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doc/md: docs for new globalid feature (#4344)

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Jannik Clausen
2025-02-25 12:42:25 +01:00
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commit 7f5f143bd2
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doc/md/migrate.md
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@@ -72,48 +72,8 @@ if err != nil {
## Universal IDs
By default, SQL primary-keys start from 1 for each table; which means that multiple entities of different types
can share the same ID. Unlike AWS Neptune, where node IDs are UUIDs.
This does not work well if you work with [GraphQL](https://graphql.org/learn/schema/#scalar-types), which requires
the object ID to be unique.
To enable the Universal-IDs support for your project, pass the `WithGlobalUniqueID` option to the migration.
:::note
Versioned-migration users should follow [the documentation](versioned-migrations.mdx#a-word-on-global-unique-ids)
when using `WithGlobalUniqueID` on MySQL 5.*.
:::
```go
package main
import (
"context"
"log"
"<project>/ent"
"<project>/ent/migrate"
)
func main() {
client, err := ent.Open("mysql", "root:pass@tcp(localhost:3306)/test")
if err != nil {
log.Fatalf("failed connecting to mysql: %v", err)
}
defer client.Close()
ctx := context.Background()
// Run migration.
if err := client.Schema.Create(ctx, migrate.WithGlobalUniqueID(true)); err != nil {
log.Fatalf("failed creating schema resources: %v", err)
}
}
```
**How does it work?** `ent` migration allocates a 1<<32 range for the IDs of each entity (table),
and store this information in a table named `ent_types`. For example, type `A` will have the range
of `[1,4294967296)` for its IDs, and type `B` will have the range of `[4294967296,8589934592)`, etc.
Note that if this option is enabled, the maximum number of possible tables is **65535**.
can share the same ID. Unlike AWS Neptune, where node IDs are UUIDs. [Read this](features.md#globally-unique-id) to
learn how to enable universally unique ids when using Ent with a SQL database.
## Offline Mode