Add PrepareStmtAutoSave option to enable PostgreSQL autosave_prepared_statements

[miladev95]

• Do only one thing
• Non breaking API changes
• Tested

This PR covers #7629 feature request.

What did this pull request do?

Add PrepareStmtAutoSave Support for PostgreSQL

Overview

Introduces new PrepareStmtAutoSave configuration option to enable PostgreSQL's autosave_prepared_statements parameter. This helps prevent prepared statement cache invalidation errors when schema changes occur during runtime.

Problem Statement

When using prepared statements with GORM:

• PostgreSQL caches prepared statements for performance
• If the schema changes (e.g., column added/removed), cached statements become invalid
• This causes execution errors like "column does not exist"
• Requires manual cache clearing or connection reconnect

Solution

Enable PostgreSQL's autosave_prepared_statements parameter to automatically invalidate cached statements when schema changes, preventing execution errors.

Changes

• New Config Field: PrepareStmtAutoSave *bool

  • nil = disabled (default, no configuration)
  • true = enable autosave
  • false = explicitly disable autosave

• New Method: configureAutoSave(ctx context.Context) error

  • Executes SET autosave_prepared_statements = true/false on PostgreSQL connection
  • Called during database initialization if PrepareStmt is enabled
  • Only applicable to PostgreSQL

• Updated: Open() function to call configureAutoSave() during initialization

Usage Example

// Enable prepared statements with autosave
trueVal := true
db, err := gorm.Open(
    postgres.Open(dsn),
    &gorm.Config{
        PrepareStmt: true,ave: &trueVal,
        PrepareStmtAutoS
    },
)

// Disable autosave
falseVal := false
db, err := gorm.Open(
    postgres.Open(dsn),
    &gorm.Config{
        PrepareStmt: true,
        PrepareStmtAutoSave: &falseVal,
    },
)

// Not set (default - no autosave configuration)
db, err := gorm.Open(
    postgres.Open(dsn),
    &gorm.Config{
        PrepareStmt: true,
    },
)

[propel-code-bot]

Add PrepareStmtAutoSave option for PostgreSQL prepared-statement autosave

Introduces a tri-state PrepareStmtAutoSave *bool field to gorm.Config and wires it into gorm.Open() through a new helper configureAutoSave(). When the flag is non-nil and the current dialect is PostgreSQL, GORM issues SET autosave_prepared_statements = <true|false> once during initialization, reducing runtime errors caused by invalidated cached prepared statements after DDL changes.
The change is self-contained to gorm.go, adds ~34 LoC, does not modify existing behaviour for other dialects, and keeps API backward-compatible.

Key Changes

• Added PrepareStmtAutoSave *bool to Config with detailed comments
• Updated Open() to invoke configureAutoSave() when PrepareStmtAutoSave is non-nil
• Implemented DB.configureAutoSave(ctx) with dialect guard, warning log, and SET autosave_prepared_statements execution
• Extended docs/comments for the new option

Affected Areas

• gorm.Config struct definition
• Open() initialization flow
• DB helper methods (new configureAutoSave())

This summary was automatically generated by @propel-code-bot

[propel-code-bot]

[BestPractice]

The configureAutoSave method is called only when PrepareStmtAutoSave is non-nil, but there's no validation that PrepareStmt is enabled. The autosave_prepared_statements parameter only applies when prepared statements are being used. If PrepareStmt is false but PrepareStmtAutoSave is set, this configuration will have no effect and may be confusing.

Suggested change

	if err == nil && config.PrepareStmtAutoSave != nil {
	if err == nil && config.PrepareStmt && config.PrepareStmtAutoSave != nil {
	err = db.configureAutoSave(context.Background())
	}

⚡ Committable suggestion

Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation.

Context for Agents

[**BestPractice**]

The `configureAutoSave` method is called only when `PrepareStmtAutoSave` is non-nil, but there's no validation that `PrepareStmt` is enabled. The `autosave_prepared_statements` parameter only applies when prepared statements are being used. If `PrepareStmt` is false but `PrepareStmtAutoSave` is set, this configuration will have no effect and may be confusing.

```suggestion
if err == nil && config.PrepareStmt && config.PrepareStmtAutoSave != nil {
	err = db.configureAutoSave(context.Background())
}
```

⚡ **Committable suggestion**

Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation.

File: gorm.go
Line: 247

[propel-code-bot]

[BestPractice]

Connection-level vs session-level configuration: Using db.Exec() to set PostgreSQL parameters only affects the current connection/session. If GORM uses a connection pool, different connections may not have this setting applied, leading to inconsistent behavior.

Consider setting this parameter in the PostgreSQL connection string instead, or document that this setting only applies to the current session.

Context for Agents

[**BestPractice**]

Connection-level vs session-level configuration: Using `db.Exec()` to set PostgreSQL parameters only affects the current connection/session. If GORM uses a connection pool, different connections may not have this setting applied, leading to inconsistent behavior.

Consider setting this parameter in the PostgreSQL connection string instead, or document that this setting only applies to the current session.

File: gorm.go
Line: 574