diff --git a/dictation_server/db/migrations/055-add_users_index.sql b/dictation_server/db/migrations/055-add_users_index.sql
new file mode 100644
index 0000000..ea50c9d
--- /dev/null
+++ b/dictation_server/db/migrations/055-add_users_index.sql
@@ -0,0 +1,5 @@
+-- +migrate Up
+ALTER TABLE `users` ADD INDEX `idx_role` (role);
+
+-- +migrate Down
+ALTER TABLE `users`  DROP INDEX `idx_role`;
\ No newline at end of file
diff --git a/dictation_server/src/repositories/user_groups/user_groups.repository.service.ts b/dictation_server/src/repositories/user_groups/user_groups.repository.service.ts
index e7db5cf..050d3e1 100644
--- a/dictation_server/src/repositories/user_groups/user_groups.repository.service.ts
+++ b/dictation_server/src/repositories/user_groups/user_groups.repository.service.ts
@@ -122,8 +122,8 @@ export class UserGroupsRepositoryService {
           role: USER_ROLES.TYPIST,
           email_verified: true,
         },
-        comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
         lock: { mode: 'pessimistic_write' },
+        comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
       });
       if (userRecords.length !== typistIds.length) {
         throw new TypistIdInvalidError(
@@ -189,8 +189,8 @@ export class UserGroupsRepositoryService {
           role: USER_ROLES.TYPIST,
           email_verified: true,
         },
-        comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
         lock: { mode: 'pessimistic_write' },
+        comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
       });
       if (userRecords.length !== typistIds.length) {
         throw new TypistIdInvalidError(
@@ -206,6 +206,7 @@ export class UserGroupsRepositoryService {
           id: typistGroupId,
           account_id: accountId,
         },
+        lock: { mode: 'pessimistic_write' },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
       });
       if (!typistGroup) {
diff --git a/dictation_server/src/repositories/workflows/workflows.repository.service.ts b/dictation_server/src/repositories/workflows/workflows.repository.service.ts
index de5e38e..2ccaf5e 100644
--- a/dictation_server/src/repositories/workflows/workflows.repository.service.ts
+++ b/dictation_server/src/repositories/workflows/workflows.repository.service.ts
@@ -101,6 +101,7 @@ export class WorkflowsRepositoryService {
         const worktypes = await worktypeRepo.find({
           where: { account_id: accountId, id: worktypeId },
           comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+          lock: { mode: 'pessimistic_write' },
         });
         if (worktypes.length === 0) {
           throw new WorktypeIdNotFoundError(
@@ -115,6 +116,7 @@ export class WorkflowsRepositoryService {
         const template = await templateRepo.findOne({
           where: { account_id: accountId, id: templateId },
           comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+          lock: { mode: 'pessimistic_write' },
         });
         if (!template) {
           throw new TemplateFileNotExistError('template not found.');
@@ -132,6 +134,7 @@ export class WorkflowsRepositoryService {
           email_verified: true,
         },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+        lock: { mode: 'pessimistic_write' },
       });
       if (typistUsers.length !== typistIds.length) {
         throw new UserNotFoundError(
@@ -147,6 +150,7 @@ export class WorkflowsRepositoryService {
       const typistGroups = await userGroupRepo.find({
         where: { account_id: accountId, id: In(groupIds) },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+        lock: { mode: 'pessimistic_write' },
       });
       if (typistGroups.length !== groupIds.length) {
         throw new TypistGroupNotExistError(
@@ -164,6 +168,7 @@ export class WorkflowsRepositoryService {
           worktype_id: worktypeId !== undefined ? worktypeId : IsNull(),
         },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+        lock: { mode: 'pessimistic_write' },
       });
       if (workflow.length !== 0) {
         throw new AuthorIdAndWorktypeIdPairAlreadyExistsError(
@@ -264,6 +269,7 @@ export class WorkflowsRepositoryService {
       const targetWorkflow = await workflowRepo.findOne({
         where: { account_id: accountId, id: workflowId },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+        lock: { mode: 'pessimistic_write' },
       });
       if (!targetWorkflow) {
         throw new WorkflowNotFoundError(
@@ -277,6 +283,7 @@ export class WorkflowsRepositoryService {
         const worktypes = await worktypeRepo.find({
           where: { account_id: accountId, id: worktypeId },
           comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+          lock: { mode: 'pessimistic_write' },
         });
         if (worktypes.length === 0) {
           throw new WorktypeIdNotFoundError(
@@ -291,6 +298,7 @@ export class WorkflowsRepositoryService {
         const template = await templateRepo.findOne({
           where: { account_id: accountId, id: templateId },
           comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+          lock: { mode: 'pessimistic_write' },
         });
         if (!template) {
           throw new TemplateFileNotExistError(
@@ -402,6 +410,7 @@ export class WorkflowsRepositoryService {
       const workflow = await workflowRepo.findOne({
         where: { account_id: accountId, id: workflowId },
         comment: `${context.getTrackingId()}_${new Date().toUTCString()}`,
+        lock: { mode: 'pessimistic_write' },
       });
       if (!workflow) {
         throw new WorkflowNotFoundError(