Mysql: LIKE CONCAT Replacement --> less performance heavy - mysql

Question

So I have a SELECT Statement that is comparing the current column content from the table_1 column "table_1_content" with the content of another column (table_2_content) in table_2, whereas content in "table_2_content" can be found anywhere in "table_1_content":
$select = "SELECT * FROM table_1, table_2 WHERE `table_1_content` LIKE CONCAT('%', table_2_content, '%')";
$result = mysqli_query($con, $select);
My problem is that LIKE CONCAT is pretty performance heavy.
Is there another way to search through two columns from different tables, so that no full table scan is performed every time the query is executed?

Answer 1

The LIKE in total free text format (% at the start and at the end of the search string) is the performance heavy part. Is the wildcard at the start of the string necessary? If so: You might have to consider pre-processing the data in a different way so that the search can use a single wildcard or no wildcard at all. This last part (depending on the data) is for example done by splitting the string by a delimiter and storing the data in separate rows, after which a much faster comparison and indexes are possible to be used.
To put data in multiple rows, we would assume a usable separator (can be multiple, the code just gets longer):
CREATE TABLE baseinfo (id INT NOT NULL auto_increment primary key,
some other columns);
CREATE TABLE explodedstring(id INT NOT NULL, str VARCHAR(200),
FOREIGN KEY (id) REFERENCES baseinfo(id));
CREATE PROCEDURE explodestring(id int, fullstr VARCHAR(4000))
BEGIN
{many examples exist already how to do this on SO}
END;
The procedure would take as input your key from the original data (id in this case), and the original string.
The output of the procedure would end up in a secondary table explodedstring against which you now could run a normal select (add some index for performance). The resulting ids would tell you which record would match.