Bagaimana MATCH AGAINST Bekerja di MariaDB

Di MariaDB, MATCH AGAINST adalah konstruksi khusus yang digunakan untuk melakukan pencarian teks lengkap pada indeks teks lengkap.

Sintaks

Sintaksnya seperti ini:

MATCH (col1,col2,...) AGAINST (expr [search_modifier])

Contoh

Misalkan kita memiliki tabel bernama Products yang mencakup data berikut:

+----+---------------------------------+-----------------------------------------+
| Id | ProductName                     | ProductDescription                      |
+----+---------------------------------+-----------------------------------------+
|  1 | Left handed screwdriver         | Purple. Includes left handed carry box. |
|  2 | Right handed screwdriver        | Blue. Includes right handed carry box.  |
|  3 | Long Weight (blue)              | Approximate 45 minute waiting period.   |
|  4 | Long Weight (green)             | Approximate 30 minute waiting period.   |
|  5 | Sledge Hammer                   | Wooden handle. Free wine glasses.       |
|  6 | Chainsaw                        | Orange. Includes spare fingers.         |
|  7 | Straw Dog Box                   | Tied with vines. Very chewable.         |
|  8 | Bottomless Coffee Mugs (4 Pack) | Brown ceramic with solid handle.        |
+----+---------------------------------+-----------------------------------------+

Tabel ini memiliki indeks teks lengkap pada ProductDescription kolom. Itu artinya kita bisa menggunakan MATCH AGAINST untuk melakukan pencarian teks lengkap terhadap kolom tersebut.

Contoh:

SELECT 
    ProductId AS "Id",
    ProductName,
    ProductDescription
FROM Products 
WHERE MATCH(ProductDescription) AGAINST('includes')
ORDER BY ProductId ASC;

Hasil:

+----+--------------------------+-----------------------------------------+
| Id | ProductName              | ProductDescription                      |
+----+--------------------------+-----------------------------------------+
|  1 | Left handed screwdriver  | Purple. Includes left handed carry box. |
|  2 | Right handed screwdriver | Blue. Includes right handed carry box.  |
|  6 | Chainsaw                 | Orange. Includes spare fingers.         |
+----+--------------------------+-----------------------------------------+

Dapatkan Skor

Kami dapat menyertakan MATCH AGAINST di SELECT list untuk mengembalikan skor relevansi kata kunci dalam kolom yang dicari:

SELECT 
    ProductDescription,
    MATCH(ProductDescription) AGAINST ('includes') AS Score
FROM Products 
WHERE MATCH(ProductDescription) AGAINST ('includes')
ORDER BY Score DESC;

Hasil:

+-----------------------------------------+---------------------+
| ProductDescription                      | Score               |
+-----------------------------------------+---------------------+
| Orange. Includes spare fingers.         |  0.4883610010147095 |
| Blue. Includes right handed carry box.  |  0.4883610010147095 |
| Purple. Includes left handed carry box. | 0.48305025696754456 |
+-----------------------------------------+---------------------+

Dalam hal ini kami juga menggunakan ORDER BY klausa untuk mengurutkan berdasarkan skor dalam urutan menurun (yaitu yang paling relevan terlebih dahulu).

Kolom Tanpa Indeks Teks Lengkap

Alasan contoh sebelumnya berhasil adalah karena saya sebelumnya telah membuat indeks teks lengkap di ProductDescription kolom. Jika saya tidak melakukan ini, saya akan menerima kesalahan.

Inilah yang terjadi ketika kami mencoba menggunakan MATCH AGAINST terhadap kolom yang tidak memiliki indeks teks lengkap:

SELECT 
    ProductId,
    ProductName,
    ProductPrice
FROM Products 
WHERE MATCH(ProductName) AGAINST('screwdriver')
ORDER BY ProductId ASC;

Hasil:

ERROR 1191 (HY000): Can't find FULLTEXT index matching the column list

Mari tambahkan indeks teks lengkap pada ProductName kolom:

ALTER TABLE Products
ADD FULLTEXT(ProductName);

Sekarang jalankan kueri lagi:

SELECT 
    ProductId,
    ProductName,
    ProductPrice
FROM Products 
WHERE MATCH(ProductName) AGAINST('screwdriver')
ORDER BY ProductId ASC;

Hasil:

+-----------+--------------------------+--------------+
| ProductId | ProductName              | ProductPrice |
+-----------+--------------------------+--------------+
|         1 | Left handed screwdriver  |        25.99 |
|         2 | Right handed screwdriver |        25.99 |
+-----------+--------------------------+--------------+

Kali ini berhasil.

Indeks Teks Lengkap pada Beberapa Kolom

Kita dapat menambahkan indeks teks lengkap pada beberapa kolom.

Contoh:

ALTER TABLE Products
ADD FULLTEXT(ProductName, ProductDescription);

Sekarang kita dapat menjalankan MATCH AGAINST terhadap indeks teks lengkap itu.

SELECT 
    ProductId AS Id, 
    ProductName, 
    ProductDescription
FROM Products 
WHERE MATCH(ProductName, ProductDescription) AGAINST ('weight')
OR MATCH(ProductName, ProductDescription) AGAINST ('ceramic')
ORDER BY Id ASC;

Hasil:

+----+---------------------------------+---------------------------------------+
| Id | ProductName                     | ProductDescription                    |
+----+---------------------------------+---------------------------------------+
|  3 | Long Weight (blue)              | Approximate 45 minute waiting period. |
|  4 | Long Weight (green)             | Approximate 30 minute waiting period. |
|  8 | Bottomless Coffee Mugs (4 Pack) | Brown ceramic with solid handle.      |
+----+---------------------------------+---------------------------------------+