Update indexes with null values links

Author: mfvanek

postgresql_indexes/create_data.sql

@@ -11,4 +11,4 @@ from generate_series(1, 1000000) as g (idx);
 select * from test order by id asc limit 100;
 
 drop index concurrently if exists idx_ref_without_nulls;					
-create index concurrently if not exists idx_ref_without_nulls on test (ref) where ref is not null;
+create index concurrently if not exists idx_ref_without_nulls on test (ref) where ref is not null;

postgresql_indexes/explain_example.sql

@@ -1,3 +1,5 @@
 set search_path to public;
 
-explain (analyze, buffers) select * from test where ref in ('00000000000000000007', '00000000000000000008', '00000000000000000009') order by 1,2;
+explain (analyze, buffers)
+select * from test where ref in ('00000000000000000007', '00000000000000000008', '00000000000000000009')
+order by 1,2;

postgresql_indexes/readme.md

@@ -1,12 +1,24 @@
 # Indexes with\without null values
-By default, PostgreSQL indexes null values and stores them to the generated index.  
-In that way, we need to exclude null values explicitly from the index in order to decrease index size and increase write performance.
+
+By default, PostgreSQL indexes the null values and stores them to the generated index.  
+In that way, we need to exclude the null values explicitly from the index
+in order to decrease index size and increase write performance.
 
 ## Documentation
-- [Create index](https://postgrespro.ru/docs/postgrespro/11/sql-createindex)
-- [pg_stats](https://postgrespro.ru/docs/postgresql/11/view-pg-stats)
+
+### RUS
+
+- [create index](https://postgrespro.ru/docs/postgresql/16/sql-createindex)
+- [pg_stats](https://postgrespro.ru/docs/postgresql/16/view-pg-stats)
+
+### ENG
+
+- [create index](https://www.postgresql.org/docs/16/sql-createindex.html)
+- [pg_stats](https://www.postgresql.org/docs/16/view-pg-stats.html)
+-
 
 ## Example
+
 |   | tablename | indexname             | num_rows | table_size | index_size | unique_idx |
 |---|-----------|-----------------------|----------|------------|------------|------------|
 | 1 | test      | idx_ref_with_nulls    | 1000000  | 46 MB      | 55 MB      | NO         |