PostgreSQL 18.1 non deterministic collation "LIKE %abc%" performance

Hi,

After the release of the PostgreSQL 18 version, I am trying non determisinstic collation with LIKE pattern matching support. I am mostly searching with "LIKE %search_term%" on about 10 text columns. As I use wildcard prefix and suffix, I can't use btree index anyways. So I decided to try non deterministic collation support so I can simplify application code. I am testing this on a table with ~60K rows. With this row count and search pattern, non deterministic collation seems at least 10 times slower than LOWER LIKE and ILIKE. Tested collations are the same ICU tr-TR collation with standard and custom based on same ICU tr-TR:

40960 | test3e                 |          2200 |        10 | i            | f                   |           -1 |             |            | tr-TR-u-ks-level2 |              | 153.128.46

Version:

etukimlik_admin=# select version();

                                                      version                                                      
--------------------------------------------------------------------------------------------------------------------
 PostgreSQL 18.1 (Debian 18.1-1.pgdg13+2) on x86_64-pc-linux-gnu, compiled by gcc (Debian 14.2.0-19) 14.2.0, 64-bit
(1 row)

Table  structure with ICU deterministic collation:

etukimlik_admin=# \d "AccountActivityLogEntries"
                                                        Table "public.AccountActivityLogEntries"
          Column          |           Type           |  Collation  | Nullable |                                 Default                                  
--------------------------+--------------------------+-------------+----------+--------------------------------------------------------------------------
 Id                       | integer                  |             | not null | generated by default as identity
 Email                    | character varying(128)   | tr-TR-x-icu | not null |
 LdapUid                  | character varying(512)   | tr-TR-x-icu |          |
 Identity                 | character varying(24)    | tr-TR-x-icu |          |
 StudentId                | text[]                   |             |          |
 EmployeeId               | character varying(24)    | tr-TR-x-icu |          |
 Name                     | character varying(1024)  | tr-TR-x-icu |          |
 Surname                  | character varying(1024)  | tr-TR-x-icu |          |
 AccountType              | text[]                   |             | not null |
 Description              | character varying(4096)  | tr-TR-x-icu | not null |
 ActivityId               | character varying(128)   | tr-TR-x-icu | not null |
 LogTypeCode              | character varying(10)    | tr-TR-x-icu | not null |
 LogType                  | character varying(64)    | tr-TR-x-icu | not null |
 LogSubType               | character varying(64)    | tr-TR-x-icu | not null |
 ActivityTime             | timestamp with time zone |             |          |
 ActivitySource           | character varying(128)   | tr-TR-x-icu | not null |
 ChangedAttribute         | character varying(128)   | tr-TR-x-icu |          |
 ChangedAttributeOldValue | character varying(4096)  | tr-TR-x-icu |          |
 ChangedAttributeNewValue | character varying(4096)  | tr-TR-x-icu |          |
 DisplayName              | character varying(2049)  | tr-TR-x-icu |          | generated always as (((("Name"::text || ' '::text) || "Surname"::text)))
Indexes:
    "PK_AccountActivityLogEntries" PRIMARY KEY, btree ("Id")

LOWER LIKE query test:

etukimlik_admin=# explain analyze select * FROM "AccountActivityLogEntries" where lower("Email") like '%duran%' or lower("LdapUid") like '%duran%' or lower("Identity") like '%duran%' or lower("Name") like '%duran%' or lower("Surname") like '%duran%' or lower("DisplayName") like '%duran%' or lower("Description") like '%duran%' or lower("EmployeeId") like '%duran%' or exists ( select from unnest("StudentId") AS value  WHERE lower(value) LIKE '%duran%') or  lower("ActivityId") like '%duran%';