perf(query): reduce user query duration (#10037)

# Which Problems Are Solved

The resource usage to query user(s) on the database was high and
therefore could have performance impact.

# How the Problems Are Solved

Database queries involving the users and loginnames table were improved
and an index was added for user by email query.

# Additional Changes

- spellchecks
- updated apis on load tests

# additional info

needs cherry pick to v3

internal/query/projection/login_name.go

@@ -2,9 +2,7 @@ package projection
 
 import (
 	"context"
-	"strings"
-
-	sq "github.com/Masterminds/squirrel"
+	_ "embed"
 
 	"github.com/zitadel/zitadel/internal/eventstore"
 	old_handler "github.com/zitadel/zitadel/internal/eventstore/handler"
@@ -58,105 +56,8 @@ const (
 	LoginNamePoliciesInstanceIDCol    = "instance_id"
 )
 
-var (
-	policyUsers = sq.Select(
-		alias(
-			col(usersAlias, LoginNameUserIDCol),
-			LoginNameUserCol,
-		),
-		col(usersAlias, LoginNameUserUserNameCol),
-		col(usersAlias, LoginNameUserInstanceIDCol),
-		col(usersAlias, LoginNameUserResourceOwnerCol),
-		alias(
-			coalesce(col(policyCustomAlias, LoginNamePoliciesMustBeDomainCol), col(policyDefaultAlias, LoginNamePoliciesMustBeDomainCol)),
-			LoginNamePoliciesMustBeDomainCol,
-		),
-	).From(alias(LoginNameUserProjectionTable, usersAlias)).
-		LeftJoin(
-			leftJoin(LoginNamePolicyProjectionTable, policyCustomAlias,
-				eq(col(policyCustomAlias, LoginNamePoliciesResourceOwnerCol), col(usersAlias, LoginNameUserResourceOwnerCol)),
-				eq(col(policyCustomAlias, LoginNamePoliciesInstanceIDCol), col(usersAlias, LoginNameUserInstanceIDCol)),
-			),
-		).
-		LeftJoin(
-			leftJoin(LoginNamePolicyProjectionTable, policyDefaultAlias,
-				eq(col(policyDefaultAlias, LoginNamePoliciesIsDefaultCol), "true"),
-				eq(col(policyDefaultAlias, LoginNamePoliciesInstanceIDCol), col(usersAlias, LoginNameUserInstanceIDCol)),
-			),
-		)
-
-	loginNamesTable = sq.Select(
-		col(policyUsersAlias, LoginNameUserCol),
-		col(policyUsersAlias, LoginNameUserUserNameCol),
-		col(policyUsersAlias, LoginNameUserResourceOwnerCol),
-		alias(col(policyUsersAlias, LoginNameUserInstanceIDCol),
-			LoginNameInstanceIDCol),
-		col(policyUsersAlias, LoginNamePoliciesMustBeDomainCol),
-		alias(col(domainsAlias, LoginNameDomainNameCol),
-			domainAlias),
-		col(domainsAlias, LoginNameDomainIsPrimaryCol),
-	).FromSelect(policyUsers, policyUsersAlias).
-		LeftJoin(
-			leftJoin(LoginNameDomainProjectionTable, domainsAlias,
-				col(policyUsersAlias, LoginNamePoliciesMustBeDomainCol),
-				eq(col(policyUsersAlias, LoginNameUserResourceOwnerCol), col(domainsAlias, LoginNameDomainResourceOwnerCol)),
-				eq(col(policyUsersAlias, LoginNamePoliciesInstanceIDCol), col(domainsAlias, LoginNameDomainInstanceIDCol)),
-			),
-		)
-
-	viewStmt, _ = sq.Select(
-		LoginNameUserCol,
-		alias(
-			whenThenElse(
-				LoginNamePoliciesMustBeDomainCol,
-				concat(LoginNameUserUserNameCol, "'@'", domainAlias),
-				LoginNameUserUserNameCol),
-			LoginNameCol),
-		alias(coalesce(LoginNameDomainIsPrimaryCol, "true"),
-			LoginNameIsPrimaryCol),
-		LoginNameInstanceIDCol,
-	).FromSelect(loginNamesTable, LoginNameTableAlias).MustSql()
-)
-
-func col(table, name string) string {
-	return table + "." + name
-}
-
-func alias(col, alias string) string {
-	return col + " AS " + alias
-}
-
-func coalesce(values ...string) string {
-	str := "COALESCE("
-	for i, value := range values {
-		if i > 0 {
-			str += ", "
-		}
-		str += value
-	}
-	str += ")"
-	return str
-}
-
-func eq(first, second string) string {
-	return first + " = " + second
-}
-
-func leftJoin(table, alias, on string, and ...string) string {
-	st := table + " " + alias + " ON " + on
-	for _, a := range and {
-		st += " AND " + a
-	}
-	return st
-}
-
-func concat(strs ...string) string {
-	return "CONCAT(" + strings.Join(strs, ", ") + ")"
-}
-
-func whenThenElse(when, then, el string) string {
-	return "(CASE WHEN " + when + " THEN " + then + " ELSE " + el + " END)"
-}
+//go:embed login_name_query.sql
+var loginNameViewStmt string
 
 type loginNameProjection struct{}
 
@@ -170,7 +71,7 @@ func (*loginNameProjection) Name() string {
 
 func (*loginNameProjection) Init() *old_handler.Check {
 	return handler.NewViewCheck(
-		viewStmt,
+		loginNameViewStmt,
 		handler.NewSuffixedTable(
 			[]*handler.InitColumn{
 				handler.NewColumn(LoginNameUserIDCol, handler.ColumnTypeText),
@@ -229,7 +130,9 @@ func (*loginNameProjection) Init() *old_handler.Check {
 			},
 			handler.NewPrimaryKey(LoginNamePoliciesInstanceIDCol, LoginNamePoliciesResourceOwnerCol),
 			loginNamePolicySuffix,
-			handler.WithIndex(handler.NewIndex("is_default", []string{LoginNamePoliciesResourceOwnerCol, LoginNamePoliciesIsDefaultCol})),
+			// this index is not used anymore, but kept for understanding why the default exists on existing systems, TODO: remove in login_names4
+			// handler.WithIndex(handler.NewIndex("is_default", []string{LoginNamePoliciesResourceOwnerCol, LoginNamePoliciesIsDefaultCol})),
+			handler.WithIndex(handler.NewIndex("is_default_owner", []string{LoginNamePoliciesInstanceIDCol, LoginNamePoliciesIsDefaultCol, LoginNamePoliciesResourceOwnerCol}, handler.WithInclude(LoginNamePoliciesMustBeDomainCol))),
 		),
 	)
 }

internal/query/projection/login_name_query.sql

@@ -0,0 +1,35 @@
+SELECT
+    u.id AS user_id
+    , CASE
+        WHEN p.must_be_domain THEN CONCAT(u.user_name, '@', d.name)
+        ELSE u.user_name
+    END AS login_name
+    , COALESCE(d.is_primary, TRUE) AS is_primary
+    , u.instance_id
+FROM
+    projections.login_names3_users AS u
+LEFT JOIN LATERAL (
+    SELECT
+        must_be_domain
+        , is_default
+    FROM
+        projections.login_names3_policies AS p
+    WHERE
+        (
+            p.instance_id = u.instance_id
+            AND NOT p.is_default
+            AND p.resource_owner = u.resource_owner
+        ) OR (
+            p.instance_id = u.instance_id
+            AND p.is_default
+        )
+    ORDER BY
+        p.is_default -- custom first
+    LIMIT 1
+) AS p ON TRUE
+LEFT JOIN 
+    projections.login_names3_domains d
+    ON 
+        p.must_be_domain 
+        AND u.resource_owner = d.resource_owner 
+        AND u.instance_id = d.instance_id

internal/query/projection/user.go

@@ -124,6 +124,7 @@ func (*userProjection) Init() *old_handler.Check {
 			handler.NewPrimaryKey(HumanUserInstanceIDCol, HumanUserIDCol),
 			UserHumanSuffix,
 			handler.WithForeignKey(handler.NewForeignKeyOfPublicKeys()),
+			handler.WithIndex(handler.NewIndex("email", []string{HumanUserInstanceIDCol, "LOWER(" + HumanEmailCol + ")"})),
 		),
 		handler.NewSuffixedTable([]*handler.InitColumn{
 			handler.NewColumn(MachineUserIDCol, handler.ColumnTypeText),