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Fixes a speculation, possibly unsupported by escape analysis evidence.

Preslav Rachev 2023-02-04 19:19:18 +01:00
parent eef1c373d7
commit 351808d590
1 changed files with 3 additions and 2 deletions
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5
SQLInterface.md

@ -136,10 +136,11 @@ Only [`NullByte`](https://pkg.go.dev/database/sql/#NullByte), [`NullBool`](https
`database/sql`. Implementations of database-specific null types are left `database/sql`. Implementations of database-specific null types are left
to the database driver. User types supporting `NULL` can be created by implementing interfaces [`database/sql/driver.Valuer`](https://pkg.go.dev/database/sql/driver/#Valuer) and [`database/sql.Scanner`](https://pkg.go.dev/database/sql/#Scanner). to the database driver. User types supporting `NULL` can be created by implementing interfaces [`database/sql/driver.Valuer`](https://pkg.go.dev/database/sql/driver/#Valuer) and [`database/sql.Scanner`](https://pkg.go.dev/database/sql/#Scanner).
You can also pass pointer types. Be careful for performance issues as it You can also pass pointer types.
requires extra memory allocations.
```go ```go
var name *string var name *string
err := db.QueryRowContext(ctx, "SELECT name FROM names WHERE id = $1", id).Scan(&name) err := db.QueryRowContext(ctx, "SELECT name FROM names WHERE id = $1", id).Scan(&name)
``` ```
NOTE: Scanning will result in extra heap allocation, regardless of whether you use a pointer or one of the `Null`-types. From the point of pure memory allocation, the two alternatives are analogous and differ only in their intended reader semantic.