Merge branch '193-settings-to-explain' into 'master'

feat: Add SETTINGS to EXPLAIN (#193)

Closes #193

See merge request postgres-ai/joe!184

Author: agneum

pkg/bot/command/explain.go

@@ -31,7 +31,11 @@ const (
 
 	// Query Explain prefixes.
 	queryExplain        = "EXPLAIN (FORMAT TEXT) "
-	queryExplainAnalyze = "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON) "
+	queryExplainAnalyze = "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON %s) "
+	settingsExplain     = ", SETTINGS TRUE"
+
+	postgresNumDiv = 10000 // Divider to get version from server_version_num.
+	pgVersion12    = 12    // Explain Settings are available starting with Postgres 12.
 
 	// locksTitle shows locks for a single query analyzed with EXPLAIN.
 	// locksTitle = "*Query heavy locks:*\n".
@@ -82,7 +86,7 @@ func Explain(ctx context.Context, msgSvc connection.Messenger, command *platform
 		return errors.Wrap(err, "failed to run explain without execution")
 	}
 
-	explainAnalyze, err := querier.DBQueryWithResponse(ctx, tx, queryExplainAnalyze+command.Query)
+	explainAnalyze, err := querier.DBQueryWithResponse(ctx, tx, analyzePrefix(session.DBVersion)+command.Query)
 	if err != nil {
 		return err
 	}
@@ -191,6 +195,16 @@ func Explain(ctx context.Context, msgSvc connection.Messenger, command *platform
 	return nil
 }
 
+func analyzePrefix(dbVersionNum int) string {
+	settingsValue := ""
+
+	if (dbVersionNum / postgresNumDiv) >= pgVersion12 {
+		settingsValue = settingsExplain
+	}
+
+	return fmt.Sprintf(queryExplainAnalyze, settingsValue)
+}
+
 func observeLocks(ctx context.Context, db *pgxpool.Pool, txPID int) ([][]string, error) {
 	observeConn, err := getConn(ctx, db)
 	if err != nil {

pkg/bot/command/explain_test.go

@@ -0,0 +1,36 @@
+package command
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAnalyzePrefix(t *testing.T) {
+	testCases := []struct {
+		input          int
+		expectedOutput string
+	}{
+		{
+			input:          0,
+			expectedOutput: "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON ) ",
+		},
+		{
+			input:          90600,
+			expectedOutput: "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON ) ",
+		},
+		{
+			input:          120000,
+			expectedOutput: "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON , SETTINGS TRUE) ",
+		},
+		{
+			input:          160000,
+			expectedOutput: "EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON , SETTINGS TRUE) ",
+		},
+	}
+
+	for _, tc := range testCases {
+		output := analyzePrefix(tc.input)
+		assert.Equal(t, tc.expectedOutput, output)
+	}
+}

pkg/foreword/foreword.go

@@ -32,22 +32,25 @@ Database state at: %s (%s ago)
 
 // Content defines data for a foreword message.
 type Content struct {
-	Duration   time.Duration
-	SessionID  string
-	AppVersion string
-	Edition    string
-	DBName     string
-	DSA        string
-	DSADiff    string
-	DBSize     string
-	DBVersion  string
+	Duration     time.Duration
+	SessionID    string
+	AppVersion   string
+	Edition      string
+	DBName       string
+	DSA          string
+	DSADiff      string
+	DBSize       string
+	DBVersion    string
+	DBVersionNum int
 }
 
 // EnrichForewordInfo adds database details to foreword data.
 func (f *Content) EnrichForewordInfo(ctx context.Context, db *pgxpool.Pool) error {
-	r := db.QueryRow(ctx, "select current_setting('server_version'), pg_size_pretty(pg_database_size($1))", f.DBName)
+	r := db.QueryRow(ctx,
+		"select current_setting('server_version'), current_setting('server_version_num')::int, pg_size_pretty(pg_database_size($1))",
+		f.DBName)
 
-	if err := r.Scan(&f.DBVersion, &f.DBSize); err != nil {
+	if err := r.Scan(&f.DBVersion, &f.DBVersionNum, &f.DBSize); err != nil {
 		return errors.Wrap(err, "failed to retrieve database meta info")
 	}
 

pkg/services/msgproc/dblab.go

@@ -144,6 +144,7 @@ func (s *ProcessingService) runSession(ctx context.Context, user *usermanager.Us
 	user.Session.CloneConnection = userConn
 	user.Session.LastActionTs = time.Now()
 	user.Session.ChannelID = incomingMessage.ChannelID
+	user.Session.DBVersion = fwData.DBVersionNum
 
 	if s.config.Platform.HistoryEnabled && incomingMessage.SessionID == "" {
 		if err := s.createPlatformSession(ctx, user, sMsg.ChannelID); err != nil {

pkg/services/usermanager/user.go

@@ -40,6 +40,7 @@ type UserSession struct {
 	ConnParams      models.Clone
 	Pool            *pgxpool.Pool `json:"-"`
 	CloneConnection *pgx.Conn     `json:"-"`
+	DBVersion       int           `json:"-"`
 }
 
 // Quota defines a user quota for requests.