MM-58683 Fixing data rention (#204)

* Adding ON DELETE CASCADE to RootPostID on LLM_Threads table for data retention

* Update to just remove table intead of migrating to avoid downtime

server/store.go

@@ -57,12 +57,18 @@ func (p *Plugin) execBuilder(b builder) (sql.Result, error) {
 
 func (p *Plugin) SetupTables() error {
 	if _, err := p.db.Exec(`
-		CREATE TABLE IF NOT EXISTS LLM_Threads (
-			RootPostID TEXT NOT NULL REFERENCES Posts(ID) PRIMARY KEY,
+		CREATE TABLE IF NOT EXISTS LLM_PostMeta (
+			RootPostID TEXT NOT NULL REFERENCES Posts(ID) ON DELETE CASCADE PRIMARY KEY,
 			Title TEXT NOT NULL
 		);
 	`); err != nil {
-		return fmt.Errorf("can't create feeback table: %w", err)
+		return fmt.Errorf("can't create llm titles table: %w", err)
+	}
+
+	// This fixes data retention issues when a post is deleted for an older version of the postmeta table.
+	// Migrate from the old table using `"INSERT INTO LLM_PostMeta(RootPostID, Title) SELECT RootPostID, Title from LLM_Threads"`
+	if _, err := p.db.Exec(`ALTER TABLE IF EXISTS LLM_Threads DROP CONSTRAINT IF EXISTS llm_threads_rootpostid_fkey;`); err != nil {
+		return fmt.Errorf("failed to migrate constraint: %w", err)
 	}
 
 	return nil
@@ -77,7 +83,7 @@ func (p *Plugin) saveTitleAsync(threadID, title string) {
 }
 
 func (p *Plugin) saveTitle(threadID, title string) error {
-	_, err := p.execBuilder(p.builder.Insert("LLM_Threads").
+	_, err := p.execBuilder(p.builder.Insert("LLM_PostMeta").
 		Columns("RootPostID", "Title").
 		Values(threadID, title).
 		Suffix("ON CONFLICT (RootPostID) DO UPDATE SET Title = ?", title))
@@ -108,7 +114,7 @@ func (p *Plugin) getAIThreads(dmChannelIDs []string) ([]AIThread, error) {
 		Where(sq.Eq{"ChannelID": dmChannelIDs}).
 		Where(sq.Eq{"RootId": ""}).
 		Where(sq.Eq{"DeleteAt": 0}).
-		LeftJoin("LLM_Threads as t ON t.RootPostID = p.Id").
+		LeftJoin("LLM_PostMeta as t ON t.RootPostID = p.Id").
 		OrderBy("CreateAt DESC").
 		Limit(60).
 		Offset(0),