Implement new pganalyze.explain_analyze() helper

.github/workflows/ci.yml

@@ -13,6 +13,15 @@ jobs:
   build:
     # Use new enough OS that has CGroupsv2 enabled (required by the integration tests)
     runs-on: ubuntu-22.04
+    env:
+      TEST_DATABASE_URL: postgresql://postgres:postgres@localhost:5432/postgres?sslmode=disable
+    services:
+      postgres:
+        image: postgres:14
+        env:
+          POSTGRES_PASSWORD: postgres
+        ports:
+          - 5432:5432
 
     steps:
 

input/postgres/explain_analyze.go

@@ -0,0 +1,66 @@
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+
+	"github.com/guregu/null"
+	"github.com/lib/pq"
+	"github.com/pganalyze/collector/util"
+)
+
+func runExplainAnalyze(ctx context.Context, db *sql.DB, query string, parameters []null.String, parameterTypes []string, analyzeFlags []string, marker string) (explainOutput string, err error) {
+	tx, err := db.BeginTx(ctx, &sql.TxOptions{ReadOnly: true})
+	if err != nil {
+		return "", err
+	}
+	defer tx.Rollback()
+
+	err = tx.QueryRowContext(ctx, marker+"SELECT pganalyze.explain_analyze($1, $2, $3, $4)", marker+query, pq.Array(parameters), pq.Array(parameterTypes), pq.Array(analyzeFlags)).Scan(&explainOutput)
+
+	return
+}
+
+func validateQuery(query string) error {
+	var isUtil []bool
+	// To be on the safe side never EXPLAIN a statement that can't be parsed,
+	// or multiple statements in one (leading to accidental execution)
+	isUtil, err := util.IsUtilityStmt(query)
+	if err != nil || len(isUtil) != 1 || isUtil[0] {
+		err = fmt.Errorf("query is not permitted to run (multi-statement or utility command?)")
+		return err
+	}
+
+	// TODO: Consider adding additional checks here (e.g. blocking known bad function calls)
+
+	return nil
+}
+
+func RunExplainAnalyzeForQueryRun(ctx context.Context, db *sql.DB, query string, parameters []null.String, parameterTypes []string, marker string) (result string, err error) {
+	err = validateQuery(query)
+	if err != nil {
+		return
+	}
+
+	// Warm up caches without collecting timing info (slightly faster)
+	_, err = runExplainAnalyze(ctx, db, query, parameters, parameterTypes, []string{"ANALYZE", "TIMING OFF"}, marker)
+
+	// Run again if it was a timeout error, to make sure we got the caches warmed up all the way
+	if err != nil && strings.Contains(err.Error(), "statement timeout") {
+		_, err = runExplainAnalyze(ctx, db, query, parameters, parameterTypes, []string{"ANALYZE", "TIMING OFF"}, marker)
+
+		// If it timed out again, capture a non-ANALYZE EXPLAIN instead
+		if err != nil && strings.Contains(err.Error(), "statement timeout") {
+			return runExplainAnalyze(ctx, db, query, parameters, parameterTypes, []string{}, marker)
+		} else if err != nil {
+			return
+		}
+	} else if err != nil {
+		return
+	}
+
+	// Run EXPLAIN ANALYZE once more to get a warm cache result (this is the one we return)
+	return runExplainAnalyze(ctx, db, query, parameters, parameterTypes, []string{"ANALYZE", "BUFFERS"}, marker)
+}