diff --git a/modules/account/tax.py b/modules/account/tax.py
index db2055893e..a5ece0f2f7 100644
--- a/modules/account/tax.py
+++ b/modules/account/tax.py
@@ -8,7 +8,7 @@ from itertools import cycle, groupby
 
 from sql import Literal
 from sql.aggregate import Sum
-from sql.conditionals import Case
+from sql.conditionals import Case, Coalesce
 
 from trytond import backend
 from trytond.i18n import gettext
@@ -164,7 +164,7 @@ class TaxCode(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.add(
-            Index(t, (t.code, Index.Similarity())))
+            Index(t, (Coalesce(t.code, ''), Index.Similarity())))
         for date in [cls.start_date, cls.end_date]:
             date.states = {
                 'readonly': (Bool(Eval('template', -1))
diff --git a/modules/analytic_account/account.py b/modules/analytic_account/account.py
index ff82b58ca8..c7360a4704 100644
--- a/modules/analytic_account/account.py
+++ b/modules/analytic_account/account.py
@@ -98,7 +98,7 @@ class Account(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.add(
-            Index(t, (t.code, Index.Similarity())))
+            Index(t, (Coalesce(t.code, ''), Index.Similarity())))
         cls._order.insert(0, ('code', 'ASC'))
         cls._order.insert(1, ('name', 'ASC'))
 
diff --git a/modules/party/country.py b/modules/party/country.py
index fcd97fa173..b17bce122e 100644
--- a/modules/party/country.py
+++ b/modules/party/country.py
@@ -1,6 +1,8 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 
+from sql.conditionals import Coalesce
+
 from trytond.model import Index
 from trytond.pool import PoolMeta
 
@@ -15,7 +17,8 @@ class PostalCode(metaclass=PoolMeta):
         cls._sql_indexes.update({
                 Index(
                     t,
-                    (Index.Unaccent(t.city), Index.Similarity()),
+                    (Index.Unaccent(Coalesce(t.city, '')),
+                        Index.Similarity()),
                     (t.country, Index.Range()),
                     (t.subdivision, Index.Range())),
                 })
diff --git a/modules/product/product.py b/modules/product/product.py
index e1b46c02c1..ad2a4733ea 100644
--- a/modules/product/product.py
+++ b/modules/product/product.py
@@ -201,7 +201,8 @@ class Template(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.code, Index.Similarity())),
+                Index(t, (Coalesce(t.code, ''), Index.Equality())),
+                Index(t, (Coalesce(t.code, ''), Index.Similarity())),
                 })
         cls._order.insert(0, ('rec_name', 'ASC'))
 
@@ -587,12 +588,17 @@ class Product(
                     & (t.code != '')),
                 'product.msg_product_code_unique'),
             ]
-        cls._sql_indexes.add(
-            Index(t, (t.code, Index.Similarity(cardinality='high'))))
-        cls._sql_indexes.add(
-            Index(t,
-                (t.position, Index.Range(order='ASC NULLS FIRST')),
-                (t.id, Index.Range(order='ASC'))))
+        cls._sql_indexes.update({
+                Index(t,
+                    (Coalesce(t.code, ''),
+                        Index.Equality(cardinality='high'))),
+                Index(t,
+                    (Coalesce(t.code, ''),
+                        Index.Similarity(cardinality='high'))),
+                Index(t,
+                    (t.position, Index.Range(order='ASC NULLS FIRST')),
+                    (t.id, Index.Range(order='ASC'))),
+                })
 
         for attr in dir(Template):
             tfield = getattr(Template, attr)
diff --git a/modules/project/work.py b/modules/project/work.py
index c7ec1898e9..ccca777ac2 100644
--- a/modules/project/work.py
+++ b/modules/project/work.py
@@ -5,6 +5,7 @@ import datetime
 from collections import defaultdict
 
 from sql import Null
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond.cache import Cache
@@ -257,9 +258,13 @@ class Work(
                 'project.msg_work_number_unique'),
             ]
         cls._sql_indexes.update({
-                Index(t, (t.number, Index.Equality(cardinality='high'))),
-                Index(t, (t.number, Index.Similarity(cardinality='high'))),
-                Index(t, (t.path, Index.Similarity(begin=True))),
+                Index(t,
+                    (Coalesce(t.number, ''),
+                        Index.Equality(cardinality='high'))),
+                Index(t,
+                    (Coalesce(t.number, ''),
+                        Index.Similarity(cardinality='high'))),
+                Index(t, (Coalesce(t.path, ''), Index.Similarity(begin=True))),
                 })
 
     @classmethod
diff --git a/modules/purchase/product.py b/modules/purchase/product.py
index 34cfe29ca7..c0be2f9720 100644
--- a/modules/purchase/product.py
+++ b/modules/purchase/product.py
@@ -4,6 +4,7 @@ import datetime
 from collections import defaultdict
 
 from sql.aggregate import Count, Max
+from sql.conditionals import Coalesce
 
 from trytond.i18n import gettext
 from trytond.model import (
@@ -324,7 +325,7 @@ class ProductSupplier(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.code, Index.Similarity())),
+                Index(t, (Coalesce(t.code, ''), Index.Similarity())),
                 })
 
     @staticmethod
diff --git a/modules/purchase/purchase.py b/modules/purchase/purchase.py
index 2719f0334f..0c073abd0c 100644
--- a/modules/purchase/purchase.py
+++ b/modules/purchase/purchase.py
@@ -8,6 +8,7 @@ from itertools import chain, groupby
 
 from sql import Null
 from sql.aggregate import Count
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond import backend
@@ -269,7 +270,7 @@ class Purchase(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(t, (t.party, Index.Range())),
                 Index(
                     t,
diff --git a/modules/purchase_blanket_agreement/purchase.py b/modules/purchase_blanket_agreement/purchase.py
index 05ec3ff9f7..91abc9ff37 100644
--- a/modules/purchase_blanket_agreement/purchase.py
+++ b/modules/purchase_blanket_agreement/purchase.py
@@ -6,6 +6,7 @@ from decimal import Decimal
 from itertools import groupby
 
 from sql import Null
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond.i18n import gettext
@@ -192,7 +193,7 @@ class BlanketAgreement(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(
                     t, (t.state, Index.Equality(cardinality='low')),
                     where=t.state.in_(['draft', 'running'])),
diff --git a/modules/purchase_request_quotation/purchase.py b/modules/purchase_request_quotation/purchase.py
index d516d4a736..6b35ec3c92 100644
--- a/modules/purchase_request_quotation/purchase.py
+++ b/modules/purchase_request_quotation/purchase.py
@@ -5,7 +5,7 @@ from functools import wraps
 from itertools import groupby
 
 from sql import Null
-from sql.conditionals import Case
+from sql.conditionals import Case, Coalesce
 from sql.functions import CharLength
 
 from trytond.i18n import gettext
@@ -140,7 +140,7 @@ class Quotation(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(
                     t, (t.state, Index.Equality(cardinality='low')),
                     where=t.state.in_(['draft', 'sent'])),
diff --git a/modules/quality/quality.py b/modules/quality/quality.py
index 53eedb6468..46f71869e1 100644
--- a/modules/quality/quality.py
+++ b/modules/quality/quality.py
@@ -5,6 +5,7 @@ import datetime as dt
 from functools import wraps
 from random import Random
 
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond.i18n import gettext, lazy_gettext
@@ -412,7 +413,7 @@ class Inspection(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 })
         cls._transitions |= {
             ('pending', 'passed'),
diff --git a/modules/sale/sale.py b/modules/sale/sale.py
index c0b753a317..9688dc9302 100644
--- a/modules/sale/sale.py
+++ b/modules/sale/sale.py
@@ -338,7 +338,7 @@ class Sale(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(t, (t.party, Index.Range())),
                 Index(
                     t,
diff --git a/modules/sale_blanket_agreement/sale.py b/modules/sale_blanket_agreement/sale.py
index ba43d104b5..235caa12af 100644
--- a/modules/sale_blanket_agreement/sale.py
+++ b/modules/sale_blanket_agreement/sale.py
@@ -6,6 +6,7 @@ from decimal import Decimal
 from itertools import groupby
 
 from sql import Null
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond.i18n import gettext
@@ -192,7 +193,7 @@ class BlanketAgreement(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(
                     t, (t.state, Index.Equality(cardinality='low')),
                     where=t.state.in_(['draft', 'running'])),
diff --git a/modules/sale_complaint/complaint.py b/modules/sale_complaint/complaint.py
index ac7c301536..fcd573ca68 100644
--- a/modules/sale_complaint/complaint.py
+++ b/modules/sale_complaint/complaint.py
@@ -6,6 +6,7 @@ from collections import defaultdict
 from decimal import Decimal
 
 from sql import Null
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond import backend
@@ -139,7 +140,7 @@ class Complaint(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(
                     t,
                     (t.state, Index.Equality(cardinality='low')),
diff --git a/modules/sale_opportunity/opportunity.py b/modules/sale_opportunity/opportunity.py
index bb90d51a2b..8ddb54d785 100644
--- a/modules/sale_opportunity/opportunity.py
+++ b/modules/sale_opportunity/opportunity.py
@@ -4,6 +4,7 @@
 import datetime
 from itertools import groupby
 
+from sql.conditionals import Coalesce
 from sql.functions import CharLength
 
 from trytond.i18n import gettext
@@ -154,7 +155,7 @@ class SaleOpportunity(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(t, (t.party, Index.Range())),
                 Index(
                     t,
diff --git a/modules/sale_rental/pyproject.toml b/modules/sale_rental/pyproject.toml
index 1da4d7d98c..fd4beaa52d 100644
--- a/modules/sale_rental/pyproject.toml
+++ b/modules/sale_rental/pyproject.toml
@@ -52,7 +52,7 @@ exclude = ['doc']
 "" = "trytond/modules/sale_rental"
 
 [tool.hatch.metadata.hooks.tryton]
-dependencies = []
+dependencies = ['python-sql']
 copyright = 'COPYRIGHT'
 readme = 'README.rst'
 
diff --git a/modules/sale_rental/sale.py b/modules/sale_rental/sale.py
index 82d73d84a6..b518fc0628 100644
--- a/modules/sale_rental/sale.py
+++ b/modules/sale_rental/sale.py
@@ -5,6 +5,8 @@ import datetime as dt
 from decimal import Decimal
 from functools import partial
 
+from sql.conditionals import Coalesce
+
 from trytond.i18n import gettext
 from trytond.ir.attachment import AttachmentCopyMixin
 from trytond.ir.note import NoteCopyMixin
@@ -277,7 +279,7 @@ class Rental(
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(t, (t.party, Index.Equality())),
                 Index(
                     t,
diff --git a/modules/sale_subscription/subscription.py b/modules/sale_subscription/subscription.py
index 52f49dc039..90c3b2a88f 100644
--- a/modules/sale_subscription/subscription.py
+++ b/modules/sale_subscription/subscription.py
@@ -172,7 +172,7 @@ class Subscription(Workflow, ModelSQL, ModelView, ChatMixin):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 Index(
                     t,
                     (t.state, Index.Equality(cardinality='low')),
diff --git a/modules/stock/location.py b/modules/stock/location.py
index 939f1dc3bd..483328762c 100644
--- a/modules/stock/location.py
+++ b/modules/stock/location.py
@@ -5,6 +5,7 @@ import operator
 from decimal import Decimal
 
 from sql import Column
+from sql.conditionals import Coalesce
 
 from trytond.cache import Cache
 from trytond.i18n import gettext
@@ -197,7 +198,7 @@ class Location(DeactivableMixin, tree(), ModelSQL, ModelView):
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.code, Index.Similarity())),
+                Index(t, (Coalesce(t.code, ''), Index.Similarity())),
                 Index(
                     t,
                     (t.left, Index.Range(cardinality='high')),
diff --git a/modules/stock/shipment.py b/modules/stock/shipment.py
index 4ed67113a5..0118ffaec8 100644
--- a/modules/stock/shipment.py
+++ b/modules/stock/shipment.py
@@ -66,7 +66,7 @@ class ShipmentMixin:
         super().__setup__()
         t = cls.__table__()
         cls._sql_indexes.update({
-                Index(t, (t.reference, Index.Similarity())),
+                Index(t, (Coalesce(t.reference, ''), Index.Similarity())),
                 })
         cls._order = [
             ('effective_date', 'ASC NULLS LAST'),
diff --git a/modules/web_user/user.py b/modules/web_user/user.py
index ecc98632a3..62b8d3b04a 100644
--- a/modules/web_user/user.py
+++ b/modules/web_user/user.py
@@ -89,10 +89,12 @@ class User(avatar_mixin(100), DeactivableMixin, ModelSQL, ModelView):
             ]
         cls._sql_indexes.update({
                 Index(
-                    table, (table.email, Index.Equality(cardinality='high'))),
+                    table, (Coalesce(table.email, ''),
+                        Index.Equality(cardinality='high'))),
                 Index(
                     table,
-                    (table.email_token, Index.Equality(cardinality='high')),
+                    (Coalesce(table.email_token, ''),
+                        Index.Equality(cardinality='high')),
                     where=table.email_token != Null),
                 })
         cls._buttons.update({
diff --git a/trytond/trytond/ir/translation.py b/trytond/trytond/ir/translation.py
index 730027ffeb..13c8490fb8 100644
--- a/trytond/trytond/ir/translation.py
+++ b/trytond/trytond/ir/translation.py
@@ -12,7 +12,7 @@ from relatorio.reporting import MIMETemplateLoader
 from relatorio.templates.opendocument import get_zip_file
 from sql import Column, Literal, Null
 from sql.aggregate import Max
-from sql.conditionals import Case
+from sql.conditionals import Case, Coalesce
 from sql.functions import CharLength, Position, Substring
 from sql.operators import Concat
 
@@ -120,9 +120,11 @@ class Translation(
 
         cls._sql_indexes.update({
                 Index(
-                    table, (Index.Unaccent(table.src), Index.Similarity())),
+                    table, (Index.Unaccent(Coalesce(table.src, '')),
+                        Index.Similarity())),
                 Index(
-                    table, (Index.Unaccent(table.value), Index.Similarity())),
+                    table, (Index.Unaccent(Coalesce(table.value, '')),
+                        Index.Similarity())),
                 Index(
                     table,
                     (table.type, Index.Equality(cardinality='low')),
@@ -130,7 +132,8 @@ class Translation(
                     (table.lang, Index.Equality(cardinality='low')),
                     (table.res_id, Index.Range()),
                     (table.fuzzy, Index.Equality(cardinality='low')),
-                    (Index.Unaccent(table.value), Index.Similarity())),
+                    (Index.Unaccent(Coalesce(table.value, '')),
+                        Index.Similarity())),
                 Index(
                     table,
                     (table.type, Index.Equality(cardinality='low')),
diff --git a/trytond/trytond/ir/ui/view.py b/trytond/trytond/ir/ui/view.py
index 76d2028a01..45aba9b029 100644
--- a/trytond/trytond/ir/ui/view.py
+++ b/trytond/trytond/ir/ui/view.py
@@ -788,7 +788,7 @@ class ViewTreeState(
                 table,
                 (table.user, Index.Range()),
                 (table.model, Index.Equality()),
-                (table.child_name, Index.Equality()),
+                (Coalesce(table.child_name, ''), Index.Equality()),
                 (table.domain, Index.Equality())))
 
     @staticmethod