A cross join — every row on the left paired with every row on the right.

CTEcte

A common table expression — a named result the main query then reads.

Default valuedefault-value

A default — the value written when the insert supplies none.

Distinctdistinct-rows

Distinct — duplicates collapsed so each row appears once.

Explain planexplain-plan

An explain plan — the tree of steps the planner chose to answer the query.

Full-text indexfull-text-index

A full-text index — words indexed so a phrase can be looked up, not just a value.

Group bygroup-by

Group by — rows gathered into buckets so each can be summarised.

Index bloatindex-bloat

Index bloat — an index grown far past the data it points at.

Covering indexindex-covering

A covering index — one that answers the query without touching the table.

Inner joininner-join

An inner join — only the rows that match on both sides.

Isolation levelisolation-level

Isolation level — how much of one transaction another is allowed to see.

Materialized viewmaterialized-view

A materialized view — a view whose answer is stored rather than recomputed.

N+1 queriesn-plus-one

The N+1 problem — one query for the list, then one more for every row in it.

Not nullnot-null-constraint

Not null — the column that refuses to be left empty.

Nullnull-value

Null — the absence of a value, which is not zero and not empty text.

Nullable columnnullable-column

A nullable column — one that is allowed to hold nothing at all.

Optimistic lockoptimistic-lock

Optimistic locking — write freely, then check the version still matches.

Order byorder-by

Order by — the rows handed back in the order the query asked for.

ORMorm

An ORM — objects on one side, tables on the other, mapped between.

Outer joinouter-join

An outer join — the matches, and the rows that had none, kept anyway.

Partitioned tablepartition-table

A partitioned table — one table stored as ranges that are queried as one.

Pessimistic lockpessimistic-lock

Pessimistic locking — take the lock first, and nobody else gets in.

Query cachequery-cache

A query cache — the answer kept so the same question is not asked twice.

Query hintquery-hint

A query hint — the directive that tells the planner which path to take.

Query timeoutquery-timeout

A query timeout — the statement cancelled because it ran too long.

Read replicaread-replica

A read replica — a copy kept in step that answers reads and takes no writes.

Referential integrityreferential-integrity

Referential integrity — every reference points at a row that exists.

Row lockrow-lock

A row lock — one row held while the rest of the table stays free.

Savepointsavepoint

A savepoint — a marked place inside a transaction to roll back to.

Seed dataseed-data

Seed data — the rows a fresh database is planted with.

Self joinself-join

A self join — a table joined to itself to compare its own rows.

Sequencesequence-db

A sequence — the generator that hands out the next number on request.

Slow queryslow-query

A slow query — the one over the threshold, found and timed.

Stored procedurestored-procedure

A stored procedure — logic that lives in the database and runs there.

Subquerysubquery

A subquery — a query nested inside the one that uses its answer.

Surrogate keysurrogate-key

A surrogate key — an id with no meaning of its own, standing in for one.

Table locktable-lock

A table lock — the whole table held, and everyone else waits.

Table scantable-scan

A table scan — every row read because no index could be used.

Transactiontransaction

A transaction — work that either all lands or none of it does.

Truncate tabletruncate-table

Truncate — every row swept out at once, the table itself left standing.

Unique constraintunique-constraint

A unique constraint — no two rows may carry the same value.

Vacuumvacuum-db

Vacuum — dead rows reclaimed and the space handed back.

Write-ahead logwrite-ahead-log

A write-ahead log — the change written to the log before it touches the page.

In code, each is one import — import { AutoIncrement } from "@iconmind/react/icons/auto-increment" — and the same name in Vue, Svelte, Solid, Preact, React Native, Astro, Blade and Flutter.

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